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Discussion Starter · #1 · (Edited)
Hello.
I have a 1970 TR6R that now is safely placed in the workshop for the winter, and I am planning a top end rebuild and wonder if anyone has any good tips on what I need to be careful about.

I have benefited greatly from reading posts from very knowledgeable members here, interesting and helpful.

The reason for this rebuild is that after we mounted the 750 kit, we had all sorts of problems with ignition and incorrect cam timing and and a insane carburetor, which resulted in very hot engine occasionally. In fact, so hot that the piston in the carburetor wedged itself,

We have now got everything in order, new carburetor, new electronic ignition, cam timing on the marks, and the bike works very well, but due to all problems, the run-in period was far from optimal, and it has resulted in the left cylinder using oil and smokes a little.

The plan now is to hone the cylinders and install new piston rings, if there are no damages I have not seen yet, which involves drilling and new pistons.

Replace valves and valve guides once the top is off.

Thinking of milling a triple angle valve seat before lapping, what do you guys mean about that? Is it a waste of energy or is it worth the work?

Another task is to measure the lobe center on both cams and try to get the optimal ones for road use.
What really makes the most sense here? Reads a lot of different opinions.
Reasonably sure that the cams are original, there is nothing that indicates that the engine has been opened before.
I dont know what cams are original on this engine, is it the same as the T120R?
Would it be ok to aim for about 100 degrees of intake, and 105 exhaust?
Here I need sensible input.

Hope someone has good tips on this.
I will post pictures when i have something too show.
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Hi, I have personal experience with ‘70 TR6R with Moho 750 kits. Runs very strong & very well. Has Boyer ignition & Amal Premire carb.

Stock cams & cam timing set to marks in shop manual.

We have poor fuel in California. Plus hot weather. I set timing back 2 degrees to 36b at 4000 rpm. Max advance is 3500rpm.

The 750 kit doesn’t seem to require different mixture, California fuel wants about 5% richer jets. 91 octane E10 is our best.

The 750 kit indeed increases power & has proven durable.

Float level is critical. Make sure it’s correct by using manometer tube. Home made one works perfectly.
Don
 

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My 750 kit is now well over 10 years old. I would not change guides,valves, springs if they are serviceable. Just a light cut with grinding paste to make sure they are not leaking should be enough. Replacing parts that are not bad just introduces new parts that might be inferior and make the engine less reliable. Jet sizes would not really need altering for the extra capacity but maybe go up one size on the main jet if using E5 petrol. Nice looking bike in spring gold colour
 

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Discussion Starter · #4 ·
Hello.
Appreciates good feedback, thanks.

TR7RVMan
We also runs Morgo 750 kit, new Amal Premiere with 270 jet (If I remember correctly, I have switched between several to find the best one).
But we run Lucas Rita Electronic Ignition, and im not quite shure if that one is optimal for the bike, i suspect that it dont advance as i should.
This will be investigated further, but it is not unlikely that we switched to for example Boyer or similar. What is recomended?
I have little faith in Lucas after all the problems we have had with the electrical system on this bike.

Here in Norway we have Ron 98 Fuel, I think this is equivalent to the Mon 91 you have in California.
In addition, I use Royal Purple Max Boost which in theory should increase the octane number by 3, and has lead replacement.,
Quite happy with it so far, less pinging/knocking when warm.

You wrote, Float level? Not shure if i understand what you mean here, are you thinking about fuel level in the carburettor?

rambo
Thanks.
The reason that i wonder about tips regarding valves/guides/valveseats is as i wrote, the engine is smoking from the left cylinder, and i still dont know if its because the cylinder it self or bad valve guides.
And im thinking once I have disassembled the engine, then I will take a thorough look at all the suspicious components that may be causing the oil use.
Its no big problem, but the bike is in good condition, so it is incredibly annoying that one exhaust smokes blue.
And I like to fix bikes so they are as good as possible, hence this project this winter.

Feel free to come up with thoughts and suggestions.
 

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Your petrol is good enough quality for this engine. I have used Boyer for 23 years on my current 750 kitted T120r It does run very well and just two failures of the black box in that time. It is common for the left cylinder to smoke if the engine is run on the side stand but there should be no smoke running on the road. A 20/50 oil suitable for air cooled engines would be the ideal for this engine
 

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Discussion Starter · #6 ·
Yea, buddies tell me that the smoke is present when we ride aswell, so i feel i must do something.
As i wrote earlier, all the trouble when the 750 kit was new, lead to a far from ideal break in periode, so i suspect that is the reason.

