Lean when leaning

[notalec]

I've got a strange one for you. I recently put a used motor into my 92 k75. Don't ask me how but I managed to lose a wrist pin on the original. I guess that's why it was only a few hundred bucks. I got a great deal on a used motor. Got it swapped out, and I am still under 1000$ on a pretty cool little bike.

Ever since I put the new motor in I am getting some strange behavior. Whenever the bike leans left I get about 500 more RPMs. Whether it's on the side stand, or if I am carving a turn.  I am thinking it might be a worn out spring on the MAF. The enigne I bought came with one (and throttle bodies, and a good clutch and a bunch of other stuff for 150$!!!) so I just used that one. I am thinking of swapping it for the MAF off of my old engine.

Anybody got any other ideas?

[Scott_]

That would be a simple test at no out of pocket cost.....and not a bad idea.

[Martin]

With the bike idling on the centre stand try moving the handle bars left and right. If the revs increase the throttle cable is pulling on the throttle body linkages.
Regards Martin.

[notalec]

Figured it out. it was a badly damaged crankcase breather tube. After replacing I realized I had the idle, "choke" and fuel cutoff all set way off to compensate for the air leak. Good to go now. Bike runs much much better all around.

[Laitch]

Figured it out. it was a badly damaged crankcase breather tube.

Thanks for updating this thread, notalec. You have an explanation for why left-leaning the bike would cause changes in idle?

[notalec]

When it was leaning left a large crack in the crankcase breather tube opened up more. Which in itself isn’t a huge amount of air. But combine it with the way the bike was tuned to compensate for the damaged tube in the first place it made quite a difference.