Plugs

[michmex]

my dirt bike keeps burning upplugs like nothing i heard if you let the bike idle for like 2 min before turing it off does this helpout is thair a problem ??

o ya its a yz426 too

[xtreme165]

Are you using BP or sunoco fuel? If so dont and your problems will go away.

[michmex]

why does that matter

[xtreme165]

I read before that the high in ethanol fuel caused the Yamaha's to foul plugs. I know 2 people that no longer get there gas from BP or Sunoco and run sheets or Citgo and have since had no problems. Just a thought you might want to check to be sure.

[grayracer513]

The first thing would be to make certain you're using the right plugs. The bike calls for a CR8E, I believe. Many people have the mistaken belief that running a colder heat range of spark plug will help their engine run cooler. In fact, the heat range of the plug has little to do with that, and everything to do with keeping the nose of the plug itself clean. If you're running a CR9E or equivalent, go back to the stock heat.

[xtreme165]

grayracer,

Do you know anything about the ethanol in fuel fouling plugs? I know for certain I read that before but what is your take on it?

The first thing would be to make certain you're using the right plugs. The bike calls for a CR8E, I believe. Many people have the mistaken belief that running a colder heat range of spark plug will help their engine run cooler. In fact, the heat range of the plug has little to do with that, and everything to do with keeping the nose of the plug itself clean. If you're running a CR9E or equivalent, go back to the stock heat.

[michmex]

yes i run a cr8e and do you think holiday foul better ?

[grayracer513]

Do you know anything about the ethanol in fuel fouling plugs? I know for certain I read that before but what is your take on it?

Ethanol should not cause fouling, but it can cause a lot of other troubles, depending on how much of it there is.

Ethanol is a low energy fuel and has to be run in much richer mixtures than gasoline in order to be run straight. It's big advantage as a high performance fuel is that it has a very high equivalent octane number, and allows the use of compression ratios as high as 16:1 at sea level. The performance boost comes 80% from the extra compression.

When used as a fuel additive in pump gas, its purpose is to add oxygen to the fuel to reduce certain categories of emissions, and sometimes for the purpose of extending the gasoline supply by using less of it in each tank. Unfortunately, the car's performance is generally reduced by these fuels to the point that any gasoline savings from "cutting" the fuel are offset by the poorer fuel economy.

The more ethanol there is in the fuel, the leaner the engine will run. The leaner it runs, the more likely it is to misfire and start hard. That could be why people say it fouls plugs; too many attempts are needed to get the bike started, and the plug suffers.

Ethanol, and all other alcohols and MTBE, are also hygroscopic, meaning they absorb water. That means they should not be stored in a fuel tank for long periods, or they can pull enough water out of the air to affect the fuel.

[DrThumper]

yes i run a cr8e and do you think holiday foul better ?

....WHAAAT?

I had experience with ethanol fuels fowling plugs a little more often, however it wasn't in a Yamaha, it was in a log splitter. I beleive the ethanol lowers the combustion temp, but I may be wrong.

As ole Grey was touching on, you don't lower the temp of the plug to lower the engine's running temp...you lower the temp of the plug if the engine is running at a lower temp. Its all about cause-and-effect, the plug is the 'effected' part if the temp is low, not the 'cause'.

[DrThumper]

Yeah, what ole Gray said! Forget what I said, he's got it. He slid in his post while I was answering the phone.

I thought MTBE was outlawed? Maybe it was just in Calif? I don't think we have it here in Utah either.