VM18 Problems

[lazar26]

First off thank you guys, I’ve gotten through a lot of trash with my bikes!

This is my performance project, which wasn’t plug and play sadly lol.

I finally got everything comfortable and ready. My VM18 Carb seems to be running very rich? I believe it has a 70 main and a 30 pilot (stock from treatland). It didn’t want to start at all at first, but I eventually raised the C-Clip to the very top with the idle screw all the way in and then at least the bike idled, and great it seems. It revs to about half throttle when the clutch is disengaged before sounding choked out. When I put the clutch in and I try to ride it, it barely fires! Smokes a bit but I am running break in through (roughly 25-28:1, nonsynth) as it doesn’t have a mile on it yet. I know some will say 32:1 for break in but I found that mix to work for me for past motors so I used it.

I figured with my mods, it should be running lean! I do have a 65 jet I can try but I feel that won’t even be enough.

Any other advice? I threw all this together with the mods below. I didn’t attempt stock anything with it.

Specs:
Runwell Wildcat “pk80” short rod
YZ85 pipe (compliments of Steve!)
VM18 Carburetor
OZ Reed valve (23mm)
Windowed piston
Ported + Polished cylinder
(Homemade air filter lol, cut up some old socks and hose clamped two layers over as any filter

 

[Chainlube]

You should try to level out the carb before you get into it too deep, maybe an intake adaptor?

 

[lazar26]

You should try to level out the carb before you get into it too deep, maybe an intake adaptor?

You think having it kinked off slightly like that would have that much of an affect?
On my YD I had my NT carb at a 45 degree angle and tilted sideways at the same time and it ran perfect lol, I suppose this is a completely different system and more finely tuned.

I think tomorrow I may try out the NT with this reed setup to see if it’s the reed block maybe? I’ve heard a lot of people say reeds killed their performance (with an untuned carb I suppose) but I should try angles before digging into things like you said.

 

[Chainlube]

Spray a little carb cleaner or open but not lit propane torch by the intake while it's idling and see if the idle changes. That's all I've heard about reeds, is they seem to have air leaks. Add too much angle to the intake along with an air leak and it will be hard to tune. The bowl just never fills up properly. With the idle screw all the way in, it should be just screaming, especially with that pipe.
I have found that the NT carb is pretty good, and not hard to tune.

 

[lazar26]

Okay, I will try that out tomorrow morning. I’ll check for leaks at the very least and go from there. I did have to rebolt this reed up several times to stop gas leaking out of it.. which I thought I finally got it, but then it got harder haha. Thank you!