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Smoking after top end job

7K views 32 replies 14 participants last post by  Triton Thrasher 
#1 ·
New guides, valves, bored block, new pistons, rings. Rings put in dry.Started first kick, but smokes out of left exhaust, only rode 2 miles, retorqued head and adjusted valves. How long should I let it smoke before becoming sad ?
 
#2 · (Edited)
After dry assembly you have to run the engine in.
Variable speed for at list 20 miles, the rest and repeat.
On second and third gears going up and down rev range to 3/4 available revs.
No or minimal period of idling, if you have to set carbs you do it after the first 20 miles ride
on hot carbs.
After first 60 miles you change the oil and ride normally keeping lower gears and higher revs.
During first 500 miles use mineral 20W50.
After this oil of your choice.
This works for me.
 
#5 ·
I always soak the cylinders with oil on a rebuild.Oil burning with new rings lasts about 500 miles.It might settle down.It is also very common that these engines smoke more on the left than the right from what i observe following behind.
Still not replaced my valves or guides as they are only 45 years old so far and 40,000 miles plus covered.They valves just get a light resurface with grinding paste about every 10 years.
 
#7 ·
Smoking

Yep! Put a few more miles on the engine riding as described by OCF and Adam. Who replaced the valve guides? Utmost care is needed here or the symptoms you describe will not clear up. You did the right thing with the 'dry' assembly although I hope you put a small amount of oil on the piston skirts only.
 
#9 ·
The head was done by a machine shop that only does bikes. The owner worked at Meriden until 1973, he is highly regarded.
I did put a few drops on the skirts. I see lots of different opinions on the dry vs oil question.
I'm using 30W for break in oil.
I have almost 20 miles so far, will try to get another spin tomorrow and retorque again.

A couple of bolts moved a tiny bit after 2 mile torque, also all valves tightened up after only 2 miles.

Possibly less smoke today, or else I stopped looking so hard !
I used a permatex exhaust sealant around the exhaust pipes and crossover, I'm getting a bit of smoke around head/pipe joint, hopefully that will burn itself away shortly.

On the positive side, the noise I was chasing away seems gone, pushrod tubes don't leak, bike seems to have good power so far.
I static timed it, but will get timing light to check.

The starter kicks back more often than it used to. When it does that, a blast comes out the carbs/air filter. Does that sound like a timing issue?

I've watched/helped others with top end rebuild, but this is my first one on my own, so I'm not surprised there are issues. I was happy it started up and runs strong, but riding 300-500 miles like this will be nerve wracking!

I appreciate all the help and comments here!

MM
 
#11 ·
I dont think i would put a 30 oil in an old Triumph engine.Spitting back through the carbs could well be timing or a stuck valve.I would check timing first .
After a little bit of running,about now perhaps,do a compression test which might show up if you have broken a ring when fitting.
If this oil burning does continue at a high rate then its back to the drawing board for your top end repairs.
I can recommend the L.F.Harris rings although they are probably bought in from another supplier.
 
#13 · (Edited)
Boyer MK4 is a good unit and not so dependent on a high battery voltage.Easy set up using a strobe and a lot easier if someone is each side of the bike so the needle alignment on the rotor can be watched as the plate is rotated.Read the instructions well.The engine has to be at fairly high speed when the pointer aligns.Paint the rotor slots white before you start.
It is difficult single handed working a strobe,throttle and adjusting while the bike is jumping along on its stand trying to get out of the garage and breaking up the concrete floor..It can be done by fitting the strobe to a tripod devise but running from one side of the bike to the other is a pain.Lucky,my lady is very handy doing timing.She is also a help in engine building when dropping barrels on etc.Tyre fitting is also a good game with 4 hands working.You just need them to get their hands dirty and buy them some nice hand cleaner for Birthdays.Mine loved her new socket set this year.
Just look at the new carpet i bought her for the garage floor.She really appreciates these presents.Got to look after her you know,and teaching her how to dig bait for fishing soon.
 

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#15 ·
Rambo: Lucky,my lady is very handy doing timing.She is also a help in engine building when dropping barrels on etc.Tyre fitting is also a good game with 4 hands working.You just need them to get their hands dirty and buy them some nice hand cleaner for Birthdays.Mine loved her new socket set this year.
Just look at the new carpet i bought her for the garage floor.She really appreciates these presents.Got to look after her you know,and teaching her how to dig bait for fishing soon.
:doublethumb!!! You got yourself a real keeper there Rambo! You did good. Get her a new tool box for Valentine's day.:hearts You're such a romantic!
 
#19 ·
If you're worried about setting an ei at 5000 rpm on a fresh rebuild, try setting it 2 or 3 degrees retarded at 3000 rpm. This is what Pazon recommends in the instructions for their Surefire kit. I don't see why it wouldn't work for a Boyer. If you look at the advance curves for most EI systems the curves really flatten out above 3000 and especially above 4000.
 
#21 ·
Yes, from full advance. Here's the curves. It actually looks like from the shape of the curves on the Boyer it would be better to set it a few degrees retarded from full advance at 4000. The Pazon and TriSpark you could do at 3000. I know it says Commando, which has a different full advance number but the same EI units are used in BSA,Triumphs and Commandos and the curves are fixed.
 
#24 ·
I've set 3 Pazon's this way, including taking them on and off a few times. Set them a couple of degrees retarded at 3000. Then blipped the throttle up to 5000 to check. They have almost always been right on the mark for full advance. I find it easier to get them close at the lower rpm without chasing the bike around the garage.
 
#29 ·
Thanks, that's cleared the names up - I still don't get the "advance curve" going backwards though. I can see why, maybe, manufacturers of EIs might think it good to help riders avoid getting kickback, but why don't they just set the EI up so that it starts at zero advance and doesn't begin to advance until 1200 RPM or so? Or start at/near zero and climb steadily but gently until at 1200 rpm or so? What advantage is there in making them start off at 5 degrees, climb to 10 degrees, then fall to 6 degrees before climbing again (Trispark), or start at zero, climb to 10 degrees, then plummet all the way to zero before starting to climb again (Boyer MD)?
 
#31 ·
Well, I'm sure the designers know exactly what they're doing, but it does look odd to an electronics ignoramus like me. Especially when the rest don't do that. If I was to chose an ignition system purely by that chart I'd go for the Pazon or the dark blue Boyer.
 
#32 ·
John, I think you'll find all the latest versions of the main EI systems share virtually the same curve and all have the idle stabilisation dip between 500 and 1200 rpm.
What it does is advance the timing quickly when the revs drop below the datum which speeds it up and retard it quickly when the revs rise above the datum and slow it down and that's why a motor fitted with one has such a constant solid, steady idle compared to one without the dip or the old mechanical AAU.
It's an electronic governor that holds the idle speed very constant.
My old Trispark had it and so does my new Pazon Altair and they both hold the idle like a sewing machine.
I wouldn't fit an EI that didn't have it.

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