So I just refreshed my top end including my power valve. But it won't hit power valve? Could it be because my jetting is to rich? Or could a dimension be apart of the issue I set my z dimension to 48mm. All other specs are set exactly as the manual says? Bogs in low rpm so I would think it would clean up if I lean out my pilot? Any suggestions?
2 Stroke 96 250 sx won't hit power valve
- Thread starter 96sx
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no it wasn't working on my last trip out and my compression was 120psi. So I rebuilt top end including my power valve and replaced my reeds. Is there a gasket that goes between my intake tube and power reeds? When I got my reeds from boysen they came with a rev plate I used it and it wouldnt start. So I put on my stock reed stops it fired right up. Also in the diagram in manual shows a gasket that goes between each reed. That wasn't included or in my old set? My z dimension was set at 48mm not sure if that is correct. It says 99' and older models. Power valve has hit after rebuild just randomly though. And I know everything is to spec and put together right. An air leak would make it hit randomly? Thanks for the feedback.
I would clean the carburetor again, set the float per the OEM specs and try again.
A 2T not coming into the 'powerband' properly with good compression, has a carburetion issue.
My thoughts are that it is too rich from a mis-adjusted float. After thorough testing with the current settings, I would say to try changing the needle position. The needle affects mid throttle changes in addition to the pilot circuit. -BIG DAN
Ok let me better explain myself. I bought the bike and after I got it I rebuilt the carb. And found that it was leaned way out. Needle last clip, 158 main, 38 pilot, air/fuel screw turned all the way in just turned 1/8 th out. Probably to make up for the super lean condition it ran really poor. But still hit power band. My first trip out was A disaster. I bought several main jets, and pilots knowing I needed to re jet it. So I started rich 172 main, 42 pilot. It ripped just fine kinda bogged a little at low rpm and spooged a lot out the exhaust. Then I lost all power thought it was because I went so rich so limped it back to camp and went leaner. Couldn't get it to get into power band. So took out my reeds realized they were way gapped out. Flipped them over but couldn't get it to hit power band anymore. After messing with it all day I gave up and stopped riding it waited to get it home and realized I had no compression. So did top end so I'm starting fresh. Talked to Ktm they said 168main, 42 pilot. Broke in with 3x heat cycle up to running temp, cool down completely. Light ride around bringing rpm up through all gears gradually. Now I'm riding it like normal But it bogs down low and hits power band randomly... I never had the bike at 100% so I'm just trying to start from fresh but can't find stock carb settings for a 96 Ktm 250sx that's when I called Ktm and the recommended that setting to start with but doesn't seem right. Or I got something else going on? Sorry for the confusion it was running poor but still went into power band. I haven't took off covers to see if it's even trying to engage and my power valve spring doesn't have an adjustment... z dimension is at 48mm
I'd check your power valve linkage setting and operation???
And check the carb agin if all checks ok.
There are some small piolet holes that are hard to see and pull out the main body where the slide sits on. Could be some junk in there??
Make sure your cap is venting as well???!!!
All else fails buy another carb to X out the issue
And check the carb agin if all checks ok.
There are some small piolet holes that are hard to see and pull out the main body where the slide sits on. Could be some junk in there??
Make sure your cap is venting as well???!!!
All else fails buy another carb to X out the issue
it helps some if us if you do tell everything. it would help me to see your used sparkplugs or had a really full detailed and comparative description of them. keep in mind, stick jetting with a float that is out of adjustment isn't going to work like the factory had planned.
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I am not a fan of this method, although it does have the advantage of eliminating one thing from the equation, but at a price.
It reminds me of the old Ford "replace with known good part" method that used to bug the shit outta me when I worked on cars for a living. To me it basically equates to guessing, which I have done much of (and been right and wrong), but to hear it coming from the mfr always bugged me, like they didn't know either.
I just picked up a bike for my kid and the prior owner said it needed 'major carburetor work'.
No, it didn't, it just needed to be cleaned, a new idle jet and gaskets/rubber parts, and assembled correctly, which btw I effed up the first time.
I am a big fan of trial and error and live and learn I guess.
But if you got the $$$ it makes it easier.
This weekend I'll go ride it and take detailed pics of spark plug. Also if I can post a video I'll do that of it running through the gears. I really appreciate all the feed back this is my first bike. I am mechanically inclined and can figure stuff out I have been reading constantly. When I tore apart my top end cylinder was in print rings were gapped to .027 and power valve bearings were frozen and siezed from carbon. So I just assumed go to original carb specs or Ktm recommended specs and boom everything all better. But nope ha maybe it's still breaking in and the rings haven't seated all the way. I know the reeds are missing a gasket between the dual stage reeds but not sure why they wouldn't send them with them if they are needed? My plug was a little dark and oily so I know I'm still on the rich side but haven't got to really open her up and has been idling to go through heat cycles so it's kinda a bad place to take information from when it hasn't been opened up yet correct? For sure this weekend I'll have a better idea where I'm at. And thanks for the help !
Also the manual I have is downloaded from offline not sure if it really is specific to my year? So far it seems to be targeted towards my year. I just know that my year is like obsolete and a bit different then newer models. Detailed pics and a full day of riding this weekend should tell us everything. I'm not sure where my float is suppose to be adjusted heighth wise. My bike is a 96 250 sx if you find any info spec wise I'll take it thanks.
When you are doing work for others out of a shop, I subscribe to the "put in a known good part" way of doing it. One, your customer probably won't even understand why it took you so long to figure something out or appreciate it, and if you end up with it coming back, it comes out of your own backside in most cases. So if you are a production mechanic you do what you have to turn the cars out and free up the stall and get the customer back on the road with the fewest comebacks. Of course y ou do your best to correct what may cause premature failures, but anything past that is lost profit and if you are trying to stay at least even with flatrate, it feeds you and yours better to do it as mentioned.