Piston Rings

[humbucker88]

Currently putting new barrels on the crankcase, getting real fed up with the piston rings, other than buying a piston ring compressor, anyone have any tips whos done this before?

[acid drop]

I've always used a compressor though you can do it if you have a couple of mates to help

[Fazerider]

I've persuaded them in by giving them a "ramp" of thin feeler gauges around the perimeter, that was on a twin though and was a pita. Four cylinders will be difficult: I'd start with the inner ones since you'll need the better access.

[humbucker88]

I've managed to get pistons 2 and 3 in by hand, struggling a bit with piston 4, feelers sound like a good idea, gonna go try it now, cheers!

[Mark YPVS]

Never done a multi cylinder (yet) :rolleyes  but on the 2 strokes I fit the piston into the barrel then lower the barrel to the conrod, not sure if that would work on a multi ??
Mark

[snapper]

Nylon ties might help !

[humbucker88]

Success! Just took patience, although I've hit a snag. The timing chain got a fair bit of slack on it at one point and now isnt turning with the crankshaft. Thatd be fine because it just means ive got to get it back on the cog but when i turn over the engine, one side of the timing chain gets pulled in and the other doesnt move. I'm very confused.

[red98]

sounds like its caught up on something....wriggle it about a bit dropping as much of the chain as you can into the sump....might take a few attempts 

[humbucker88]

It's definitely caught on something, doesnt seem to wanna come loose, no idea what it could be caught on either, really dont wanna have to take the barrels off again!

[Gnasher]

Can you turn the crankshaft?

If so turn it so as to get the pistons as high up the block as possible, then lit the block as high as you can without dropping the piston rings out you should then be able to see what is causing the problem. 

[humbucker88]

Sounds like a very good plan Gnasher, will give it a go in the morning

[Gnasher]

Sometimes just SLOWLY turning the crank both ways will sort the problem without having to life the barrel block.

[Razgruff]

I find old wire coat handers or brazing rods with a small hook bent onto the end useful when doing cam chains, it is possible sometimes for the chain to go behind the cogs and rotate a small amount before jamming up.

I also bend rods through the chain to stop it dropping into the engine, something that I've had happen  :'(

[humbucker88]

had a look down there, couldnt see much, pulled the barrels up a bit, still couldnt see anything, took barrels off and it appears the timing chain has doubled over itself. At the point where its longest, theres just two links doubled over themselves, but are caught underneath the crankshaft! I'll keep pulling and rocking the crankshaft, but if it comes to it, does anyone know if I can get decent access to it if i remove the sump?

[humbucker88]

Update: Got pissed off and thought fuck it, if it breaks, it breaks and turned the crank as hard as I could and the chain came loose! However, this is what i'm now left with: http://imgur.com/55ibY6u

The two links are completely stuck, any tricks or tips to unfusing them? If not I might just get a new timing chain due to the stress I've put this one under by now.

[unfazed]

If it is the original chain, I would change it and the guides as you have the motor stripped.
Out of curiosity what mileage is on the bike and why are you changing the rings?

[Gnasher]

The two links are completely stuck, any tricks or tips to unfusing them?

You have bent a side plate/s if you look chain very carefully you should be able to see where, it is possible to straighten it/them but only if the deflection is small.  You do his by laying the chain on a hard flat surface insert a quality small flat bladed screw driver (or similar) that is big enough so as not to go though a good link. Insert it into the damaged link gently and slowly tap the the driver in just enough to straighten the link, you must not over do it or flex the link to much especially near the link pin.

I STRESS this point this will only work where the damage is slight, if there is any damage to the link pin or the plates are really bent it WILL NOT work and the chain must be binned. Chances are it's shot but I've rescued one or two this way in the past and they've gone on to function in the normal way.       

If you have any doubt BIN it and like unfazed says consider changing the guides while our there.

[Dead Eye]

If it is the original chain, I would change it and the guides as you have the motor stripped.
Out of curiosity what mileage is on the bike and why are you changing the rings?

Out of interest, have you found anywhere reasonable to get the chain guides? I was looking at replacing these (since I have the block split at the moment) but the price is extortionate!! £50+ for one and £80+ for the other  :'(

[unfazed]

Every place I ever checked were all around the same price :thumbdown
I use www.kfm-motorraeder.de or http://www.cmsnl.com . Generally KFM are slightly cheaper
If you find any one cheaper let us know.