Spring? time to fix my jetting for real

[andrewsw]

Hey folks, long time...

So it's time for me to really fix my jetting. Most of my riding is in town, short hops, so I don't get a lot of opportunity to really test changes. See here http://forums.banditalley.net/index.php?topic=9085.msg70621#msg70621 for details on the current setup with the following caveat. I've tweaked the float levels even more to about 17mm, which is probably too far.

The other day while riding on the freeway, I got the opportunity to make a long steep hill climb in top gear, and she just couldn't pull past 8k, 80 mph with throttle wide open. SHe pulls jsut fine in lower gears all the way to redline, but it's hard to know if that's just gear-ratio. I suspect this is fuel level starving her at high rpm, but it could also be a problem with my main being just too big. It's just darn hard to tell as I don't have a lot of good road to do plug chops on... I'll have to make a special trip for that. (Everything is either too busy, or not long-straight-uphill enough to get a good safe run). And then that means doing a plug chop out in the middle of nowhere...

Anyway, my plan is to fix two things at once (I know, bad idea...) by moving back to 102.5 mains and resetting the float level to the recommended 15mm.

I've suspected for a while that the mains were too big anyway (seeing as I'm a somewhat bigger than everyone else *and* I'm much higher than most...). And I know the float level is probably out of whack. So from there it's back to iteratively tweaking it.

The real problem I'm trying to solve is softness at very small throttle openings at around 5k rpm when very warm. IOW just a slight rich problem I guess on the pilot jet and fuel/air screw. I can't lean out the fuel-air screw because I'll get lean surge at idle (currently at 3.25 turns). And I can't increase the pilot jet (I think) because of that softness at 5k -- bigger pilot jet will just make that worse, I think.

The other option is to carve big holes in my airbox to force everything lean and then sneak up on it again. heh heh...

thoughts appreciated.

[Banditmax]

I would say come back to the 97.5's that where in the factory kit.

[andrewsw]

Yeah, I just saw your post in the jetting thread. I'm almost definitely over jetter on the main, though I'm pretty sure I had some improvement moving from whatever was in there before... been a while now... to 102.5. The move up to 105 was to see if that improvement continued, and I think it's pretty clear it didn't. I'll take her down at least a couple of sizes and try again...

[gsxr400 racer]

plug chop can be done in any gear dont need a mile

[andrewsw]

plug chop can be done in any gear dont need a mile

yeah, thanks. I guess I knew that, but really wanting to find out what's going on high-rev top gear means I need some space. see below though...

I would say come back to the 97.5's that where in the factory kit.

That's what I've done, as well as reset float level to 15mm. Running like a champ, but still...

Okay, here's the current issue... this is a '93 with the 7(?) wire CDI. I think that means it's limited.

Currently it pulls like a champ up to 100mph in fourth gear (redline, essentially) but when I shift into 5th or 6th, no juice. Considering how strongly she pulls in 4th at that speed, there should be *something* more.

I haven't been able to do a real methodical test of this as my particular spot was a little heavy in traffic. But still, the power was real weak in 5 or 6 up above 80mph while 4th was still pulling great.

I'm guessing this is the limiter kicking in for 5th or 6th gear. Anyone know for sure or is it still subject to debate?

A

[gsxr400 racer]

simple enough to mod the gear indicator

[andrewsw]

Indeed. I was figuring I'd just determine whether the wire went high or low on 5th and 6th and then attach it permanently in the appropriate position...

[gsxr400 racer]

email me at the usual place and i will send you the info i have

[andrewsw]

done...

[Banditmax]

Or you could buy an m-max derestrictor box. ive got 3 and only use 1.....

[gsxr400 racer]

there's a idea