2000 YZ 250 Not Hitting Powerband??

I bout a cherry 2000 YZ 250 from a guy very little wear. It has about 15 hrs on top end. It does have a rough throttle cable slightly kinked still works though. Anyways when accelerating and gets to the powerband its kind of jumpy like it wants to hit but won't. It's smooth on the top side but feels a little lacking on punch. All I've read I'm thinking powervalve or reeds. The bike ran fine when put away for winter then this spring he cleaned the carb and now it's doing this? So would it be the powervalve from sitting all winter? He's said he thought it was clutch cable or throttle cable as. Which that is why I'm asking this question can a sticky or kinked throttle cable or bad clutch cable cause it to be jumpy at powerband and not want to kick in and be a little lacking on top end. There's no bucking and jerking in forth and fifth gear just 1St-3rd!

If that throttle is not smooth, find out why and fix it now....could get you killed. Ride it to where it cuts out and hold it there for a few seconds and then hit the kill switch.....read the plug.

ur powervalve is prolly a bit gummed up. same sthing happend to my ktm 250 2 stroke

Exhaust is plugged if its not powervalve

Thanks guys! Exhaust is brand new. Checked reeds they were fine. We have it narrowed down to the clutch the more I tighten the clutch cable the better it gets. Changed the plug and fuel runs strong now! There is some slipping of the clutch going on so I'm wonedering if this could be a tired clutch cable?

Or a tired clutch?

Or a tired clutch?

Is the clutch something that can be attempted with a manual? I'm slightly mechanically inclined.

The clutch is one of the easiest internal motor parts to replace, esp. with a manual.

Take a peek at the parts fiche there is one odd bolt in the cover, and one lock tab that you need to open to pull the basket....its just bolts. Word to the wise, do not over tighten the cover bolts.

Okay it looks mint inside




I had it on the track today for the first time felt much stronger than my buddy's built CR250. Except for the little jump when on the throttle. As I tight the clutch cable it did get better but still doing it. I've got a clutch cable coming so I'll let you know.

How does the basket look? Check the "fingers" for grooving from the adjacent fingers on the fibers.

Measure the thickness of the fibers and steels and reference a service manual to see if they are in spec.

I find it hard to believe the clutch cable was causing this unless it was WAY to tight, but I guess I have seen weirder things. Adjust the cable to have a good half to full inch of free play at the level. Take it for a quick spin and see if the symptom is still there. If it is still there, it is probably not cable related. But the cable is cheap and easy to replace.

Also replace that throttle cable if it has a bend. You don't want that sticking in the sleeve leaving you WOT!

Ya thank you I ordered a new throttle cable and clutch cable? So you think too tight of a clutch cable can cause a slip like symptom? It never had any play and I just kept tightening it (newbie). The basket and everything inside look mint condition. One other quick question after taking it apart i can't remember where the washer with the fingers that slide perfectly over the shaft go?

What did the basket look like?

Basket looks fine as well. I just read were a guy was having some slipping with a new clutch and basket. He was told to add a plate do you think this could be my problem mabey I'm missing a plate.

I'm thinking its the powervalve or it could be the governor spring may not being opening the powervalve.

Try cleaning the powervalve then go from there

i had the exact same problem as you! mine started acting up after it sat all winter also. in my case, it was a dirty powervalve. so i took the top end off and cleaned the powervalve and put a new pison ring on there just for grins (the bike had low hours so the piston was like new), and i honed the cyllinder. now that its all put back together i broke the motor in yesterday...and i'm plannin on givin her the berries tonight!:confused::thumbsup:

Basket looks fine as well. I just read were a guy was having some slipping with a new clutch and basket. He was told to add a plate do you think this could be my problem mabey I'm missing a plate.

How many plates do you have? I misplaced a plate once and knew immediately when I started the bike... lots of rattling and noise. Make sure you have all the washers, shims, etc. in there in the right order. One missing washer will throw thing off just enough to not be able to adjust the clutch to get rid of the slop. However I doubt thats your issue. My guess would be a stretched cable???

8 clutch plates and 7 friction (smooth) plates. The adjust screw on the perch was like cross threaded so I ordered a new perch. I also have a manual coming thursday so I wont be such a bother lol. 250stroker my buddy with a newer yz250 rode it and said it felt as strong as his if not stronger so I'm not sure it's the powervalve. It feels like a jolt when hammering on the throttle and got better when I tighten the clutch lever? What about the clutch spring being weak and not grabbing as hard as it's supposed to.

Yea based on that description, Ill put my money on a stretched clutch cable. The lever may have a little to do with it though but not much if any.

Okay well it wasnt the cable its still doing it. When accelerating it 1-3 its worse than 4-5 its almost like the clutches arent grabbing when on the throttle.

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