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Discussion Starter · #1 · (Edited)
Hello everyone! I just recently purchased a new girlfriend and she needs a little tuning. I have a 05 honda trx450r that sat for about 4 months from previous owner. The wheeler has a mild cam, full hmf exhaust and a rev box, also has no air box lid. It starts hard and when warmed up I will have a hanging idle when the throttle is pushed. Revs for about 30 seconds then will drop to a barely hanging on idle and die. Also the head pipe will get cherry red. I pulled the plug and it's got carbon buildup. The previous owner has a 175 main jet and a stock keihin 48 pilot, the needle is on 3rd position. I live at 995 ft sea level. I would really appreciate it if someone can help me! Thanks!
 

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Dirty carburetor or vacuum leak between the carb and intake manifold.

I will also bet the fuel has ethanol in it and is old. Not good in either case. You could also have a dirty fuel tank cap vent that traps a vacuum and stops fuel from leaving the tank.

Your valves also might be too tight. Basically, you need a no holds barred, Texas style, fight to the finish, by the book tuneup. Chasing gremlins before doing a tuneup is like rearranging the deck chairs on the Titanic.

A complete waste of time.

Rick

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Discussion Starter · #3 ·
Do you think the jetting is correct? I have the carb out and torn apart on my work bench, I will be getting carb spray after work and a new plug. Any recommendations on plug or stay with what it's got?
 

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I'd stick with the NGK Spark plug, They last and they aren't that expensive. That's what I run on my quads. Good luck, let us know if you have any other questions.
Cameron
 

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Your valves also might be too tight. Basically, you need a no holds barred, Texas style, fight to the finish, by the book tuneup. Chasing gremlins before doing a tuneup is like rearranging the deck chairs on the Titanic.

Funny shit right there! I love it!


After looking at your picture, it appears to be running very rich as its full of carbon deposits. However, you say the pipe gets cherry red? IF so that tells me it should be running lean... Clean the carb right up. Check the choke as well.
 

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Discussion Starter · #6 ·
Okay I'll be doing that tonight after work. Jet sizes seem good enough though with the mods done to the wheeler? 175 main, 48 pilot, needle on 3rd notch? So basically so far y'all just think she needs a good hard cleaning and new plug?
 

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Nothing should have been loose! Soot is caused by being too rich... Not having a proper combustion cycle. So something seems off there....
 

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Discussion Starter · #10 ·
Well I cleaned every aspect of the carb. Put the new plug in and started the ole girl. She does the same thing with it idling too high then low. That's all it does though. No backfire, no skip, and runs like an animal. Could it be the no airbox lid or the old air filter? Or maybe because of it being cold out?
 

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I have used Denso on other bikes - worked OK. You need to watch that plug for changes to the color of the internal porcelain. Sooty, black like that first picture is pig rich! Way too much fuel or not enough air - how clean is your air filter? You want a nice, chocolate tan on the spark plug for Goldilocks bike operation . . . not too hot, not too cold, not too lean, not too rich . . . . just right.

Rick
 
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