im just wondering what the advantages are or whether i need to run my bike on 50/50.i know alot of 2stroke proddie lads do mix it,but as its going to be my first go at production 250 im not sure.the bike is tuned but is running on unleaded at the moment.also ive found in the spares a hrc jet kit and needles,are these worth fitting or are they just a bit of a gimick. thanks.

The question is; do you need to run avgas?

If the bike is set for ULG then running avgas will probably lose you power, unless you modify the motor, and jet correctly to take advantage of the characteristics.

Steve's F3 is making over 70 gee gees on ULG so it ain't that bad.

100LL avgas would need higher compression than ULG, more ignition advance and leaner jetting. If you just pour it in without changing anything you'll run rich and the fuel can't burn properly or completely.

Many people think that just throwing in the best fuel available is the way to make power, and this theory may work on an engine that can adjust all it's parameters to suit with fancy ignition systems and clever ECU's, but unfortunately the NSR is only as clever as the guy twirling the tools.

One good thing about 100LL is that it's quite forgiving on the jetting. ULG will make power right up to a point, and then start to detonate. Avgas will lose power at the point of no return, but doesn't tend to detonate unless you get silly with the jetting.

So you want some advice I suppose? Well, if the rules say you can run avgas then use it and reset the motor to suit. You get more power and it smells great It just costs you more

As for the jet kit, chances are that it's a ULG kit, so it'll work better on the ULG than 100LL. The major difference is in the needles. The ULG needles are richer than the 100LL needles. However, I've used the ULG kit successfully with 100LL. The best thing with the kit is the adjustable needles. They are certainly not a gimmick.

Talking of fuels, anyone remember the old 5 star they used to sell at the pumps? And the teams in GP and F1 walking around in biohazard suits whenever they handled the leaded go faster juice. And I mentioned on here a while back the 2WW spitfires using 150 octane aviation fuel. Lets set up an NSR to run on that!
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NSR300R - Why did i ever have a 250...

I run 50/50 only to ensure total reliability.

I am led to believe that the little bit of lead helps lubricate bits and the extra octane rating means I can be slightly lazier with the jetting and not blow it up if I get it wrong.

As setup it offers no power advantage.

We ran a test on the dyno last time we were there. Full avgas v full superunleaded. Power no difference what so ever.

It is a pain to get hold off, but it appeals to the ego saying I run 50/50 sounds better than just pump fuel, and it helps prevent det. You won't get extra power unless you set up the motor to work with it that is compression, ignition and pipes.

MJ43 wrote:I run 50/50 only to ensure total reliability.

Does it work?

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