Should i re-jet my carb on a 97 scrambler 4x4 500 after a new piston bored .40 over? It starts and idles but after changing the needle clip position 5 times it still wont run right in the mid range and acts like it is cold ( hard to start)after 5 minutes of being off.

A little history: top end rebuild, new piston, rings, gaskets, carb rebuilt and cleaned, new fuel pump kit and hoses,

After all that is STILL will not run right. Can anyone help me?

 

what is the compression now adter rebuild? i don't think moving the clip would be needed just from boring out the cylinder if you didn't change any thing else. imo

 

SET YOUR THUMB THROTTLE CABLE TO 1/8" PLAY AT THE THUMB!!!ALL I HAVE TO DO IS LOOK AT THE BIKE WRONG(brow beat it)and the cable changes let alone take the carb off or something......adjust at three inches from thumb piece.....wrongly adjusted ETC control will make it stumble at any and all ranges.....

 

The comp test was 150 psi. If I set the play at the thumb to 1/8", what do I set it at for the carb? Thank you!

 

you just adjust the idle,mine is at 1050 rpm because they say anything lower can strip a flywheel key and anything higher is for rough engagement..............

 

NO DICE! on the throttle cable adjustment. Here is what it does:

It will not start with the choke closed hot or cold. It starts on its own hot or cold with the choke pulled, it idles high and crappy when the choke is open. when closed it idles like every other stroke and like crap! I have adjusted the throttle stop screw in and out with no success. It will help it idle faster but it will still run like crap. It will NOT allow anything past 1/10th throttle to stay running. It feels like it is either too rich or too lean once i open the throttle. I dont know how to tell the difference. once returned to idle, it will stay running...poorly. I have adjusted the needle valve thru all 5 positions with no success or variance in the performance of this thing. Items replaced are: fuel pump, lines, filter, gas in tank is 93 octane and clean, float valve, carb completely cleaned and inspected by a motorcycle tech, new piston and rings, comp 150 psi after install,

I am approaching my wits end and will destroy this thing if i cant get it fixed. Someone PLEASE help me!...AGAIN!

 

is that a brand new gapped sparkplug??? are the valves adjusted properly,the valves can be barely open and still give a good compression reading,i've actually witnessed that!!++are you sure your timed correctly?? get atiming light on that thing,if you can't see the line there you go...........

 

?? get atiming light on that thing,if you can't see the line there you go...........[/QUOTE]

Will a regular timing light for a vehicle work? I know the clamp around the spark plug wire and positive to positive battery terminal but where do i shoot it at? Into the inspection hole? When i disassembled everything the timing marks were lined up on the sprokets and i didnt move it during re-assembly. Yes the spark plug is new and gapped according to the service manual. The valves were lashed at .006" ran and rechecked. I read on another post about worn cams...where would i measure to see if mine is bad? Both valves move when it turns over. It ran ok for a bit but now it cant run at all without help. Thanks!

 

hey, Firemedicsafd,yeah its under the plug on top of the pull start,but thats not your problem if it ran otay before.............be very careful and have a fire extinquesher handy (you probably will anyway since what your surname is) and carefully spray carb cleaner into the carb while its runnin,if it runs better its fuel related, if it don't than its spark related, pull black wire on rev box..............as far as the camshaft is concerned,if the lift is even on both rockers its probably okay thinkin how can it go bad so damn quickly..............check your timinchain autotentioner after the fuel test,make sure it didn't retract and make the chain jump time..........