bike problems

[hellomoto]

i have an 06 yz250f down at gpf training facility. and have gone through 4 clutches in 30 hours of practice. had 250's, 125's, and 80,s for years and never had to replace clutches. also bike has reduced power and the valves have been adjusted twice, and new piston and rings. use bell ray thumper oil changed every couple of hours. any suggestions????

[ATAZ]

WOW. I have never herd of a 250F needing so much service in so little time. How hard are you riding it?

[NYMXer]

Are you sure your rear brake isn't dragging or something similar? Also, measure your clutch springs.

[FOX426]

Troll elsewhere Hellomoto/ newbie ?

[Matt96xr6]

Okay, answer the following questions to get help:

1. what is the clutch spring length presently?

2. is there ANY marks in the finger of the basket?

3. what SPECIFIC oil are you using?

4. are you changing oil filters

5. you said you adjusted valves 2x, what were and ARE the specs now on both adjustments. What shims did you change from and change to?

6. how much compression is there in 5 kicks with the throttle at WOT?

7. What jetting are you using? what elevation?

&%$#@! is reduced power? Is this a seat butt dyno or what?

We need all those answers. If you have documented your maintenance on the bike it will be a simple answer. If you have not and just trusted someone else with maintenance or are BSing here, it will come out very quickly.

[hellomoto]

i am up in Maine and my son is down at the Georgia practice facility so the info i have right now is .............

1. clutch springs are stock replacement parts

2. no marks on the fingers of the basket

3. oil is bell ray thumper 20w-50

the answers to 4,5,6 i do not know right now but i am going down to Georgia this week and the person that has been doing the work on the bike is a full time Honda mechanic for a race team but helping us out. we have drilled 8 more holes in the clutch basket to see if that would help and it seemed to last a little longer. each time we do the clutch we change the springs, fibers, and steels.

the reduced power issue is it just seems to have less power all over then when we first got the bike but this is from my son talking to me over the phone . again i will get more info later next week.

i am not BSing on any of this so thanks for any and all info. i posted on this sight because the Yamaha cust service said to bring the bike to the nearest Yamaha dealer. but i do not like to bring my race bikes to a dealer. there is going to be a yamaha trailer down there this week so i will have them look at the bike then. THANKS FOR THE HELP!

[Matt96xr6]

1. MEASURE the springs. I dont care if they are stock, aftermarket or what ever. I want a length of the springs. (ie page 4-52 in the 06 service manual Clutch Spring Free length - 40.4mm - 1.59in. Limit 39.4mm - 1.55in )

2. If you have the stock basket, I find it hard you have no marks in the fingers. But if you race the bike, you should just toss the stocker and get a Hinson or aftermarket basket now.

3. use a lighter oil in the bike. You may have oil starved part of the motor causing problems. I run 0w40 on mine up to 10w40. Never any heavier. ALso try switching brands of oil. You never did say what specific Belray you were using either.

Without knowing your buddy, he may be a good or just crappy mechanic. I know a lot of the guys wrenching for the pros dont know crap. They can assemble a bike, but troubleshoot one they cannot.

Also when you install the new fiber plates in the clutch, do you put in the clutch boss spring correctly with the correseponding fiber after it? If you do not assemble this correctly, you will have issues with clutch slipage.

[BIG_FAT_&_SLOW]

I bet it's the springs, oem springs aren't worth shittt, they can't take the heat and shrink way past the service limit. Once that happens they can't hold the plates together resulting in slippage. On oem springs I hit the service limit in 4 rides. Let us know. All these guys seem to be really smart so the better you answer their question the more likely they'll be able to help diagnose your problem and give you help.

BFS

[hellomoto]

the specific oil is Bel ray thumper racing 4 stroke 20w 50 synthetic oil. this bike has to stay stock for the stock class, but my other bike is getting done with a hinson clutch. motor is being built by PR2. i will measure the clutch springs on Thurs. but we are going to take a new clutch assembly and drill more holes in the basket to try and get more oil, and mill down 5 millimeters on the fingers on the primary driven gear comp. i am told by some engine builders that it will give you 10 lbs of pressure per spring. do you think this oil is too heavy? Thanks for the help!

[Matt96xr6]

Well here is the problem. You are asking questions, but someone else is doing the work. You are not going to solve any answers over the internet like that.

for the clutch, you might want to research the 79 cent washer fix. But like I said make sure you are installing the frictions correctly with the spring washer. If not, you will slip the clutch all the time.

[JetBlueJoe]

i have an 06 yz250f down at gpf training facility. and have gone through 4 clutches in 30 hours of practice. had 250's, 125's, and 80,s for years and never had to replace clutches. also bike has reduced power and the valves have been adjusted twice, and new piston and rings. use bell ray thumper oil changed every couple of hours. any suggestions????

? Sounds like your son should stop riding the 250F like a 2-stroke. Those are all 2-strokes mentioned above aren't they? Isn't the problem obvious? No offense but ?