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KX450f Fuel Recommendations

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I recently traded up from my '03 KX250 to my new, sweet ride, the '07 KX450f. I know, good move. However, to my dismay, ( :applause: ) when the bike sits and idles for modest periods of time (such as when warming up before riding), the head-pipe glows beat red. I know this is bad and do not want to ride again untill this problem is resolved. My valve clearances are as they should be, and jetting as far as I can see is proper for my altitude and climate. A freind suggested that I am running the wrong octane fuel. I currently am using 94 octane with 100+ octane booster (mixed appropriately). Could this be what is causing my problem? Or am I missing something completely here? Please help me, as any suggestions are appriciated. This is my first post here so if I missed any details, let me know.

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94 octane should be more then enough for the bike in stock form. Most likely your bike is a little lean, causing the engine and pipe to get hotter. Try turning your fuel screw in 1.5 turns.

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Please forgive my noobish-ness. I know that fuel screws on 4-strokes are backwards from 2-strokes. Turning "IN" the fuel screw is.... Richer?

Also, are you saying that I should try just plain 94 octane fuel w\o the octane boost?

-Thanks

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how long do you let your bike warm up for? i never let my 450 idle for more than 5 minutes. and i would either buy straight 94 octane without additives or buy 110 octane race gas. but since you put octane booster i dont know if i would go back to straight 94 gas.

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Usually, I don't grab the stopwatch when I go to warm up the bike. As I have been riding since I was tall enough to get on a bike, I know not to spend an excessive amount of time letting the bike warm up. As a practice, as soon as it idles smoothly w\o the choke on, I get moving. My pipe is beat red before you can turn off the choke. Usually less than 5 minutes. After the initial warm up and I get going, the pipe seems to stay cool, even if I stop and idle for awhile. My problem seems to be mostly during the initial warm-up period. :applause:

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Turning "IN" the fuel screw is.... Richer?

-Thanks

no turning in the fuel screw is restricting the fuel flow = leaner / turning it out allows more fuel = richer

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With the KX450, its not uncommon to have a glowing pipe within a few minutes. The titanium is pretty thin and will glow very quickly.

I believe stock fuel screw adjustment is two turns out and I wouldn't recommend more than 2.5 turns out. As for gas, I've been running pump 93 just fine. Not sure what your combo of 94 with the Octane booster will do. You shouldn't need too much octane since the stock compression ratio isn't that terribly high. If you want to go that route, I'd go with a good race gas and not have to deal with addatives. As for the choke, I normally leave mine on for 30 seconds to a minute.

Next time you go to start it, do yourself a favor and break out a watch. Start the bike and time it to see how long it takes for the pipes to get red. If less than a couple minutes then you are probably running lean.

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no turning in the fuel screw is restricting the fuel flow = leaner / turning it out allows more fuel = richer

Correct, out for richer, in for leaner.

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OMG! another "my pipe is read" thread.

All the 4-storkes do it. It is normal.

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if he has the choke on for a long time doesnt that lean the fuel mixture???

I could be wrong but I thought the choke added fuel to keep the idle up.

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Yeah, when you turn on the choke, it does idle higher. I am going to try some gas w\o additives, and also going to check my air\fuel screw. Another thing I thought about was temperature. It's ALOT colder now then when I jetted the bike. Maybe that is contributing to my lean pilot circuit. Thanks for all the help folks. I'll post my results as soon as I get some.

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If your bike won't idle without the choke after about 30 seconds or so, of running with the choke on, then your pilot is lean or the fuel screw is lean, too far in. Glowing head pipe usually means its a little lean. It will do it also if you leave the choke on too long. Try starting it and let it run on the choke for just a few seconds then turn the choke off, if it dies back your fuel screw out half a turn and see if it gets any better. What temp is it. When it got cold i had to go richer on the pilot.

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As said by a fellow Moto-Head..."pump" 93 should be fine.

The best "Race Gas" for the money is Sunoco Unleaded 100 and that should go for around $4.50/Gallon in your area.

It's not the "Octane" that's such a big deal. It's the "Clean/Even" burn you get from a well formulated fuel.

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:lol: Finally after toying around with different settings, I discovered the fix for the glowing red exhaust pipe problem. Turns out that my air\fuel screw was in-fact set too lean. Factory preset is supposed to be 2 turns out. Mine was 1 turn out. Fixing this helped some, but the pipe would still glow after awhile. Turns out that the octane booster I was using contains methanol. According to the manual, when methanol fuel additives or mixtures are used, you HAVE to go up on your jet sizes. I did not take this into account when I jetted the bike. After putting in normal 94 octane pump gas and fixing the air\fuel screw, I can let it sit there and idle for ever and the pipe doesn't glow at all. :applause:

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:lol: Finally after toying around with different settings, I discovered the fix for the glowing red exhaust pipe problem. Turns out that my air\fuel screw was in-fact set too lean. Factory preset is supposed to be 2 turns out. Mine was 1 turn out. Fixing this helped some, but the pipe would still glow after awhile. Turns out that the octane booster I was using contains methanol. According to the manual, when methanol fuel additives or mixtures are used, you HAVE to go up on your jet sizes. I did not take this into account when I jetted the bike. After putting in normal 94 octane pump gas and fixing the air\fuel screw, I can let it sit there and idle for ever and the pipe doesn't glow at all. :applause:

Excellent news! Yeah, in stock configuration, fresh 93+ pump gas is just fine.

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Fuel additives, I have never used them before and I think I need to because I have recently found out that because South Africa uses the RON measuring system and not the avarage between the RON and MON our 95 octane(RON) fuel is actually a 91/92 Octane!(Basically we get a poorer fuel quality) Now we all know that these inferior fuels tend to predetonate causing more heat and we know that when Titanium gets really hot and cold repeatedly the metal becomes soft and you have valve issues. A study was done here that showed a set of valves could do 3 full racing seasons in the USA, here 1 season and in Mexico 10 hours all because of poor fuel quality.

What octane booster should I be using and will any help?

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...

What octane booster should I be using and will any help?

Unfortunately, I'm not very knowledgable in boosters. Can you get your hands on a good quality race gace? Even the lower end race gases will be better than your pump gas.

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