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Post by golfmech on Aug 3, 2020 20:15:14 GMT -5
So I made the swap from a 47mm bbk to a 50mm that came with a milled head. my Issue is coming right off idle it wants to stall or bog I have a factory air box and idle jet with a 90 main. the main is the same as what i was running on the 47 because the plug showed it was already running rich.
turning the mixture screw out seemed to make the bog worse so i have it at a about 1 1/2 out right now it runs ok but if I let it idle for about 10 sec or so then hit the throttle it either stalls or bogs really hard. also if i try to restart when its hot or just died I have to hold it wide open... almost like its flooded or running really rich?
how is it possible that I am running too rich after going to a bigger bbk with the same jets? with the 47mm it ran great at wide open and from off idle. I'm kinds nervous to go much smaller then a 90 main on a 50mm has anyone here ever had to down jet after going to a bigger bbk?
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Post by bullybike on Aug 14, 2020 21:05:25 GMT -5
something just isnt right.
take apart carb and clean pilot and main jet. inspect the accelerator pump. I actually disable mine by removing the little lever as i dont like the accl pump.
very wierd tho rich on a bigger bore
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Post by bullybike on Aug 14, 2020 21:06:25 GMT -5
you may want to upgrade your ignition /spark wire/plug
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Aug 15, 2020 9:40:49 GMT -5
Get rid of the stock air box. That is the thing I trash when I upgrade. I run my 50mm with a 23mm carb from a 150 scoot and a 102 main jet. 41 pilot. Get a pod filter and #95.
Stock cdi and coil are good to use. The performance ones are crap.
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Post by GrumpyUnk on Aug 15, 2020 10:37:36 GMT -5
Sure glad we have all the graduate engineers telling you to throw away all those parts. They must not be needed, otherwise why put them on the machine? Hmmm, Chevy and Ford(no more Plymouth) spend money trying to save a few pennies per vehicle... and the Chinese put extra parts on just because?
No, I don't think so.
They install an accelerator pump on the 'good' carbs, and leave it off on the lower-priced models. Keihin doesn't know beans about these things, right? I vote the other way. They designed and built them, and if you want to take parts off and toss them in the bin, go for it. I know what an accelerator pump is for, and why it should be kept, but won't reveal the secret on this thread. Find it elsewhere.
As far as the airbox, unless you go through the hassle of finding the exact jet that will work best, on that day, at that hour, with that ambient temperature, with that relative humidity, you are just wasting your time. Without the airbox, you get the air that is churned up by the rear wheel. Comlete with water, mud, rocks, dirt, and whatever leaves, grass and seeds are found on the roadway. Direct to your cone or filter.
Fine, go that way. I don't care. I won't. Not if I want it to run reasonably well on all days. Not the peak on any but coincidence, but pretty decent on all other days, too.
If it bogs, it is either rich or lean, in most cases. In most cases, it would be lean as the accelerator pump only squirts what it can, when it is moved by the throttle control.
tom
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Aug 15, 2020 14:09:16 GMT -5
I guess that we should just keep the 49cc scoot always a 49cc. No need for a bbk.
Also we should keep the Chinese EGR valve crap too.
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Post by tortoise2 on Aug 15, 2020 14:29:17 GMT -5
I guess that we should just keep the 49cc scoot always a 49cc. No need for a bbk. Perhaps an 85 main jet and tinker with the CVT drive a little . . but be content with 35-40 MPH. If your speed criteria is faster . . for best reliability select at least a 125cc and keep it stock! |
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Post by golfmech on Aug 23, 2020 13:00:43 GMT -5
well sorry for taking to long to get back to everyone. I feel kinda dumb because my stalling and bog problem was all just moisture in the CDI plugs I blew them out with air and a little WD-40 now it idles perfect no stalling and no problems getting restarted when hot. whats the deal with people saying leave 49cc scoots stock? this is my toy I like modding because its cheap and fun to see what kind of improvements can be made on a budget. I have a xj650 for reliable two wheeled transportation.
on a side note I didnt notice a huge power increase going from 47mm to 50mm but I no longer get constant spark knock! on my 47mm even running 93 I could hear a knocking/rattling at wot in the head area. with the 50mm and milled head she purrs right along no more spark knock/detonation
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