Can't figure this out

[gary55]

I checked to make sure the threads are the right length. When tight it sits perfectly flush with the inside of head

So we are talking 2 stroke?

 

[YetiWoodz]

So we are talking 2 stroke?

Yeah 2 stroke

 

[gary55]

Did you do any work on it before this started to happen or did it just quit all of a sudden?

 

[YetiWoodz]

Did you do any work on it before rhis started to happen or did it just quit all of a sudden?

I did put on a modified kx65 expansion chamber, but I didn't do anything else. I tried my other pipe afterwards and still the same issue. Before, my bike would take a little while to start and usually after it fires normally for like 10-20 seconds, it stops firing completely and I need to start pedaling again till it works. I didn't think anything of it but I wonder if that problem was ongoing for a while and it just kinda crapped out the other day. Also it just so happened to be the first cold day this year that I rode it.

 

[YetiWoodz]

Spark plug only really wants to fire if I do a quick yank all the way back on the throttle as soon as I pop the clutch.

 

[YetiWoodz]

I'm gonna order a new cdi and magneto. Any recommendations to which ones you guys tried and are pretty good? Or are they all generally good?

 

[Chainlube]

I've never replaced a CDI, but had to replace a couple coils. Check all your connections first, one bad connection can spoil all your fun. Where you have connectors put a little dab of dielectric grease before you put them together.

 

[gary55]

I did put on a modified kx65 expansion chamber, but I didn't do anything else. I tried my other pipe afterwards and still the same issue. Before, my bike would take a little while to start and usually after it fires normally for like 10-20 seconds, it stops firing completely and I need to start pedaling again till it works. I didn't think anything of it but I wonder if that problem was ongoing for a while and it just kinda crapped out the other day. Also it just so happened to be the first cold day this year that I rode it.

I have seen CDI's go bad slowly. They are very hard to diagnose as they will run well briefly then after running while they slowly start crapping out till they completely fail. After left sit a while they will start again and run okay shortly and fail again. So a new CDI and Mag is not a bad place to start. If they are not the issue now they will be someday and you will have the spares on hand.

In my exp. when CDI's act like this the plug is usually wet and appears rich when pulled due to getting fuel but no or poor spark. Since your plug looks on the lean side it might be a good idea while waiting for parts to thoroughly clean the carb and make sure the jet is not getting clogged by some debris floating around in the bowl getting sucked up to the jet while running then falling away when stopped. The increased exhaust noise and smoke is different. So popping off the head and inspecting for warping and having a look around at the cyl. wouldn't hurt. A warped head can cause some weird issues too.
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[YetiWoodz]

I just checked electrical connections. I took em out and put em back in too. I checked for spark. Looks perfectly fine. Blue with white in color, jumps around electrode, doesn't skip or anything.

 

[gary55]

I just checked electrical connections. I took em out and put em back in too. I checked for spark. Looks perfectly fine. Blue with white in color, jumps around electrode, doesn't skip or anything.

Might wanna have a look at that head a good cleanup on the carb.. Again though the CDI's I seen that were slowly going would show good spark when cold. That's part of what made them hard to diagnose.