Using Valvoline VR1 20W-50 oil.
 

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Hei Oyvjohns,
The Lucas Rita has a long advance curve very much suited to the Triumph engine, the units are analog so are very robust. They are also repairable (AO Services ... Home page) as they do not have potted electronics. Make sure the case is ‘earthed with a cable. Their weakest point is the 5PU pickup (Edit: correction originally said ab5) but the later alternative cures this.
Are you setting the timing with a strobe lamp at 3000 rpm? (Edit: please note this is a question).

I would guess on the left side ring/bore damage due to overheating, maybe a partial seizure the left side gets a less oil than the right side so is more sensitive to extreme heat. You will only know by looking.

3 angle valve seat is nice to have, but difficult to achieve successfully. Concentric running of the valve in the seat is the key, which in effect means the valve guides need to be unworn and installed (and honed if required) concentric to the valve seat, the valve seat needs to be perpendicular to the valve guide hole and square in the head or pocketed.
I realised years ago that I don’t have the equipment or skills for this cylinder head micr-surgery, so I give it to someone who does-it’s not cheap to do. Unless you are racing or making a daily driver it might not be worth the effort or cost.

If you are lucky you will get a reply from @Truckedup he is very clever with valve timing.

If I understand you correctly 100/105. Lobe centres you want to move the exhaust cam timing quite a lot, is there a reason for this, are you intending high rpm running only?
I understand you still have 3134 grind, standard 55/34-34/55 cam profiles?
In ((34+55+180)/2)-34=100.5 lobe centre. IO+IC+180= duration. (Duration/2)-IO=lobe centre
Ex ((55+34+180)/2)-34 = 100.5 lobe centre EO+EC+180=duration. (Duration/2)-EC=lobe centre

If you dial the cams in then remember to set the dial gauge on the pushrod end of the rocker or direct on the cam follower, the rocker arm is not a 1:1 ratio, measuring on the valve end will skew your readings.

I am better aquatinted with T140 valve timing, but not the short rod conversion.
But in the absence of any extra information, then I would be tempted to leave the timing as standard. It is a simple task to experiment once the engine is bedded in.

regards
Peg.
 

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Discussion Starter · #8 ·
Hi Peg, thanks for wery good and informative answer. 👍
I have strobed the ignition on 3000 rpm, but im not happy with the result. Way too high with lots of ping knock. Wonder if my strobe lamp is way off. Cheap model.
Im running static timing now and its much better. Engine on the mark and the rotor 5 mm before the picup working ok. Still a little ping on low rpm when hot, but useable.

Im not aiming for high rpm power, i read that increasing exhaust too 105 gives good low and midrange power, just what i want but i dont have any experience with this and thats why i seek information.
The cams will be thoroughly measured when the cylinder head is off, then i know how they are timed now.

Thanks again.
Very good information
 

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Hi Oyvjohns, I don't know anything about Rita. When you get motor running again, you'll very plainly see the timing advancing. To stock AAU with points full advance was 38b at 2000rpm. Even with no tach you can feel, here motor revving way faster with AAU before the 38b line meets pointer.

3 angle valve job is very desirable. I've done many valve jobs. A few thoughts. On these motors the valve seat is straight on the inner angle. So factory only did 2 angle job. This is very common in automotive & works perfectly. With new head, new valve the valve face contact position on valve was right where you'd want it.

As the seat wears it goes oval. You lap the valve it rounds out seat & works good even though the seat width is not even all around. In real life practice this lapping works really well even though on paper it's not ideal.

At the same time seat & valve the 45deg angle face wears in a curve. Lapping will not cure the curve, but no matter, it still seals well in real life & can still give long service life.

However when these types of wear occur you loose some gas flow. So for highest performance you must grind seat & valve back to 45 & correct inner & outer angles. Again in real life, if you just ride the bike for pleasure I'll wager you'll never notice a difference. So long as the 45 is sealing perfectly the bike runs fine. Even pocketed valves on these bikes where seat has been ground & valve sits deeper in head than it should, it stills runs great. Does it loose horse power. Yes, but I've never seen an owner notice. Again high performance riders or racers will.

