76' cyclone 440 high idle

larky · Post by **larky** » Thu Feb 07, 2008 3:20 pm

Just got done putting all the right jets etc. back in my carb and now I can't get the idle to come down. Its at 3000 rpm no matter what I do with the idle adjustment screw.
the carb identification numbers are 34 124 (mikuni)

main jet 410 was 300
pilot jet 20 was 30
needle jet Q-0 was correct
jet needle 6fl14 was correct
air screw 1 turn out
throttle valve 3.0

the only other thing i can think might be causing it is a possible carb-to-intake gasket leak. whats a good way to check for that?

should I go back to the 30 pilot jet?

one more thing, it doesn't have much top end. that could be a weak primary clutch spring right?

thanks for any help you guys can give
Matt

larky · Post by **larky** » Thu Feb 07, 2008 4:02 pm

the throttle cable adjustment screw is screwed all the way in. I haven't taken the air box off yet to see if the throttle valve is in fact retuning back to the bottom, but I can do that easy enough. what do you think about going back to the 30 pilot jet?

the top end issue: I know I have to get into the chain case and inspect, while I am in there I will check the gearing. if that turns out to be correct, how can i check the clutch spring? just replace it?
thanks
Matt

larky · Post by **larky** » Thu Feb 07, 2008 6:52 pm

went and checked, throttle valve appears to be returning back to the bottom.

harleysportster · Post by **harleysportster** » Thu Feb 07, 2008 7:17 pm

Matt,
My cyclone is set up with the factory original jetting and runs just fine. I think you have another problem, maybe a warped carb insulator block.
What condition is the fuel pump, needle/seat or float level.
Spray carb cleaner around the carb insulator block with the engine running and see if the rpm's change.

larky · Post by **larky** » Thu Feb 07, 2008 7:47 pm

harley: the needle and seat looked good. both the needle jet(#11) and the float needle seat (# 34)assembly seem fine. everything is clean. I will try the carb cleaner trick and report back.

larky · Post by **larky** » Thu Feb 07, 2008 8:24 pm

sprayed carb cleaner on the whole thing..........no change. I walked away from it while it was running and then it idled down but became erratic. it stayed like that for about two minutes, then was idling high again. I think I'm going to take a break from this thing for a few days. I'm getting pissed.

another strange thing: something made me pull the plugs and have a look. the pto side looks normal, but the mag side looks like brand new. Now a little history, I recently put all new gaskets in it after a pto cylinder melt down. I replaced the burnt piston and cylinder, the gaskets and did the pressure test. turned out perfect. compression on both cylinders is 150 #.

on what part of the sled should i start smashing my skull?

harleysportster · Post by **harleysportster** » Thu Feb 07, 2008 9:00 pm

Matt,
Did you replace the missing air-jet?

larky · Post by **larky** » Thu Feb 07, 2008 9:26 pm

no, I was under the impression that it was the carb that was changed in which the air jet had been eliminated.
numbers stamped on carb body are 34 124

harleysportster · Post by **harleysportster** » Thu Feb 07, 2008 9:35 pm

Matt,
With the carb jetted using the 76 specs, the air-jet is needed. The carb is problably getting to much air in the idle circuit.

larky · Post by **larky** » Thu Feb 07, 2008 10:11 pm

I hope its that easy. what size air jet should i get? I live at about 1000 ft above sea level(if that matters)?

harleysportster · Post by **harleysportster** » Thu Feb 07, 2008 10:24 pm

M66499, Mikuni 0.5

larky · Post by **larky** » Thu Feb 07, 2008 10:35 pm

Thanks again harley. I will try that and let ya know. I wasn't sure if I saw threads in that hole or not. I'm going to remove the carb completely and get it under some good light and verify if there is threads in there or not