Eric: 03 KX250 Motor???

[Marcad]

I recently purchased an 03 KX250. It's a great bike but it needs help in the motor department. Plenty of bottom, though a little sluggish and plenty of mid.

You had mentioned that you heard somone tell you that there was a possibility about a defect in the design of the powervalve and that it might be what's causing the engine to go flat on top. Have you heard or learned anything else concerning this motor? I would like to try to get some more top end pull.

I once had a 98 KX250. It too was a bottom to mid motor but made the bike a lot easier to ride. Had a stronger hit and didn't fall flat the way the 03 motor does.

What can be done to make the 03 motor more like the 98 motor?

Are there any porting fixes?

Could more displacement help?

The 03 and 98 cylinders share many parts. Even the powervalve mechanism seems to have gone through very little change. Can the 03 cylinder be swapped with the 98 cylinder?

Really would like to do something soon. I'm going to try a V-Force reed cage, jetting and maybe a pipe but would like more than just a band aid fix. The bike is a dream but now I need it to rip!!!

 

[marcusgunby]

Eric wont be around for a while as him mum is sick-his website has info.

 

[Marcad]

Sorry to hear that. I wish him and his mom the best of luck.

Marcus, I don't see any info on the 03 KX250 motor on Eric's web site. Got a link?

 

[marcusgunby]

MArcad sorry i meant he has info about his present situation.

 

[G92Joe]

Eric, Hope your mother is feeliong better; Has there been any news on getting more power out of the 03kx250? thanks!

 

[G92Joe]

Bump - anyone else have any luck getting more power out of the 03kx250?

 

[Marcad]

Yea, I'm still looking myself. No good answers yet. Hasn't anyone tried something on this bike? Does anyone else have this bike? Everything is great except for the suspension being a little soft and the way it falls flat on top. Still, with nothing done except adding some oil to the forks, I'm going faster on the track on this bike than I was on my 01 CR250.

 

[G92Joe]

MARCAD
Check out Tom Morgan's website TMR.com I think - he makes a 327 kit, 38 ft-lbs torque, 60 HP for $2100

 

[G92Joe]

That's TOMMORGANRACING.COM - I have the dyno sheet that shows the torque curve compared to a 01yz426 - more everywhere across the rpm range, especially 5-8,000 rpm

 

[Studboy]

E-Gorr also does a 310 kit (non stroker) for a fraction of the cost...and less cost for rebuilds and less hassle. Everybody that has one likes it.

 

[Marcad]

I was thinking about having my buddy punch it out for WAY LESS than a Tom Morgan kit. I don't think Eric Gorr can get a piston for the 310 kit.

 

[Marcad]

Also, I don't want to stroke the motor. I'm only going to keep this bike until the 04s come out. I want something more but with reliability in mind. Just some porting and displacement.

 

[Studboy]

Eric has a Wiseco piston for the 310 kit. Stock stroke, that is.

 

[Luft]

Ask FMF about thier powervavle gevernor shim for the 03 KX 250

 

[Luft]

Ask FMF about their powervalve governor shim for the 03 KX 250

 

[Marcad]

I read what you posted in another thread Luft. Thanks and I'm going to look into it.

I have a buddy who had called Eric about the piston for a 310 kit. Eric told him he didn't have one and that only RPM has them. Maybe he didn't want to sell him one because he isn't sending the cylinder in, I don't know. RPM doesn't want to sell a piston unless they do the work.

There are couple of projects we would like to attempt but no one wants to help. I would be more than glad to share any info. Seems like us 03 KX250 guys are being left out in the cold.

 

[EZ-Rider]

My understanding is that another shop owns the rights to the 310 piston design, meaning they are the authorized retailer of that item. But if you do like I did and call wiseco you can order it directly from them if you have the model #. Once eric chimes in and says whether or not the 93-02 310 pistons will fit I can give you the part number if needed. You will also need to get the gasket kit directly from cometic to save some money there. If you do the EG 310 kit I guarantee you will be happy with the power. It will turn your bike into the ultimate sleeper bike and make your choice of back tires more important.

 

[Faded]

I think YOU need to call Eric. He isn't one of those "I won't do anything unless I can sell you something" kind of guys.

 

[Studboy]

You guys on the 03 KX250's must not be too low on power especially low to mid. I was watching arenacross today, and the 03 KX250's took 1, 2, 3 podium spots! Sweet.

 

[KX'er]

I have an Eric Gorr '00 KX310, and must say he did a hell of a job. The engine was completely transformed, power everywhere. The only complaint that I have it that it has slight low end carburation problems that I have not been able to get rid of. Also, rear tires don't last nearly as long now. Other than that though, the thing rips. He does all of the machine work and sends you all the right size gaskets, but you must get the piston and rings from Weisco or Max Power. Not really a big deal.. He also ports it to your liking, which is included in the price. Well worth the money.

 

[Onore GT]

I did not mind the lack of top initially but the first time I had the bike out at a track were the dirt was a little loose I knew I needed to do something to move the power up in the RPMs a bit. If you want to just bolt stuff on, the Moto Tassinari reed cage and FMF SST pipe work very well. Install the power valve governor shim that comes with the pipe and that is a pretty good setup. The power is softer on the bottom but response is good and the bottom feeds into a nice solid, long, middle. The motor revs up higher and feels more free revving.

If you want to do some additional mods, or don't really want to spend the money on a bunch of aftermarket stuff (like me) the transfer ports are pretty low on the 03 KX 250. Just raising the transfers slightly will move the power up a bit and let it rev further on top. Everybodies tastes are a bit different on motor setup and what they want, but I ended up with the transfers raised a bit, slightly raised compression, stock pipe, stock power valve governor, a little heavier flywheel (4.5 kg, 4.0 is stock), and a Moto Tassinari reed cage. This setup has a nice solid chuck of power that is softer on the bottom than stock, but response is improved and the feels more free revving. On top you can hold a gear if you want rather than having to shift with the stock setup.

Anybody else making any changes that help?

 

['00kx250spode]

KX'er: I had Eric set up my 2000 KX310 for C-12, so this may not apply for you. I had to drop down 2 main jets and I went with a needle that was 1 step leaner in the straight part. That cleaned up the jetting for me. No spooge and the excess smoke I was having is gone.