e50 with Treats Reed & VM20 carb issues

My set-up is a Puch Magnum, E50 motor, a Treats 45mm Reed Kit and an Estoril Techno exhaust and 16x40 gearing. Pietcard CDI timing set at 15 degrees at idle, goes to 18 degrees with some throttle.

I have a VM20 carb (UNI filter) attached with an MLM Intake.

Using a 22.5 pilot and started out with a 180 main which I thought would be too rich and I'd work my way down through the main jets while tuning the carb.

The bike starts great, seems to run well - but when I check of the plug after WOT for a few minutes its white, several runs and still white - electrode looks silvery too.

Rechecked for air leaks with starter fluid and found none, double checked torque on my head bolts and checked intake/carb/filter bolts where tightened enough.

After all that and a few more runs its still running lean. Went up through jets all the way to a 220 main and the plug is still white. Engine still runs fine, and temps never go above 300f.

I've searched through the wiki and forums here and read about the vm series on other websites - no luck. Everyone else seems to be running similar setups with a 160 main (or less).... I'd be afraid my motor would seize if I even tried that. I'm obviously missing something, anyone see anything I missed or am doing wrong? Or have a suggestion on something else I can check or change.

Thanks! (edited)

Re: e50 with Treats Reed & VM20 carb issues

Probably Fred /

Goggle plug chop chart

Your supposed to look at the ring down below not the electrode

and only one run at full throttle

Re: e50 with Treats Reed & VM20 carb issues

155 main is what all my friends run on there VM20 pretty much the same setup. I run 160 main on my VM but my kit a bit ported and its a Tomos. You should be running hotter then that. 350 to 400 air temps effects your power band of your bike/pipe.

Re: e50 with Treats Reed & VM20 carb issues

I have 2 of these setup right now....

what head are you running?

here's my setups

Hi Hi comp head

70 reed treats kit

4 pedal reed block


Idle 22.5 or 25 (one of each in each setup)

Needle 4th position

2.0 slide

Main Jet 170 and 175 (one on each setup)

Timing 14 degrees (one is using points and the other powerdynamo)

MLM cali Pipe (one side bleed and one straight pipe)

If you are running a hi comp or hi hi comp your timing needs to be at 14 degrees (especially as the RPMs increase) to control temps and if your timing it too far advanced it will have issues giving you a good plug chop it may even start to melt your electrode on the plug.

also your air mixture screw on a VM responds reverse to a PHBG.

turning your air screw in on a VM will Richen your circuit.

Re: e50 with Treats Reed & VM20 carb issues

I tried the treats cdi with pietcard 2041 and it advanced too. Now I'm running an hpi mini. I have that kit and carb with polini flat reeds and an MLM cali. I'm running a 210 main jet, if that helps any.

Re: e50 with Treats Reed & VM20 carb issues

Thanks a lot everyone, will try it again this weekend.

Re: e50 with Treats Reed & VM20 carb issues

Ross, did you have any luck this weekend figuring things out?

Re: e50 with Treats Reed & VM20 carb issues

Mikey Antonakakis /

My Tomos has a similar setup I think, 45mm Alukit reed with VM20 and Techno Circuit. Runs well right up to 45mph, not slow. But it likes big jets (210 usually). I'm sure I probably have an airleak somewhere, as I never changed seals. But it runs and runs and runs. Always starts first kick. I've just been ignoring the fact that I am running bigger jets than almost everyone else, it runs best this way. Maybe one day I'll go and actually check the timing and replace the crank seals, but it's been remarkably reliable. No issues with probably 600 miles on the kit, ride WOT/full speed everywhere.

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