air screw doesnt afected RPM

[nelly001]

sorry was being a bit rash.i cant believe how unresponsive it is to big changes in jetting.i have gone real rich with a 60 pilot lean with a 40 and no real change idle still hangs for ever.im no newby i had ktms from 1998 2 and 4 stroke.i had a 2001 ec 300 a few years back and loved the engine real strong and rideable which is what prompted me to buy this 2009 ec 250.squish was the next step for me any tips on doing this.i would like to get the rb mods done but this is the only bike i have running at the moment so just wanted to get it rideable until i could do without it for a while.a friend has just done the squish on his ktm he used a laith to correct it so i can get the machining done no problem.another thing when i get the rb mods done which is the best carb to use i have the screw on top but could get hold of something else as a friend runs a breakers yard.any help would be greatly apreciated as i love the way this bike handles and want to get some use out of it but its annoying when the revs wont come down and it just drags you on .rant over

 

[nelly001]

rb mods

rb mods are out as he no longer ships outside the us.

 

[Jakobi]

Any capable 2T tuner should be able to point you in the right direction re head mod. Someone with some machining skills etc. You could get the info from here if you wanted.

I had the same problems (and still do to a lesser extent). I went from 2.6mm squish to 1.8mm with an S3 head (no machine work). My take on it is that its so unstable or inconsistant as part of the fuel charge is actually trapped under the squish band. Sometimes you get lots of fuel, sometimes not enough, but in general enough variance to making tuning painful. Do you find the idle will hang for a few seconds and then drop low, or flame out, opposed to a racing idle that just screams forever.

 

[nelly001]

im convinced its the squish as its so inconsistant.i will get the squish measured anyone know the perfect squish measurement

 

[nelly001]

yes will hang then drop and flame out whats the g3 head

 

[nelly001]

sorry s3 its the petrol fumes

 

[Jakobi]

Squish ideally tighter is better. 1mm - 1.3mm, but you need to have the volume adjusted to maintain compression ratio usually. The squish band itself doesn't really need any adjustment.

S3 is just after market bling head with 3 x inserts to allow you to change squish and compression. Not really worth it for performance. It does look good though The still need more work to be within the specs listed above, so you're best just working with the head you have.

 

[cchracer77]

If the squish is epicly huge, as some are. Mine was 2.6mm! you can face all sorts of inconsistancies, and most are more noticable at idle as so many circuits are at work at once. Bringing the squish back will make it easier to jet with more consistant results across a wider variety of conditions.

I'd been chasing the jetting demons for a while on my '10 300. Didn't have any idle issues, but sometimes it would feel rich, sometimes lean. Intake side of plug would be wet, exhaust side white. I finally decided to check everything when the pipe turned blue, but the plug was wet with a 163 main! I checked the squish, 3mm solder was the thickest I could find, did not touch! Turned 1.5mm off of the head, down to 1.7mm squish. I can't believe that these things will even run like that.

 

[Jakobi]

3mm!!! I think thats the new record!!

I've said it before and I'll say it again. I think that setting the squish is an essential part of 2T setup and tuning. If I find myself buying another one it'll be the first thing I do. Head off, set squish, and then jet.

 

[cchracer77]

Yeah, that's why I was asking about the ignition timing the other day. I thought that it might be way retarded or something to turn the pipe blue. Surprisingly the thing didn't actually run that bad, it would still pull a box stock 300 "orange bike" by about 1 length. Gonna take another shot at my brother's "300 sx" woods bike, I think I can outpower him now.

 

[Jakobi]

I put a good 150kms of wet sloppy trail on my 300 yesterday. It quite happily ran at the same pace as a 250SX when up on the pipe. What I did notice was that the 250 appeared to come onto the pipe much faster and he could keep the bike singing much more. No doubt there was alot of rider skill involved as the young bloke on it was super quick through the rutted and rocky sections. Not so surprising though was when things tightened up and the ground went slick with mud the 300 seemed to hook up and track and out turn it. I'm really looking forward to converting my 300 to a 250. I've been told they are also easier to jet than the 300 (which I've put heaps of hours into). It'll also be nice to be running a minimum squish.

Nelly, where abouts are you located? I'm sure someone can point you in the right direction to get your head sorted. If you were to put your feelers out I'm pretty sure you could even arrange someone on this site to receive it and then forward to RB for mods, and then return it. Might cost a bit more and take a bit more time, but may be easier than having to source out your own person to do the work. In saying that, almost any machining shop will be able to shave the head to whatever amount you specify. Correcting the volume might be a little bit more work.

 

[nelly001]

squish

im in the uk wales,i can get the head turned down no problem just need to find some solder and measure the gap.i think were on the right track here i have never come across this problem before my last attempt at jetting was on a kx 250 and was a challenge but ran perfect in the end but i expect compression would be higher on a motox bike,anyone scimmed the head to correct squish and cced the head for correct volume.