Kick-backs for dicussion...

[paulkx5]

I experienced what I think is the same problem on my 90, when I let off the gas it would pop and there was a power surge, bad enough that the bike would buck pretty hard. In my case this was caused by a rich condition in the carb's idle/ slow circuit. I changed the slow jet from stock to a leaner jet, I can't remember exatly what size though, this completely cured my problem. Might be worth a try. Good luck.

[kawdude]

I personally will try anything to make this condition go away.  It's annoying as hell.

[paulkx5]

kawdude,
 I wish I could remember what  jet size I ended up with (been over a year), but I think it was a 52 or even a 50. I went through several progressively smaller jets, and the problem kept getting better, and it finally went away with just the jetting change.  Hope this helps.

[kawdude]

That's ok.  Mine currently has a 162 main with a 62 pilot with the clip on the top notch so something definately isn't right.  I personally think that it's very rich.  Has no go past mid throttle and lots of splooge.

[paulkx5]

Ialso had to drop my main jet several steps to get my plug reading correctly. This helped a lot with power and with the splooge.
As far as lacking power above mid throttle, have you checked your KIPS valves to make sure they are timed, and/ or not sticking?

[YUNGGUNNAZ]

good point paul on kips valve.put the cover and drop pipe and a light open and close valve by hand noticing position of cut out of the drums as well as the movement of the exhaust flap.stay small on the pilot jet,noticing idle and watch oil mixture.i personally don't like the bel-ray.seen a lot of gummed up systems.this is to say the rest of the top end is in good shape.

[John]

Kawdude,

A simple test; adjust the idle screw all the way out so the bike does not idle - at all. If you then ride the bike and it still bucks you have a carburetor problem as in worn out throttle.

The engine should not get any air/petrol mix ergo should not be able to ignite.

//John

[kawdude]

Good points.  One thing I notice that may or may not be related is that the needle on the slide moves up and down within the slide.  Not a lot but enough for me to say that has to effect something.

Kips valves seem to be in good shape (surprisingly).  How far does or should the lever from the lower case move?  With the jug off I see that a lot of movement is needed to open the side valves and raise the center because of play in the KIPS gears.
 
Currently the idle screw is all the way in and the bike "kinda" idles.  I will adjust it and see what happens.

[John]

Kawdude,

With regards to the carburetor, the needle doesn't have anything to do with the lower rews but it does affects lower-mid / mid-high (you might call that middle rews?).

I had the very same symptoms as you did until I changed the carburetor. Tried it all, tweaked the timing searched for leaks etc. but fact remains, the engine does not ignite unless it's got air/fuel...

Changing the idle jets to really small ones will also work. No fuel - no kick-backs...

If you dismount the carburetor and check the throttle-play when the throttle is mounted you will probably find it is not a perfect fit... That?s causing your problem. It sure caused mine.

I do agree, it's very frustrating when the bike almost throws you off the road just because you do not rew it.

//John

[kawdude]

I'll certainly check what you suggest.  I think it's odd that the idle screw is all the way in now and it barely idles.  That along with the needle bouncing up and has got to cause a problem somewhere.  I agree that the needle does not come into play until mid but should the needle move up and down in the slide.  Thoughts on what this sloppiness would do.