Poor idle quality after upgrades?

[EVOL Tweety Bird]

Hey all, Hemi all done and back in the bike. ARC billet rod (stock length),billet flywheel, 22 pound springs, mod 2 cam, 10 thous. metal head gasket, governor completely removed, valve lash set @ 3 thous. Also has the OldMiniBikes 140 emulsion tube,36 jet, high flow air filter, header with muffler, stock carb. Added a blow by fitting where the governor rod was and it ties into the breather tube of the head and into a breather filter.

Sounds pure "EVOL", and runs like an assaulted ape,but idle quality is pretty sad. Feels like it's not getting enough gas at idle, I had to crank up the idle speed to keep it running. But that in turn has the clutch trying to engage, so she doesn't want to coast at idle, keeps on pulling. Odd thing I did notice was that it runs faster when the choke is on, again like there's not enough gas flowing at idle. I did pull the idle jet and make sure it was open, and sprayed around the carb/intake to check for a vacuum leak.

Maybe pull the carb off and try and clean out the idle circuit? Any other things I might be missing?

 

[OUTLAWD]

Try opening up the idle jet? I went with 0.020" IIRC

 

[minibikin']

The stock idle is .018” I believe. OutlawD is correct, a .020” should get you close. I’m not sure what sea level you’re at but the .036 Main may be a little small. Go up in the idle, install a fresh plug and do a wide open run. Shut it down with no idle time and read the plug. I’d bet you need a little more fuel across the board.


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[EVOL Tweety Bird]

Will give it a whirl, thanks guys. By the way I'm at all of 200 ft above sea level.

 

[MattG]

Very similar issue with my bike, especially noticeable at 10-20% throttle. Otherwise runs very strong. I'm at the same sea level as you as well and also running a .036 main and stock low speed jet on stock carb. Based on the symptoms, I read its possibly the low speed jet so I ordered the .022 and .024 from ARC to try out. Before hand I also switched to a .037 main jet but it didnt affect my issue.

Jets should arrive early next week and I'll report back.

 

[EVOL Tweety Bird]

Keep us/me posted. I'm going to open up my idle jet to 20 and see if it improves any. If it seems to show some improvement I'll go the same route getting larger jets from ARC.

 

[EVOL Tweety Bird]

Well I have to admit I screwed up. I had checked multiple times for a vacuum leak, and not once did it change idle. Just now I was going to pull the carb off just to make sure the idle circuit was open. For whatever reason I decided to check one more time for a vacuum leak. I hosed the heck out of the carb/intake area with brake clean, flooded the area, and all of a sudden the idle cleared up. Odd, gave it another squirt and it didn't change. Tried a third time drowning the area and after a second it started to idle again. WTH?

Then it dawned on me, when I flooded the area, fluid ran around and down under, so I shot some stuff under the same area and it instantly idled up. Okay WTH again? Figured I better pull the carb and intake and check the gaskets.

Last one, the one between the head and intake plastic cover, some dumb asp had installed the gasket backwards. And yep it was leaking at the bottom. Flipped the gasket around, reinstalled everything, and she fired right up not using the choke and idles like a charm. Well if you can consider the rump/rap of a cammed engine a charm.

Took it out for it's first ride and holy bat sheep! This thing is scary fast. Before it used to haul at a decent clip, but now 1/2 throttle has it beat by a mile, I never even opened it up as I didn't have enough road. :scared:

There I said it, my Homer Simpson moment...DUH!!! :anon.sml:

 

[Havasu Dave]

Thanks for posting up what you found. I know I make mistakes all the time, sometimes costing me time and parts. Glad you found it. It's a pretty good feeling fixing something, no matter "who" broke it. :thumbsup: