RM-Z250 2012 Suzuki RM-Z 250 top end help

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Anitomical

SRAD97750:
That is strange. Could it be the cover binding?
-BIG DAN:thumb:
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The cover isn’t binding and theres no signs of wear on the cover either. I put the kick starter on when i had the over off and i didnt put much pressure on it since it didn’t have the support from the case and it still felt like it had extremely high resistance. I tried to spin the clutch basket by hand too and no luck. The collar for the clutch basket is perfect fine and same for the bearing. I double checked the teeth on the back just to make sure and just look for anything out of the blue or something that looked off but everything looks perfectly fine.
 
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Anitomical

Ok so I found some of the problem I think. The cam chain seems extremely tight like absolutely no play, it has a brand new chain so im not sure if its to small or what. And when the stator is on it has a bit of resistance and once you take it off it spins absolutely freely. To me the stator and flywheel looks perfect so I dont know what would be causing that. And when i even hand tighten the front sprocket you can barely turn it and yes its in neutral.
 
2Wheels

2Wheels

Not sure about the suz but kawi cam chain tensioner has to be completely retracted and reset before reinstalling. Like a non retractable ratchet.
 
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Anitomical

2Wheels:
Not sure about the suz but kawi cam chain tensioner has to be completely retracted and reset before reinstalling. Like a non retractable ratchet.
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Oh I did that just it was still extremely tight. I took the camchain off and compared it to the old one and the old one is just slightly bigger but thats because it was stretched slightly. Honestly it was hard to tell the old one was stretched next to the new one
 
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Nighthawk016:
Did you figure out the issue?
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Well kinda, i tore the entire thing apart again and I found literally nothing wrong and everything was in place and moved perfectly. I put it back together being very sure everything was smooth and going right and well now it spins over smoothly. And the transmission i found out that the front sprocket was rubbing on the cover on the back of the sprocket so i grounded that down and now it spins perfectly. Now I just dont have any fuel going out the injector… the fuel pump is working perfectly, it has spark but no matter what I do I can’t get the injector to fire.
 
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Ok so I cleaned the injector and now it actually sprays the gas. But now all it does it backfire and shoot flames but it wont start. I don’t know if it’s something with my technique or if i dont have enough force into it or what. The valves are in spec and timed, it has good spark and a brand new spark plug and it has good fuel flow so maybe I just cant put enough force into it? Im definitely not a big dude so that could be honest be it but it seems like it wants to go like itll hit once ad then the next few kicks there’s nothing or it shoots a fire ball.IMG_4278.jpegIMG_4279.jpeg
 
SRAD97750

SRAD97750

Moderator
Staff member
Are you able to bump start it with a friend?
If you can push it along in 2nd gear, dump the clutch and keep pushing till it lights?
-BIG DAN:thumb:
 
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2Wheels:
Have you tried spraying some starting fluid?
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No I haven’t because the looks if the flame, the sheer sound of the backfires, and when i was cleaning the injector i was making sure that is was fully clean and shooting enough fuel and it definitely was. I’ll try that later today just incase though
 
2Wheels

2Wheels

Somethings wrong.
I put a fresh top end on a '14 YZ250F new valves, seats and new piston/cyl quick shot of throttle body cleaner and started it with my fist. If yours wont light up I would double check everything. The backfire is trying to tell you something
 
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Anitomical

2Wheels:
Somethings wrong.
I put a fresh top end on a '14 YZ250F new valves, seats and new piston/cyl quick shot of throttle body cleaner and started it with my fist. If yours wont light up I would double check everything. The backfire is trying to tell you something
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What do you think would be wrong then? It has a brand new spark plug and the gap is 0.035. The valves are within spec, .5 intake and .7 exhaust. None of the valves are bent or damaged in anyway. The piston is in the right orientation and the piston ring gap is 0.02. The cams are perfectly timed. I mean maybe it has something to do with the ignition timing? But I didnt mess with any of that stuff
 
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