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50cc
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Posted by: jetmedic

My 50 drx has a new motor and makes it a half lap the dies for a couple of seconds, not stalling, but power comes way off then its starts going again. I have changed everything from fuel filter,carb,stator,rotor,coil and ck'd crank seals. Any suggestions?

Posted by: humboldt hills

Sounds like jetting, but you have changed the carb.
Is it running hot?

Posted by: Andyman17dad

it does the exact same thing with 2 different carbs.

Gary, how about something up in the kill switch or a ground or something, you still have all the kill switches hooked up, right?

Posted by: jetmedic

Yup, I'm going to eliminate everything today. No more elec start or anything. I will take another ign sys I have with just a kill switch on it and see how it works.

Posted by: hotquads1

check vent in gas cap , sounds like it may not be venting , therefore causing fuel system to create a vacuum effect and begin starving the engine for fuel . I have seen this before.
marc

Posted by: mxdad

quote:
Originally posted by hotquads1
check vent in gas cap , sounds like it may not be venting , therefore causing fuel system to create a vacuum effect and begin starving the engine for fuel . I have seen this before.
marc

This happened to us on our first DRR but it would completely shut off and wouldn't start for about 5 minutes.

Posted by: jetmedic

I will try it. let you know

Posted by: jetmedic

not the tank vent. head temp 250 @ spark plug when it dies.

Posted by: Nichols Atvs

I had a CDI box with one wire that was lose and when we got to high rpm it would do the same thing break down and when ya got slowed down pick back up probly not the same but that was my prob. I met you this weekend at mx 207 your boy flies on that 70. Hes a good rider .

Posted by: airtime821

you know i was having almost the same problem and it turned out to be one of the wires in the harness coming off the key switch came loose in all i have had three of the wires do this i dont know if they had a bad run of the switches but its worth a check.

Posted by: jetmedic

Thanks for the replies fellas. I am still trying.

Posted by: jetmedic

Riddle me this Batman, When I was assembling engine I notice the piston could not be inserted thru the top of the cyl. I know this is not the way to assemble but all the engines I have put together I have been able to at least rest the piston in the cyl through the top when its on the work bench. Are these cyl's tapered? Brand new from DRR.

Posted by: hotquads1

any sign of scuffing on the cyl wall? beginning to seize? did you take off an OKO and replace with an OKO , when you did the carb swap? still sounds lean, how does plug look?
marc

Posted by: markvette

now that you mentioned that it sounds like the motor is seizing when it gets hot. i would pull the cylinder and check it out.

Mark

Posted by: Nichols Atvs

Well Robin what did ya find out ? Poor cyl ?

Posted by: jetmedic

Runnning good now.

Posted by: hotquads1

let us know what fixed it , I'm curious.
marc

Posted by: jetmedic

Cant really pinpoint what fixed it. I removed the new drr pipe)the one that come s on the 90 and just kept riding. Maybe it just needed a good break in.