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Hello I am a new member and i just got a new bike.

I haven't ridden very much and I just got a 2006 yz450f for a trade for my snowmobile and i have a couple questions.

Pretty sure the bike has been raced and is modded.

High comp piston and two brothers exhaust so it runs turbo blue race gas is that normal?

Took a couple pics of the spark plug so you guys could tell me if its too lean or too fat, I have no clue?

There is a small leak in the exhaust, was planning on just having someone weld it, is that a bad idea?

It has a reusable oil filter, would you recommend this, also what kind of oil do i use when i change it, probably going to right away.

It pops quite a bit but after reading on here it says the exhaust leak could be causing it, any opinions?

It doesn't have a cover over the front sprocket cover and i would like one any suggestions?

If i can think of anything else I will let you know.

Thanks for any help.

Also does anyone know how to mix race gas, turbo blue is 110 and I'm not sure if i can get it in my town. Thanks.



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First, you can't really tell anything from reading a spark plug unless the engine is running leaded fuel and is run under the condition you're checking and then shut down without letting it idle or run afterward. Checking the main, for example, must be done by running it at full throttle through at least 4th gear, then cutting the engine and reading the plug after coasting to a stop. Unleaded fuel takes the whole idea out of the picture. Instead, read this:


With regard to the oil and filter question, Scotts makes an excellent, very trustworthy, high quality American made reusable filter that I recommend and use. Others, not so much, one or two, uh-uh. Read these:



On the exhaust leak, if by welding the leak you mean welding the mid pipe to the header, I'd say you should try removing the pipe with the header on it before you do that. My guess is it's not a good idea. Try some high temp sealant first.

Race fuel is probably not necessary, even with the 13.5:1 piston, unless you ride at less than 1000 feet in cold weather and the local premium is pretty poor quality. Most times, pump premium labeled at 91 or higher will do the job. If you hear pinging, the cheapest cure is to add 10-15% toluene (some use as high as 20%) to your fuel. Most big paint/hardware stores carry it. You may have to go up one step on the main jet.

Sprocket covers are great for packing mud and debris around the output shaft, and I have always removed them. They're available from Yamaha if you want one.

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Thanks for all the info.

Also there is a knob with numbers on it on the carb. I believe the guy that i got it from said its by moose, any ides?

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