reliability of 72 cc kits

[lostforawhile]

I was wondering about the reliability of 72 cc kits, I know many of the larger big bore kits, are supposed to cause issues with the cranks and crank bearings, but what about these smaller kits, I was thinking about one and a performance clutch variator kit. The increase wouldn't be so big that the cops might notice, but just a little extra kick for hills etc. 

[AtariGuy]

Assuming you mean 4T...

I'm told the 80cc (72 actual cc) kits hold up a bit longer on the crank rod bearing than the 100cc kits do. I suggest checking in the 4 stroke performance section for the 47mm bbk thread for a better understanding. You can go with a taiwanese crank, they have the quality bearings needed to run the 50mm kits. Or go with a lightweight airsal piston in 50mm, it weighs nearly identical to the 47mm piston.

[dan50]

I just installed a 47mm BBK on my Dongfang build. The reason I went with the 47mm is because it is suggested for a first time install. The reliability of the 47mm is really good from what I've learned. The 47mm works well with the stock crank, the 50mm needs a heavy duty crank.

I bought a Glixal 47mm BBK kit with a Glixal A-9 cam and a 47mm head.

Big difference in power over the stock motor. Goes up hills and into the wind really well without slowing down much (the main reason for a BBK). I gained 4mph with the 47mm BBK. Top speed stock was 42mph (after tuning the carb & CVT) with the 47mm BBK I do 46mph top speed. I might get some more mph with more CVT tuning.

I did buy a 20mm carb for it with free flow air filter and non restricted exhaust.

I ordered a Malossi Multivar for the CVT. I currently use a stock variator with 5 gram rollers, stock clutch and torque sheave with 1.5k (red) clutch springs and 1k contra spring and a Mitsoboshi 681x17.7x30 belt (stock belts 669mm in length are too short on my shortcase and don't allow full travel of the variator, the 681mm belt allows full travel.

As long as you do the speed limit, the cops will never know!

[dan50]

Previous post was my 3,000 post!

[milly]

I fitted an 80cc kit and holding up well on original crank. I kept the original carb and up jetted with information from here. I have a naraku 70cc kit to use at some point but will fit a naraku crank with it when I do.
Link to info below on this forum.
www.49ccscoot.com/faq/whichkit.html.

[greggkinney]

i ran an 80 kit (72cc) for over 6 months with no problems whatsoever. when i toreit down it still looked great and my crank was still in a-1 shape. only changed because i wanted to try a 50 and then 52mm. honestly i believe the 47mm accelerated faster and was only a cpl mph slower than the others. heck, it even done 3" power wheelies of the line (but i only weigh 125)