2006 yz450f


9 replies to this topic
  • privateerconnection

Posted August 08, 2011 - 01:50 PM

#1

I have a 06 yz450f that has been sitting in a garage for a couple of years. The bike ran great when it was parked and now it gets very very hot very very fast and it also pops and backfires like crazy. I have went through and thoroughly cleaned the carb even went with a larger pilot jet with the same results. I also completly drained the fuel tank and put fresh fuel in it when I cleaned the carb and also replaced the spark plug. Have also checked and the valves are in spec and the timing is correct. I have also tried a new stator and it acts the same. Any help would be greatly appreciated.

  • Justin Pearson

Posted August 08, 2011 - 01:56 PM

#2

I hate to say it, but you probably missed something in the pilot circuit when you cleaned the carb. Or, if you simply dumped the gas and replaced it without actually cleaning the tank out, then you most likely washed some junk back into the carb...

  • LemonDrizzle

Posted August 08, 2011 - 03:24 PM

#3

I have a 06 yz450f that has been sitting in a garage for a couple of years. The bike ran great when it was parked and now it gets very very hot very very fast and it also pops and backfires like crazy. I have went through and thoroughly cleaned the carb even went with a larger pilot jet with the same results. I also completly drained the fuel tank and put fresh fuel in it when I cleaned the carb and also replaced the spark plug. Have also checked and the valves are in spec and the timing is correct. I have also tried a new stator and it acts the same. Any help would be greatly appreciated.


As far as the hot part goes, take the cap off of your radiator and you should be able to see the coolant flowing when you rev the engine, this is assuming there is coolant in it, of course. If you can, then I would think you are fine. I have an 06 as well and mine gets hotter than a fire cracker in a very short period of time. They aren't meant to sit and idle. Mine will start puking coolant from the overflow hose in about 3-5 minutes if I just let it sit and idle. Also, if you are running lean it won't help matters much. It will make the bike run hotter.

For the popping and backfiring, you could also trying checking your exhaust for leaks. Make sure the header is tight and make sure the joint at the mid-pipe is tight and has a good seal. Justin Pearson is probably right though, you probably have junk in your carb yet. If you parked it without draining the gas then there is no telling how much varnish may be in the carb or where it is at.

  • grayracer513

Posted August 08, 2011 - 03:58 PM

#4

The odds are very good that you have a layer of dried varnish in your pilot jet. The difference between a #45 and a #40 is only .002", so it doesn't have to be much of a dried film to really make a difference. It will look clear, and air and fluid will pass through it, but it will still be so clogged as to act way too small.

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  • Wiz636

Posted August 08, 2011 - 06:16 PM

#5

When you changed to a larger pilot jet did you check how many turns out your fuel screw was? What size PJ did you install? Also, check to see that your hot start plunger is not hanging up. And as mentioned earlier, check all your exhaust connections, especially where the header attaches to the cylinder head.

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  • privateerconnection

Posted August 09, 2011 - 05:16 AM

#6

I did forget to mention a few items that I have checked and replaced. It has a 45 pilot in it now but I went all the way up to a 50 and nothing changed. I have played with the fuel mixture screw all the way from 1.5-3 turns out and no difference. Believe it or not the carb actually looked really good when I took it apart I was expecting the green funk of death and it actually looked perfectly fine but I still totally disassembled it and cleaned it. The header that was on the bike did have a dent in it when it came in to my shop and I had a brand new stock take off hanging on the shelf so I installed that also and still no change. I am thinking carb myself but I have had it off several times and everthing is clean as a whistle. The head pipe will glow from front all the way back to the shock in less than a minute. I do know these modern 4strokes get very hot very fast but I think this is a bit over the top. Keep the ideas coming though any and all help is greatly appreciated.

  • 1talbotj

Posted August 09, 2011 - 05:27 AM

#7

re-clean all carb components with carb cleaner and re-assemble...dont just look at the pieces...

  • grayracer513

Posted August 09, 2011 - 07:16 AM

#8

Pat particular attention to the area in the pilot passageways where the fuel screw needle seats, and to the idle discharge port in the carb throat.

  • Justin Pearson

Posted August 09, 2011 - 09:29 AM

#9

I have seen people put 2 fuel screw o-rings in when one gets stuck up in the carb and they dont realize it, replacing it, thinking it was lost, when in fact it has been driven up into the port. Remember if the pilot passage way is obstructed, even a 60 pilot isnt going to make a change since the "bottle neck" of flow is somewhere else after the pilot jet.

  • LemonDrizzle

Posted August 09, 2011 - 02:24 PM

#10

Maybe the intake boot between the head and carb has a crack or split and is sucking air? Or maybe it is loose?





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