ISDE Aftermath

[SpeedyManiac]

Hi guys,
I finally got my bike back from the ISDE and tore it down this evening. The piston seized in two spots on the exhaust side, right by the side exhaust ports. Must've been too lean on the needle, but I still don't get why it did it at the end of the day instead of the start.

The cylinder needs to be replated and a new piston and rings installed, but that seems to be the only damage. Bottom end looks good, same with the rod, head, etc. The question is, do I bigbore or not. I'm thinking of making it a 275...Opinions?

[iancp5]

Looks a similar seizure to mine recently. I was running very lean in tight woods, when I did a more open Rally type event and it was held at constant speed a slight restriction in fuel flow pushed it over the edge.

As for 275 I'm the wrong person to comment - I have a 300 but would like a smaller motor. If I lived anywhere near you I'd offer to swap!

[cladoo]

I think it was that deeper sand with the needle too lean that did it in. I used to ride in sand alot and we had to go up on the main also.

[Berkyboy]

At the last minute, just before impounding in Chile, we jetted Brian Hasslen's 300 a little fatter then he was using on the test track in La Serena.

His 300 is a little less finacky when running rich, compared to how a 250 would run, and we decided it would be safer to run rich for the first day and adjust the jetting leaner later on if we needed too.

The first mistake a lot of Six Days "first timers" do is run too lean of jetting and over the year's, I've been to 12 Six Days, I've seen a lot of riders make that mistake and lean sieze.

A good Day-One Six Days approach is to run your jetting on the safe side, at least until you figure out how your bike is going to run using local fuels. The jetting track gets you close but there's no replacement for a couple hours in the saddle under race conditions.

From some of your more recent posts it sounds like your comfortable shooting for a silver medal this year ( in Greece ) and a little fatter jetting isn't going to keep you off that pace.

[SpeedyManiac]

Hey Steve,
Lesson learned. Silver in Greece is my goal. I was on silver in Chile when my bike died and I wasn't overly comfortable in the sand or special tests. Greece looks like the terrain around here so hopefully I'll do better there.

I'm also still toying with tryiing the Romaniacs, but I gotta do a lot of fundraising to afford both races and a month in Europe. We'll see.

[Berkyboy]

If your budget can afford it I'd go for the complete 300 stock cylinder, head and piston, that way if you need to do a top end either between or during Romanics or Six Days you'll be able to find parts.