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onelugnut

WR 450 What octane fuel ?

19 posts in this topic

Went for my first real ride on my 05.I noticed alot off noise at low rpm.It sounds like the timing chain is going to knock the side of the case off.Could it be from detonation?The service manual calls for 95 octane or better we only have 91 here in ca :cry: I have lots of tuning to do to get this thing to run right.

Thanks all for the info

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I run my 426 on 98. If 91 is all you can get and you are sure it's detonating you can rev it more (don't load the engine up hard at low rpm's). Going richer on the pilot/needle may also help.

I wouldnt mind betting that the noise you are hearing is the chain slider slapping around on the swingarm. I'm pretty sure Yamaha havent fixed this problem yet. The fix is to sikaflex a piece of thim rubber between the swingarm and the slider. Over time sand and grit gets between the slider and the swingarm and wears the swingarm out. The other thing to remember is that these thin cased engines are pretty noisy. Uncork the pipe or get a YZ/aftermarket item, rev the hell out of it and you wont notice it anymore :cry:

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Well, the 05 compression is slightly lower. I run 92 in my 04 with no problems. You may just go to the fuel place and bring your own 5 gallon jug and buy the good stuff. Expect to pay a bit for it.

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I run 92 in my '02 426. I started boosting the octane with a capful of booster in each tank, but the time I forgot, I didn't notice a difference.

Remember, octane doesn't boost horsepower directly, it makes gasoline burn hotter. A hotter burn is a cleaner burn...blah, blah, blah.

I think you will be fine on the 91. I dont think its contributing to your engine noise. Mine is similar and loud too!

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Hey lugnut, I am also in CA (southern) and what the local dealership told me to do was buy the red VP Racing Fuel and mix it with 87, 89, or 91 to get the octane down to around 95 or so. Guesswork as far as I am concerned but there has got to be some kinda formula to get it near right. The other day my buddy at work said that the salesman at the oil product supply place told him to mix the VP with 87 octane instead of 91 because the 87 is supposed to have a higher oxygen content. Not sure if that statement holds any truth to it or not though........ Has anyone else here heard of or done the race gas mixing with pump gas? I believe that we mixed 3 gallons of pump gas to one gallon of 110 octane VP. I am about to do it for the first time on my 05 wr450 in the morning....... previously had only done it with my bro's yz426. Goodness i hope the rain goes away by morning....

peace

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just curious re fuel supply over there in CA. What do you guys run factory supercharged/turbo'd cars on if 91 is all you can get?

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I usually run f&l 111octane race gas 50/50 w/ 91 pump gas... or whatever 110 octane gas i can find... been doin just peachy for the 2 years i have had this thing... :cry: i usually only burn thru 5 gallons a weekend one weekend i burned thru 10 gallons of this stuff man that was a helluva weekend... :cry:

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just curious re fuel supply over there in CA. What do you guys run factory supercharged/turbo'd cars on if 91 is all you can get?

The cars here in ca are set up factory to run 87-91 octane.I have herd That aussie gas has a different rating system.

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...

Remember, octane doesn't boost horsepower directly, it makes gasoline burn hotter. A hotter burn is a cleaner burn...blah, blah, blah....

Yes, high octane fuel burns slower, more controlled, but compressed, it will produce more energy. But if your timing isnt calculated in, you can feel a loss in performance. Basically, get just enough octane to where you wont get the top end rattle. Over doing it is a waste and may actually reduce some power too.

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I too think that US fuel is more octane efficent than in other parts of the world, so our 95 octane is close to yours 91

so 91 should do for the blue

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Go to your local airport and get aviation fuel. It costs about $2.90 per gal and has an octane rating of 108. Aviation fuel does not contain alchohol like pump gas does. Premium pump gas octane ratings are not consistant from batch to batch. Aviation fuel octane is very consistant, do you think the FAA would let them put out inferior fuels? When you consider that you are paying $2.50+ for premium pump gas or $7.80+ for 110 race fuel, the aviation fuel is a bargain. :cry:

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When I got my 04WR 450 I heard a lot of the same noises. Turned out to be the chain tension was too loose. Keep an eye on it. I am using Maxima octane boost which bring our 91 up to 95, I think. I check the plug and it looks the same as before, that nice light brown color. Still have the stock pipe, just uncorked. Have been messing with the fuel screw setting and to be honest it all runs pretty much the same. Have not changed the jetting or needle position, mainly because it doesn't seem to need it. If it runs good why mess with it?

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Atlasrider

How did you check the cam chain tensioner and what am I looking for?I thought they were automatic.

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You are exactly right. Octane slows the burn, which means as the piston is on the down stroke there is still some burning going on. Which makes alittle more power. Octane is not hotter, it's slower.

I have never felt the need to use anything higher than 91 octane useing a 13 to 1 piston. I did try one tank of 108 and felt no difference, why waste the money on gas. :cry:

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I run 93 or 94 when I can get it, but out west you sometimes get stuck buying 89 and it seems to work OK at the higher altitudes. :cry:

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There are several independent fuel stations that have high octane fuels in California. Most have 108+ fuels. I mix mine with 91 pump gas at a 2 to 3 ratio. This gets around 95+ octane. This will prevent the popping on decel as long as your jetting is correct. Just remember, most race gas are leaded and you don't want to put it in your car!

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