Carb drilling

So, I took my 12mm carb and drilled it out to 19/32. I sanded it down smooth everywhere, and it looks really good. I took everything out so it was just the carb body, so I didn't hit the brass piece. I put it on my maxi, and it won't run. I think I have the right jet, it starts but won't idle. I can get it to run if I give it gas, but even then it dies out after like 5- 10 seconds. Any thoughts?

Re: Carb drilling

i'm not familiar with puch carbs but on my tomos dellorto carb i drilled mine out similar but i removed my emulsification tube i think thats the brass tube your reffering to on your carb, when i installed it i made sure that the tiny holes faced the flow of air when the engine is running, i'd make sure the tube is clean and clear of burs with a piece of mechanics wire and the holes are clear as well and facing the right way, also make sure that your float isn't stuck closed preventing fuel or enough fuel from entering the bowl and getting drawn up the tube. maybe the float adjustment became bent. and of course check your main jet and any other holes with the wire and blast it out with some carb clean usually its something stupid that was overlooked when assembling the carb that is an easy fix. good luck

Re: Carb drilling

I was referring to the "jet holder" that goes up the middle of the carb. Is that the piece? Mine doesn't have tiny holes. Everything is squeaky clean, no meal shavings or dust or anything. Right now we are experiencing a ridiculous ice storm, so I can't deal with it today, but if anyone else has had this problem, I thought there might be an easy/clear issue.

Re: Carb drilling

what size jet are you at? Have you tried varying the airflow like seeing how choke or no air filter affect its starting/running? how does it do with starting fluid ?

Re: Carb drilling

stock e50 with biturbo pipe and high flow air filter

jet = 76

choke in or out doesn't make a difference. no air/ stock air doesn't make a difference. Haven't tried starter fluid, what would that do? Is it possible to ruin it by drilling?

Re: Carb drilling

starting fluid will pretty much get anything that is correctly timed to run- if you turn off the gas flow and spray in starting fluid and it starts and runs better than off of your gas, you know your jet size is off--just spray it into the airbox opening or carburetor inlet, let it evaporate for a few seconds and then try and start it. beware of wet plugs, from a flooded cylinder, they will throw off results of any tests you might be doing. wet plugs threw me for a loop earlier this winter, everything was even set up to stock spec and it wasn't wanting to start even on starting fluid and it turned out I was trying too hard to start it, the plug got wet after the cylinder flooded then just didn't want to start, I threw in a fresh dry plug and it took off. try a fresh plug maybe it'll help

Re: Carb drilling

Jet sounds awfully large for a stock e50. try in the 64-70 range

Re: Carb drilling

daFishSticks /

yeah that jet sounds huge.

Re: Carb drilling

Well, I have a 15mm Bing on my newport with a stock e50 and biturbo with a the stock air box (I want to get to the high flow filter, but that is another long story) and that uses a 74 with the stock air box. Thursday is supposed to be not freezing ("not freezing" is the best you can hope for in March in upstate NY) so maybe I'll get a chance to play then. I have every jet from 56 - 88 so I'll try em all and I'll post my results. Thanks!

Re: Carb drilling

Does the throttle slide still block the bore completely when throttle is closed?

Re: Carb drilling

Bings dont have an emulsion tube that you can take out. Just a little brass nub where the throttle slide needle goes in (that thing you dont wanna hit with the drill). It was working before right? Can you post any pics? Maybe you just got some fillings in your jet. Lotsa people drill out there carbs, I am sure you did a good job and that it will be fine and that it is prolly something simple. Keep us posted.

Re: Carb drilling

dude i have a maxi with a tecno boss, and everyhting else is stock, the 68 jet i have on it is too big, i think you are just using too big of a jet. i am not a moped god or anything like that, i don't even consider myself a newb, but i would say jet is way too big.

Re: Carb drilling

you're probably around a 72 or a 74 with low gearing.

you probably have an air leak from not putting it on right. either the clamp, manifold gasket, top of the carb, or something else. I usually go that big on my bings, and they dont leak.

Re: Carb drilling

The news is in and I didn't believe it myself. First off, my float was sticking, and my carb was "bleeding" gas like crazy. That might have been part of the problem. Anyway, with the high flow air filter, biturbo exhaust, and the bored out 12mm bing to around 15mm, I tried jets 70 - 82. The best results were with the 78 and 80 jet. Surprising at first, but there are two things to consider with my setup:

1.) It was 40 degrees here today. I read somewhere that 20 degrees = 1 jet size, which means come june I'll need to down-jet 2 sizes to a 74 or so, which makes more sense.

2.) Gearing is 14 x 38 does that matter at all.

Thanks everyone for your help and suggestions.

Next up - porting :)

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