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Discussion Starter #1
Well I tried the sled out with the little bit of snow we had and i got a problem. D&D suggested 390-420 mains for the single that i put on then I went up another 3sizes for the K&N filters. So i'm running 450s. What happens is for about 30 secs it runs great after letting it warm up. Then it boggs out and won't go above about 7000rpm and no snap. It will come out of it for a few secs at a time. If I let it cool down it still does it, tell it sits for a half hour or so. The plug color is a nice brownish tan color and the egt temps(don't know how acurate yet, but are around 700 at the high). I had a bad tank of gas last spring and this summer had to clean the carbs which had a green slime in them. I emptied the tank completely and replaced the filter. Also it seems really rich at idle. Any suggestions or ideas would be greatly appreciated.
 

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Discussion Starter #3
I was thinking either that or something was plugged being its fine at first. I didn't have time to play with it tonight so I will jet down and try again when I get back home again.
 

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Rich,way rich from the sounds of it. Here is a classic case like in cars. Cars and sled efi's use a cold start which riches the fuel delivered then leans out as it warms up. That is why your runing ok cold then bad once it's warmed up. But it was better to be same than sorry. You can always lean it out but you can't richen after a meltdown lol.
Caleb
 

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I am thinking rich too. If you call D&D they may be able to tell you what to jet to with the K&Ns or tell them you are using there power breather. That number of 420 they gave you was probably a high number to be on the safe side in case you are running a K&N etc. But like was said before. Better to be safe than sorry. I think I would maybe even back down to 420's .
 

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D&D should be able to give you some sort of a baseline for your set up. Keep in mind when your jetting down, its way cheaper to waste a couple of bucks on jets than the big bucks on pistons/ruined engine.
 

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Check your choke cables. Maybe too tight and slighty lifting the plungers causing a rich condition.

newf
 

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Discussion Starter #8
Thanks for the help guys. I had the same feeling when I went high. I really didn't want to have a engine meltdown. I picked up a bunch of sizes so I will start working my way down. I definetly agree its better to be safe then sorry.
 

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I would definitely check the CHOKE operation first, to verify that its working properly...... because if you jet down to get it working, and the choke is the culprit, when it does finally release, BOOM, there goes the motor......
 

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Discussion Starter #12
Thanks for the tips guys. I plan to move it to the heated shop now that it moves its getting to cold to work in the unheated shop. I'm going to take the carburators out and completely clean them. Resync the carbs and chokes and then I'll work with the jetting.
 

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One last suggestion...make sure that your gas tank is not getting air locked. Clogged air vent could be restricting fuel flow.

Learned this one from experience.
 

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Discussion Starter #14
Good idea. I never would have thought of that and with rebuilding it all I might have misrouted the cable. i will definetly check that to. I don't know what I would do without this site.
 
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