Hanging rev 250r air cooled passed leak down test

[knipfeldustin]

Yes I agree that's why I was thinking new carb because I have also leak tested the intake boot while running with starting fluid and no change in rpm. This leads me to believe if it is an air issue it has to be carb related. It could be something all together such as the things Barnett suggested I just haven't had a chance to test further yet.............................wouldn't sell for less $1600. Pretty much everything except frame handlebars and engine cases and forks are old school aftermarket.

[yaegerb]

deleted, due to you already checking...LOL. I assume you are using fresh, high octane gas? What you are explaining sounds to me like a death rev which also occurs when you close the petcock and let the bowl drain. When there is more air than gas it will start accelerating RPM's......perhaps its was too lean on the main. Have you tried larger jets yet? 2 stroke bogging goes both ways...lean and rich (thanks Bryan )

[knipfeldustin]

Well maybe I can post pics

[knipfeldustin]

Bryan I bought 2 lower jets and 2 higher. Started off at 380 main. Didn't even check pilot as it starts and idles great. Took down to a 370 and it felt the best overall to me and I ran a plug test and cut the threads off and plug looked good. I'm going to try a 390 jet tommorrow and see what that does. I'm also going to pick up a gallon of 110 leaded and try that. 170 is what the compression test said but if the gauges can be off as much as Barnett stated it may need the race gas. It's definitely pulls hard up top

[knipfeldustin]

And what you described is exactly what it is doing Bryan, I believe I have 93 octane in it now

[nicker71]

The power valve probably went bad

[knipfeldustin]

This is plug from the 370 jet test.

[yaegerb]

No worries, but I am Brendon. The only reason I said thanks Bryan is because BKM (Bryan Melugin) taught me a few things last week. No worries though and yes try some race gas and some bigger mains and let us know how it works.

[knipfeldustin]

Oh sorry bud. Appreciate the help !

[sick85crownvic]

You can always send me the head and piston for mirror polishing! lol We've done this to a number of 2 stroke machines with great results as it significantly reduces the chances for detonation. I just did a YZ125 with some top secret port work and it now EATS 450F's. I love two strokes! Let us know how the jetting shenanigans go...a few weekends ago we went bat-crap crazy trying to get a blaster dialed in....owner cleaned his K&N air filter and while it was still wet, oiled it enough to cover 12 K&N filter services...this was done after it was brought in, as we were replacing reeds...once we figured that out and got everything set up, the jetting made a phenomenal difference...hoping you can get'er figured out sooner rather than later and we can all learn a little bit and you can get back on the track with it(and show up some Kawi guys! lol)

Good luck,
Don

[YTZ drew]

To me that plug is still reading a tiny bit lean, but others may differ. Is it possible that what you initially thought was a rich plug was actually dark due to burning a little tranny fluid (bad drive end crank seal)? If the bearing is heating up and getting loose after a hard run, there would be your air leak. Also, why not pull the head off and check for a burr? Or, if you have access to one of those little inspection cameras, pull the exhaust and go looking in through the port. A burr or divot with a raised edge will definitely cause a hot spot.

[knipfeldustin]

I hadn't thought of or heard of the tranny fluid burning ? Is this common ? First time I've dealt with this also so maybe I'm out of the loop
Eventually I'll tear into the engine and see what I've got goin I just want to rule out all the simple quick tests first.
Don do u offer porting or just the polishing service ?

[El Camexican]

This is plug from the 370 jet test.

That sure looks lean to me. How long did you use that plug for?

[knipfeldustin]

Just for the test. Warmed bike up with a different plug. Pulled that plug out installed new plug (pictured) and and went wot through the gears til top of 5th immediately pulled killswitch and coasted to stop. Pulled plug and chopped threads.

[danbur55]

Gonna ask a question more than offer any help. But is oil gas mixture any way relative to WOT runs vs say mid to low range? As I said don't know that much but curios if possible. Thanks