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Dimelol

2003 Yamaha Kodiak 450 troubleshooting ignition system

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Well, it has to slide freely but can't have much play at all - the only way to know is to compare it to a new one usually. It's kind of hard to tell with the naked eye. Your slide did appear to move normally and if it was worn down that would allow extra air through making it leaner, right?!

Another thing to watch for is the o-ring on the float valve (needle & seat) - was a new one used when the parts were changed out?

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8 hours ago, spock58 said:

Well, it has to slide freely but can't have much play at all - the only way to know is to compare it to a new one usually. It's kind of hard to tell with the naked eye. Your slide did appear to move normally and if it was worn down that would allow extra air through making it leaner, right?!

Another thing to watch for is the o-ring on the float valve (needle & seat) - was a new one used when the parts were changed out?

Yeah, i swapped out all of the o-rings and installed a new needle/seat assembly, pressure tested as well. The old one was shot. You are right that would make sense. I'll see how much free play it has tomorrow, It is hard to see in the pictures but it seems like the needle is resting on one side of the nozzle, as if the needle is a little off center. I don't know if that's normal, but it's the only thing I have been able to find that has made me suspicious. 

If that doesn't work, I think at this point i am just going to buy this cheap amazon carb and see what happens when i install it. If it solves the issue maybe i can compare it to the OEM one and find out what's going on. Just knowing is worth the 40.00 to me at this point. 

https://www.amazon.com/dp/B00FTGCBD4/?coliid=IF4ZSB0FNTMC4&colid=1BQOQJI1T7NLS&psc=1&ref_=lv_ov_lig_dp_it

 

 

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@Frank Angerano @spock58 I put everything back together well enough to start the 4 wheeler to see if it changed anything, no luck. I did record a clip of how it sounds at idle for you guys to see if it gives you any new clues. When I initially start it it hovers at around 2500 rpm for about 30-45 seconds then works it's way down to sounding like this, which is around 1500 rpm (what it should be according to the book). I forgot to record the initial cold start so you won't hear that unfortunately. I figured it couldn't hurt since you guys are experienced with these 4 strokes. I ended up ordering that cheap amazon carb to see if it makes a difference at all. Should be here mid week.

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That’s a way high rpm for a start up. A cold start rpm should be about 1500 and come down to 800-900.   Hopefully your new cheap carb will give you some good indicators as to what’s going on. My guess is the engine will fire right up, idle and run well sitting.  Once you go to ride it then you will see how the cheap carbs react and have flat spots on the throttle but maybe you will get lucky.   

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On 8/19/2019 at 6:42 AM, Frank Angerano said:

That’s a way high rpm for a start up. A cold start rpm should be about 1500 and come down to 800-900.   Hopefully your new cheap carb will give you some good indicators as to what’s going on. My guess is the engine will fire right up, idle and run well sitting.  Once you go to ride it then you will see how the cheap carbs react and have flat spots on the throttle but maybe you will get lucky.   

I installed the new carb today and it idles much better. I am having an issue now where it backfires past a quarter throttle or so. I suppose it is running a little lean now. What you would adjust first to try an remedy that? The needle is easy to access but the fuel air mixture screw is a pain in the ass that requires the carb to be removed all the way. I have it set at 2 turns out. 

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So guess what screw needs to be adjusted? 

The air fuel mixture screw!!!!!!!  Sucks but yes that’s the one.

Please tell me you put a good quality carb on, maybe oem ? 

Double check the specs and see where they have it set at and put it there. You may need to adjust a hair either way but that gets you close.   

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