need guidance on bing setup/ changes (jets mainly)

Alright so here's the deal. I got my maxi last summer as a non runner and wasn't going to upgrade anything until i got it running well stock. got it running and it was Ok but never felt like it was running how it should. I figured it was good enough so i ordered a Boss pipe, new air filter, some jets... first time upgrading newb stuff.

Come to find out the dude bought it from put a 15mm carb on it, but didn't put a larger intake on it so it's still at 12. I know i have to replace that before I can dial anything in and get it running really well, but when I ordered my stuff I just checked the jet (82) and got the next 3 sizes larger not realizing my intake was smaller, thinking that would be sufficient for the time being at least until I decide to get a kit.

I found this thread which is helpful but doesn't answer everything...

https://www.mopedarmy.com/forums/discuss/read.php?f=7&i=130973&t=130795

so my question is, with a stock cylinder, a 15mm bing, (and a 15mm intake when i get one) hi flow air filter, and a boss, is it a pretty good chance that I'm going to have to go higher than 3 sizes larger on my jet? and along those same lines, what sort of range do most of you keep on hand for jet sizes (below and above what you are running, whether it is kitted or not)?

and another question along these lines, is your carb really as useful size wiase as the intake? like is mine simply acting like a stock 12 should? or is it just a real bad idea?

thanks in advance, sorry this is a bit of a novel... and if there is a thread i am missing just point me to it and we'll call it a day. thanks.

Re: need guidance on bing setup/ changes (jets mai

seriously, no help?

Re: need guidance on bing setup/ changes (jets mai

The 82 jet came in the carb. That is why you couldn't nget it to run correctly. Your 15mm carb is chokeed to 12mm at the intake. If you keep running the 12mm intake, port match the intake to the carb or drill out the intake. I've dremeled a few out and it makes a world of difference in flow. 82 might be too rich for that setup. I would just get a set of micro drills and some solder. Drill your jet up, or solder and redrill a smaller jet.

I only own 1 extra jet. I drill out anything I need and I always have the right jet. As a plus, I've saved quite a bit of money too.

Re: need guidance on bing setup/ changes (jets mai

Unless you've got crazy air leaks, I think an 82 is going to be way too big for your setup. You should check the spreadsheet to verify, but you've got about the same setup I've got, and I'm running like a 76 (and I don't have a 12mm intake). If I were you, I'd order the 15mm Bing intake from treats, and then get ... I dunno, maybe like 70, 72, 74, 76, and 78 jets. That should be a good starting point, and if you decide you need bigger or smaller after that, you can always order more. Or yeah, you can drill/solder, but I prefer having the correct jets ahead of time. It's bad enough with all the temperature changes around here that I need to keep changing jets -- it'd be way more annoying if I had to redrill and solder it each time too.

I can't say for sure how much effect your smaller intake has on how the system runs, but I would think that it is restricting the power of the 15mm carb significantly. I mean, does it matter how big your carb is if it only has a 12mm hole to go through? That's just speculation, though.

Re: need guidance on bing setup/ changes (jets mai

Thanks linda! I had a feeling I'd have to go lower than what have because of the whole mismatched intake thing but for the most part I had no clue haha. Thanks for the advice and hopefully that does the trick.

You wouldn't believe how many times this week I've been told to go to lawrence, KS this week... is it all it's cracked up to be?

Re: need guidance on bing setup/ changes (jets mai

Motobee Goode /

My first "mods" were a 15mm bing (and intake), a techno boss, and a high flow filter. I think I was running a 74. Your ped is running like shit b/c of the 82 jet (it's probably four stroking). It should take something in the mid to high 60s fully stock.

Re: need guidance on bing setup/ changes (jets mai

update- got a proper sized intake and hopefully the appropriate jets on the way! mmmmtreats.

yeah it was 4 stoking a bit but not as bad as it would have been because of the smaller intake. but nothing i was doing was changing it in the fall, but i know better now!

thanks again everyone, I appreciate it greatly!

just curious for those of you who have said this is similar to your setup or past setups, were you running a stock gearing? how was your low end? top speed?

not a big deal, i'll see for myself soon enough, just wondering is all.

Re: need guidance on bing setup/ changes (jets mai

Yes, I'm still actually running stock gearing on mine (14x45). My initial throttle response sucks, (although that's probably a different issue that I need to look at). I don't have a whole lot of grounds for comparison, but I think my low end and mid-range are pretty good. Top speed on flats is 36 GPS/38 speedo, although it doesn't always run that well. A more realistic average top speed is probably like, 33-34.

Re: need guidance on bing setup/ changes (jets mai

If you got a Bing then I highly recommend the spark plug tool from treats. It has a wrench end that fits the bottom of the bing, two screwdrivers on the sides. One screw diver to take the bing off and one designed for the jets. One tool for a complete plug chop and jet job. It'll make your trial and error phase so much easier as well as changing for conditions.

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