2001 CR250 Help!!!!

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3/14/2020 7:13 PM
Edited Date/Time: 3/15/2020 4:39 AM

Ok so I'm at a loss......
I purchased a 2001 Cr250 a few months ago and I feel like all I do is work on it. Day 1 it had no top end. I think the previous owner misaligned the fork. Then I got a surge and revving when I was riding and let off the throttle. I rebuilt the carb, rejet the carb, swapped the carb and rebuilt and rejet the new carb to no avail. I then did a leak down test and it came back complete crap. I tore the motor apart, split the cases, replaced bearings and replaced all of the seals and gaskets in the motor... got it back together tonight, jet the Air striker to 178 main 50 pilot needle 3rd slot, air screw 1.5 out and tested it. (Edit Bike has FMF Gold series pipe, FMF turbinecore, V-force 3 reeds and I'm at sea level)

On choke, it revved to the moon, turned choke off and on idle it died. Went to 1 turn out on air screw and it would idle, would rev with only a small hesitation if I whacked it hard, but as soon as I try to go ride it 2 seconds into attempting to accelerate it dies. Starts back up 1st kick, then dies as soon as I try to accelerate again..... please keep me from blowing this thing up with some C4.......

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3/15/2020 12:52 AM

On my 01, I went with 175 main, 45 pilot, second clip position, 1.5 AS.
I have a Pro Circuit pipe and V-Force reed’s.
Elevation 1500-3000

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3/15/2020 4:06 AM
Edited Date/Time: 3/15/2020 4:10 AM

Sorry I should have mentioned those as well... I have an fmf gold series pipe, fmf turbinecore silencer, new v-force 3 reeds, and I'm at straight up sea level....
When I had my air leak, I ran jet settings from leaner than this to richer than this and all of them would at least let me ride the bike.... I've never experienced this dying out before...

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3/15/2020 7:30 AM
Edited Date/Time: 3/15/2020 7:38 AM

Did you check the float height?
Is the pilot jet 100% clean?
Did you do another leak test after you did the engine work? You may still have a leak issue.

Long shot issues to review...
Bad spark plug and ignition coil.

Paw Paw

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3/15/2020 10:35 AM
Edited Date/Time: 3/15/2020 10:36 AM

Ok update. I switched back to the old Mikuni. Jetted at a 420 main and 36 pilot and 2 turns on air screw and after a lot of ups and downs the bike is running a lot better. HOWEVER, the power valve isn't working..... I know I aligned the fork properly, I paid extra close attention putting it together. But its only rotating 45 degrees and it feels lazy up top. I did a test and secured my power valve wide open and took it for a test ride and now I'm not entirely sure my power valve has ever worked right lol. So now I've gotta track this issue down.....

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3/15/2020 12:56 PM

The rotating type power valve on that generation of engine was pretty notorious for getting sticky with carbon. Remove the pipe and the right side cover on the cylinder. Disconnect the linkage arm from the valve assembly. With the arm removed, you should be able to rotate the valve by hand freely through the entire 90 deg range. If you can't, it is carbon'ed up and needs to be disassembled and completely cleaned and polished until it moves smoothly and easily.

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Powerband in every gear !

3/15/2020 1:20 PM
Edited Date/Time: 3/15/2020 1:21 PM

FGR01 wrote:

The rotating type power valve on that generation of engine was pretty notorious for getting sticky with carbon. Remove the pipe and the right side cover on the cylinder. Disconnect the linkage arm from the valve assembly. With the arm removed, you should be able to rotate the valve by hand freely through the entire 90 deg range. If you can't, it is carbon'ed up and needs to be disassembled and completely cleaned and polished until it moves smoothly and easily.

So when I loosen the set screw I can easily rotate the valve through its entire range of motion. But it only rotates 45 degrees when revving. I temporarily set the power valve incorrectly so it's slightly open at idle and opens fully at WOT.... The bike feels better than it ever has if I'm completely honest. Ive lost a smidge of torque but have gobs more power up top. I dont want to leave it like this though. Is there something down in the governor assembly, something missing or adjusted wrong or misaligned that could cause the valve not to go through it's full range of motion?

