I’ve been searching everywhere but I can’t figure this one out. So a little back story: I got a good deal on this quad with no compression. Somebody forgot one of the dowel pins for the cam bearings and the cam walked over and broke the sprocket and chain. So I bought a 440 kit and a new head and pulled some left over parts from an old build. Got it all back together and I’m having a few issues that I’ve never seen but right now my main problem is that I cannot get this thing to idle without giving it a quarter or so on the throttle lever. The idle adjuster is maxed out and it won’t idle in this position. I HAVE to give it more throttle at the lever to get it to just barely idle.

Stock carb. I’ve tried 38, 40, and 42 pilot jets all with no effect on idle. I cleaned the carb very well and installed a fresh rebuild kit with brand new Keihin jets. The choke lever has been removed. (and plugged) Accelerator pump works perfect and bike starts easy cold or hot. (As long as I give it a few squirts)

K&N filter with holes drilled in lid, snorkel tube plugged off

Fresh 440 kit from Niche Industries (Ebay) advertised 10:1 ratio. This piston is flat top I’m not sure if it’s actually 10:1. it seems to be 9:1. Compression test shows 120 psi so either it’s low or not 10:1. I haven’t been able to give it a proper break as I have yet to get the carb tuned because of this idle issue.

Fresh head from Niche as well. Used valves.

Here’s the other strange issue I’ve having. I noticed when it is running, it has a slight oil leak from the head cover gasket towards the exhaust side, just above the header. After shutting it off and cleaning the oil and letting it sit over night, I came back in the morning to find that it continues to leak very slowly while not running. When running however, it leaks faster and I can even see very small bubbles coming through the oil. Not sure if there’s compression blow-by pressurizing case. The gasket must be bad, although it looked to be in perfect shape and I used a spray on copper based gasket sealant.

Anyway, thanks for reading and thanks for any tips or thoughts on the carb issue. I took the carb off and I’m going through it one more time to make sure everything is clean! I’m stumped!