New to me 1986 YZ250 Questions

[rho]

I finally bought a my first 2 wheeled motor vehicle. As stated it is a 86 YZ250 (bottom/top end rebuilt 09/01) and various other goodies on it.

Here are my impressions and questions following, from the first time I took it off-road. The bike is very fast (for me anyway). When the motor warmed up (about 15-25 minutes of use) I notice what I assume people call 'comes on the pipe' or 'hit'... this bike after about 1/4 throttle just 'hits' what feels like afterburners, and takes off. In the straights it is managable for me but while I was on the MX practice track at Prairie City in CA it got a bit hair raising thru corners and other obstacles.

I understand as my skills improve it will not be as much of a problem but in the interim, below are the suggestions I have found searching the archives and web.

Flywheel wieght
Re-jet
Retard ignition

Which would be the most effective to achieve a more 'even' throttle response.

My stats: 37 years old, 6'2", 210lbs

Thanks,

Robert

 

[KTA]

a flywheel wieght will help a great deal.. ..about 10oz or so should do it. But yes, the 250's are extremely powerful and peppy. . i also ride a 1986 250 (kx). . . they may be old but they still spin the tires

 

[rickyd]

rto,
This may help you, try "fanning" the clutch.. What that is, is when you are on the gas, you slip/ride the clutch to feed the rear wheel power.. It helps from wheelieing too.. Hope this helps you out..
Rick

 

[rho]

Did not think of feathering the clutch... thanks for the tip!

Robert

 

[Wakisashi]

I had an `86 YZ250 , check your powervalve to see that it is working right. I don`t remember the bike being that pipey , your valve could be sticking.

I dropped the needle one notch and never had any other jetting issues at 400 ft. above sea level.

I ran an ATK spring kit , 21 lb springs , in the forks and had RT cut the rear spring to match my 200 lbs.

That bike was probably the most dependable bike I ever owned.

 

[Mr. Clean]

I had an 85 yz 250. I am almost postive the power valve is the same on your bike. This is your solution; retard the amount of movement on the power valve. With the cover removed, you will see where the arm from the engine mounts to the valve. The connection is slotted allowing fine tuning. Loosen the slotted connection and rotate the valve counter clockwise and re-tighten. This will take away the hit and make the engine extremely smooth. Trust me I know this to be a fact. As your skills increase move the power valve back in small increments.

Your ridin' bud, Kurt :D

 

[rho]

Thanks Kurt for that killer advice...

I'll start tak'n the bike apart next week and check the valve and adjust it. I'm going riding tomorrow so I'll just deal with if for one more ride.

Robert

 

[Mr. Clean]

Just in case you don't know exactly where the part is, it is under the rectangular cover on the right side of the cylinder. It shouldn't take more than 5 or 6 minutes to do. If the pipe needs to be removed it may take additional time. I just wanted to make sure you knew because it sounded as if you didn't have enough time to do it before your next ride. Let us know how it works out!

Your ridin' bud, Kurt