I am having a 1970 650 TR6 rebuilt. Its easy at this stage to put a 750 kit on it and rebalance it. Is there any downside to this? I wonder if it makes a difference that can be felt? The stock 650 is fine but this is a modification that might make it even nicer or am I making something worse?
IMO, yes, it's a improvement over the 650, a little more torque. It's noticeable but not huge. The main thing is you state you're going to get it balanced, that's a nice improvement all by itself. If you need to lower the compression you can do that and still be a little faster. I can't think of a down side.
For anyone interested the motor was torn down a few days ago. The stock pistons had already been replaced with .010 over and they still fit good, all it really needs is rings. The crank is within factory specs and just needs new main bearings and new rod bearings. This will freshen up the lower end. Since the engine is apart it seems like the perfect time to go to the 750 conversion. Tomorrow or Friday the engine cases and rocker boxes will go to the Vapor Blaster. The timing case cover and the gearbox and primary cover will go to the polishers. This bike was supposedly restored by Bill Hoard but it was an auction bike and I don't
know if that is true information or not. In any case I have someone who has done many Brit bike restorations for me over the last 15 years and he will b get the bike back to where I like it. I also purchased a new five speed transmission for it. My last three Triumphs were all pre unit and we put the five speed clusters in them and I liked it. This bike still needs new swing arm bushings and stiffer fork springs which will be looked after once the motor and trans are done. the bike has sat in a collection for some years and has been cared for cosmetically but not ridden much if ever. The gas went bad so the tank will be cleaned and I'll probably buy a new carb unless the old one is real good. The clutch plates are sticking a little but we will see about them too. The bike started and ran pretty good and was actually pretty quiet as Triumphs go. I am a fussy guy so the whole thing came apart. I figured on that when I bought it. Never had a unit bike before
and figured a 1970 was at the end of the line and would be a good unit bike. I also like the brakes and the color green. Here is a picture of a 62 TR6 pre unit that was modified with the later brakes and a five speed and aluminum wheels. I sold it about 2 years ago and it was my last Triumph and actually the best running
one I ever had. I bought my first NEW one in 1959 from Cliff Major who at the time worked for Bud Ekins. I was seventeen at the time and I traded in a 1946 Knucklehead on it.
My T120 has been using a 750 kit for about 13 years so far.There is a huge increase in its low down pulling power.The kit bolted on with no rebalancing as the pistons are machined to be the same weight as the 650 pistons.I selected 8.5 to 1 compression to lower the amount of pinking due to the lower octane fuel available now.At 10,000 miles,i changed the rings as the top end was apart curing a pushrod tube leak.It was not using much oil at that point and uses virtually none now.Rings are standard T140 when replacements are needed.
I would never use 650 barrels again as i like it with this extra pulling power,especially when carrying a passenger.
I cannot see any point in reboring a 650 when you consider how much more new barrels and pistons of the 750 kit are in comparison.
I still use a 2 row primary chain and it stands up well to the extra torque.
There are no down sides at all,in fact,the engine will run cooler and pull a higher gear.Using a 20 tooth engine sprocket and it suits it well.
Just fit the kit and you will notice as soon as it pulls away from a start.
Best modification i ever did.
You may have noted I have a RT. It is my opinion a 750 kit gives more power & bottom end grunt BUT there will be a bit more vibration. The Routt kits, used on the RT's, pistons weighed the same as the factory pistons so I doubt any fancy balancing will be required. Pat Owens, who put over 400,000 on an RT felt the factory Trans was off for a 750. Note Owens bike had Chantland barrels not Routt. As you are having a 5-Speed installed should negate that problem. I like the way Rambo did it do to fuel now available.
Just a thought as far as you have it down maybe a set of Megacycle cams.....
I had a 750 T120 that I sold last year. 1970 with a 1960's Routt barrel, MAP forged pistons and rods, hotter intake cam, stock exhaust cam...I noticed more mid range power, maybe a bit more vibration but about the same as my friend's T140 but faster...Since all 650-750's vibrate noticeably, a bit more or less vibration isn't a big deal..
The larger 750 bore does allow the builder to take advantage of more quench to inhibit detonation (pinging). Mine had 9.5 actual compression and with a bit of tuning it ran on 91 octane without excessive detonation when ridden like a Triumph should be.....
I am going with a kit made in England that has a little more rounded barrels than the popular Morgo kit. The fellow that is building the motor has used this kit in the past and likes it. The rounded barrels are harder to tell from the stock 650 ones than the Morgo ones. I think any of the kits will be fine if set up properly. I notice that some guys did not balance their motors after the conversion and say their is no problem. Rambo has got over 10000 miles and a bunch of years on his and seems as happy as a lark with it. It can never hurt to have the motor balanced and since its apart anyway it seems a good idea to do it.
