I wonder if you boys can give me a bit of assistance?
I stopped Road riding a few years back after a big off to concentrate on Track Days. Recognising my corner speed was poor, I had a great time borrowing first a TZ250 then an RS250.

Seeing the benefit of a light chassis with loads of feedback led me to ride my MC28 and VJ23 on track as much as I could in the last 2 years.
I've had a brilliant time.

However, running either bike hasn't been cheap.
So much so, that I'm considering running an RS250 or TZ instead.
Do you think it is possible to have either bike in a state of tune that would allow me to do a few track days without strpping the bike?
If I could run pump gas, reduce compression, replace the pistons after [say] 5 days on track [thats 10hrs track time] with all the associated maintainence, that would be fine.
What I DON'T want is to be twirling spanners when I could be riding.
I don't mind setting up, but want to re-build at home in the garage - you know?

I figured that as the 250 class is quiet in the UK I could pick up a 250 for sensible money?

What do you guys think?
It sure would be nice to have 75-80bhp to play with, do you think this is realistic with a soft state of tune?

Any help appreciated.

Sounds perfectly feasible to me. As a track only bike, either will be fine, although the state of tune will be dependant on the previous owners I guess!

Have a look at the NG forum and perhaps ask there for a few tips from those that actually run them.

http://www.ngroadracing.org/phpBB2/
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That really would be perfect Clarkie.

A stock, well prepped but otherwise stock RS will certainly be around 75-80hp if you are looking at an earlier Pro-Arm model (70-75 for a pre '92... if you can find one in "stock" condition!), and if looked after, i.e. scheduled rebuilds, could actually be cheaper to run than the NSR as the top-end is cheaper!!

Setup really isn't much different to the NSR. Unless you are striving for that last 1hp, running it a tiny bit rich and leaving it there won't hurt; just like most do with an NSR or any other 250/2-stroke to be honest. Sometimes you may pick up 1-2hp, sometimes you may loose 1-2hp, but with 75-80 on tap, and it all just being for fun, it really doesn't matter!

Smiles per miles though... priceless!
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Andy.
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Clarkie, I have a good friend with a 93/98 RS that does just that. He's my 'consultant' on anything technical and I trust his mechanical judgment, and runs his RS with a very conservative set-up. It makes 83bhp at the wheel and he usually gets 5-8 track days out it before a rebuild. Each time the old parts have looked pretty much perfect. Rebuilds are about 30% less than the nsr too from memory... He runs it on AvGas though and it's probably the safest fuel to keep them on. Another guy runs his 2000 RS on Supergreen with octane booster but Supergreen is about 13 quid a litre I think!!
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NSR300R - Why did i ever have a 250...

Oh yeah, give Graham File a call - 01303262222, he's usually got his answer phone on but he'll pick up if you start talking. He'll tell you excatly what can be done with no bullshit what so ever...
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NSR300R - Why did i ever have a 250...

Thanx Max.
Not got a contact for Avgas and DARE not start using pukka race fuel, I couldn't afford to wake up!

I would stay away from pump gas on an RS. It wasn't mean to run on that low of an octane, and you will be creating so much carbon build up, your rebuilds will take twice as long as you clean the flapper valves, exhaust ports, and chambers of the crap.

Use a good quality oil with a higher octane race gas mixing at 24:1, with a richer main, and the top end will go the full 300 miles between rebuilds.

Thanks
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Charles Gallant

Hi..
i was just reading through this post and you guys mention the rs250 needs a rebuild every 5-7 track days!

i am thinkin of using my nsr as a racebike next year....how often am i looking at a rebuild?!
i cant believe a rs250 rebuild costs more than a nsr..can anyone fill me in why please...

cheers...
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Philip Ahn
MC21 NSR250R

im poor...

Biatchy,

The cost is about the same, just more frequint. I ran an NSR for an entire season before doing a top end. By the end of the season it was tired and ready, but it did make it all season. That is eight race weekends, and about 8 track weekends/days. Think a total of about 30 days on the track.

I would probably do a rebuild after maybe 15 days, so the power would still be nice by the end of the season. If I were to do it over again.

Thanks
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Charles Gallant

hey thats not too bad....so on a nsr..for an entire season if tuning is up to scratch..i can expect maybe only 1 rebuild during the season?
thats not as bad as i tought...

cheers...
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Philip Ahn
MC21 NSR250R

im poor...

I would stay away from pump gas on an RS. It wasn't mean to run on that low of an octane, and you will be creating so much carbon build up, your rebuilds will take twice as long as you clean the flapper valves, exhaust ports, and chambers of the crap.

Could you clarify why there would be more carbon build up? As I understood it Av Gas (or blue gas) is merely regular pump gas without the extra benzine added but with a whole bunch of Tetra-ethyl lead added (around 4~5%).

As the carbon in build up comes from the fuel/oil mix, if you are not putting in extra oil and are running the same AFR the amount of carbon in the exhaust will be the same to all intents and purposes.

I believe that the combustion temeprature is roughly the same between the two types of fuel (the calorific value is about the same), the extra power in the Av Gas comes from the fact that lead is a better knock supressor than benzine so the engine can run at a higher CR which helps deliver more of the combustion heat to the crankshaft.

Cheers

What about the cost difference in tires?
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james
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cost of tires are about the same. The Race compound tires I was buying for the NSR were about the same price as the slicks I run on my RS. I do find however, that the RS goes through tires a little quicker, so your replacing them sooner, paying more money over the same period of time.
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Charles Gallant

Avgas, I think, has a lower calorific value than Optimax (or unleaded) - but it runs a bit cooler. RS250's, particularly early ones, run far better on Avgas as they were designed to run on it, although most have been converted to run on unleaded (Optimax is best).

You run higher compression on Avgas which gives more midrange torque, but they also seem to get more peak power out as well, but this won't matter much for track days. As the man says run it a bit rich and it will be fine. You probably won't give it the stick it would get in a race anyway.

You need quite different settings for Avgas or unleaded - heads, jetting and ignition curves - so I would just stick with whatever set up you have - measure the head chambers if you are unsure - assuming everything is set up correctly.

I don't think running either significantly affects engine life. I always thought carbon build up was more due to the premix used - 747 is what most people recommend, but fuel may make a difference.

The biggest risk is cold seizures caused by not warming the bike up properly or not applying enough tape to the radiator.

The only problem I had with carbon build up was sticking rings, assuming you clean everything when you rebuild it.

Mike

dont know how you will find it cheaper a good rs will make about 80bhp on a good day and it costs alot more to get over 80.my last rs which i couldnt get on with for some reason only made 83bhp after i spent £1500 at frank wrathalls.clutches dont take much stick i was getting about 5 meetings out of one.dont know about unleaded conversion but unless you run unleaded race fuel you will lose alot of performance and a top end will still only do about 500 miles.add your new crank every 1500 miles{you cant rebuild them} also 10 more bhp will hurt tyres over a production bike.just my ten pence worth but in the end only you can decide what you want.