Bigger oil cooler for XR300?

[ptguy]

Does anyone here have a thermo dipstick with their XR300 kit (big bore kit). I just had thumper do a 300 kit on my bike, I'll be putting things back together soon, but am wondering out loud if the 20% increase in displacement will add to much extra heat/thermal load on the oil. It would be interesting to know the oil temps on a stock XR250R, and what oil temps run on an XR300. I know Dwight says the XR250's run real hot, necessitating the use f high quality oil. Just wondering if the engine runs much hotter. If so, I'll be looking for an XR400 oil cooler, which look to have 2-3 extra cooling fins, relative to the stock XR250 oil cooler.

Anyone have any experience with the above, comments, etc?

Thanks in advance.

Mike

[2strokes_rule]

I ran an XR250 at its biggest cylinder bore (roughly 289cc), and had no problems at all. This was in tight woods, with lots of hill climbing.

I would add a few extra cc's of oil (2 quarts vs 1.8 suggested), and change it (and filter) every two/three rides.

[ptguy]

What did you think of your XR290? Did you notice much power increase? Howd it do on hills? I'm wondering how this 300 will feel.

[ptguy]

What did you think of your XR290? Did you notice much power increase? Howd it do on hills? I'm wondering how this 300 will feel.

[2strokes_rule]

It was honestly a whole different bike. I used a higher than stock compression ratio on the piston, and ported the head myself with a Dremel Tool. Russel Hicks at Thumper Racing gave me some beginner porting advice over the phone (free...nice guy). Added a bigger jet, and that thing ripped! People used to ask me what size it was. It was the perfect hill machine. Pure traction, with just the right mix of Thump. I used lower gearing too (forget sizes).

That thing was an '87, so I'm sure the '96 and newer models would be a blast to soup up. That '87 started my Thumping addiction really (not counting my first 50cc). Later I had Thumper Racing 440 a '97 XR for me.

Only thing I would say....you like lots of ho' power, get a CRF ?.

Have Fun ~Jim

[2strokes_rule]

I just saw you had Thumper do your kit. You'll be fine...they build reliable kits. It's their whole thing.

What year is your 250......err 300 ???

[ptguy]

My XR is a 1988. I am in process of restoring it (inspired by the bike building shows). Also pumping up the power a bit (300 kit). Cant wait to ride it!

[Dwight_Rudder]

You will not have a problem if you use a high quality oil.

I prefer full synthetic but go with at least a semi-synthetic MOTORCYCLE oil with a JASO [MA] rating. The clutch is the weak point here. Be sure to run H/D clutch springs. I recommend to run the full recommended amount of oil but running too much can cause excessive foaming in the engine.

Cher'o,

Dwight

[that guy]

It was honestly a whole different bike. I used a higher than stock compression ratio on the piston, and ported the head myself with a Dremel Tool.

Ahh, the dremel. Thank god im not the only one who's tried that.

[FULLPIN]

I added the Scott Summers 250 oil cooler kit ($391.95) to my 280 just to be safe and to extend the time between oil changes. The kit is complete and installs easily. Check out http://www.srcinc.net/