Mine are the round barrel type.Made by Aerco.Pistons are federal mogal and came with the kit complete with bigger head gasket.You will find the gudgeon pins are thicker metal than in the 650 pistons but fit standard small ends.I had owned this bike and ran it as a 650 for a few years before fitting the kit and no more vibration.It had been quite a smooth running engine already.3 years ago i did have to replace the crank due to it snapping possibly due to shutting off the throttle from full go to no throttle at about 85mph after a run of 10 miles of 85mph.Just seemed a metal fatigue problem of a very old standard crank.I replaced this with a 1969 TR6C crank with a 10 thou grind and it ran exactly the same as when the previous crank was in.
The big bore is fairly close to the middle stud of the 9 stud head.With this in mind,i use Hylomar blue on the gasket and fill in the machined groove in the barrels with the sealant.Not had any head gasket failures yet.Pistons have a flat machined area around the circumference of the crown so that there is a bit of space for the smaller head circumference of the 650 head.I kept standard T120 cams as these are still fine after 40,000 miles plus so far.
Power of an extra 100cc is hard to guess but might be an extra 6 to 8 bhp .You will notice that the bike is still eager to pull hard at 80 mph up to 100 mph without crouching down.I ride it quite hard as intended but normally try to keep below 80 mph.It will need less restrictive exhausts than standard on my bike but if you have 1970 type,they are usually free flowing.Best silencers for top end pull were tulip upswept type with baffle pipes.They lost power with the baffles removed.I am trying some long Thruxton pipes as fitted to the racers of 1967 at the moment.They are mid range for noise and very free flowing at the 80 mph range.Any of the restrictive pipes i have used slow the engine down at 80 mph.
Using no silencers will slow it down quite a bit although it will sound fast.I have tried 7 combinations of silencer arrangement and the current Emgo short megaphone lets it breathe well but is the noisiest one i found.
I intend keeping this bike for life so it will have its ups and downs to report on.
When using the short megaphones,they are standard with the end cones.Inside,there is a perforated tube which you can see right through,and half way along that tube,a mesh screen.Its the cheap ones on ebay by Emgo.Not bad chrome and very noisy.This type in the picture.Or,in the video.https://youtu.be/cQl4JbE6BCw
Rambo thanks for the info on your bike. It sounds like you're happy with it. I also purchased the AERCO kit. My builder said he has used lots of AERCO kits without any problems. The main reason I decided to go with the 750cc instead of leaving it stock is because of the extra 25 pounds I now weigh. I weigh about 230 now which is no big deal on a modern bike but on a vintage 40 cubic inch Triumph it is. If it will be happy at 75 mph I will be thrilled. That would let me ride it on the freeway from time to time besides just the mountain roads. Today the cam bushings were removed from the cases and tomorrow the cases go to the vapor blasters. The project is moving right along. here is a picture of a bike rarely seen that I sold about 5 years ago. Its a 1964 G15 Matchless that was a 750. It wasn't as fast as my 650 Triumphs but it was a real nice bike and different.
I suppose i am over 200lbs now and my wife often comes pillion on it.Always interesting on the classic rides in the steeper areas with 2 on it.When we stop,a few riders ask how it goes up hills so easily and faster than their bike with just a rider.Some great advantages and i use 4 gears as it goes up most hills in 4th easily.Makes it a relaxing ride with less gearchanges.
That Matchless looks like the one with a Norton Atlas engine.Quite a lot of those hybrids are being returned to the UK now.Model P11.Yours is made earlier than the factory bikes so must have an interesting history.
RAMBO, The Matchless did have a Norton engine. I never saw another one while I owned it which was for about 4 years. I rode it on several british bike rides. I had a period of about three or four years where I took a liking to square fours. I had a few really nice ones but in reality they are not as good as a bike as the
twins. They require MANY mods to make them dependable at freeway speeds for any length of time. They are great looking and great sounding and thats the draw.
There where a lot of these Matchless and Nortons in my area back in the 60s, we had the main Norton importer in Toronto. The models were G15 MK11 , G15 CS, G15CSR, N15CS, and the P11 and P11A and probably a few I missed. These models were street scramblers, café racers and touring bikes like the one in the picture.
I never did figure out how many differences there were but each model was different in many ways. They were available in Canada from 64 to 68, I bought a 67 MK11 in blue like the one in the picture and over the years have had a CSR and several P11s. Very neat bikes.
As far as i know,the Matchless Norton was not available in the UK.Back then,the USA wanted bigger bikes and more power when British bikes ruled the World.Triumph seemed to win the battle for the popular T140 and most other British manufacturers gave up on the USA battle for sales.By then,the industry was all but over.
In 1968,i saw my first BSA Rocket 3 in red and cream and it appeared huge.Just the one locally and heads turned everywhere it went.Very soon,along came the 750 four and we saw it as a gigantic bike.Locally,the bikers rode old 650s and a few single cylinder bikes,the whole lot were just falling apart but fun to ride about 15 miles,usually at night,then count up how many came back.Quite a few lost their lives trying to ride just a little faster and get back to the Wimpy bar.1969 and i got a licence and still drooled over the old 650 bikes with the rattles and noise.Us learners had to go for little bikes,so,it was Japanese as they would go a little better than a Bantam or C15 BSA.The industry was failing fast then as the new riders accepted the Jap bikes and could ride distances on them.
