New Cylinder Head required for 1E40QMB Big Bore?  By  Chaapa'ai (Read 3,999 times)

You can use the stock head alot of people use a second base gasket to lower the compression some I used my stock head with out using the 2nd base gasket and no problem

The 70cc BBKs I see come with a head . On a 4T I have myself reused the stock head with an Air Sal 50mm BBK since it was designed to use it and had high compression . Yes some use and extra base to lower it . Now on my 2T I bought a MODCycles 47mm BBK which came with a head . You need to measure the width of the wristpins as they come in 10mm and 12mm sizes . Mine is 10mm . Now on a 2T the head is basically a lid or cap for the engine as the ports are in the cylinder instead of the head like a 4T . It may work but a proper size head may work better , Hopefully someone here has already tried this and will post their findings .

A BBK will have more power but will require a larger idle jet and testing of larger main jets as 2T jetting is more picky . Some only have a 17.5mm carb or smaller and you may opt to get a larger size carb . Mine has a 19mm TK carb . I had a 40 idle jet and a 68 main jet but I installed a 75 MJ so it ran better when it was a 50 . With the installation of a 47mm BBK I bought a few MJs to test since I also put on an unrestricted exhaust pipe and a Uni airfilter . After testing I liked how a 120 MJ worked . I first kept the 40 IJ as they are hard to find for a TK carb , but the MJs are common Mikuni VM11/22 size . I later installed a 45 IJ as it started fine , but always needing the idle to be adjusted as the temperature changed and it would not idle for a long time without wanting to stall . I used to give it just a sip of throttle to start it but with the 45 no throttle needed to start or idle .

To truly get the most out of it you will need to get a decent exhaust pipe with an expansion chamber in it . Some stock pipes are only tubing and a muffler . The expansion chamber plays a huge factor in getting the most out of the engine . You may also need to tune the CVT . I had 5 gram rollers which worked fine when it was a 50 but 5g is too light with a BBK and stock gearing .

If you can afford it , around 500 dollars I would get a complete Power Kit with the engine , new CVT parts , carb , intake and exhaust like this one by Hoca at PFS www.partsforscooters.com/169-210_Power_Pack?sc=34&category=133366 . If bought separately it would be a lot more

Bump!

has anyone here Actually installed a 1E40QMB Big bore AND used the stock head ?

Wow that price with no head? This a better deal and I buy many for customers Scoots. Talk about power and high quality too! It is an EXACT clone of the Hoca BBK..right down to exact port sizes and port timing.---> www.ebay.com/itm/181114468307?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

You can use the stock head, but might not get the best performance you can always mill it down to help out.

most sellers dont ever reply on sat and sunday some sell on ebay from there mom and pop shops that are not open weekends not saying that is the case here but your safe with ebay and paypal

Update!

Big Bore installed, super high quality port work, i am 100% satisfied with this package! A++

Stock Cylinder head fits!