Motorcycle engine rebuild shop - West of Toronto - Recommendations ?

Rockman said:
Hi Brian;

Finally got around to sending the bike to an experienced mechanic. Diagnosis is as follows:
*Leak-down test shows Cylinder 1 has ~34% loss (acceptable), Cylinder 2 has 75% loss (unacceptable), with significant air leakage at the intake
valves. Cylinder 3 has 80% loss also with significant air leakage at the intake valves.
* Valve clearances all within specification. However, some valves appear new, suggesting the valve seats were likely not cut or set properly.
* Re oil consumption, with all pistons to BDC, camera inspection showed severe scoring on cylinders 2 and 3, light scoring on cylinder 1.

Recommendations:
* Replace cylinder liners and piston rings to address the scoring and excessive oil
consumption.
* Rebuild the cylinder head to ensure proper valve seating.


It would be nice to replace the pistons with new ones even though they appear OK, given new liners. However, Triumph no longer has the pistons nor do any dealers have leftover stock so that leaves me with custom pistons as the only option. Can be done but given minimum number of piston order (4 at Wossner, 12 at Wiseco, and beyond that on this bike there are two different pistons) not worth it.

Probably not a reflection of the bike's reliability (only 34,000km!!) but rather most likely shoddy work by whoever worked on the motor last.
Click to expand...

IMO she's done. Look for a complete engine, or get another bike and part that one out.

Interestingly, the parts diagram suggests that this engine (955i?) has replaceable cylinder liners, which is really unusual in bike engines nowadays ... but it's of no help if the parts are no longer available. That engine was used in several different models back then, which means there might be some hope of finding another complete engine.

Check with Rob at Pro 6 Cycle. He knows people. He has a Triumph, but I think his is older.

How much do you know of your bike's history? Do you know if someone has been in there before? It would seem unusual at that young mileage. Seems more likely that the damage resulted from an event of some sort ... extreme overheating, or running out of oil, or a fuel delivery fault combined with driving patterns that lead to excessive carbon build-up and stuck piston rings, etc.
 
If it's a sleeved motor, Millennium Cylinder or LA Sleeve will have sleeves or will make you some, if it's not a sleeved motor; talk to them, they might be able to sleeve it anyway.
Giovanni (or whatever his name was) , that used to work for McBride knows 955i's

Who is Rob at Pro6? Big Rob from Cycleworld?
 
Guys - thanks for your feedback - will follow up with the guys mentioned. This model has liners and they are still available at Triumph, as are most of the other engine parts...except the pistons, which are discontinued - I was not able to find any leftover stock. So it looks like either new liners and existing pistons, or oversize custom pistons with bored liners. Anybody have experience with JE custom pistons? Of course the repair does not make economic sense, unless one considers the replacement cost, like a BMWR1250 RS or a GSX-S1000GT+...
 
Potentially Triumph Sprint ST 1050 pistons could fit? That motor apparently has same bore but longer stroke than 955i?
 
You had better check with the experts on that. If the piston is the same part number then carry on. Otherwise, it needs to match or at least be compatible in many dimensions beyond just the bore size. Pin diameter, deck height, valve clearance pockets, shape of the skirts such that it clears the crank counterweights, etc. If the 955 and 1050 engines are from the same design family, there is a fair chance of having compatible parts. The most likely difference would be for the 1050 pistons to have a smaller dome or bigger bowl, i.e. bigger combustion chamber volume, and if used on the smaller (shorter stroke) engine, you will end up with a lower compression ratio.

Find the experts, see if anyone has done it.
 
A couple of pictures - pistons and rings quite good, cylinder head...well, not so good. Looks like water/coolant sat there for a while, and somebody did a trash valve job...
 

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That piston looks fine from here, so that is good news. If the cylinder walls look decent, potentially just have them refinished ("honed") and use new rings. Appears that this engine uses cast-iron liners, so this should be simple for someone who knows what they're doing.

Obviously, you found a shop to do this. Who?
 
I'd like to see that head after you run the wire wheel over it. Maybe not as as bad once you clean off the kyfe.
 
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Cylinder liners are scored so they'll be replaced as well. Motorcycle Republic out of Cambridge is doing the work - Matt used to work at Ace Moto Tech and they highly recommend him. I'll send more photos as I get them.
 
Scored liners explains the oil consumption and at least part of the low compression (poor valve sealing is probably the other part of it).

A good question is WHY the liners were scored. Overheating? Oil changes left too long?
 
Who knows. Of course if you need to add 0.5l of fresh oil every 400km,the oil stays pretty fresh, but it also would have been easy to run low on oil until you realized there was an issue... I was about a liter down by the time I realized - prior owner did not disclose oil consumption issue.
 
As you're probably aware you can barely give away a Triumph 955 so an option could be to pick up an entire used bike for peanuts and swap the motor. End up saving money compared to a rebuild and have spare parts to boot.
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