Engine won't start

[jdb4whlr28]

Thanks for the advice. Do you know of anywhere to get a decent 72cc kit? It's hard to tell which ones are junk and which ones will actually last.

[90GTVert]

I know what you mean. The kit I bought for my 50cc was a great price, but it showed up new in the box with rust in the bore.

Enviromoto sells quality stuff at good prices. Jeremy, the owner/operator, was kind enough to provide a 10% off coupon code for members of the forum too! Use coupon code "49ccScoot" with Google checkout to receive the discount.

BBK Only
enviromoto.ecrater.com/product.php?pid=3369520

Power Pack
enviromoto.ecrater.com/product.php?pid=3956695

You may notice that the kits don't include a cylinder head. That's because the smaller combustion chamber of the stock head boosts compression to make more power and better throttle response. Most of the 47mm heads you'll find are little more than a stock head with the combustion chamber enlarged.

[jdb4whlr28]

So I would have to buy a cylinder head somewhere else? Or is the one thats already on there good enough?

[90GTVert]

If you want more power, keep the stock 39mm bore head. It has a smaller combustion chamber than the 47mm, which means it will create higher compression. Higher compression makes more power and snappier throttle response. Of course you already have a stock head, so the added benefit is that it's free. ;D

[jdb4whlr28]

Awesome. Another question I had was, is the carb that's already on there going to get the job done with the bigger cylinder? I noticed in the power kit that it included a new jet. Is that something that's going to make a big difference? Also, do the roller weights need to be changed if going up to 72cc's?

[shiftless]

A setup that works for me with a 72cc 4t is stock carb, 88-90 main jet, uni filter, perf exhaust or gutted stock exh & 7.5g sliders
You should see signifigant gains

[90GTVert]

The stock carb should would just fine. If you go with a UNI filter you'll definitely need to upjet. If you stick with the stock airbox you probably still will need a little bigger jet. A lot of folks say they run on the lean side stock anyway.

Roller weights may or may not need to be changed. Some manufacturers use different weights than others. Your weight and riding style or preferences comes into play there as well.

The setup shiftless mentioned and what's in Enviromoto's power pack are setups that have shown great results for many people.

[jdb4whlr28]

So I just got done testing the new CDI box. Unfortunately, upon opening the package, I could see that it was a lot smaller than the existing CDI box. I popped the new one in and tried it anyway... As assumed, it did not work. So I emailed the person I bought it off of and he told me that I probably had a DC cdi box and the one that he had sold me was an AC cdi box. Upon more research, I found out that 99% of the Chinese GY6 engines come with an AC cdi. Mine falls in that 1% that are stock with DC cdis. I've been looking around for a DC box and so far all I've come up with is one for a 150cc engine but it looks identical to the one that came on my moped. I noticed that with the AC boxes, all the websites say it will fit 50cc, 125cc, and 150cc. So I didn't know if this 150cc box would fit my 50cc machine???

[90GTVert]

That sucks. A 150cc CDI should work. Some sites sell them as 50/150 CDIs.

[2strokd]

Got one in the garage, a GY6 49cc that is....Has spark,and after i adjusted the valves good compression, and i cleaned the carb, its getting fuel. Wont even try to start, any tips?
It did have the ex. valve hanging open a bit too long before the adjustment. The owner says it developed a starting problem and got worse and worse until it wouldnt start.

[90GTVert]

Have you tried spraying carb cleaner through th carb or into the cylinder? Even when there's gas in the carb and I've cleaned the carb I do that if it still won't start just to be sure fuel is getting through the carb to the engine.

[2strokd]

Yeah, i tried starting fluid and it wouldnt even sputter, backfire, nothin. As a last ditch effort before pulling the motor i tried another carb and it fired right up! Weird that it wouldnt even fire with s/fluid? Thanks for the reply!
Im not to fond of these stock CV style carbs..This is the third GY6 scooter ive worked on with bad carbs that no kinda cleaning will fix. One had a crack that caused idle/air whackyness.
Another just wouldnt stop leaking nomatter what i did or switched around on it. Seems like one outta 5 maybe is ok? Maybe thats why i see em on ebay for $30 new and a discount if ya buy more than 10 lol! Why would ya need 10 carbs! LMAO!
Im happy tho! It puts a buck or ten in me pocket! All get off my soapbox, sorry!
Brent, you ever try a different carb on yours? I was thinking of trying my Mikuni VM18 on my
GY6 50 wanna these days to see if it helps?

[90GTVert]

I tried 2 stock 50cc carbs and a stock 150cc carb. Never a different style. Might be worth a shot.?.

[shiftless]

The cv carbs are pretty reliable, until problems arise
I'm not fond of the enricher/chokes on em either

I like an OKO on a GY6