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Post by sailracer on Aug 12, 2013 18:39:49 GMT -5
 Ok in my last thread, i was happy,-now, not so much. I got the engine rinning, does great on the center stand, not hot, responds crisp tough to start though. When I put it on the ground and try to ride, it starts making sort of a brapping noise.almosy like valves slamming shut! Is this a jetting problem? fyel/air mix? too much compression I need some help here when i twist the throttle on the center stand, i get a couple of clacks, but it revs ,and dissapears. alleyoop, millsc larry--- HELP!! ANYBODY 
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Post by millsc on Aug 12, 2013 18:46:37 GMT -5
take a vid may need another base gasket, i usually get rid of the airbox with kits over 47mm and jet #  -  |
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Post by sailracer on Aug 12, 2013 18:51:24 GMT -5
[replyingto=millsc]millsc[/replyingto]not sure how to do that. I did have two base gaskets, but removed one .remember, i was grttting like 130psi. Maybe my compression tester is no good?
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Post by millsc on Aug 12, 2013 19:18:59 GMT -5
try to upjet first, always the simple stuff first, ive never had any luck with the airbox with 50mm kits and the airbox with the gt5 i put a 72cc kit that had the expansion chamber type pipe didn't work right with the airbox either
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Post by sailracer on Aug 12, 2013 19:26:13 GMT -5
before I take it back out, I'll try that. I got a box of jets from  -105 i think. Ishould be able to find one there. I also have a 20mm carb, but i'd rather not use it. maybe ill try that too thanks. |
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Post by millsc on Aug 12, 2013 19:39:05 GMT -5
Doubt the piston is hitting the valves with a 47mm combustion chamber head, i have ran 50mm kits with the stock head and one gasket no issues, try upjetting and take the airbox loose from the carb and see if it runs ok
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Post by sailracer on Aug 12, 2013 20:08:26 GMT -5
Oh it's definitely not hitting,it runs great until i put a load on the motor. I'm going to try to let it breathe more. It definitely has a lot of compression, maybe too much. If I open the throttle just a little bit while cranking, it stops cranking. and thats with a tractor battery 250 cranking amps. Maybe I have tto put the two gaskets back  |
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Post by scootnwinn on Aug 12, 2013 20:52:46 GMT -5
Sounds too rich to me. Does it smell like gas if you take the plug out after its running?
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Post by sailracer on Aug 12, 2013 21:12:22 GMT -5
[replyingto=scootnwinn]scootnwinn[/replyingto]no, not at all, and the plug doesn't have carbon on it  |
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Post by scootnwinn on Aug 12, 2013 21:47:01 GMT -5
I still say too rich if it was too lean it would run like a freakin mad horse till it blew up. Too rich it goes brap brap and then stalls
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Post by millsc on Aug 12, 2013 22:09:04 GMT -5
jet on 100cc kit should be lean I run on 80cc kits |
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Post by brandjur on Aug 12, 2013 22:14:57 GMT -5
It can get tricky. Sometimes the extra fuel in a rich condition can wash out the carbon. Not saying that it is happening or not. I would try the higher main jet first before going to a leaner one. It gets even more tricky when you have a higher compression because the "sweet spot" for the air fuel mixture is tighter. The higher compression might even need a colder plug (not less spark, just better cooling via insulator)
Did you measure the piston ring gaps before installing?
I will say that I looked at the Hoca pistons and they have a cut out side piston skirt which is good for higher revving as there is less mass. The downside is more rocking in the cylinder, this leads to more wear. You might have to bump the idle speed higher with the Hoca piston and maybe even add that 2nd gasket if you have starting trouble with the regular battery.
Lastly, double check the timing (without the tensioner) and if it's possible to accidentally plug the enricher to a different plug, double check that.
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Post by sailracer on Aug 12, 2013 23:10:29 GMT -5
scootnwinn, the dam thing revved over 10000 on the center stand.
Brandjur, yes, I had to up the idle. I think I am going to try fool;ing with the fuel/air ratio and prob. add a 2nd base gasket
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Post by millsc on Aug 12, 2013 23:11:22 GMT -5
up the jet first
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Post by scootnwinn on Aug 12, 2013 23:32:02 GMT -5
Well upjet and see then you have them ready right...
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jet
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-105 i think. Ishould be able to find one there. I also have a 20mm carb, but i'd rather not use it. maybe ill try that too thanks.
MJ, Orange coil, Blue Performance CDI (Orange NCY did not work), NGK Iridium, 5g Sliders