One you remove metal you cannot get it back. Original seats are cast into head with dovetail making them impossible to fall out. Seats can be replaced, but they are pressed in, which is not as secure.

Valve margin is very important on Triumph. New valves already have a narrow margin. Grinding 45 to flatten the curved face most often leaves margin too thing to properly transfer heat & the edge of valve runs hot. So if lapping is not enough you most often will need new valves.

Moving to guides. If guides are good, or good enough, & valves are still good enough, I would recommend just lapping valves. I can tell by your bike you probably don't race or ride really aggressively. So long as you do a good lap & leak test the lapping, the motor will run perfectly. Now... if you have burned valves, or seats, guides are worn, you must correct this.

Here's where things get complicated. You need guides. When you replace guides you want the new guide to be exactly centered over seat as the original factory was. We & shops do best we can. In real life the new guide will not be perfectly centered. So now we need to actually cut the 45 to make it concentric with new guide.

Now the 45 is oven not even with the seat as it was from factory. Now the seat is not only wider, but the other angles top & bottom are not concentric with the 45. Remember inner angle was straight (90deg). This is where skill & judgment of you or machinist comes in. The top & bottom is cut such it positions 45 on valve face where you want it & seat width is what you want.

The 45 on seat has been ground. I prefer grinding stone on 45, but hand cutter will work for 45. On Triumphs I start with the inner. Using 70deg hand cutter just remove a trace of the inner. Just enough to make it concentric. Really easy to over cut this. Using dividers I find where inner angle will fall on valve face. Most often will be very acceptable.

I then move to top angle. Triumph used spherical cutter. I use 15deg. Again go easy not to remove too much. I make the 15 concentric to 45. Now I can see exact seat width & position on valve. You can use bluing or dividers to verify position. Shop manual states 3/32 wide seat face of the 45. I do best I can to get that. So I'll remove metal from 15 as/if needed to get top of seat where I want it. Same on the 70. Since the port is straight at seat the 70 doesn't need much.

When all this is where I want it I lap valve with fine compound. This gives a visual real life verification of seat position & verifies the valve face indeed matches the 45 of seat.

Very important when lapping old or new vavles hold head such guide is vertical. If at angle the normal play in guide will lap it crooked.

Finally put head together perfectly clean. Put solvent or gas in combustion chamber. Hold head such valve head is submerged. If valve seal is perfect it will not leak or even seep solvent by. The seal is perfect. Hold it at least 15-20 seconds to check for tiny seeps. It should have no seeps. Relap valves as needed. Again must be perfectly clean as a a speck of dirt will cause seep.

Spring tension matters. At higher rpm even 5000 weak springs can cause valve float. Fitted spring length matters. If just doing lapping it doesn't change things much. Even light grinding of seats if you use new valves fitted spring length doesn't change much. Fitting springs is another subject.

Where things go wrong is when new guide is crooked compared to original. Now you have to remove much metal from seat... Same with high miles head were seats have been ground prior. That's another subject.

Choosing a good machinist is very important. Machinists have "system" you ask for what you want. They do what they like to do. Real life!

Head gasket surface must be flat. A gentle curve can pull flat. Dips, between bolts are really a problem for seeping or blowing head gasket. At a point you must skim head if you have sealing problems. Again... you can't put metal back.
There is a difference between bent head that can be flattened & dips. You can't flatten dips or high spots.

But if it's bad it's bad. Not flat well never seal properly. Head will need skimming. Thicker head gaskets are available from Morgo should it be required.

So as Rambo suggested start with guide wear evaluation & go from there. Worn guides are worn. They will need replacing.
Don
 

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Static timing is fairly close with points. But is not good for electronic ignition. Static for electronic is just close enough to get motor running.

If you have old school timing light without the adjustable advance functions etc. it will be reading accurately. The "modern" electronic timing light with the knobs etc to read advance can give errors if internal electronics are faulty. Old ones where you just push the button & they flash, I've never seen give errors.

3000 rpm is probably too low. Don't set at a specific rpm. Set at full advance. So hook up light & start motor. Always use fan in front of bike to keep motor cool when setting timing.

Light hooked up, start motor. Look at mark. Slowly rev motor faster & faster. Mark should move closer to pointer as rpm raises. Keep revving higher until mark will no longer advance. That's full advance. No matter the rpm, set the mark to pointer at full advance. However if RPM is crazy fast like 4500 or something way up there the EI has some sort of fault. Of course EI depends on a good battery & charging system. Do not power timing light off motor cycle battery. That can skew the reading. Use separate battery to power timing light. Some timing lights (like mine) has internal battery so its never an issue.