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3/15/2020 4:09 PM

FGR01 wrote:

The rotating type power valve on that generation of engine was pretty notorious for getting sticky with carbon. Remove the pipe and the right side cover on the cylinder. Disconnect the linkage arm from the valve assembly. With the arm removed, you should be able to rotate the valve by hand freely through the entire 90 deg range. If you can't, it is carbon'ed up and needs to be disassembled and completely cleaned and polished until it moves smoothly and easily.

navyslideby wrote:

So when I loosen the set screw I can easily rotate the valve through its entire range of motion. But it only rotates 45 degrees when revving. I temporarily set the power valve incorrectly so it's slightly open at idle and opens fully at WOT.... The bike feels better than it ever has if I'm completely honest. Ive lost a smidge of torque but have gobs more power up top. I dont want to leave it like this though. Is there something down in the governor assembly, something missing or adjusted wrong or misaligned that could cause the valve not to go through it's full range of motion?

The power valve governor assembly could be worn and sticking. I checked just now and there are a number of them on ebay for fairly cheap. Don't know if they are still available new....Check all the various splines on the shafts for wear and check for any play in the shafts as well

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3/15/2020 7:57 PM

mxracer666 wrote:

The power valve governor assembly could be worn and sticking. I checked just now and there are a number of them on ebay for fairly cheap. Don't know if they are still available new....Check all the various splines on the shafts for wear and check for any play in the shafts as well

Ok so I took a look at a governor assembly and I think I've got my mind around how it works.... I think you may be right. If the governor is worn or sticky or just not expanding right for some reason that would cause my issue. Is there an adjustment for the governor itself? Can the spring tension be adjusted or anything like that or does it just have to be replaced? My fear is if I get a used one I'll run into the same issue, and thus far I cant find a brand new one as you said.....

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3/15/2020 8:21 PM

Well, in the meantime due to the affordability of them on the secondhand market I ordered one off of ebay. Hopefully this will get my bike to 100% and I will update you when I get it installed

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3/15/2020 8:53 PM

The governor is not meant to be serviced and there are no replacement parts

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3/16/2020 4:46 AM
Edited Date/Time: 3/16/2020 5:42 AM

mxracer666 wrote:

The governor is not meant to be serviced and there are no replacement parts

Alright, replaced entirely it is.... I've got a hare scramble this weekend (as long as Corona doesnt ruin it) so I think the valve is going to remain Ill adjusted for this race as the bike actually runs pretty damn well in it's current form. But after the race I'll pull the cover and change the governor!

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3/16/2020 6:50 AM

the powervalve has a massive effect on jetting. It goes with out saying that once you get the PV fully operational, the jetting will change.

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3/16/2020 7:09 AM
Edited Date/Time: 3/16/2020 8:28 AM

DynoDan22 wrote:

the powervalve has a massive effect on jetting. It goes with out saying that once you get the PV fully operational, the jetting will change.

Hmmm... well as the bike sits now, I feel like it is jetted pretty much perfectly. It's got crisp throttle response, runs stronger than it ever has since I've owned it without a doubt. And I'm on stock honda main jet sizing. But it will pull a power wheelie coming on the pipe in 3rd gear. That's pretty impressive considering before I had to chop or clutch it up in 2nd before... so I now feel like I know what the bike Should feel like up top, and with the power valve eternally closed I previously had gobs of torque, so mix those 2 worlds and that's what my bike should be like. That's motivation for me lol.

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3/28/2020 11:27 AM

Ok, so I ordered another governor assembly and replaced it. Still doesn't work. The new governor is actually compressible with my hand somewhat, seemed nice and clean and bearing rotates freely, however it only rotates like 25* and the old one would rotate 45*.... I know every section rotates freely, I know the rack and pinion shaft will move through their full range of motion easily and have no play. I'm not missing either washer on the governor assembly. Its adjusted per the honda manual... I'm just at a loss right now... I may just leave it adjusted improperly!!!!!

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3/28/2020 5:11 PM

The powervalve drum on the left side (under the cap on left hand side) should rotate 90 degrees from full closed to full open. There is an "L" and "H" mark on the side of the cylinder. Is your PV not opening or not closing completely?

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3/28/2020 7:00 PM

It being closed is simply an adjustment. But opening is the issue. With my original governor the valve will only open halfway to the H.... this gives me no top end power. So I set it halfway open at idle and it opens fully now, but obviously this isn't right....

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3/28/2020 9:31 PM

Do you have a service manual?

It sounds like the lower part of the PV linkage is off a tooth.

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3/29/2020 6:11 AM

erik_94COBRA wrote:

Do you have a service manual?

It sounds like the lower part of the PV linkage is off a tooth.

Yes I have a Honda manual. You're saying this step here may not have been completed properly?

Photo

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