Help yx 150 won't rev up backfiring

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Mland.514

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I bought a klx 110l with a yx 150 motor in it with two bros. pipe and silancer. The kid I bought it from just put a new flywheel/outside rotor ignition with new CDI on it. It starts right up and once I get it to 1/8th throttle it backfires really bad sounds like fireworks. I can ride it and get all the way to 4th gear just can't give it much gas or it goes nuts and pops like crazy
I have set valve lash to .003 intake and .004 exhaust. Still backfires a lot
Cleaned out carb 3 times, took off the flywheel because it seemed like it was loose, so I put in new woodruff key and tightend back up good. Brand new spark plug. It's spitting gas out of the carb

I'm running out of ideas still am not sure if this is a spark issue or a carb issue.

Anyone?????
Thanks
 
leaking intake valve or incorrect timing when setting lash
 
How do I adjust timing?? Flywheel is on a key and pick up magnet doesn't slide around at all
 
yeah i agree with Zac,
was it at TDC when you did the valve clearances ?
with the Cam gear pointer lined up at 9 o'clock, and the flywheel mark lined up at 12 o 'clock?


with the carby clean, did you remove the 3 jets and make sure all the holes were clean/open?
and where the Pilot jet screws into, is the hole at the bottom of the threads where it screws into in the carby base open, so you can see light though into the carby bore ?
also did you blow some compressed air through the small intake ports on the air filter side of the carby,
making sure you can feel air coming out the jet holes underneath the carby base?

and how many turns out is the mixture screw set at ?


while you are here too, drop by and say g'day in our introduce yourself thread- http://www.miniriders.com/general-chat/20824-introduce-yourself.html


cheers, craig
 
Yes piston was at tdc when I set valve clearances.
I sprayed out carb with carb cleaner removed main and piolet jets and took a wire through them blew all out with air gun and repeated same process 3 times

Here's a pic of my bike/ ignition setup, yeah sorry the bikes dirty right now


 
nice looking Alloy Frame, it looks like a good quality bike.
what brand is it ?
also what carby are you running on it ?


ok so the hole through the middle of the Pilot jet is clear, what about the holes that go across through the sides of that jet ?

and where the Pilot jet screws into the base of the carby,
if you shine a torch into the hole, you should be able to see a tiny hole that goes through to the main bore of the carby,
if this is partly blocked then it wont idle too well, and if you pull the throttle on fast it will hesitate and cut out.


the other place to look is the Needle Jet, it's the long brass jet that screws into the carby base, and is the part that the Main Jet screws into.
take that out and check that the holes that go across it are all open too
 
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I believe it's a moloki carb? Yes it's all very clean I will go through it once again today. Do u think this could be electrical or timing?
And the frame is a 2009 Kawasaki klx 110 l
 
so is it backfiring through the exhaust?
or is it popping through the carby ?

is the air filter a foam one, and is it oiled?
do you know how many turns out the mixture screw is ?

might pay to post a couple of pics of the carby too, from different angles
 
Popping from exhaust air screw is 1.5 turns out i tryed messing with that and didnt help. Foam filter. Ill get pics tonight
 
do you know if the previous owner jetted the carb to suit the pipe? it'll most likely have a larger diamtre pipe, making your bike run lean with the jets currently in it.
 
with the popping check that the exhaust nuts are nipped up tight into the head

i would pull all the electrical connections apart and spray some wd40 spray into them
and take the earth wire off the frame, clean it and the frame up then refit it.


have you thrown away the original china spark plug from it, and replaced it with a genuine NGK C7HSA ?

and double check all those holes in the jets that i mentioned before too
i have never heard of that brand carby before ?
 
I have replaced the plug with c7hsa the jets do not say anything on them so I have no clue what size they are!

On the other hand when I took off my carb is noticed somthing.. The spacer between the intake tube and carb was upside down! So It was blocking about 1/4th of the intake tube. Not sure of this was my problem or not but I'm hoping that's it! And That would explaine why I couldn't run with the choke on. I pulled the spark plug it looks okay I think actually maybe a bit rich. I stripped out my damn kickstart so I'm just going to weld it on one of these days temporarily. I also checked cam timing and I will post up a pic of all of this for you guys here in a few min.
 
If you have just stripped the kick start do not weld it onto the shaft. You're better off buying a new one and not worrying about if somthing goes wrong in the motor how your going to get the cases off
 
Snaptrax said:
If you have just stripped the kick start do not weld it onto the shaft. You're better off buying a new one and not worrying about if somthing goes wrong in the motor how your going to get the cases off
Click to expand...
Right, but I stripped the shaft on the bike so both kickstart and shaft are already junk might as well just weld it and cut it off and replace it later on when I need to take that cover off. Like I said, this will be temporary
 
TIMING PICS

Ok so I know in the pics it is lined up at f on the mark on the flywheel I didn't have enough hands to hold it at T and hold light and camera haha I think the magnet just pulls it down to the F because it wouldn't stay at T But I think you can get the picture at least





 
Mland.514 said:
Right, but I stripped the shaft on the bike so both kickstart and shaft are already junk might as well just weld it and cut it off and replace it later on when I need to take that cover off. Like I said, this will be temporary
Click to expand...
Its pretty easy to replace tbh..
If your going to weld ensure you have a good ground on the shaft in question so it does not arc out your bearings
 
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