EX250/250R Racing Everything you need to know

ask and you shall receive...LOL just measured it. Rear BT003 R/S 140/17 with 25psi cold. 77 and 5/8 inches in circumference.

 

Awesome Mr. Yo. I knew I could count on you. I think I may try to run some of that "off-road" diesel fuel. I heard it makes great power and is so high in octane (cetane) it actually self ignites. You don't even need spark plugs! One more way to save weight.

 

Excellent, thank you much!

 

140/70/17 Bt003R/S has a circumference of 1967mm.

 

Or this, sorry, didn't see it.

 

No worries, thanks for the numbers. It's interesting that I am getting all kinds of different numbers for the same tire. How many miles/laps/weekends do you have on yours? A new BT003 was recently measured for me at 1994mm, compared to your dim of 1967, and mkinzer's 1971.7. Looks like quite a variation, but they all look close enough to the 1995 of the 16" GT501 I have for gearing calculation.

 

Mine was brand new, but not on a wheel. Def. gonna go re-measure.

And what size GT501 are you talking about? I got 1989mm for a 130/90/16, on the rim. But that's pretty close, and it's had a few race weekends on it.

By my calculations we are talking about a 7mm difference in height between these two tires. I find it interesting the that the 17in is the shorter one.

 

Same size GT501 with one weekend on it. About 2 track day sessions, 2 practices, and 2 races. 110 miles, IIRC.

Taking the numbers game, I tried this-
130 width X .9 sidewall + 16 wheel diameter = 133
140 width X .7 sidewall + 17 wheel diameter = 115
115/133 = .8647 = BT003Rs is 86.5% height of GT501. The 90% sidewall is the big difference.

But, when I look really close at the numbers, it isn't even really worth changing the sprockets even one tooth. It's like a half tooth difference between the two tires so I'm not really worried about it.

 

Does anyone know what jets I should put in a stock bike with a full jardine RT5 exhaust?

 

I remeasured with the tires on the rims and 25 psi:

Front Bt003 120/70/17 = 1887
Rear Bt003R/S 140/70/17 = 1975

 

Who sells the Area P exhaust?

 

Area P

 

Yeah, a quick Google search told me that after I posted that question.

I feel dumb.

Almost as dumb as Huey looked while dynoing my 250 on Saturday.

 

No worries; I tried to be as gentle as possible considering we are on the beeb!

 

Oh boy...What new "parts" were you dynoing? LOL. I think we may have all started an arms race.

 

Mine is slightly smaller due to my awesome corner exit power slides and backin' it in. LOL

 

Let's hope not.

 

None at all. It's still stock as an emeffer. Huey's doing the forks, fitting a set of BT003s, and fitting the sharkskins.

If there's enough time before the MarMo trackday on the 28th, I'm going to try to fit an Area P, jet it, and/or install my s1000 engine in the frame.

 

My KTM 990 SuperDuke motor fits just fine in mine, but any time I apply throttle the chassis twists up like a soft pretzel. LOL

Are you coming to RRR this weekend?

BTW, the Area P and jet kit made a world of difference in mine.

 

Does anybody know what jets to use for 87 pump gas and stock air filter?