Most EI will give full advance around 3500 or so. Trust me, you will see line stop moving when it's at full advance.

Another issue is if the rotor mark is correct!!! This can be a problem. Using TDC tool put motor to 38b position. Now look at line. The TDC tool does not lie. Some lines can be a few mm off. Make a new mark if needed. If line is way off, you have tool in TDC slot by mistake or the rotor has slipped on it's center.

Sorting all this out takes some time & practice.

On a complete aside. After you repair cylinder, use break in oil for running in. Very important the oil you use for running in. Morgo sells it. Web search will show break in oil of various brands. I don't know that brand matters. 30 or 40w depending on ambient temperature. Break in oil is a very smart thing to use & safe bet. Normal oils often do not allow breaking in.

I forgot to mention on valves. The valve does much of it's cooling when valve is closed through the seats. So the wide 3/32 in shop manual is best practice. Modern motors use much narrower seat. Not these.

Back to break in. The pistons do much of their cooling through rings to cyl wall. So poor break in means rings may not have full face contact, which results in rings, pistons overheating... No magic here. Just use break in oil. Start motor & ride it a good 15-20 miles right away. Follow break in riding like owners hand book. Not pulling hard in too high of gear, or revving too fast in lower gears. Simple. Real ring compressors for our motors work really well. Almost guarantee easy assembly & no ring damage.

All this stuff matters. We don't want another failure.
Don
 

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Hi,
run Lucas Rita Electronic Ignition, and im not quite shure if that one is optimal for the bike, i suspect that it dont advance as i should.
This will be investigated further, but it is not unlikely that we switched to for example Boyer or similar. What is recomended?
I have little faith in Lucas after all the problems we have had with the electrical system on this bike.
The Rita is very much better quality than any other available electronic ignition, with the possible exception of the Tri-Spark.

I am very disappointed with the poor information in earlier posts, :mad: particularly when one posted, "I don't know anything about Rita" ...

Before any more poor advice, could you post photographs of the "amplifier" (electronics box) and "pickup" behind the circular cover in the corner of the timing cover?

Make sure the case is ‘earthed with a cable.
If the case requires a cable connection, it must be specifically from one of the Rita amplifier case bolts to the battery 'earth' terminal (as standard on your bike, the battery +ve terminal).

Whether the case requires requires the cable connection to a battery terminal depends on the Rita model and version - only the very last version of the AB11 did not require the cable connection from new. If an AB11 has been rebuilt, it is rebuilt to the latest standard.

Their weakest point is the ab5 pickup, but the later alternative cures this.
This is confused.

AB5 is the earliest common version of the Rita amplifier.

The "weakest ... pickup" Peg is thinking of is the "5PU"; unless your bike's system was taken complete from a '79-on Triumph, it is not likely to have this, although a photograph of what is behind the 'points' cover would be useful confirmation.

The 5PU is the "later" pickup. It is the earlier pickup, supplied as standard with aftermarket Ritas for years before '79, that is more reliable.

Are you setting the timing with a strobe lamp at 3000 rpm?
strobed the ignition on 3000 rpm, but im not happy with the result.
if RPM is crazy fast like 4500 or something way up there the EI has some sort of fault.
Without knowing which Rita amplifier and pickup are on the your bike, this is very poor information. :mad:

If it is an "aftermarket Rita", 3,000 rpm is much, much too low rpm to be "setting the timing", full advance is 6,500 rpm (no, that is not a mistake :devilish:).

Hope this helps.

Regards,
 

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Discussion Starter · #13 ·
Very grateful for very good information.
I will sit down and read thoroughly when I have time.
Am a bit busy with work these days, but I hope to get a few hours in the workshop this weekend and will then take pictures of everything you have requested.
Will also answer every question you have about the bike.
You provide good and important information and I try to get everything in between the ears.
Thanks.
 

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Discussion Starter · #14 ·
Before any more poor advice, could you post photographs of the "amplifier" (electronics box) and "pickup" behind the circular cover in the corner of the timing cover?
Hi again.
Had some minutes to spare and got a couple of photos as required.
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The amplifier box, with ground wire as you see on the right.
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Rotor and pickup.

