Would a loose header/silencer collar make it difficult to start?

rodH · Mar 16, 2006

My bike has been very very hard to start as some of you may have read. Also, I have noticed over the past couple rides that it backfires a LOT!!

I did a search on this site and someone mentioned that the header bolts might be loose. Mine where fine, but I checked the seal/collar for the header/silencer, and guess what? No bolt, the collar was totally loose.

So, I am 100% sure that is why it was backfiring, BUT, would that make it hard to start (cold or hot??). I know back pressure is a huge thing for 4 strokes, so maybe that is one of my main problems with my starting troubles, or is it NO big deal (re:starting)???

Thoughts?

TimberPig · Mar 16, 2006

Well the behaviour you are describing is consistent with a lean air fuel mix. That can be caused by carb jetting that is too lean, or by an exhaust leak that has increased exhaust flow and thus leaned the mix out by increasing flow out without an increase in the air/fuel mix flowing into the cylinder. If fixing the exhaust doesn't solve it, look for too lean carb jetting, or possibly a carb to cylinder air leak.

Rich Rohrich · Mar 17, 2006

When the engine isn't running the pressure is equalized at atmospheric in the intake, the exhaust, and the cylinder. A loose exhaust has nothing to do with how the engine starts.

If you haven't checked the decompressor clearance and the intake valve clearance you are just wasting your time looking for little problems. Just check the valve clearance and be done with it. It's the single most common cause of the problems you've described on your CRF.

Would a loose header/silencer collar make it difficult to start?

rodH

TimberPig

Rich Rohrich

Moderator / BioHazard

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Would a loose header/silencer collar make it difficult to start?

rodH

TimberPig

Rich Rohrich

Moderator / BioHazard

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