MC-02-50b By deepcrk06 (Read 3,728 times)

[deepcrk06]

I recently was given this scooter, body is in good shape but the motor is shot, no compression at all, I am not sure but I think this is a 139qmb motor and I would like to completely tear down and rebuild it using a BBK kit. My question is what BBK would be good for this, also I live in the mountains so a lot of up\down hill riding so what cvt\clutch would be good for the hills and also speed. Any recommendations will be a big help.

[Alleyoop]

I will let MILLSC chime in because he also lives in a hilly area and he has 50cc modded with a BBK and his CVT setup to crank up the hills pretty good. You will loose a little of your top end in order to handle the hills good but not much.
Alleyoop

[Alleyoop]

If MILLSC doesn't respond I will tell you what will work pretty good for your situation.
But I am hopeing he sees my pm to him and helps you out since he already has done it.
Alleyoop

[jct842]

There is always the possibility that the valves are open or stuck. You might take the valve cover off and check that they have clearance and are not stuck. Might be able to beat a few more miles out of it before you have to tear into it. Chinese scooters have a poor track record of a lot of valve adjustments compared to jap scooters/

[deepcrk06]

Thanks Ally, will await response.

JCT, already checked valves on this, they adjusted to .04 / .04
I inserted a small straw into the spark plug hole and think the piston is
shot on this thing as I lost the straw into the chamber. lol

this is a free bee scooter, I already have another one that I ride, and with nothing better to do, thought it would be fun to tear this one down and modify it. Retired here and will give me something to do over the summer lol.

[Alleyoop]

HAHAHA, now that is funny sticking a straw down the spark plug hole and seeing it disappear.
Yea looks like there is a hole in the piston or the whole dome is gone.
Alleyoop

[millsc]

depending on how much you are trying to spend you can get a ebay 100cc kit for under 60 bucks or a expensive hoca or naraku kit for 300 the ebay kit does good ive installed several without issue. I used to have the ebay kit also it ran good but not as good as my scrappy 52mm kit with the hoca performance head. If you want hill climbing power get you a 100cc kit, 1500 torque spring and a good belt with dr pulley slider weights i can send you links to the stuff depending on your budget its doable for around 200 bucks

[millsc]

www.ebay.com/itm/100cc-Big-Bore-Kit-Performance-Power-Pack-Silver-Exhaust-QMB139-Scooter-Parts-/160866280093?pt=Other_Vehicle_Parts&hash=item257460a29d&vxp=mtr get this and www.ebay.com/itm/1-5K-YELLOW-TORQUE-SPRING-CLUTCH-PERFORMANCE-GY6-50-Baja-Roketa-Sunl-/160864607378?pt=Other_Vehicle_Parts&hash=item2574471c92&vxp=mtr and this with these www.partsforscooters.com/169-217_Dr_Pulley_Roller_Weights will get you up the hills quite fast and this belt www.ebay.com/itm/Scooter-Belt-Gates-Powerlink-669-18-30-50cc-669-18-1-30-/271052744454?pt=Other_Vehicle_Parts&hash=item3f1c00a706&vxp=mtr

[deepcrk06]

Millsc, thank you for the links, those prices are within my budget so that looks good.

Can I still use the stock carb, even with the new jets? or should I go ahead and go to a performance carb and air filter?

Ally, I pulled the head off and their was a big hole in the piston, but I did find my straw, lol.

[millsc]

you can use any 18 -20mm carb and a 92 jet works great for the set up www.ebay.com/itm/221178822377?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 this is a good carb used it for months and get a open air filter 38mm www.ebay.com/itm/261153022404?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 www.power-barn.com/servlet/the-1539/Keihin-99101-dsh-116-dsh-XXX-Main-Jet/Detail 92 jet

[Alleyoop]

HAHAHA, Your a good man deepcrk06, Good to have a great attitude guy on the forum.
We will all help in your build if you need it. But I believe Millsc will set you up good he has lots of experience with the 50s.
Alleyoop

[millsc]

im going this route for my roketa i just bought its cheaper this www.ebay.com/itm/330459445932?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 and this pipe www.ebay.com/itm/121014423681?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 plus the torque spring i already have the rest of the stuff im gonna keep the stock variator and run 7 gram sliders with the 1.5k spring which is equal to 5 gram sliders with stock spring im almost 200lbs

[buford1488]

what's the hoca head have that scrappys dont?

[millsc]

different size valves and an egr port that i blocked off www.partsforscooters.com/50cc-GY6-Cylinder-set-169-54_2 i have the hoca head

[millsc]

the pic shows a non egr head but mine had the holes when it came in, i just didn't want to wait a month to get scrappys head, scrappys head is 17 and 22 valves the hoca has 21.5 and 18.9 valves add them together the hoca has bigger valves overall