help with 19mm carb tuning... wot mis fire?

[yama916]

just yestarday, on the way home, my zuma just died ( for 2 days prior to this zuma was stumbling at wot and it was getting worse). i had to push it home a good 30min walk...

i thought the plug was just dirty and i had to make the zuma run leaner. cleaned the plug really good, installed a size smaller jet and tried it out. accelerate good, idle's good but once it gets to the high rpm WOT condition it starts to miss and stumble... it keeps doing this... some times it back fires and makes loud sounds.. so from that i thought maybe its running too rich at wot.. the spark plug is actually brown now... j

when i turn the throttle down a little, it seems to run better but obviously not as fast...

any idea on this? im gonna go pull the carb out again and inspect the jet and things.. just cant figure this out...

:mad:

[pinkymingeo]

Which carb? If it's the Arreche, with stock airbox the main jet is 80, 20 pilot. If you think you're lean at WOT, which is what it sounds like, try 85/15.

[yama916]

hey thanks for the tip... but just finished working on it... finally it runs perfect!!!!

the problem with mine WAS the darn plug... it fouled and i guess even with all the cleaning it still is bad.. cant figure it out though..

so with 2nd stage, im using 85 main, pilot i dont have any other ones so im using the one it came with, stock air box has four 1/2 inch holes. it runs PERFECT!!!!

ended up using a BPR 7HS plug out of my 50cc because i didnt have an extra 9HS.. but with the 7HS, it runs great... the 7HS seems to enter little deeper into the combustion chamber too..

as for the malossi vario it came with some heavy weights.. so i took the weights out of the 3 weights and put them back with no weight inside.. really its just like using three heavy weights.. but RPM is perfect at the start, and it stays in the power all the way to top speed.. it could launch a little harder but with the stock clutch.. oh well, ill replace that when it wears out..

[yama916]

so forgot to mention, if some one out there buys a stage 2, and want to go the cheapest route.. i think i found the cheapest way, modify the stock box, and modify the weights in the vario.. that is if you bought the malossi kit and doesnt come with any other weights... this set up runs great, im sure not up to jereds speed but for what the cost of the kit only its relatively cheap and its much much much faster than stock.

i think next chepest mod would be to get an upgear kit.. this motor feels like it can definetly push a little higher gear!

[XPS1210]

this on an airsal...? it runs higher compression and you need the cool plug the 9 heat not the 7 heat....

change it when you can....

[pinkymingeo]

Also, the stock plug is a BPR. That P means it has an extended tip. You should not have that plug in a 70cc cylinder.

[cant drive 55]

Yea, running a plug that extends into the cylinder more is a very bad idea. You run the risk of the piston coming up and hitting the tip of the electrode. If that happens then you might have a little piece of metal flying around in there. ;no

[jeffrop]

Which carb? If it's the Arreche, with stock airbox the main jet is 80, 20 pilot. If you think you're lean at WOT, which is what it sounds like, try 85/15.

I have the stage 2 w/Arreche carb on mine and I don't know of a "20 pilot". What is that? Mine is running bad everywhere BUT WOT. Got the lighest weights(Silver) in the rollers with the new Vario. I also put the Red clutch springs on the stock clutch.

[pinkymingeo]

The carb has two jets, main and pilot. The pilot, which you have to pull the float bowl to access, controls the bottom. The main controls the top end. The air screw (opposite the knurled idle adjuster) changes pilot mixture. The needle controls the middle. I've only tuned the 19mm with stock airbox. It would run with 80 main/20 pilot or 85/15. I finally settled on 80/20, air screw 1 turn open, needle richest. This was a little rich in the middle, but was safe and ran well. Needle middle clip might be better for you. Trial and error.

[mikhail masevich]

Im premixing but not sure that my oil pump is out im running a derbi carb in my zuma it smores and spark plug is kinda white

[pinkymingeo]

You have to remove your oil pump, or at least it's drive gear. You're getting way too much oil, which leans your mixture. You won't be able to tune your carb until you get your mixture right.