Reed petals disintegrating

[be_lain]

I’m working on a buddy’s ski which has a 61x w/ JM ported top end kit at 82.5mm. He was complaining about it running like trash so I’m trying to diagnose the problem.

I found that the carbon tech reed petals are beginning to disintegrate and I’m thinking this could be the issue. Looks like the cylinder with the worst petals was running a bit richer as it had more oil buildup/residue than the other cyl. All else looks good inside the motor so far.

Anyone have any insight to this? Can these reeds be affecting fuel delivery that significantly?

The pic shows the worst of the reed petals but they are all starting to fray at the bottom edge in a similar way. Dont mind the clump of yamabond in the pic lol

 

[Blue]

The reeds job is the same as a valve in a four stroke engine. They should seal closed with no gaps between the reeds pedal and the housing. If its chipped away enough to not close or has a chunk missing it will cause issues. I will pm you my number call me later i will see if i can help you with it.

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[john zigler]

Bad reeds can cause a lean condition, as your fuel / air mixture will go back into the intake and up the carb.

Your reeds definitely need replacing, but I am not sure that is your poor running issue. Yours look like they are just beginning to go bad.

 

[bernard]

I was told to use a reed spacer or the reeds would not last with my carbon reeds.