Hitchcocks Forum

Hello Bulleteers,

I have a year 2000 Bullet 500 which I'm very much fond of. During last winter I had the barrel rebored and installed the high comp piston (9:1 with 2mm pressure plate). While I was there I also lapped the valves lightly.

Last weekend I started the bike first time after the rehaul. The first start was fine and the bike appeared to run well. I only made a short run over the block due to very cold weather. Next Morning I started the bike again intending to have a longer ride to start the running in period - and oh man it was embarrasing. The thing did smoke very badly for the first couple of minutes until settled to normal running and exhaust with no severe smoke anymore. And this repeated next Morning...

Now, before the rebore the bike had never shown any remarkable signs of wet sumping or any excess smoking wgat so ever. Hence, I suspect the behaviour is somehow due to the disassembly/assembly I made during the winter.

Any ideas what could be the cause? One of the piston rings had small text "top" and I carefully assembled that ring topmost, the text facing upwards.

Regards,
Jyrki

TOP will refer to ring orientation when fitted and it's position on the piston.

In other words the middle/second ring could also have TOP etched on it!

Try leaving the piston at TDC when you stop the engine. I do this and get no wet sumping on start up. Ian

If only one compression ring had the word 'top' on it, this is usually a second ring and an indication of its' orientation. This is the case where one compression ring has an almost chrome like appearance and no wording - this will be the top ring and can be fitted either way up. If there is a dark grey / black ring with the word 'top' on it, this will be the middle ring and needs to be fitted with 'top' facing upwards.
Your wet sumping may have always been present, but maybe your new rings just need to bed in more to help them stop oil getting past them for the first couple of minutes running, or maybe you have fitted the rings incorrectly. What was your engine like before the rebore and why was the rebore done? Regards, Paul.

The uppermost ring is [almost] always a chrome ring, to withstand the greater stress and wear. The word 'top' stamped on the ring only refers to the fact that the surface of the ring with that word stamped on it should face upwards. As ric says, it does not indicate that that ring should be placed in the uppermost groove.



Wet sumping is very unlikely to be due to a problem with the rings, though ‘blow-by’ could be caused by poor ring fitment. Blow-by can also occur before the rings are fully run-in. Blow-by might well cause clouds of white smoke. This may be more obvious at start-up and clear a little as the engine warms up.

As Presto says. I think you have assumed white smoke (oil burning) on start-up is always a sign of wet sumping. It could be in this case that it's actually a symptom of wrongly fitted piston rings or even just additional "rebuild" oil burning out of the cylinder in which case it'll quickly settle down. One other thing I've found is that if the new piston and rings are Indian made they can be of poor quality and take a very long time to "bed in" and achieve proper ring to bore oil sealing.

REgards, Mark

Just to be clear, when I referred to 'the first couple of minutes running', I meant EACH TIME the engine is run for the first few minutes and not just the first couple of minutes after the top end rebuild. If the engine smokes for a few minutes, but then clears, it is probably wet sumping, but if it smokes and keeps on doing so, I would suspect the piston rings and / or their fitment. Some Indian rings can cause terrible smoking, as Mark M says, due to burnt oil. the best place for them is in the bin. Regards, Paul.

Hello,

And thanks for the comments so far.

The bike smokes very baddly for few minutes after every start. After that runs normally. The rebore was done due to quite small seizure last summer, after a pretty hard ride.. Anyway, even after the seizure the bike was running quite ok altought was a bit noisy when cold. There was no signs of smoking or wet sumping thought. That appeared only after the rebore and replazing the piston.

I have now removed the head and barrer and need to check the piston rings again. The piston is from our host - the "american" high pressure one.

Jyrki

jyrkik, are you sure you haven't put too much oil in the bike?

Yes I am. It's about half between the marks.