First 88 Build, Fail. Idles But Thats All

[fish1200]

hey thanks for helping out. im trying to put a 88 race head kit on my xr50. i got the kit used on ebay from a private seller. he said it was the right piston for the head, it looked domed w big valve reliefs. i got a 18mm carb on it. a sheng wey or whatever it is. i know its not the best but should run.

i have never done a top end on one of these but it seems simple. i got the cam in with the lobes facing to the piston and the "o" on the cam gear at 9 o'clock at the engraved mark on the head w the flywheel T on the mark on the motor. still nothing but a idle. 1st it would only run with the choke on and still bad then. i cant barley get it off idle. not i adjusted the rocker arms and the intake was too tight and now it idles great but cant get anything off idle...just pops and sometimes backfires.

ive adjusted the timing on the cam gear one tooth in either direction and no change in results, even went 180 degrees for fun and it still ran the same. bad. im stumped. i dont think the carb is clogged. i have two and swapped them. even checked the one i took off and it was fine. new plug. all the basics covered...i think.

any advice is greatly appreciated. im about to give in a buy a used motor from someone on here. sooo fusterated right now. i need to compression check it to make sure the piston is right but the kickstarter feels super strong like the compression is there.



here are some photos maybe someone can identify the brand



whoops wrong section can a mod move it?

[PlanetMinis.com]

[Oo p0op oO]

what jets are you running? when you add a race head you will have to totally re jet your bike. those carbs are hard to get dialed in. what notch is the clip setting on the needle for the carb? and im assuming your possitive your cables connected correctly and seated inside the carb properly?

[fish1200]

Yes cable is right I can see the slide seated. Needle is in the middle. Ill have to check what jets r in there. U think its possibly the Carb being so outta tune? Not enough fuel?

[JanssonK]

Have you checked the color of the spark plug?



Black to rich, white to lean

[Oo p0op oO]

Yes cable is right I can see the slide seated. Needle is in the middle. Ill have to check what jets r in there. U think its possibly the Carb being so outta tune? Not enough fuel?

yes i think thats your problem...like the other guy said check your spark plug and if the tip is black its too rich (overfueled) and if its white its too lean (not enough fuel)



i can tell you i had to go DOWN in pilots and main jets when i added a big bore exhaust system and a TB racehead to my 88 kit. its alot of trial an error for sure!



hope this helps

[T Bolt USA]

Engine and Carb quick check list - TBolt USA Tech Database!



1)Install Intake manifold to head and carb, oil gaskets and tighten bolts lightly at first then torque then down gradually in a cross pattern to provide a good seal and avoid air leaks



2)Make sure the carb is 100% clean, free of debris and you can see light thru both main and pilot jets



3)Double check you valve tappet adjustment .003intake and .004exh.



4)Make sure your exhaust gasket is installed properly.



5)Make sure all electrical connections are tight and you have a solid ground from the engine to the frame.



6)Check for good fuel flow and fresh fuel.



7)See our jetting guide and do a plug read.

http://www.tboltusa.com/store/tech.php?pid=61

[fish1200]

thanks everyone ill get on it tomorrow!