Problems Continue

[sidecarKev]

Took some time tonite to look into my problems again. Bike starts right up no problem with enrichener all the way out. Slowly revs up and kicks out enrichener. Will sit and idle for about 30 seconds then it slowly revs up on its own. Next problem, ride the bike for a minute and it no longer idles. To take off you have to rev it up to about 4000 to keep the engine from dying. It will only get up to 4000 if you kinda baby it up there, slowly. If you give it quick throttle it dies. Get it over 4000 and everything is good. Lots of power. I have checked the pickups about 10 times. Spark at all cylinders when testing. Carbs have been CLEANED twice, floats set,new plugs, new filters, pretty much done everything I can think of for now. Air mixture screws out 1 1/2 turns. Checked the plugs, all are tan colored. Sometimes it sounds like cyl 3 or 4 isn't firing, sounds based on exhaust sound and feel. I know, I know lots of issues. Any feedback would be appreciated.

[2fast]

Check the pipe temps and see if they all get to about the same heat range. It sounds similar to mine when it was running on 3. If they are all hitting, power should not be an issue.
2fast

[randy]

Sounds like a vacuum leak to me. Check your hoses for cracks and the base of the boots at the cylinder head. A quick and dirty test of the boots is to spray WD-40 at the joint while running. If the idle rises, you've got a leak. HTH

randy

[sidecarKev]

Well all pipes are hot, but that may be from higher RPMs. I'll try checking the pipes right away at startup. I tried the WD trick to the intakes. Nothing. When I had the bike apart I inspected the intakes, no cracks that actually went through. I did seal the visible cracks up though. Keep the suggestions coming, we'll see if there is something I missed.

[sidecarKev]

I stole this text from a post by Ken Talbot.:

To work the pilot screws without a Colortune unit, you want to get the snyc as close as possible and the idle speed well below 1000 - down to about 600 or 700 if you can manage it. Then, one screw at a time, turn the screw out a good couple of turns and listed vary carefully for a change in idle speed. You should hear the idle pick up just a bit, then start to fall off again. Carefully, turn the screw back in until you hear that sweet spot again, and turn just a bit past it. Tweak it by turning the screw out and in so you absolutely nail down the sweet spot. Repeat this for the three other carbs. If, as you're doing this, the idle speed climbs up anywhere near 1000, bring it back down again. You want the lowest possible idle speed so you are truly running on the pilot circouit, and not moving onto any of the mid range.

When I went through my carbs I set my pilot screws to 1 1/2 turns out, and never touched them again. I did do a static bread tie synch. It says to get the idle speed below 1000, I don't think I can get that to happen. When I try it just coughs and sputterand dies. I'd say I could maybe get down to 1200. But reading through past posts I see that similar problems have been fixed with pilot screws. I guess its something I haven't looked at yet.

[randy]

OK,

How about the tops of the carbs. Any leaks there?

Randy

[sidecarKev]

I'll have to check that one out.

[TheDjost]

To me, it sounds like it's running lean. And 1.5 turns is not much. Try to back the pilot screws a bit more... like around 3 turns out, and try that. In my book it's better to run the bike a bit rich than a bit lean. It's a heat thing.

Warm up the engine, get the idle as low as you can and turn the idle screws out one turn per carb. The idle should pick up a bit, so turn it down again. As low as it will go. Keep at it until you find that "swet spot". I found that in some cases, I had the pilot screws 6 or even 7 turns out. In those extreme cases, a couple of gas tanks with double doses of carb cleaner additive and I started running rich again at idle, so back in came the pilot screws. That means that the pilot circuit was still gummed up a little. I wouldn't worry under 4 turns out though. These are old bikes and some adjustments that need to be set out of the 25 year old specs can be expected. Just don't go too far, and once you are done, check plug color after half an hour of idling with new plugs. That will give you an indication that you are running spot on.

-Justin

[mn2346]

Originally posted by sidecarKev
I stole this text from a post by Ken Talbot.:


When I went through my carbs I set my pilot screws to 1 1/2 turns out, and never touched them again. I did do a static bread tie synch. It says to get the idle speed below 1000, I don't think I can get that to happen. When I try it just coughs and sputterand dies. I'd say I could maybe get down to 1200. But reading through past posts I see that similar problems have been fixed with pilot screws. I guess its something I haven't looked at yet.

It might be perfectly normal to not able to idle below (or at) 1000 before sync. IF (and this is a real big if) everything else is OK. You might need to sync the carbs at the lowest possible idle and then take multiple rounds until you can achieve the 600-800 idle level. Then raise the idle a little to achieve the idle you want.

Is your XS modified?
With a std. setup you should not need to change the jetting.

-M

[randy]

And,

Your bowl vent tubes ( the hoses above the trottle shaft ) need to be vented to the atmosphere. They are usually ported to open nipples on the air box. On some later air boxes, these nipples are plugged.

So...

If you've changed air boxes, check out your nipples.


OR...

If youve deleted the air box, make sure your vent hoses are free to breath.

Randy

[allornot65]

Kevin,

I am not a mechanical genius but the PO for my bike (78E) had the exact same problem. He rode the bike from So. California to here in Albuquerque(from sea level to 5,00Ft). After he arrived the bike would not run properly under 4000 RPMs and would stall when ever he stopped. He had to rejet the carbs. After he did that, the carbs have not been touched in 9 Years. I don't know if this makes sense but that is what he told me.

Good luck

Doug

[randy]

Key phrase here is:

"carbs have not been touched in 9 years"

It's time they were touched.

Check for a vacuum leak.

Randy