250 for motocross

[willoughby]

Just wondering if anyone uses their 250 for mx and if so what sprocket combo your using. On both the Sl and Ed first gear is so low that if you use sprockets that make first gear useful, fifth is way too fast. Conversely , if you gear it so fifth can be used, it seems like first will be useless. Either way you basically end up with a four speed. Has anyone found the perfect combo ?

[MWL]

I have ridden my 250 in ahrma cross country events using 14/48 gearing. The biggest issue I have noticed is the wide gap between 2nd and 3rd gear. You lose your momentum when you shift from 2nd to 3rd and unfortunately, you use those 2 gears a lot. I never tried different gearing because it seemed ok otherwise and don't think you would ever overcome that issue.
Mike

[willoughby]

Do you have an Sl or an Ed transmission ? Also wonder which would be better : a heavy flywheel or a light one with the ratio gaps

[racerclam]

Your gearing issue isnt an issue when you build the power band correctly. In piston port form that engine behaves like a big 100 and yes you will loose momentum when you back off the throttle or grab a gear that is too high . I do make a reed valve manifold for that and it uses a modern V Force reed. You can see it on my web site richstaylordporting.com. Also get rid of the flywheel and find an ignition ( stator and rotor from a suzuki TM 250) its a bolt on that will really wake it up. The crank is plenty heavy with out a flywheel. With the right mods that engine can be more than competitive. I have done alot with these .

Rich

[willoughby]

Rich , All those modifications look great! I would love to do that to my 250. My goal is to try to fix up a 250 ( as an mx bike) and restore my super combat before the next Hodaka Days next June . If things go well (time wise and financially) I'll send my motor up your way to have it breathed on

[racerclam]

sounds good you should give me a call so we can discuss in depth your project.

Rich

[MWL]

"Do you have an Sl or an Ed transmission ? Also wonder which would be better : a heavy flywheel or a light one with the ratio gaps"

I have the ED trans with a PVL ignition and no flywheel. Good luck with your project.
Mike

[racerclam]

I have bikes with both tranys , no big deal either way, flywheel ! the lighter the better as I said that crank has enough weight of its own. If you need lights then the MZB ignition is the way to go as it has a much lighter flywheel than the stock one.

Rich

[willoughby]

Thanks to both of you for the info. I bought a tm250 stator and rotor for the project and I'll use a 14/48 sprocket combo and probably use an Sl transmission

[racerclam]

you will have to notch the TM stator plate for the wire harness location , its a bit different on the Hodaka , no big deal. Also If your racing I wouldnt recommend using the Thunder dog cdi box because it advances timing at high RPM. I use the super combat or super Rat box since it retards at high RPM , It plugs right in . If I remember right the suzuki box also advances dont use! You also will need to slot the stator plate 5 mm to rotate 5 degrees more advance into it cuz the super combat box starts 5 degrees behind when this combo is used. You will need to fabricate a diferent mount for that box too.

Rich

[willoughby]

Can the 250 coil be used ? It has a different part # than the Super Combat

[racerclam]

Yes the coil will work. WE should talk when you get a chance

Rich

[willoughby]

I,ll call early next week,
Rick