Suzuki 2 Strokes

My 550 is back to its old nonsense of terrible slow to return to idle. Like about 10 - 12 seconds from 4,000 down to 1,250. Also the idle is poor. Wants to just fall off and die.
Is this a sign of too rich or too lean on the pilot jets? Everything is cleaned and re cleaned. There are no air leaks. I played with the mixture screws (ie. 1 - 1 1/2 - 2) turns out but that hs little or no affect.
I am currently 1 over on the pilots. I have a set of 2 overs that I took out a few months ago because I thought that was the issue. I did run great for a few months but it's back to doing its thing.
Jets are in increments of 2.5
You can bring the R's down easily by feathering in some clutch while in gear.

Do you think the temperature has changed enough to make a difference?

When you took out the larger pilots didn't you find that the syncronization was all out of whack. Then it ran OK after you matched the slides?

Now thst the slides are matched I would try #30 pilot just to see what happens.

Could be an intake rubber leaking between the carb and cylinder? An air leak or running lean will do that to you.

FINALLY got around to messing with it today. Then first thing I did was add a little more slack in the throttle cable. This seemed to help it a little but not much. I notice when the engine is cold and I'm running with choke, it returns to idle normally. With choke off it starts with the never ending SLOW return to idle. When the engine gets good and hot, it won't idle anymore. It just falls away and dies. It will hold 1500 for a few seconds and then just die off. Idles normally when cold / warm but not hot.
Correct me if I'm wrong but doesn't it sound like the pilot system is way too lean?
Son is coming over tomorrow and plan A is to check for air leaks by spraying WD-40 on the intake rubbers. I seriously doubt this will turn up anything as the rubbers 'appear' to be in really good shape. Plan B is to put the 2 over pilot jets back in. If that makes a significant change for the better ( I think it will), I might be looking at a set of 3 over pilots There is no reason why this issue can't be resolved. Other than that the bike runs great.
On a side note, the center cylinder smokes more than the outer 2. It also gets a slight oily build up on the chamber tip. Does this sound like a seal issue? Don't get me wrong. There is not a huge cloud of smoke. The outers have nearly no smoke at all and the center has slightly more. SRIS has been removed and everything has been plugged properly.

I think that the pilots are lean. It sounds as if you are headed the right way.



Lane

It is strange how the engine has been runing OK for a bit and now this problem again ?

Coyote wrote: I notice when the engine is cold and I'm running with choke, it returns to idle normally. With choke off it starts with the never ending SLOW return to idle. When the engine gets good and hot, it won't idle anymore. It just falls away and dies. It will hold 1500 for a few seconds and then just die off. Idles normally when cold / warm but not hot.
Correct me if I'm wrong but doesn't it sound like the pilot system is way too lean?

Nope. Exactly the opposite. I think the cold performance with the choke on may be a red herring here. If the engine idles better when it's cold and gets worse as it warms up, it's too rich. If it really was too lean, it should idle better when it gets hot. The slow return to idle is one symptom of uneven fuel levels in the float bowls. You could have a bad fuel inlet needle or a leaky float that's filling with fuel.

Stu

In another posting, someone had issues with the choke slides screwing up the works. Maybe they warrant checking here as well. Are they moving freely? Are they closing fully? Are the seal ends intact. That kinda thing. I'm sure that a solution will present itself. Cheers.
Fred

Zero progress today. I glanced at it once in passing. Son never came around and I spent most of the day trying to recover my wife's crashed computer. At least I was succesful at that.
Will keep you posted when, if / as progress is made.

Checked again for air leaks. Zippo. Checked to make sure all the slides were dropping all the way and together when closing the throttle. Everything working correctly.
Pulled the rack, removed the 1 over pilots and replaced them with 2 overs. This made about a 50% improvement. Set the air screws at 1 turn instead of the book 1 1/2. This improved it a little more but it's still lagging some on throttle return. Is it possible that I need 3 over pilots?

I have run both 27.5 and 30 pilots on my 550 and had no return to idle problems at all with either. Air screw 1.5 out.

I don't know what it is but I vote for air leak. Do you have new intake tubes? The old ones on mine looked good and were flexible but wtih them off the bike when I would bend them they had some pretty good cracks that showed up under stess.

I think it's strange it was running good for a while and now it's back to this behavior. My guess would also be a float or float valve. I'm actually having the same trouble with my 550 but I've figured out which carb the issues with. Now I have to sort out whether it's the float or the valve. I have spares of both so I might just replace them together and keep my fingers crossed.

Good info Mark. I didn't even think of the floats but that could be the case if a float had some ballast in it and was flowing some extra gas when it was not supposed to.

When I took my rack apart for the first time I had two floats with liquid in them. I have 3 good floats and I did replace the needle valves in all of mine. I used the viton tipped size 2.5 valves from HVC cycle. Not cheap but they work good.

Took it out for a ride today (it's way too hot here). Anyway, a few other things have notably changed since upping the pilots yesterday.
For starters it now idles perfectly from just after start up till it gets HOT. It no longer falls off a dies when it gets hot.
The slow return to idle all but disappears when the engine is hot.