Chinese gy6 250cc kart, low top speed. (Coolster)

dniksich

New member
Messages
18
Reaction score
15
I'm working on a Coolster Challenger 250cc kart trying to get the top speed it had before back. Used to do almost 50mph and now it maxes out at about 29? I was here last year with this problem and thought it was the clutch but it's been replaced and is working but the engine has no high rpm. I have the rear jacked up and I can hold full throttle and it just hits a rpm wall at a little over half throttle and that's it. Plug was black so I thought maybe it was too rich so I swapped the carb with a Keihin carb that I think was original and it didn't help. Adjusted the valves too with no change. Idles and throttle response is good but refuses to rev high. Any ideas? TIA
 

dniksich

New member
Messages
18
Reaction score
15
Is the carb opening all the way? Perhaps the adjustment was fiddled with?
Has the cdi been changed since you had it last?
Perhaps from an open limiter to a stock limiter type?
Yes, it is opening all the way. CDI has been changed. Just used a Amazon one. I'll have to check the order and see if I can find anything out about it.
 

dniksich

New member
Messages
18
Reaction score
15
Last edited:

Whitetrashrocker

Inmate #952016
Messages
2,775
Reaction score
643
Location
Southern New Mexico
I'm actually messing with different cdi units on my kart.
I'm running an ac style but probably the same guts inside.

The plain black (stock) i got seems to have a 4k rev limiter on it. Or so says my little induction tach/hr meter.
The orange one has no limiter but it also is just full advance. No curve. Makes hard starting. And they have 2 kinds of adjustable ones. Dip switch or rheostat. Got one to play with.
but haven't got there yet.
 

dniksich

New member
Messages
18
Reaction score
15
I'm actually messing with different cdi units on my kart.
I'm running an ac style but probably the same guts inside.

The plain black (stock) i got seems to have a 4k rev limiter on it. Or so says my little induction tach/hr meter.
The orange one has no limiter but it also is just full advance. No curve. Makes hard starting. And they have 2 kinds of adjustable ones. Dip switch or rheostat. Got one to play with.
but haven't got there yet.
That 4000 limit sounds about right with this one. Maybe I'll try a orange box. I think he'll be happier with the speed over easy starting. lol
 

Whitetrashrocker

Inmate #952016
Messages
2,775
Reaction score
643
Location
Southern New Mexico
Cheap enough to play with. Lots of people on the chinariders forums have tried all color cdi boxes and have all went back to using the slightly more expensive stock black box.
Some have had good luck with the performance stuff, others could tell no difference.

What engine you have?
 

panchothedog

Well-known member
Messages
1,861
Reaction score
2,469
May I offer you some VERY biased and opinionated advice. Your problem sure sounds like it's the ignition related. I don't know anything about the GY-6 engine in particular. But I do see that Coolster vehicles are still sold brand new. A quick 3 minute search brought up 2 big go kart shops that handle them. There are probably several more. Instead of buying STUFF off of Amazon ( where you are nothing more than an order #, a package #, and a credit card #.) They don't know, or care about your kart or your problem. Most all real go kart supply shops have a technical person or trouble shooter that you can either talk to on the phone, or
E-MAIL your questions to. I really think you stand a better chance from a business that deals with that brand than hoping you find the right one on Amazon. My 2 cents worth.
 

dniksich

New member
Messages
18
Reaction score
15
May I offer you some VERY biased and opinionated advice. Your problem sure sounds like it's the ignition related. I don't know anything about the GY-6 engine in particular. But I do see that Coolster vehicles are still sold brand new. A quick 3 minute search brought up 2 big go kart shops that handle them. There are probably several more. Instead of buying STUFF off of Amazon ( where you are nothing more than an order #, a package #, and a credit card #.) They don't know, or care about your kart or your problem. Most all real go kart supply shops have a technical person or trouble shooter that you can either talk to on the phone, or
E-MAIL your questions to. I really think you stand a better chance from a business that deals with that brand than hoping you find the right one on Amazon. My 2 cents worth.
Good idea, I just emailed them asking about it. Amazon has too many to try and pick from w/o knowing.
 

Whitetrashrocker

Inmate #952016
Messages
2,775
Reaction score
643
Location
Southern New Mexico
And my opinion on that is its still a china kart. China parts.
You can call the dealer and they will sell you a really marked up china cdi box. Even the kart stores we all love have what looks like just a generic black box, a performance orange, or the same adjustable.


For the 10 dollars or so I'd just order one. If it's not what you want throw it in the tool bag for when one quits on you. It will get you home then.
 

dniksich

New member
Messages
18
Reaction score
15
Oh no, definitely not gonna buy one from them but just asked about it. I see they don't even sell parts for this kart anymore. For a few bucks, I'll try a orange box and see what it does. Like you said, I can always keep it for a spare.
 
Top