2010 YZ 450 Leaded Fuel

10 replies to this topic
  • yam2010

Posted June 09, 2011 - 04:04 AM


Hi All,

Is it safe to run leaded fuel (ie avgas) through the injected YZ 450?

I believe the lead only damages (over a period of time) o2 sensors, of which the injected YZ 450s have none of??

Cheers! :ride:

  • yz450fcranker

Posted June 09, 2011 - 04:35 AM


run some c12 worlds most used leaded fuel av gas is like pepsi compared to the c12 which is like red bull

  • yz450fcranker

Posted June 09, 2011 - 04:36 AM


quality of fuel is key av gas is a by product of real fuel

  • yam2010

Posted June 09, 2011 - 04:49 AM


Thanks for the reply, also for the heads up on c12.
So in answer to my question, leaded fuel is ok to run in an injected 450?

  • grayracer513

Posted June 09, 2011 - 07:02 AM


Consider the source....

Avgas is NOT a good fuel to run in a motorcycle engine simply because the blend and vaporization rates are totally incorrect for a high RPM engine that changes throttle state constantly and operates at low altitude in high temperatures. As much as 30% of the potential energy of the fuel is released outside the cylinder, and the incomplete combustion that results leaves the combustion chamber dirty.

Which fuel you should run depends on what you are trying to accomplish. If you have a pinging problem, a higher octane fuel will fix it, but lead isn't necessarily required to reach a higher octane value. The lead content in a correctly blended fuel will not cause you any problems, though, since that's what you asked.

If you don't need the octane to prevent pinging, there is no point in paying for a higher octane number, as you will get nothing from it. You can also boost the octane value of pump fuel significantly by mixing 10-15% toluene with it. You'll need to rejet.

If power is what you're after, then a racing fuel blended for motorcycles can provide a small gain. This is true, but again, it is NOT dependent on the octane rating. That number only needs to be high enough to prevent pinging/detonation. Some of the best four-stroke racing fuels are no more than 92 Motor octane. The most power you should expect once correctly jetted would be about 1.5 hp gain at peak. Not a fabulous bang for the buck.

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  • yam2010

Posted June 09, 2011 - 02:12 PM


Thanks for that grayracer513.

The reasoning behind my initial question re leaded fuel is that I will be soon running fairly large compression 13.75:1 as well as being stroked and o/size.

I have a similar setup to this now on a non injected 450 which I run on methanol so there is no problems with ping / detonation.

As running methanol in the new injected 450s is a bit out of the question for what i'm willing to pay (I believe you need new injector / nozzles as well as $$$custom computer & tank etc??), I was looking for a fuel that would have a higher RON to reduce ping / detonation.

My understanding is that avgas was minimum 100 RON (is that correct??), although it contains lead and I was unsure as to whether it would have any adverse effects on the injected 450.

However, now that you have enlightened me on avgas, I will probably look into a VP race fuel.

Thanks for your help.

  • grayracer513

Posted June 09, 2011 - 02:30 PM


You could test a batch of a high quality pump premium at 95 RON or better with 15% toluene. Toluene is not a particularly exotic fuel additive by any means, and is a component of most good unleaded fuels, and lots of race fuels of any kind. If it does the job, it could be much cheaper than a "real" race fuel.

  • yam2010

Posted June 10, 2011 - 01:10 AM


Testing is a scary thing for me though. Having spent $4-5k on an engine, whacking in some pump fuel and some toluene and going for a lap could be disastrous if it doesn't do the job.
How can you test for ping / detonation without damaging components?

  • jratcliffe3

Posted June 10, 2011 - 04:17 AM


Having spent a lot on your engine, and having changed the bike a lot from standard, I would want to be choosing a fuel and getting it on the dyno, with an O2 sensor fitted.

Then I would map it very rich, and come down till you find a good mixture. You might find if you run it with a standard map that it knocks from being too lean, whatever fuel you run.

  • grayracer513

Posted June 10, 2011 - 06:35 AM


How can you test for ping / detonation without damaging components?

You know, of course, that your engine will run along happily at a 4000 RPM cruise on 87 octane. It's only when a load is applied that there's enough dynamic compression to cause any detonation.

All pinging is detonation, from the slightest knock to the worst destructive rap. The engine is most prone to knock at the lowest RPM it can run under a full load, so we try rolling into the throttle gradually by stages until you have run it at full throttle from as low a speed as it will do it. Using a higher gear helps magnify the load. If it pings, you will hear it when it's only slight and harmless.

Another advantage you have with the FI bike is the ability to alter the ignition timing. It sounds like the machine is a serious racer (in which case you may want to use serious race fuel anyway). That being the case, I would look into a Power Commander for the bike because it allows the adjustment of the fuel and advance curves in much finer increments than does the GYT-R Tuner.

  • Chazmagnum

Posted June 10, 2011 - 08:03 AM


I have been running vpU4.4 since new with no problems other than a dwindleing bank account. Not cheap in the long run. I have 70hrs on my 2010. But the way it makes the bike run is addicting.

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