Jump to content
Sign in to follow this  

Kx250 fouling plugs every ride

Recommended Posts

So sick of putting a new plug in every time I ride.

Plug is fine all morning until I stop to have some food and then go to start the bike again and runs for 30seconds and then fouls the plug. Tried playing around with mixtures, defiantly riding the bike hard enough any ideas??

Share this post


Link to post
Share on other sites

If you lug around in the bush, even if you lug hard your sparkplug prbably ain't hot enough. Most 2 stroke mx bikes run pretty cold plugs stock cuz they're designed to be ridden on the pipe literally all the time. Haven't been on bikes all that long so I can't say much else

Share this post


Link to post
Share on other sites

I was just about to say clutch side crank seal, but I got beat. I'd definitely make sure that was new if you're doubting it.

Share this post


Link to post
Share on other sites

Yer the seal was the first thing I checked out and it's fine was only put in about 1hrs worth of riding ago. The next thing on the list was to pull the carby down and check the jetting. Still a new bike to me and previous owner has no idea about it.

So I guess I hit the jetting next!

Share this post


Link to post
Share on other sites

My sons 2002 KX250 did the same thing to him when he first stated riding it. We went to Super M oil, changed the ratio from 32:1 to 40:1 and adjusted the air/ fuel mixture a little. Hasn't fouled in over a year now. Didn't change jetting because the bike had been ridden at about the same temp and altitude prior. The only change we make on it now is air/fuel mix based on air temp.

Share this post


Link to post
Share on other sites

?  Reference to "checking crank seal"  How, pray-tell do you "check" it?! 

You don't....you replace it.

Share this post


Link to post
Share on other sites

Does the bike visibly smoke when riding after its warmed up?

 

I have not fouled a plug in at least ten years.  Never in my 250.  If the jetting is close and there's nothing wrong with the motor it should not happen.


?  Reference to "checking crank seal"  How, pray-tell do you "check" it?! 

You don't....you replace it.

 

If the crank seal is bad it'll be smoking like a chimney.  That's how you check.

Share this post


Link to post
Share on other sites

Does the bike visibly smoke when riding after its warmed up?

I have not fouled a plug in at least ten years. Never in my 250. If the jetting is close and there's nothing wrong with the motor it should not happen.

If the crank seal is bad it'll be smoking like a chimney. That's how you check.

Yer it isn't smoking like a chimney and the brand new seal.

That's why I'm thinking the might be something wrong with the jetting because I've never fouled plugs before until I got the kx

Edited by kx250dan

Share this post


Link to post
Share on other sites

What jets are you running currently?  Depending on your elevation you might try a 45-48 pilot.  These things come rich stock, even for sea level. 

Share this post


Link to post
Share on other sites

? Reference to "checking crank seal" How, pray-tell do you "check" it?!

You don't....you replace it.

Pressure test. If the crankcase holds pressure the seal is holding. I'd still perform this test because it isn't the first time a seal has been damaged on installation.

Share this post


Link to post
Share on other sites

What jets are you running currently? Depending on your elevation you might try a 45-48 pilot. These things come rich stock, even for sea level.

I'm not to sure as its a new bike with the previous owner knowing nothing so hopefully pull it down and have a look to see what it's running

Share this post


Link to post
Share on other sites

Really??

 

Leak down test, cork off carb manifold, cork of exaust spigot, pressureize with correct amount of air in the cylinder, remove unnecessary mechincal parts obscuring view of said seals, spray all junctions with soapy water, and if air bubbles are forming, theres your leak!

Share this post


Link to post
Share on other sites

Leak down test, cork off carb manifold, cork of exaust spigot, pressureize with correct amount of air in the cylinder, remove unnecessary mechincal parts obscuring view of said seals, spray all junctions with soapy water, and if air bubbles are forming, theres your leak!

Specifics on pressure testing a two stroke here

 

https://thumpertalk.com/topic/432226-pressure-testing-a-2-stroke/

  • Like 1

Share this post


Link to post
Share on other sites

Leak down test, cork off carb manifold, cork of exaust spigot, pressureize with correct amount of air in the cylinder, remove unnecessary mechincal parts obscuring view of said seals, spray all junctions with soapy water, and if air bubbles are forming, theres your leak!

Haha thanks. I know. That was just my lame attempt at sarcasm. Sometimes I wonder why people post their obtuse "advice" in such an obnoxious way when they obviously don't really know what they're talking about. They could at least be nice about it, then they wouldn't look foolish.

I'm actually in the middle of that project right now on my KX100, but can't figure out how to plug the case vent next to the PV. Any ideas? I'll ask on my other thread. Sorry to OP for thread hijack.

Edited by Bron-Yr-Aur

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...