need some advice on big bore « Thread Started on Aug 24, 2011, 6:02pm »
whats up guys, no time no see. scooter has been running pretty good for the last year or so, totally shocked. i do have some things i need advice on tho. im thinking of getting the 72cc big bore kit from scrappy dog scooters. for the price and power potential, it really cant be beat. in any case i have already upgraded my main jet in my carb to the #88. my first question is, when i do the bbk will i have to put an idle jet upgrade in as well? or will i be able to get that extra fuel out of the air/fuel screw? now, as it stands i think im having a little bit of a clutch fade issue as well and i plan on getting a high performance clutch. however im unsure as to what spring tension to get it with? i do alot of city driving so id kind of like to keep it on the lower end so im not revving quite as high off the line. i have 3x5.5 and 3x6.5 weights in it now and they allow it to rev a little higher but still kick in second gear at a decent rate. anyone who could give me some gems would be much appreciated! thanks!
Joined: May 2010 Gender: Male Posts: 570 Location: Indianapolis, IN
Re: need some advice on big bore « Reply #3 on Aug 25, 2011, 12:30am »
That kit has been kicked around this forum for ages. It's a good kit for the price, but like so many, unnecessarily misrepresented. I am almost sure that is a 72cc BBK.
Why they do it, nobody knows, but it does undermine confidence somewhat. I can't tell, is that a big valve head that is included? I guess someone needs to get one and do some measurements.
There is a difference in kits for sure. They do stress that their Chinese kits, don't come from China, they are in stock in Wisconsin! Ok. It's a common upgrade, and most who carry them stock them, doesn't make them any better quality than the next guy. The mph gains IMO are also misrepresented, but that's for another thread altogether.
All said, I'd probably buy one, especially if danillobh84 says his is a good one!
Roketa MC10K50~JMStar 139QMB Scoot Dawg PDI NGK Iridium Plug Fram Fuel Filter Fuel\Vacuum Line Mods~Blue's Way Red Perf Coil Blue Perf CDI 6.5gr Dr Pulley Sliders Gates Powerlink Belt 18mm Carb/Accel Pump Perf Disc Air Filter Mod'd OEM Exhaust
Re: need some advice on big bore « Reply #5 on Aug 25, 2011, 2:59pm »
okay, thanks for not answering any of my questions. not tryin to be a prick but i simply need to know if ill need to upjet on the idle side when doing this kit and what spring rate i should set my clutch for with the extra get-up. i know where im getting the kit, and it certainly isnt off ebay. cheaper is not always better my friend. and especially of such a vital component on the scoot. be it a seat cover or a light bulb thats different. i trust scrappydog, never had an issue that led me astray thus far. i dont need rollers, a flywheel, an oil pump, and all these other crazy gaskets. besides the 72cc kit from scrappy can still utilize the stock head. so to me id rather spend the same money on less parts but of a better quality. taiwanese parts are notoriously better than the mass produced china equivalents. i can personally vouch for that. ive gotten a few taiwanese parts that have lasted double if not triple the life of the chinese knock offs. in any case its not really top speed mph im looking for, its still at heart only a little one cylinder. and honestly i dont know if id want to take it over 50. if i wanted a gsxr1100TT thats what id have gotten instead of the scoot. but i just hate creeping up the speedo. so, essentially, torque is the key to that picture. and 72cc kit from scrappy will provide just that but im trying to find out as much info as i can so i can get everything at once and then tackle everything in a weekend and be blasting down the road monday morning to work. thanks all
Re: need some advice on big bore « Reply #6 on Aug 25, 2011, 8:03pm »
I just ordered a bbk and it comes with a 100 main and a different slow jet. the clip needs to go into the lowest position on the needle as well. That is for the kit I ordered though and it also comes with a different air filter.
Re: need some advice on big bore « Reply #7 on Aug 27, 2011, 1:03am »
Alot of these '100cc " kits are really 82 or 85 since being above 80 they round it up which is misleading . I think these scooters have iron block and head which costs less and weighs more . My 80cc Air Sal has aluminum cylinder with nickel sleeve inserted .Its harder than aluminum , cast alum you can scratch it with fingernail .I looked at some of the high priced BBKs and they looked like they were aluminum billet ( pure block of alum and part is machined out of it versus cast liquid metal poured into a mold ) I looked for forged pistons since they are stronger than just cast . I looked at www.wiseco.com but no 139QMB or Gy6 was listed and wondered if a piston for Honda XR80 would fit since these China scooters use a old Honda design .Wiseco is much better quality , lighter , usally shorter skirt on piston , and made in the USA !!! . I used a Wiseco in my CR125 .60 over with chromoly sleeve pressed in which got back to being .30 . At .60 with cheap piston and ran way too hot . Once I rebuilt it the second time I drove it like I stole it for 2 years with no problems . I change the oil way more than most , I d rather spend a few extra on oil than do a rebuild
Joined: Aug 2011 Gender: Male Posts: 18 Location: michigan
Re: need some advice on big bore « Reply #9 on Aug 28, 2011, 8:31pm »
if you want a quality bb kit then try http://www.scooterdomain.com/QMB139_Gas_Scooter_Parts_p/qmbhk302396.htm it comes with the a9 cam for 20 dollars more than scrappydogs 72cc kit and it is drilled for egr cover.as for jetting i have stock 18mm carb with 85 jet and two washers on needle.with 72cc bbk and stock air box swiss cheesed.just tape the holes on inside with black electrical tape and open one hole at a time till you get the right setup.
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