[Guest]

I have a tuning problem with my 1986 Indy 400. I can't set the idle speed after the engine has warmed up. After the engine has warmed up, the idle drops to around 1000 rpm and bogs when you open the throttle. You must first open the throttle untill the idle picks up to about 2200 rpm to eliminate the bog. However, when it comes back down from a run, the idle drops back down to 1000 rpm, no matter where the idle screws are set at. Other than that, it runs fine. Any ideas?

 

[Polaris-Man]

First, clean the carbs. Then check the sync, then check the air screws.

If it's bogging when you punch it from 1000 RPM, there is no way to fix that, you should just feather the throttle until it's around 3000 RPM before punching it, that way you get a better start.

When the engine is warm, it's supposed to idle lower then when it's cold, my '97 (with '98 engine) XCR 440 idles around 3000 to 3200 RPM and when it's warm it idles around 900 RPM.

"Might Be Crazy But I Ain't Dumb" - Cooter

 

[TriumphoverU]

I would pull the All the jets out of the carb(s) and make sure that they are all clean. I agree with polaris man in the fact that a warm engine will idle slower than a cold one. But adjusting the idle screws should allow you to adjust your idle where ever you want it to be. I would bet on either a half plugged jet or plugged passage in the carb. I found one in my last sled that was plugged and had similar symptoms as yours does. To unplug it i ended up totally dissasembling the carb and soaking the main body of it in carb cleaner for about 24 hours. Then i took compressed air and blew through each passage. That solved my problem

Hope this Helps,
TriumphoverU

Studs and gauges are on the way!

 

[Polaris-Man]

Yes, Triumph is right, you should be able to set it wherever you want. At idle, I'd guess the pilot jets probably have garbage in them. usually a shot of compressed air is enough to clean them out, but sometimes, depending on the junk caught in there, you have to soak them quite well before it becomes completely clean.

"Might Be Crazy But I Ain't Dumb" - Cooter