Author Topic: Help - rebuilt bonnie engine is smoking horribly  (Read 13924 times)

Offline Goldie

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Re: Help - rebuilt bonnie engine is smoking horribly
« Reply #15 on: February 02, 2009, 12:26:19 PM »
once again i ask the question "Have you checked the valve guide tolerences?"

I had a Triumph years ago which was smoking and i thaught it was the rings, but it was the valve guides that were the problem

Offline Hunter

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Re: Help - rebuilt bonnie engine is smoking horribly
« Reply #16 on: February 03, 2009, 06:43:59 PM »
For what its worth, my opinion would be to run the bike for a short time to see if the smoking calms down after the engine has run-in a bit longer. You say it has been re-bored and honed, but I suspect not with the pistons and rings fitted,so there is likely to be a little settling as the parts mate together, this should sort itself out after a few miles. If not then you will have to pull it down to see whats wrong. Don,t forget more oil is better than too little.

Offline OneManAndHisBike

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Re: Help - rebuilt bonnie engine is smoking horribly
« Reply #17 on: March 22, 2009, 01:24:33 PM »
Regarding your smoking Bonnie, you say that you had it rebored, but what about the honing? People often forget how important honing is to get a good oil "shield" on the inside of the bore. Without honing, you can have either a dry or an overwet bore depending on how the rebore was handled. Also, you may have sticky piston rings. Replacement parts aren't always accurately made. The rings could be tight in their grooves. Either way, if it's smoking as bad as you say, you'll have to take the top end down and measure things. Take nothing for granted. It sounds like a vernier and micrometer job. Remember that if it's smoking continously, it's the bottom end. If it's the valves, you'll probably get smoking only on the overrun; i.e. when you open the throttle and then shut it off. Of course, you might just run it for a few miles. It just might need settling in. Lastly, Bonnies usually smoke on the left cylinder if they lean over too much on the centrestand. I think you said that the right side was really the problem. I assume you haven't got the bike on a slope or something when you're running it up? Hope this helps. Almost forgot, are you sure it's oil smoke and not just running rich?