Help with 2-Stroke sportbike tuning?

[supraluke]

I am curious if anybody knows of any shops around here that can help me tune my Honda NSR250 MC28 for unleaded gas for the Reno/Sparks elevation.  I just can't seem to get it right and I'm tired of fooling around with it. Only places that seem to know what they are doing is down in L.A. with RS250's I don't want to drive that far for a tune that will be off for this elevation.

[n10sive]

*paging 2strokeyardsale to the white courtesy phone*

[Yard Sale]

No two stroke specialty shops that I know of. The closest thing is that Rocket Factory or something that does Banshee quads. There are motorcycle shops that you'll just have to call and see if the mechanic is willing to put up with you, because your problem is going to be tuning it, trying it out, and coming back for more tuning.

Maybe SPL can get it close with a dyno tune and pipe sniffer. The two stroke race tuners tell me air:fuel ratio tuning on a dyno is not the way to go, but I've done a few runs of my race bike on the SPL dyno with a pipe sniffer and what was good on the track was close on the dyno and sniffer.

Anyway here are some local shops to try:

http://www.sierrasportbike.com/smf/index.php?action=profile;u=180 2 Wheel Custom Performance
http://www.sierrasportbike.com/smf/index.php?action=profile;u=213 Independent
http://www.sierrasportbike.com/smf/index.php?action=profile;u=207 Superbike Performance Lab
http://www.twfracing.com/contact.html TwinWorks Factory


It should already be built and tuned for unleaded pump gasoline. It's a streetbike with an airbox and the elevation shouldn't affect the carburetion too much. Set the carbs back to stock. (Also, doesn't that bike use special cards with different ignition maps? If you have some funky race kit map, use the stock card.)

The elevation mostly drops the compression, which hurts power.

One thing you could try is just use lower octane gas at the pump. Say if the bike calls for 93 you don't really need that octane up here with the low compression. 89 or 87 would burn faster and might change the jetting slightly.

[dmh2000]

I can't help you with the tuning buts that's a nice looking bike!

[supraluke]

Thanks yardsale,
most shops that I called thought they could do it untill they see what it is and then they suddenly they don't want to touch it. The bike was never stock. Previous owner raced it down in L.A. and hence it was jetted for down there and already had a few hop up parts in it (different jets for unleaded fuel ((japan didn't which to unleaded gas untill 1997, mine is a 1995)), colder plugs, carbon reeds, stuffers, ect.). It does NOT have the a HRC ignition card in it, just the stock one. I put the street bodywork on it.  It ran great down in L.A. when I took it down for the Redbull GP as well. It sat for a while and I had to clean the carbs and now it doesn't run very good at all. I've always used the 93 oct fuel from the VP station in it. 93 oct is the min oct suggested in the japanese manual if I remember correctly. What oct do you use in your tz250? I didn't know Rocket Factory was still around. My dad dynoed his Yamaha RZV500 on their dyno back when they were across the street from summit racing. Where are they now? Thanks again i'll give these shops as call.

Thanks dmh2000 for the compliment. It's painted after Rossi's 2000/2001 NSR500.

[n10sive]

Alberto is going to want that for Luca

[Yard Sale]

My 250 uses VP C12, which I think is like 112 octane. But it has much smaller combustion chambers, less squish clearance, and much more ignition advance than a comparable two stroke street bike.

There are no special jets for unleaded fuel. The motor is either set up for high octane fuel, with high compression and lots of ignition advance, or it's not. Typically, high octane fuels are leaded. But there are high octane unleaded fuels, like VP StreetBlaze 100 you can buy at pumps around town.

Are you sure you just didn't fuxor something when you cleaned the carbs? Drop a pilot jet, change the float height? Last time I played with the carb on my dirt bike the pilot jet fell out on the test ride.

I would love to see that thing at a RFR trackday!

[Team Gorgonzola]

Alberto is going to want that for Luca

I wish.....

[supraluke]

Pretty sure i didn't screw something up. It never ran great up here. After it sat for over a year (I wrecked it) and wouldn't run, hence cleaning up the carbs. It runs now again, but just worse than before I dropped it. So I start playing around with jetting adjustments. I made it worse, then better, then worse again. I kinda feel I need a pro or at least someone more familar with it to help me out.

I don't know if i'd take it out for a trackday when and if I get it running right. Because of what it is, getting replacement parts is a huge pain as I learned trying to rebuild it after the wreck. Getting parts for the for the Yamaha RZV500 I plan on building up next (and funds willing) has been easy compared to the NSR (so far).  I'd love to get the NSR on the track but if I wrecked it worse than the 1st time I think getting parts for it again could turn out to be impossible.

[TedG]

If you know how to access the carbs, pilot jets, needles, and main jets I can give you some advice. I was a factory trained Yamaha, Kawasaki, Suzuki, KTM, Triumph, Can-am, yada, yada mechanic in my younger years.
Many here know me, and you have may have seen me at PJs.

[repsol71]

Just a thought, I was checking out this site yesterday, tz250racing.com maybe some of those guys can point you in the right direction, they had rs250's on there and forums to talk to other people, maybe someone might be in the area. Hope it helps. +1 on the bike too.