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Fredtech

2006 YZ450F too lean after been stored for 6 months

10 posts in this topic

I got the bike almost new. It was running to lean (like all of them brand new) so I installed the JD Jetting kit and it was Perfect!

Stored it for the winter and when I started it back after 6 months it was running extremely lean (loud pop, lots of heat). I thought no big deal I'll just clean the carb! No success.

I checked the valves and they are perfect. Cleaned and dismantled 4 times and I am puzzled...

Anybody experienced that?

I live in Houston, TX

No elevation, 80 degree

2.25 turn, 170 main, 50 jet.

Thanks in advance

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I got the bike almost new. It was running to lean (like all of them brand new) so I installed the JD Jetting kit and it was Perfect!

Stored it for the winter and when I started it back after 6 months it was running extremely lean (loud pop, lots of heat). I thought no big deal I'll just clean the carb! No success.

I checked the valves and they are perfect. Cleaned and dismantled 4 times and I am puzzled...

Anybody experienced that?

I live in Houston, TX

No elevation, 80 degree

2.25 turn, 170 main, 50 jet.

Thanks in advance

Not saying you dont know how to clean a carb properly.....but I would clean the carb again properly. Pay special attention to the pilot jet and leak jet and leak jet passage that goes through the carb body. remember even though you can see daylight through the pilot jet...that doesnt mean its clean or sized properly. A 50 pilot seems awful big?? And if thats perfectly clean there is no way that thing should pop...unless you have a big air leak with the pipe.

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The orifice in a #45 pilot is about .015", and if it has a .002 film of varnish on it, it will still look open, still pass liquid through it, but it will be effectively over 20% smaller than it is supposed to be. Push the shank of a #79 drill through your pilot jet and try that.

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The orifice in a #45 pilot is about .015", and if it has a .002 film of varnish on it, it will still look open, still pass liquid through it, but it will be effectively over 20% smaller than it is supposed to be. Push the shank of a #79 drill through your pilot jet and try that.
I have a chart at work...Pilot size# equals drill size # conversion and I believe a 77 is a 45. Not 100% on that though.

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I have a chart at work...Pilot size# equals drill size # conversion and I believe a 77 is a 45. Not 100% on that though.
Post the chart. Or, if you can't, PM me. That would be handy.

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I got the bike almost new. It was running to lean (like all of them brand new) so I installed the JD Jetting kit and it was Perfect!

Stored it for the winter and when I started it back after 6 months it was running extremely lean (loud pop, lots of heat). I thought no big deal I'll just clean the carb! No success.

I checked the valves and they are perfect. Cleaned and dismantled 4 times and I am puzzled...

Anybody experienced that?

I live in Houston, TX

No elevation, 80 degree

2.25 turn, 170 main, 50 jet.

Thanks in advance

Are you running E10 fuel ? If so, E10 is BAD when left in your fuel system for extended periods of time beyond a month or so. E10 leaves a corrosive fungus residue on the fuel system components and will cause all kinds of ill running issues. Make sure in the future you use some type of E10 stabilizer fuel additive. I strongly recommend Startron. There is also Stabil Marine, and I recently saw Stabil has a specific E10 formula too.

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Post the chart. Or, if you can't, PM me. That would be handy.
I posted it some time ago...dont know if you can pull it up but..I will run a copy tomorrow and post it up for you. I know the ones I use the most are 77,78 and 79.

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Found it:

http://www.thumpertalk.com/forum/showthread.php?p=5418114#post5418114

Thanks.

I should make the point that the drills should ONLY be used BY HAND or with a pin vise, and very carefully.

I use a pin vise or I'll hold the drill bit with some Duckbill pliers and "Spin" the jet with my fingers on the drill bit. Yeah,,,,,,,for sure breaking one of those off is not good....and expensive.

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