This electronic ignition is about 20 years old im been told, and as i said before its now running on static timing.
Engine on the 38 degree mark, and the rotor set 5mm from pickup as its written in the manual.

With this setting, the engine is wery easy to start, both cold and warm, and is running good.
Only issue is that i have a litle ping/knock on low rpms whith hot engine.

What do you think?
 

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Hi,

Thanks for the photos. (y)
View attachment 767360
The amplifier box, with ground wire as you see on the right.
The other end of the "ground wire" is connected to the whichever battery terminal is "ground" on your bike? '70 is 'positive ground' as standard.

It is not actually a "ground" wire, the Rita amplifier is 'ground-independent', having insulated -ve (Black) and +ve (White/Yellow) wires for normal operation. The wire is for Voltage spike protection - the electronics are protected by the case, is why the wire connected to the case bolt must also be connected to the battery terminal itself.

The pickup has been installed upside-down. :) Does not matter for operation but, if you wish to change the wires' connections for a more-reliable method, the complete pickup needs to be rotated 180 degrees. Regrettably, the wires connections, with the ring terminals, collection of fibre and metal washers, insulating plastic sleeve, tiny nuts, is the least-reliable part of the Rita. (n) Say if you would like any information on a more-reliable connection method.

I think also the pickup is not a original but a replacement; certainly, I have not seen an original with a Yellow wire, only White (with the other Black wire).

Two wires exactly the same colours connecting the pickup to the AB11 is also a (n) idea. For the Rita's electronic advance-retard to work, the pickup wires must be connected correctly to the AB11's White/Purple and White/Orange wires; if the connections are swapped, the Rita will still work but the timing will remain fixed wherever it is set statically ... I have sent an email to someone I know to check but, if your pickup's Yellow and Black wires should be connected the same as the pickup White and Black wires on my bikes:-

. pickup Yellow should be connected to AB11 White/Purple;

. pickup Black should be connected to AB11 White/Orange;

... then the electronic advance-retard should work. (y) If I am emailed differently, I will post a correction.

now running on static timing.
Engine on the 38 degree mark, and the rotor set 5mm from pickup as its written in the manual.
With this setting, the engine is wery easy to start,
Even if the pickup is connected to the AB11 correctly and the electronic advance-retard is working, this is quite retarded - the manual setting is only so you can start the engine so it can be timed with a strobe. :) Once we are sure the pickup and AB11 are connected so the electronic advance-retard works, if you strobe-time it (if you have neighbours nearby, maybe when they are out? :whistle:), you should feel an improvement particularly in the bike's acceleration?

Hth.

Regards,
 

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Discussion Starter · #16 ·
Thanks for very good information.
I will absolutely follow every input that will make the function as good as it can get.

Say if you would like any information on a more-reliable connection method.
Yes please.

I think also the pickup is not a original but a replacement; certainly, I have not seen an original with a Yellow wire, only White (with the other Black wire).
I have no idea, the bike came with this installed, i always thought that it was original, but im glad if you can provide information regarding this.

if you have neighbours nearby, maybe when they are out? :whistle:
New neighbours, so its important to break them in properly with some strobe timing :cool:
 

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Discussion Starter · #17 ·
Two wires exactly the same colours connecting the pickup to the AB11 is also a (n) idea.
The picture you commented lied, it had two different wires, black/yellow and black/white, and they are wired correct to the Lucas box as you wrote.
So im thinking that the bike runs ok with the igition the way it is now, and i have started to dismantle the engine top end, so i will let it stay the way it is until new parts have had a break in periode.
After that i will strobe it on hight rpm to see if i can get it on the mark.

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After the cylinder head was removed, i have carefully measured the cam lift on the tappets.
I was a bit curious about this, because we found the intake cam 1 tooth off earlier this summer.
The results was both intake and exhaust 100,5 degrees lobe center. (y) And the lift is 7,55mm on both.
The question now is: Will i get better low and midrange power if i adjust the exhaust closer to 105?
Or is it waste of time and energy? Hopefully someone has some good information regarding this?

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One thing i diddent like was that it looks like it has been some leak between the cylinders.
Is this normal to this engines?
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Here you see the same black trail on the cylinder head.