Still the local Wild Bunch road the old bikes and built the hybrids in sheds and many never had a Jap bike.Nowadays,i still see these older riders,now with no bike,and watch their faces as they see my old Triumph rattle through town.I doubt they remember how us 16 year olds admired what they rode back then.
I visited one of these riders just a few years back and he had bought a new T110.Then,he said its still in the garage so i had a look at this one owner original bike,offered to buy it and ride it around again but he still will not sell it.One of the others has a Triton he built back in the 60s and that still sits in the garage.He says he must build it up again,but thats been heard for 40 years now and he is close to 70 now.
Small little seafront town which had a good mix of people and i know most old bikes and their owners including one stash of over 100 old British bikes at one farm.That owner is 84 now and cannot ride but still buying more and selling none.They are worth in excess of £250,000 now even as rusty old wrecks.
Must look in and see the old sod and try again at buying one.
RAMBO, I'm 75 in less than 60 days but lucky to still be able to ride. I started riding big bike in 1957 but in 1955 I had scooters and motorbikes. I've seen many changes in the motorcycle world. The one thing that stays
constant is the FUN. They also really help to keep you young. I have two V8 powered bikes with 400 horsepower motors each that are way different but lots of fun.
It would have sucked for me if I lived in the UK when I got my license. There is no restriction here on age and motorcycle size. First bike I owned was a T100R, then a XLCH883. I fell down on both of those numerous times. I'm glad I knew my limitations back then and did not make the purchase of the 73 Kawasaki Z1 900 after the test ride, told the salesman that if I bought it I would probably not live long enough to make the first payment (I was 20). Dave, that's a cool chop, better than any Boss Hoss I've seen. I bet it is a fun ride.:smile2:
Back in 1969,we were limited to 250cc for a learner licence.This went down to 125cc later as bikes were getting just a little faster than an old Villiers twin 2 stroke.The test was just a ride around local streets avoiding hitting cars or people,a bit of arm waving and putting the brakes on when the examiner jumps out into the road.Now,it is very difficult to begin riding a motorcycle if young.Not looked at the criteria recently but it takes a lot of time,practice and study now.People starting riding when older can do an intensive course of a week to gain a full licence for the larger bikes.2 of my sons took this route to riding motorcycles when starting at over 30 years old.Both passed first time.
Here in the US a new rider can take a weekend course and pretty much get a license no matter what the age, at least here in Nevada. There is no restriction on size or horsepower.
Same here in NY... You also can take a written test, schedule a road test........The first bike I bought was a 65 650 BSA around 1972.. I had only a car license and had only ridden a 90cc step through briefly., the BSA had the usual extended forks and was seriously junky...I got on, started it pulled into the road and opened up the throttle...It stuck, I ran wide and crashed head on into a wall...I was ok but the extended forks were bananas...Never did that again....:grin2:
When I got my license they would give you a motorcycle license at 15&1/2 years old. Actually it was a regular license but you couldn't drive a car until you were 16. There was no driving test only a written one. The license was black and white and only had your name and address and thumb print on it. There were no police cars with computers in them, they had real slow tube type radios that went to the station but the station couldn't look up anything because there were no computers. You could lie to the cops and say you don't have your wallet and if they didn't already know you they would write the ticket to whatever name you gave them. Being a motorcycle rider usually meant that you were a hooligan and the police generally knew you were lying but they couldn't do anything about it. Since at that young age you normally raced anything that moved you would acquire many tickets under fake names and never go to court. This would eventually lead to a warrant for your arrest for failing to appear. Eventually you would run into a cop that remembered you but you could not remember what name you last used but somehow he could. He would take you to jail and get you for some of your fake name tickets because the of the bikes license number. This required lots of work for him as there was no computer system with your bikes license number in it. When you went to court the judge would be furious and you would do about 5 days in jail for each ticket if you were at least 18 years old. If you were younger they would call your parents and reprimand them as well as you and try to get them to take away your Triumph.
I used the Morgo kit on my 1970 TR6R. I notice only a slight difference on low end grunt. No additional balancing was done. Morgo does not have the drilling for the oil feed to the tappet that others do. No leaks or problems with about 5k miles on it.
That is interesting about not having a tappet oil feed on the Morgo cylinders.Most Bikes i have seen with the Morgo unit are running well and it is well tested over the years.One of the reasons i liked the Aerco kit was the original looking round barrels so it looks standard.
You are fortunate in having the later cams with the extra hardening of the surfaces so i suppose it will be alright with a little less oil.Plenty gets splashed around with oil flying off the crank anyway.
Tomorrow or Wednesday the crankshaft goes to the welder to have the crank bolts welded in and then the whole assembly, crank, rods, bearings, pistons and rings, etc goes to the balancer. I guess he will have it for a week or so.
Thats unusual Dave,they do not normally undo if held with a thread compound.I suppose just a small tack weld will not distort or cause too much metal stress on the flywheel.I will be interested to hear your opinion on the extra cc,s when it runs.It will burn a fair bit of oil for about 500 miles before rings are bedded in.
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