FZRSupport: the FZROnline Archive

Ok I rebuilt my carbs with new gaskets and everything idles perfectly. Now it seems to be stumbling after 4k and poping slightly through exhaust. I set the mixture screws (pilot fuel screws) to 2.5 turns out. It has alittle greyish exhaust smoke when its being gassed under load but none while sitting in the driveway. I think its lean but not sure as the poping points to being rich. It was really puffing whitish grey smoke before I got the carb gaskets in it and it would rev on its own (leaking inside the carbs). Now idles about pretty smooth and does not need choke to idle. My testpilot/guinea pig said it feels like loosing power after 4k.

Check all exhaust connections, could be leaking somewhere. Also what are the needle clip positions set at ? Usually there are either 5 or 6 positions, depending on whether it is DynoJet or FactoryPro jet kit. Or is it stock (?)

Did you sync the carbs ? Did you fool with the float heights at all ? Dr. Rockso has a thread about this somewhere, where he adjusted the mixture screws about 20 times. See if you can find that thread, maybe it will help. He gives the correct settings in that thread.

If you crank on the throttle harder when it stumbles after 4k does it eventually clear out and pick up power / speed ? Or does it continue to die ?

If your jet kit is from Factory Pro they have a website with good detailed information, if you still can't figure it out, they might have a phone number.

I was reading the ultimate carb thread in the archives and someone mentioned a way to check if it was lean. I adjusted idle to 1k and blipped throttle several times, there was no hesitation or lag or otherwise getting back to idle.

The jets/needles are stock. put new float needles in but no adjustments to height, carbs are not synced.

when I was messing with it just now I revved to 5k + and no hesitation/stumble or smoke. Seems to be having issue under load only.

Yeah, i had that a few weeks ago. It must have load to show up usually. It probably just needs the needle clips moved 1 or 2 more steps towards LEAN. I forget which direction that is... and with stock needles... argh, I've ONLY had the jet kits so I really don't know. Find that post by DR. ROCKSO and you should be golden. I think RageDigital posted some pictures of needles there with full explanation.


viewtopic.php?f=8&t=571 TRY THIS ONE ALSO.

White smoke is usually an indication you are leaking radiator fluid into the engine and burning it. It may take the load to get it to happen which is why you are only having the issue under load.

Beyond that, grab a IR heat gun and tune the air/fuel screws off header temp. If you are stock and all you did was rebuild the carbs and didn't change anything that will help along with a carb sync. The sync does wonders.

thatkid wrote:White smoke is usually an indication you are leaking radiator fluid into the engine and burning it. It may take the load to get it to happen which is why you are only having the issue under load.

Beyond that, grab a IR heat gun and tune the air/fuel screws off header temp. If you are stock and all you did was rebuild the carbs and didn't change anything that will help along with a carb sync. The sync does wonders.

Well the only thing is that it was blowing the grey white smoke at idle until I put the carb gaskets in. now its only under load, I still think its carb related, but the sync is def in order, where to buy the sync checker?

what temp am I shooting for on the headers?

I had a shop sync mine, I don't know how complicated it is, but seemed too complicated for me. Fraidknot (on FZR Archives I believe) has a design for using bottles and tubes to sync the carbs. I never really looked into it, but others claimed that it works great. Go search for that or get a shop to do it is my best advice. Easiest way is probably just to search thru the last year of FRAIDKNOT's posts, use the Advanced Search with a key word CARBS or something to that effect.

As far as header temps, I have no idea. But don't get the cheap infrared gun I got, it only goes to 250 degrees I think, and the headers get a lot hotter than that.