Torque down low but no top end balls - Fresh rebuild (help)

[GarbatyA4]

Hey everyone,

I'd appreciate your help.

1992 CR250R, Just rebuilt top and bottom end. Wiseco.

I bought the bike in pieces when it needed the rebuild. Anyways....

It's torquey down low, but top end in the rev range it has nothing. Actually feel like the motor is slowing down or struggling to make power. I lost racing down the road against my friends stock 1992 yz125.
I should have crushed him.

Any Ideas?

What could this be?

 

[dirt bike dave]

Is the power valve is opening?

When you set the cylinder on the cases, it is easy to mis-align the power valve actuator. If it is not lined up just right, the power valve will not open. If this is the problem, you will have to pull the cylinder off and try again.

BTW, there should be an inspection cap on the left side of the cylinder. If you remove that and start the motor, you should be able to see the shaft at the end of the powervavle rotate 90 degrees when you rev the motor. If it does not rotate, your powervalve is stuck.

 

[GarbatyA4]

Another thing I've noticed. It looks like the choke only goes half way down. I took it out last night. It looks a little bent. And when It idles, it seems to have prolonged cycles. instead of a fast ba-ba-ba-ba-ba. Its ba---ba---ba, doesn't miss a beat, just longer strokes/cycles.

 

[GarbatyA4]

Is the power valve is opening?

When you set the cylinder on the cases, it is easy to mis-align the power valve actuator. If it is not lined up just right, the power valve will not open. If this is the problem, you will have to pull the cylinder off and try again.

BTW, there should be an inspection cap on the left side of the cylinder. If you remove that and start the motor, you should be able to see the shaft at the end of the powervavle rotate 90 degrees when you rev the motor. If it does not rotate, your powervalve is stuck.

Awesome, I will check that out today at lunch. Appreciate it :cool:

I'm sure its aligned but it is possible i mis-aligned. I'm also wondering when the shaft rotates, the linkage uptop in the powervalve compartment isn't rotating.

ps. powervalve is new

Thanks again.

 

[GarbatyA4]

Another Question:

Should the governor shaft be pre-loaded (the spring) to the vertical shaft going to the power valve assembly area?

 

[GarbatyA4]

thanks for the replies guys.

I'll find out at lunch if the powervalve is working

 

[GarbatyA4]

update...

Went home for lunch... let the bike warm up, and took off the inspection plug to see if the powervalve is rotating from high to low and It's not. :yell:

It's stuck on low aka open all the way and I road for an hour or 2 yesterday.

So... does anyone know if cr250's have to have the governor spring preloaded.

I want to check if I mis-aligned the shafts between the motor and barrel. Can I just loosen the nuts and lift the barrel up a bit and align it? Will coolant leak?

 

[MikeT]

You need to drain the coolant before lifting the cylinder up or as you thought, the coolant will flow out.

 

[GarbatyA4]

cool, thanks.

 

[GarbatyA4]

Fixed the problem, went got a engine gasket kit.
took off the clutch cover and split cover (didn't split the casings)

I bought hte bike as a basket case... motor was half apart, I put the governer in backwards. Luckily no damage was done. Everything is perfect now. Bike rocks wheelies like no tommorrow.

Here she is after buying her in pieces for 100 bucks. Put in Wiesco Crank, Piston, new bearings and seals. Came with a couple goodies

 

[GarbatyA4]

 

[dirt bike dave]

Nice work! Looks like you are putting it to good use.