72cc BBK

[09agility50]

I have recently installed a 72cc BBK and wanted to share my experiences. So far i am happy with the kit. It was and easy install everything went together well. You do lose the Exhaust gas recalculation stuff, but who needs that on a scooter! The low end torque is the biggest gain. from a stop to 30mph it pulls hard(for a scooter!). On the top end i gained about 4-5MPH over the stock 50cc. on the 50 and 72 i had a ncy cvt kit. i did put in an 87.5 main jet and it did help out a bit too. overall with 72cc, ncy cvt kit, and 87.5 jet i can do 50mph on flat ground with no wind. I also cut the cdi but that didnt cost anything.

[skippy]

thats good to hear. keep us updated. want to put a 72 kit on mine soon so feedback is good

[streido]

Yeah i fancy a kit too eventually. So its pretty easy to fit then? No problems? Which kit is it, got a link for it?

[mono]

When you get used to the extra power and you're looking for something extra, I can recommend the NCY T2 camshaft, which is a perfect companion for a 72cc BBK...

It will not only increase power above 6000rpm or so, but it will also extend the powerband of the engine well beyond 8500rpm - which is especially noticeable in acceleration above 50km/h - it will make you smile, I guarantee  

[LoveMyKymco]

I second that on the cam, its such a difference. I thought wow ok so the 50mm kit made it faster but still no guts up top, finally installed the cam...BAM! day and night. Im running the NCY kit I love it. I have the 52.4mm naraku kit also but I would rather wait till I get a better crank.

[blue]

BANG......................another one bits the dust.....................

[09agility50]

Yes it was a fairly easy install. I would recommend having some mechanical ability for the install. A second set of hands is nice too. No problems so far only has less than 15 miles on it though. was going to run the stock head since valves are the same size, but on the new head the valve springs are stiffer so went ahead and used the new head. I am planning on a different cam down the road. Another thing i noticed, not a big deal, the new piston is dished compared to the 50cc piston which is domed. therefore the compression is actually a lot lower on the 72cc kit.

Link: http://www.monsterscooterparts.com/50cc-72cc-high-performance-scooter-engine-kit-.html

Can't beat the performance for 100 bucks!

[skippy]

 http://www.monsterscooterparts.com/50cc-72cc-high-performance-scooter-engine-kit-.html

on the picture listing it has everything. even an oil pump....is that nessery? i meen when you change to a bbk, do you need to change the oil pump as well?

[mono]

There's a reason that BBK kits from decent brands and suppliers don't include an oil pump :

You don't need to change the oil pump, the OEM one is just fine - and a cheapo chinese copy is only more likely to fail...


When you see a BBK kit with an oil pump included, it's very likely that the supplier just tossed in a cheap piece of sh** to make an already cheap piece of other sh** look more attractive  

[09agility50]

The oil pump isnt really necessary. I didn't change it on mine i left the stock one in it. I dint want to split the case to install it so i just left that part alone. BTW it isnt any more chinese than kymco is! I am not talking bad about kymco either i prefer my kymco over beamers and zumas and other scooters. My agility 50 will beat theirs all day even before a BBK.

[skippy]

just as i thought. what makes of bbk do people recomend? so many on the market. whats the best? i keep looking at the narkau 72 kit. in the uk seems a good price at £50. but last thing i want is to put as cheep polish made bbk on that will brake and wreck the engine.

[mono]

BTW it isnt any more chinese than kymco is!

Lots of Kymco parts are made in China, but Kymco does a lot of quality control, and they use only a few selected well known manufacturers, whose brands are imprinted on those parts, together with the Kymco brand.

This is completely different from the generic no-brand GY6 and 139QMB parts out there, like those cheap BBKs, which can come from any source and without any sane quality check - and if you let those manufacturers decide for themselves how to manufacture cheap sh**, it will not only be cheap, but sh** indeed 

just as i thought. what makes of bbk do people recomend?

I'm very happy with my NCY 85cc BBK (including a cylinder head with larger valves) so far : quality and finish looks good to me, all fits well, runs well, sounds well, no excessive oil use... My engine runs like it was designed and manufactured this way 

[LoveMyKymco]

What size is the 85? 50mm comes out to 82cc 51 is 86, 52 - 90, 52.4-92cc.

[mono]

It was a lot larger than the 72cc that it replaced, and since a few cc more or less is completely irrelevant, I didn't check the exact size...

The design of the cylinder head makes a lot more difference than the exact number of ccs - but for those interested in meaningless numbers : the NCY catalogue says 50mm... which means 82cc (if LoveMyKymco is correct) - which is nice, considered that even well known motorcycle manufacturers often exaggerate the displacement of their engines by a larger margin... (it's standard industry practice to name round numbers instead of the exact sizes)

[LoveMyKymco]

Stroke times pi times radius squared divided by 1000. Stroke x (pi 3.14 ( radius squared)/ 1000
41.4(3.14( 25 x 25)/1000= 81.2475 cc so its actually closer to 81cc but they like to round up rather than down in engineering. A few irreverent CCs makes a generous 4-5% increase in bore size. Its funny how the Chinese don't know the same math the rest of the world does. I know mine quite well.