I am posting this for a buddy of mine that has a 98 CR 250, as do I. The bike simply wont come on pipe. It has great low end power, almost as good as mine, but will not ever come on pipe. The bike doesnt foul plugs, get hot, or do anything out of the ordinary. He thought it needed rebuilt, so it was bored and got a new piston and rings. That fixed nothing.We swapped out my carb, coil and pipe/silencer. Still wont come on pipe. Does anyone have any advice on what to look at next? We are stumped and he is losing patience with his bike. Any help would be GREATLY appreciated!
98 CR250 wont come on pipe!
- Thread starter Chapman
- Start date
First off, if he bored the cylinder without having it replated, then he is going to have to tear it back down and do so. It uses Nikasil plating, and boring it removes the plating. Only iron liners can be bored and used without plating.
You don't mention having tried your CDI on his bike. If that was malfunctioning, it could prevent proper advance and retard of the timing. Next I would suggest ensuring the flywheel key is not sheared. If it was sheared, the timing could be way off. The only other thing that comes to mind is something is horribly wrong in the jetting in the mid to top circuits, those being the needle and main jets.
You don't mention having tried your CDI on his bike. If that was malfunctioning, it could prevent proper advance and retard of the timing. Next I would suggest ensuring the flywheel key is not sheared. If it was sheared, the timing could be way off. The only other thing that comes to mind is something is horribly wrong in the jetting in the mid to top circuits, those being the needle and main jets.
Faded
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- Jan 7, 2003
- 842
- 0
I agree with blackjack, and it's a quick and easy check. Here's a cut and paste from one of my previous posts;
It sounds like the exhaust valve is stuck part way...open.
When people do top-ends on these bike they don't realize that they need to line up the crow's foot actuator arm on the bottom of the cylinder with a corresponding arm on the crank case. The result is the actuator arm gets pinched (and ruined) and the exhaust valve is rendered inoperable and the bike has a powerband much like you've described.
The easiest way to check is to pull the 17mm round cover off of the left hand side of the cylinder. Underneath will be a shaft that looks like the head of a flat blade screw. On the cylinder surrounding the cover there should be two markings, an "L" and an "H". At idle and lower RPMS the flat notch in the shaft should point at the "L", when you rev up the motor the shaft should turn and the flat notch should point at the "H". If the shaft does not rotate when you rev the bike then you have a problem that needs to be fixed.
Hope this helps.
It sounds like the exhaust valve is stuck part way...open.
When people do top-ends on these bike they don't realize that they need to line up the crow's foot actuator arm on the bottom of the cylinder with a corresponding arm on the crank case. The result is the actuator arm gets pinched (and ruined) and the exhaust valve is rendered inoperable and the bike has a powerband much like you've described.
The easiest way to check is to pull the 17mm round cover off of the left hand side of the cylinder. Underneath will be a shaft that looks like the head of a flat blade screw. On the cylinder surrounding the cover there should be two markings, an "L" and an "H". At idle and lower RPMS the flat notch in the shaft should point at the "L", when you rev up the motor the shaft should turn and the flat notch should point at the "H". If the shaft does not rotate when you rev the bike then you have a problem that needs to be fixed.
Hope this helps.
yo its matt!
Member
- Aug 26, 2000
- 69
- 0
i just bought a 99 cr and the jetting was way off! it had a 190 main and most of the specs ive found recommend a 170, i went to a 178 and though i havent had time to ride it much but its alot better. first bike i have had with a powervalve ill have to check mine now!
