Confounding problem: 93 CR250

[SilverSurfer]

Ok, I purchased a used and in need of a lot of TLC 93 CR250R. I have completely rebuilt the bike to the tune of the following:

1. Rebuilt entire motor. (Wiseco piston/Hot Rods crank)
2. Replaced COIL
3. Replaced STATOR
4. Rebuilt carb (stock jets/needle)
5. New air filter/spark plug
6. Rebuilt suspension.
7. New chain/sprockets
8. New bars/ASV levers.
9. New kill switch
10. All bearings/seals replaced.
11. All new plastics
12. FMF Fatty/Spark arrestor pipe.

Basically it's almost like a new bike. Except for one problem. The bike starts fine after a few kicks. On the low end it runs perfectly. It will yank the front wheel right up. However, once I hit midrange or beyond it just runs flat.

It's accellerating but not like a normal 250 does. It's just not pulling hard at all. It's pulling more like a cr80 than a 250. I just can't figure it out. The jetting is spot on where FMF says it should be. It's not smoking too much and I don't think it's running lean at all.

My question is WHY is it doing this? It's not sputtering from midrange and up. It's just not pulling like it should. It's pulling like it's way way too rich.

Any idea why it's running like this?

 

[evenslower]

Powervalve linkage hooked up correctly? Sounds like PV not opening. Are you sure the fork on the bottom of the actuator arm that runs up the cylinder is aligned properly on the pin in the bottom end. If I remember right they are almost 90 deg to each other when connected properly.

Check to make sure everything is tight too and no PV flapping is going on.

www.ericgorr.com

I think there is some good info there. Good luck.

 

[nickyd]

repack the silencer

 

[SilverSurfer]

Powervalve linkage hooked up correctly? Sounds like PV not opening. Are you sure the fork on the bottom of the actuator arm that runs up the cylinder is aligned properly on the pin in the bottom end. If I remember right they are almost 90 deg to each other when connected properly.

Check to make sure everything is tight too and no PV flapping is going on.

I think there is some good info there. Good luck.

Powervalve is working properly (checked it myself). Moves as advertised. It's running like the pv isn't working but I know it is.

Thanks for the link, I'll check it out.

 

[SilverSurfer]

repack the silencer

It's brand new...

 

[evenslower]

Are you sure its opening all the way? I know from experience that center flap can get carbon build up in the slot that stops it from travelling through its full range.

Aside from that ignition????

 

[SilverSurfer]

Are you sure its opening all the way? I know from experience that center flap can get carbon build up in the slot that stops it from travelling through its full range.

When I pulled the head I cleaned the valve up completely. There's no carbon build up. When you look through the peep hole on the left side of the head and rev the engine you can see it move the full range of motion.

Aside from that ignition????

I replaced the coil and stator. The only thing I haven't replaced is the ignition module. I heard those don't go bad often but they are very expensive. I wonder if there is any way to test it.

 

[2-strokes-4-life]

I replaced the coil and stator. The only thing I haven't replaced is the ignition module. I heard those don't go bad often but they are very expensive. I wonder if there is any way to test it.[/QUOTE]

there is no test for the cdi unit.when diagnosing an ignition problem if all other components test out fine,that usually means the cdi is at fault

 

[SilverSurfer]

there is no test for the cdi unit.when diagnosing an ignition problem if all other components test out fine,that usually means the cdi is at fault

If the CDI is bad, would it even start? I checked the plug, looks perfectly fine.

The only thing because the CDI would be the timing which I think I have to adjust since the new stator can be rotated slightly and I don't know that it's timed perfectly.

 

[SilverSurfer]

Anyone?

 

[cal9126]

maybe its all in your head bro....

 

[SilverSurfer]

Bump!

 

[kamchuka]

at idle?

are you getting good snap.
is it idleing well?
you can pop that side cover off and do the old school timing just to see.
leave your bolts hand tight, start it twist a few, get a feel. shut her down, move it, fire her up, twist a few.....etc.
aside from that if that cdi box is bad it may fire and not provide the right spark at the right time. i just put a special one on mine, as i do more woods riding, that allows me to play with the timing simply by flipping some knobs. its well worth the 250 i spent for it. i get more traction in the ruff stuff and a smoother power band, especially with a 7oz. flywheel weight.
also is it bogging or just weak?

 

[SilverSurfer]

It boggs a bit in the upper rpm band but not badly. It seemed to be OK and maybe it's just the fatty pipe.

I'm going to have the carb rebuilt and go from there. Thanks again for the timing advice!

 

[bleeds]

Mine was doing something like this..and as silly as it was.. I found that the PIN/NEEDLE in the carb was set all the way to the bottom and was basically flooding me at midrange and beyond. I moved it back to the middle where the honda factory service manual said it belonged..and runs like a champ now. TONS of bottom end lug (to the point of chug chug chug) and revs out till my teeth chatter. Its just another point of view..
my $.02

Bleeds

 

[SilverSurfer]

I had mine set in the middle as well, that wasn't it.

I think my issues are float bowl related.