heeersjohnny
Scoot Junior
New to this forum as of July 29th 20017. HELLO.
Posts: 9 
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Post by heeersjohnny on Jul 29, 2017 6:59:53 GMT -5
I have a 2004 Kymco zx50 that was modified with an OKO 24m carb and bored out to be an 80cc.
It ran perfect until taking it on an all day trip. Riding for about 2 hours at a time. The last few miles it was not accelerating, slow to pick up and never reaching over 30 mph.
There is gas on the spark plug. I cleaned the jets and changed the plug. It still looses power after running about 15 minutes.
Before I go to the next step I wanted to hear anyone's input that may have experienced this. I know it could be many different things but hope to narrow down the process of elimination.
Also has anyone had problems with these OKO large Carburetors? I have two of them one is on a Spree and it has problems too, I can't get the jets right.
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Post by jdl357 on Jul 30, 2017 2:37:31 GMT -5
I don't know much about the oko carbs, but a 24mm carb for an 80cc scoot is way too big from all the reading and research I've done on 2 stroke scoots. Your probably going to have to check over the CVT and the fuel system because your problem is probably in there somewhere. It's hard to tell you what to do because there could be multiple causes to your dilemma. What does the color on your plug look like? Black, tan, white?
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Post by gsx600racer on Jul 30, 2017 2:53:47 GMT -5
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heeersjohnny
Scoot Junior
New to this forum as of July 29th 20017. HELLO.
Posts: 9
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Post by heeersjohnny on Jul 30, 2017 12:09:09 GMT -5
The plug was pretty clean just wet, I run rich so I tend to replace plugs a lot. I thought these carbs were too much. I'm thinking about selling them both and replacing them now. I appreciate the input.
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Post by AtariGuy on Jul 30, 2017 12:17:08 GMT -5
In my research, its possible that such a large bore on your carb could be losing the pulse vacuum signal from the engine. Step down into a 19-21mm carb. Do you use a uni pod style filter or the stock airbox? Its easier to tune the carb with the stock box and they still flow great for sport bbk cylinders.
Also check your compression when it gets warmed up. Or do a leakdown test. If you have a case leak when its warm, you could be losing power too
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Post by tsimi on Jul 30, 2017 18:43:09 GMT -5
How does your CVT setup look like?
All stock? What torque spring do you run?
24mm is maybe a bit big but I have seen guys running 24 or even 28mm carbs on 70cc setups without issues unless you call bad gas mileage an issue. :-)
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Post by lostforawhile on Jul 30, 2017 22:33:24 GMT -5
In my research, its possible that such a large bore on your carb could be losing the pulse vacuum signal from the engine. Step down into a 19-21mm carb. Do you use a uni pod style filter or the stock airbox? Its easier to tune the carb with the stock box and they still flow great for sport bbk cylinders. Also check your compression when it gets warmed up. Or do a leakdown test. If you have a case leak when its warm, you could be losing power too This is probably the same reason that the stock airbox works better, even on a smaller carb, with these small displacement engines, there isn't a very strong vacuum signal, and the short pod filters cut out what little velocity the intake can build up in the intake tubing |
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Post by lostforawhile on Jul 30, 2017 22:38:35 GMT -5
it's weird, even on a 4-t they are as ticky about the airbox, airbox restrictions etc, as a 2t
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Post by AtariGuy on Jul 30, 2017 22:39:24 GMT -5
How does your CVT setup look like? All stock? What torque spring do you run? 24mm is maybe a bit big but I have seen guys running 24 or even 28mm carbs on 70cc setups without issues unless you call bad gas mileage an issue. :-) i'd see it on them badass hyper race 70cc class scoots lol so if its a badass stage 6 47.6mm r/t cylinder with a yasuni c21... or 'O'Verse and his rc-one... |
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heeersjohnny
Scoot Junior
New to this forum as of July 29th 20017. HELLO.
Posts: 9
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Post by heeersjohnny on Jul 30, 2017 23:52:20 GMT -5
Thanks everyone for the input.
I do think I am going to step down on the carb, I need it to go steady more than fast, I like to go on long rides.
Both my 86 spree and this 04 Kymco have that Carburetor and unipod filters. They look great all big and sh@*t. but for me it's more practical to use a matching carburator.
The Spree was used for 1/4 mile races and when I got it I blew it up trying to go a few miles on a hot day. It was so bored out the cylinder burned right through the steel. LOL. so that's when I got a 70 cc bore kit but can't get it to run with that 44 mm carburetor. That is a whole other issue.
I still haven't got a chance to look at the CVT, just got in and read your posts. I noticed tonight the headlight dims and gets brighter as I give it gas. Is this a clue? belt. CVT, something else maybe?
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Post by lostforawhile on Jul 31, 2017 0:38:00 GMT -5
Thanks everyone for the input. I do think I am going to step down on the carb, I need it to go steady more than fast, I like to go on long rides. Both my 86 spree and this 04 Kymco have that Carburetor and unipod filters. They look great all big and sh@*t. but for me it's more practical to use a matching carburator. The Spree was used for 1/4 mile races and when I got it I blew it up trying to go a few miles on a hot day. It was so bored out the cylinder burned right through the steel. LOL. so that's when I got a 70 cc bore kit but can't get it to run with that 44 mm carburetor. That is a whole other issue. I still haven't got a chance to look at the CVT, just got in and read your posts. I noticed tonight the headlight dims and gets brighter as I give it gas. Is this a clue? belt. CVT, something else maybe? sounds like a bad stator or maybe a voltage regulator, if your CDI voltage is low you won't get a good spark |
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heeersjohnny
Scoot Junior
New to this forum as of July 29th 20017. HELLO.
Posts: 9
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Post by heeersjohnny on Jul 31, 2017 3:15:41 GMT -5
I wonder which would cause the lights to go brighter with acceleration, maybe the Stator.
The CVT might be causing rotation to be unstable. I will check it out.
Thanks
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