First Ride Impressions 2011 250 Race

[GMP]

You should jet the bike in the high (sun) mode. Less difference on a 250 than a 300 though.

[singletracker]

Originally Posted by GMP

You should jet the bike in the high (sun) mode. Less difference on a 250 than a 300 though.

Thanks for the advice. I'll play with the jetting some more on the next ride. I kind-of had a brain fart when breaking it in....I forgot all about the map switch and just left it where the dealer had it.

[twowheels]

I have the Fastway Fit I system here - along with the longer clutch hose discussed, and the needle that will make your carburetion better - if you're interested. I have an order in for the carb-body-mounted choke kit that should be here in time for Christmas.

For any handguard mount w Twinwalls you need to put some tubing (that I supply) over the end-of-bar insert.

The new clutch hose has a 90 degree elbow at the MC so you can slide it in somewhat without having the hose foul the bars.

The needle will do wonders, but you should have a look at squish as well. I've sent a couple heads to RB Designs, but also had one customer achieve correct values with base gaskets.

[singletracker]

twowheels,

Thanks for the offer, but I already ordered the handguards from Hall's. I'm not following you on the tube at the end of bar insert?

What needle are you referring to? I have the NEDW and NECW on order from the local Suzuki dealer.

I've measured what KTM calls the "X" dimension before but it took a special tool to do it accurately. I know the squish has to do with the deck height, but I think there is more to it than that. I'll probably wait until I've played with the jetting some more before I make any other adjustments. Hopefully the jetting and map switch will give me the little extra that I want down low.

Thanks again.

[Jakobi]

Your squish band is the distance between the outer edge of the piston at TDC and the head itself. You want to be somewhere between 1.2mm-1.8mm depending on what characteristics you are looking for. Tighter = snappier stronger power but may require more stable fuel loads. IE Race gas.

Moving the cylinder by a certain amount will then also effect the squish by that same amount so its best to settle on the number of base gaskets you want before machining the head. I personally set the exhaust port flush with the top of the piston at BDC. This gives a mellow bottom end with a strong mid - top.

Then compression ratio has to be set depending on what you want to achieve. I increased compression which then gives some more back to the bottom - mid range.

All this talk makes me wonder if I really want to buy a 2012 and go through it all again Ahh of course I do!

[GMP]

For a 250, 1 - 1.2 mm is a good target that Ron works with. Compression is adjusted to suit fuel, not squish, but figure 200 PSI max for USA puimp gas. My RBD head 250s came in at 190+ PSI and run great. I now consider this mod a must do, like a suspension revalve and a skid plate. You will gain low end without loosing top, as the burn effieciency is increased.

[Neil E.]

The stock squish band is quite narrow (at least it is on mine). You can judge this by the length of squish on your solder when you check it. I think the big value of machining is changing the angle so the squish band is a closer match to the piston shape. Mine was about 1.5 mm and the compression was 200 psi. Good enough for me.

[singletracker]

I checked my compression after about on hour of use and it was 191 psi. I'm guessing it wasn't fully broken in yet, so it may go up a little more. According to the numbers you are giving it looks like my compression is close to where it should be. Does this give an indication of what my stock squish is likely to be? Close or not close?

[twowheels]

Originally Posted by Jakobi

All this talk makes me wonder if I really want to buy a 2012 and go through it all again Ahh of course I do!

And we want you to! Heck, I bet even the factory wants you to!

Maybe we should take up a collection so that you can get the first 2012 and continue the development process ...

[Neil E.]

Originally Posted by singletracker

I checked my compression after about on hour of use and it was 191 psi. I'm guessing it wasn't fully broken in yet, so it may go up a little more. According to the numbers you are giving it looks like my compression is close to where it should be. Does this give an indication of what my stock squish is likely to be? Close or not close?

That compression is fine. You do need to measure the squish to be sure, but it's probably reasonable. Only you can decide if the bike's power is OK for your style of riding. On a used bike, you never know if someone changed the base gasket thickness.