someone help im stumped

reignman

reignman

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okay something really weird is up with my sisters bike. its a 1990 ninja 250. did some work over the winter (repainted, replaced the brake pads, clutch plates and adjusted the valves). so during the valve adjustment, i noticed the rocker arm on one of the intake valves was broken. replaced that and go to start it and it wont. turns over and im getting spark but no start. clean the carbs for the h*ll of it and get new spark plugs. now it starts but the right cylinder makes an awful, repetitive clunk noise (every time that cylinder would be firing). the right cylinder and header aren't even getting warm. so i pull the plug to make sure its sparking (forgetting to pull the wire on the other cylinder), and it starts up better than it did with both plugs in. WTF is going on lol:wtf::banghead:
 
I just happen to have this laying here on my coffee table. I'll take a look to see what it says. I may find something.

IMG_4581_zps63bcd695.jpg
 
well technically the rocker should require pulling the intake cam off... but i cheated and just depressed the valve partially and slid the rocker in. i know thats not ideal but at tdc the valve barely had to be depressed to slide the rocker in at the minimum adjustment
 
lol what a coincidence. thanks let me know if you find anything! i guess i should double check timing even though i didnt do anything to disturb that
 
I was thinking as to why the Rocker Arm would break in the first place. These motors are pretty bullet proof. I'm just wondering if there is something deeper going on that caused the failure in the first place.
 
Was the right getting spark? Is it possable that valve is hung up or stuck shut, and that is bogging the motor down when the plug is in?
 
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idk why the rocker arm broke, it was just the tiny retainer tab on the side that keeps it seated on the valve not like the entire rocker arm was broke in half.

ya the right was getting good spark. how would i check see if a valve is hung up? i guess i need to pull the valve cover off, verify timing is correct and look at the valves
 
reignman said:
idk why the rocker arm broke, it was just the tiny retainer tab on the side that keeps it seated on the valve not like the entire rocker arm was broke in half.

ya the right was getting good spark. how would i check see if a valve is hung up? i guess i need to pull the valve cover off, verify timing is correct and look at the valves
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I would at least pull the cover and before measuring any gaps, turn the motor manually a few revolutions to make sure that the valves on that side are at least opening and closing. You may be able to hear the noise with the cover off to get a better idea of what is happening.
 
If by chance you need the manual, just PM me your name and shipping address and I'll send it out to you. Once you get it just take my address from the envelope and throw a ten dollar bill in an envelope and send it my way to cover shipping and handling. I don't really need it anymore since selling my son's Ninja and it's brand new.
 
I would do what Billy says, and re-check the timing, and also re-check the clearances. You might have thought that the valves were closed when you checked them, but its possible it was on the wrong stroke.
 
YZFRiderNY said:
I just happen to have this laying here on my coffee table. I'll take a look to see what it says. I may find something.

IMG_4581_zps63bcd695.jpg
Click to expand...

And this is the power of the internet forum in all it's glory.

"Ohh wait I happen to have the exact service manual you need for a 20+ year old motorcycle here on my coffee table." LOL Awesome.
 
Ssky0078 said:
And this is the power of the internet forum in all it's glory.

"Ohh wait I happen to have the exact service manual you need for a 20+ year old motorcycle here on my coffee table." LOL Awesome.
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Hahahaha!!!! And here's my coffee table!!

IMG_4583_zpsa7a01e9e.jpg



I always keep my manuals handy as any gearhead should. You never know when you'll need them!!
 
Ssky0078 said:
And this is the power of the internet forum in all it's glory.

"Ohh wait I happen to have the exact service manual you need for a 20+ year old motorcycle here on my coffee table." LOL Awesome.
Click to expand...

ya i thought that was pretty hilarious lol

so i pulled the valve cover back off to look. another weird thing i noticed that is gets hard to turn when the right cylinder valves are opening. it spins freely while the left is and then hard for a moment as the intakes on the right compress and then free for a moment and then hard to turn while the exhaust valves are compressing. im sure thats the problem but idk what that means or what else to check
 
reignman said:
ya i thought that was pretty hilarious lol

so i pulled the valve cover back off to look. another weird thing i noticed that is gets hard to turn when the right cylinder valves are opening. it spins freely while the left is and then hard for a moment as the intakes on the right compress and then free for a moment and then hard to turn while the exhaust valves are compressing. im sure thats the problem but idk what that means or what else to check
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It may be because of the compression stroke. Pull the plugs first out of both cylinders, then rotate her again.
 
stretched06 said:
Good call Billy. If he pulls the carbs would anything in question be visable?
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I don't think he'd see anything through the intake ports, but being that it's only two carbs, it wouldn't hurt at this point. I believe that the problem is somewhere with the valves themselves. Maybe a bent valve stem or such. These motors usually have little or no problems at all.
 
The plugs are already out. Something valve wise has to be messed up. I'll wait on that manual and start tearing the heads off to inspect the valves probably. Idk what else I can check without tearing it apart more
 
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