One surprising thing i found on the cylinder head, was that the intake valve guides had valve caps.
I havent dismantled the valves yet, but i clearely see the caps inside the intake valve springs.
So maybe the valves and guides have been replaced on this cylinder head, and if they still are good, i have one less thing to do. (y)
The rocker arms, push rods, valve ends and tappets all look in great condition as well, so maybe i just lapp the valves on this head after waterblasting.

The cylinder needs a light hone job, and piston rings will be replaced ofcourse.
So I'm reasonably happy with the result so far, no unpleasant surprises..

Hope you comment if you see anything in the pictures that you think I should take a closer look at.
 

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One thing i diddent like was that it looks like it has been some leak between the cylinders.
Is this normal to this engines?
Leaking between the cylinders is not desirable on any engine, but it is a fault that can occur on Triumph twin engines, it is a more common fault on 750cc engines than 650cc.
It is worth checking the cylinder head for flatness, and having it pressed flat if it is bowed.
Sometimes the cylinder head requires machining, generally it is considered better if this can be avoided.
Upward pressure from the pushrod tubes can relieve the clamping pressure on the cylinder head, unfortunately this is right in line with division between the cylinders. If the pushrod tubes are too tight this can cause premature seal failure and promote bowing of the cylinder head.
You will not be able to reuse that head gasket, blow-by gasses have already started burning it away.

Things that can help avoid reoccurrence include:
Making sure the cylinder head and block are flat.
The new head gasket should be a perfect fit around the cylinders with good clearance around the studs.
The new head gasket should be annealed before fitting, copper age hardens, even when siting on the suppliers shelf.
The pressure exerted on the pushrod tube seals should be carefully adjusted.
The head should be torqued down carefully several times after the rebuild, until you don’t need to turn the nuts and bolts to re-establish the clamping pressure any more.
Checking the head nuts and bolts for tightness periodically.

regards
Peg.
 

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Discussion Starter · #19 ·
Many thanks, good tips its always welcome. (y)
it is a more common fault on 750cc engines than 650cc.
This is a 750 cylinder, it was mounted about 18 19 years ago, but the bike has very few miles after this, because of all sorts of trouble as i wrote before.

My first though was to skimm both the cylinder and the head just a little so we are shure they both are flat, but then it becomes a problem with the pushrod tubes.
Is there a good way to measure exactly how long the tubes must be? Or could it be an option to compensate with a slightly thicker head gasket?

Regards
Ø
 

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Hi Ø,
My first though was to skimm both the cylinder and the head just a little so we are shure they both are flat, but then it becomes a problem with the pushrod tubes.
Is there a good way to measure exactly how long the tubes must be?
'70 pushrod tubes should be E9349 (70-9349); here says they should be 4.867 inches "shoulder [where the cylinder head O-ring fits] to bottom face".

That article also says that the recess in the head should measure 1.140 inch inside diameter while the O-ring fitted on the pushrod tube should be 1.200 inch outside diameter. Also, the O-ring should be 71-1283 (E11283), not the E7310 shown in the parts book.

Unfortunately, the article does not give the depth of the pushrod tube/O-ring recess in the head; I know it has been posted in another forum, I just have to find it ...

All the above - and the 3/16 inch thickness of the large diameter of the tappet guide block in the cylinder block - is important because:-

. the seals, pushrod tube and cylinder head recess dimensions were all changed for the '69 model year;

. however, regrettably, far from preventing pushrod tube leaks, the changes actually increased their likelihood ... :oops:

. early in the '70 model year, Meriden made a bodge; it is this bodge, if applied without checking, that can cause cylinder heads to be bent and cylinders not to be sealed properly. :(

The bodge was to add another seal between the bottom of the pushrod tube and the tappet guide block. The part number that appears in the '71 650 parts book is E4752; however, this seal is 0.125 inch thick but must be "crushed" only ~0.030 inch when the head is torqued down; however, there never was around 1/10-inch gap between the pushrod tube and the tappet guide block to be taken up by any seal, is why fitting this extra seal was a bodge. (n)

. Simply fitting the E4752 seal (or the 0.100 inch thick E3547) and torquing-down the head, without checking the pushrod tubes fit in the cylinder head correctly and the size of any gap between pushrod tube and tappet guide block, is one reason twins' cylinder heads are bent. :(

could it be an option to compensate with a slightly thicker head gasket?
Another problem with simply skimming a bent head on the cylinder gasket side is the rocker-box gasket side remains bent ...

Hope this helps.

Regards,
 
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