Apollo DB-36 new carb and revving issues...

[ANDY9236]

I recently picked up a 2017 DB-36. been working on it the past few days and finally got my carb (mikuni clone off amazon, 30mm, vm26) and jets in yesterday. last night i went ahead and installed the new carb and switched out the 100 jet for the 110 jet, and pieced everything back together. whenever i switched the carb over i used the new parts for everything, including the spring for the throttle cable. the only part i did not use was the new elbow fitting into the head.

After getting it started and adjusting the fuel screw on the side of the carb, it idles really well. My only problem now is whenever it is idling and you rev it sometimes it will stay at a higher RPM anywhere from 5-30 seconds.
I have not adjusted the air screw on the bottom of the carb, but I do not know if i need to do that.

also i am located in baton rouge, Louisiana and from my understanding the 110 main jet is what i should be using if not the 115.

[JerryHawk250]

Sounds like you either have a intake leak or need to adjust the idle mixture screw on the bottom. Check to make sure the gaskets' oring and intake are not damaged. BTW Welcome aboard to another Louisiana neighbor. :hi: I'm down in Houma.

[ANDY9236]

Sounds like you either have a intake leak or need to adjust the idle mixture screw on the bottom. Check to make sure the gaskets' oring and intake are not damaged. BTW Welcome aboard to another Louisiana neighbor. :hi: I'm down in Houma.

thank you, not a whole lot of these bikes around here.
when i get off work today ill try adjusting the mixture screw on the bottom. i ended up using the old gaskets and orings from the manifold because the new ones did not fit the old manifold. the carb itself had a new oring on it.

[JerryHawk250]

I've only seen one other Chine bike around here and it was an old beat up one but was still running.

[Weldangrind]

I'm with Jerry that it could be a vacuum leak; I've seen that on two different China machines. In my case, it was where the intake tube met the head. The o-ring groove was cut too deeply in one case, meaning that the o-ring could not properly squish against the aluminum. In the other case, the o-ring had slipped out of the groove on assembly at the factory, so only part of it was installed properly.


With the groove that was cut too deeply, I used two O-rings to temporarily solve it. The proper fix is to sand down the aluminum surface (ideally on a bench-top belt sander or on a milling machine if you have access) to the point where the groove is much shallower. With the one where the o-ring had popped out on assembly, I just replaced the o-ring. In both cases, revs settled quickly after repairs.

[ANDY9236]

I think I found my problem. The plastic “shim” (for the lack of a better word or what it’s actually called) inbetween the carb manifold and the carb itself was cracked in half.

[ANDY9236]

I just bypassed it and put the gasket on so now that manifold elbow bolts directly to the carb. Not sure what that shim was really there for. Any ideas?

[pete]

I just bypassed it and put the gasket on so now that manifold elbow bolts directly to the carb. Not sure what that shim was really there for. Any ideas?


the idea of it is to stop / reduce heat transfer and vibration to the carb...



..

[Weldangrind]

^ this.


It's often called a phenolic spacer.

[ANDY9236]

i repaired the spacer as best i could using some hightemp epoxy. new one is on the way along with a new, longer fuel mixture screw with the finger dial on the bottom. right now it runs fine and idles fine, but when you rev it they still stay high, higher than before. I flipped the choke switch, causing it to rev high and then turned the choke off and it also stayed revving high. I figure doing that eliminates the chance of there being a throttle cable issue.

Hopefully the new spacer will fix this issue, along with the new screw that will make it easier to adjust the fuel/air mixture.