jetting maybe?

So i started my e50 maxi today for the first time since rebuilding it and it starts right up and idles.but when you go to take off it bogs when you give it throttle but if your easy on the throttle you can slowly wind out.its a 15mm bing and boss.50cc intake and exaust ports matched with super stuffed crank and uch running a 74 jet is that too big?

Re: jetting maybe?

Are you still using the stock intake?

Sometimes descriptions are hard to guess without seeing or hearing. A bog could be too lean or too rich.


Your carb literally mixes gas and air. you just need the correct ratio.

One thing you can do is put the bike at idle.

Partially cover the carb's air intake inlet while you rev and see if your problems gets better or worse.

If covering it up makes it better, that means you are getting too much air. You should probably up jet so that you are getting the right amount of gas for the amount of air your bike will take in.

If covering it up makes it worse, then down jet some.

Also, I haven't played with a bing in ages (I use phbgs on all my bikes).

If you can change the needle setting, you should look at where that is at.

This is very general, but hopefully it is better than nothing.

Re: jetting maybe?

74 sounds approximately reasonable for that setup, so if it's off, I don't think it's massively off.

Have you checked for air leaks? That's really important on a new build, and it could be responsible for the bogging.

Also, did you have that kit/carb/pipe setup running on that bike before you rebuilt it, or is the whole setup new? If all of those parts are newly combined, I bet you just need to tune it. The chances that you install the correct jet size first try on a new build are pretty small. Re-jet (I'd go up first) and see where that gets you. Playing with the needle is also a great idea, especially since you have issues with it at lower throttle ranges.

If you don't have other jets and you just want to experiment with it a bit now, then you can try putting a little bit of tape over the air filter, blocking ... let's say, 25% of the exposed air filter surface. If it runs better, you're lean. If it runs worse, you're probably rich. The needle (again) is a good thing to mess with for now too if you don't have jets.

How confident are you that the timing on that CDI is set correctly? Did you set it up with a timing light and all that, or is it just "rotated to full advance"?

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