IndyMX

Crash Test Dummy
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Jul 18, 2006
5,548
2
Amo, IN
So.. I adjusted my intake valves. They were .003 too tight.

They measure in spec now. The exhaust valves are supposed to be .0110 +- .0012, they measure .090 and that feeler was just a touch loose. .010 won't go in though. so.. A tiny bit tight, but I don't think it's too tight to run. Correct me if I'm wrong.

I just changed the hot start valve & the cold start valve (choke). Both were worn. Thoroughly cleaned the carb. (tore it down, used solvent and air to blast it clean)

Made sure the pipe isn't loose and sucking air, also made sure the carb is attached properly and no air leaks.

The problem. It idles very rough and dies. When I rev and let go it pops like crazy.

I have no clue where to look now. I think I have all the bases covered for why it would be running like this. But it seems that nothing I do helps.

Anyone have any ideas?
 

pesky nz

Member
Sep 13, 2010
296
0
My apprentice had a simmilar problem and we tracked it back to him putting the slide plate in upside down, bottom should be flat with small cut out in the middle and arrow shape to the top (out of sight) caused lots of backfire when throttle opened
 

_JOE_

~SPONSOR~
May 10, 2007
4,697
3
I hope you meant the exhaust valves measured .009 not .090. That would be really bad! Anyone you know have a leak down kit? Did it start acting like this all of a sudden? Have you changed the plug?
 

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
2
Merrillville,Indiana
I can sure make mine do this through jetting! You still use the fuel screw to get the pilot, but the leak jet, just have to change it, or get an adjustable set up. I cheat, and use the choke to see if it makes the fire and popping better or worse. BUT, what Joe said, will do this also, bad seats. How do you know, how many shim sizes the bike was from new? 3 strikes, they are toast. Take the head off and pour fuel in for leakage works also. My exhaust valves are beating my intakes. Pete and Eric are around.
 

IndyMX

Crash Test Dummy
~SPONSOR~
Jul 18, 2006
5,548
2
Amo, IN
Ooops.. so I did have that plate upside down.. It's in correctly, and I'll try to fire it up in a few minutes.
 

IndyMX

Crash Test Dummy
~SPONSOR~
Jul 18, 2006
5,548
2
Amo, IN
I definitely will.. It started up and ran great. Just need to tune the fuel & idle and it'll be perfect.

Thanks!!
 

IndyMX

Crash Test Dummy
~SPONSOR~
Jul 18, 2006
5,548
2
Amo, IN
Absolutely Bob..

I would have gave one from my last race, but it was such a crappy run, I didn't think it warranted mention.

I spent more time trying to get the damned thing to run, than I did actually riding it.
 
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