250-500cc 1996 250wxc Bog - Not Jetting?

This new-to-me 250 is difficult to start. It was likewise when I bought it; plenty of kicks then it eventually came to life; seemed/ran like the gas was old, and since it had been sitting for so long (original front tire, sun damage to plastic) I figured it just needed some TLC. I bought it due to low hours and the 6-speed trans; there aren't many in the Southwest.

So to be on the safe side before riding it, I installed the recommended PWK38 Quad-Vent AS and 42 PJ, 165 MJ; 1472 needle mid-clip. #6 slide (I have #7 and 8 if need be.) The float is at 16/17mm. Elevation is 4000' in dry New Mexico, Klotz R-50 @ 50:1 with pump fuel. Air filter freshly done. Crank seals/bearings tight. New intake and air box boots. Fuel pees out of the overflow when tipped as normal.

It still was a hard start, and has a strange lean-like bog when I whack the throttle at lower to mid RPMs; it will come into power if I clutch it/remove load. No amount of air screw adjustment seems to change things with 40-52 pilots, nor clip positions of the needles below. It will at best idle on its own for a few seconds, then die.

No changing of jets and needles made any difference. 1472M, 1470-something, 1469L, NOZH, N1ED, and JD blue; and main jets from 165-175.

After exhausting my patience with Keihin, I swapped it for the stock Mikuni TM: 30 PJ, 380 main, stock needle and slide. No improvement. Uncle. Then it dawned on me: this could be an electrical problem, of which I have little trouble-shooting experience. I do have a multimeter, though the owners manual I have (2004) lists no target or range of resistance.

Anyone have numbers for the CDI, coil, stator?

I could swap 2001 my WR360 electrical parts to see if there's any change.

Any clues?

It is unlikely to be an ignition fault if it does start and run. Is there any misfire when running? for the cost it is always worth fitting a new plug. Your problem still sounds like jetting, what is your airscrew set at? PJ sounds quite big - I have a 38 in 300 which is perfect. A good indicator is that if the airscrew is much more than 2 turns out then the pj is too large.
Have you done a plug chop - put in a fresh plug and do WOT plug chop and check the colour.

Yes it did start though with many kicks. Once warm it starts well. When it runs it stumbles off of the bottom, moreover when whacking the throttle, as in a typical lean-pilot condition. Which is why I changed many pilots to begin with. Though when the way it rand did not change I tried needles and mains.

Did not do a plug chop yesterday as the main seemed fairly close - had plenty of power, ran very well mid to top. This condition resembles a lean pilot jet.

New plug did no good.

Air screw set at 1.5 turns out. No moving of the air screw with any aforementioned pilots had an effect, other than idling would stop at full in or 2+ turns out with most pilots. No typical lean (rev) or rich (blubber) when the screw was moved in/out with any - strange. This was getting too consistent with all the pilot changes; hence, moving to other circuits and then finally considering electrical.

I reinstalled the PWK today and changed jetting to 40 PJ, 160 MJ, 1472 needle in middle just to see if anything would happen. No start after way too many kicks. And I know how to start Huskies as I also have the mother of them all, a 360.

Oh: the reeds look like new, fully seating flat. No apparent leaks at the base nor head gasket.

It may not be the CDI is would be reliable, made in Japan; I have a spare and an extra coil/cap. Though I'm still thinking the ignition is not responding as it should. The flywheel does have corrosion. Is the nut LH or RH thread? I'd like to look at the stator.

Try a Sudco CEK needle and lean the bike over until gas leaks out the over flow on the carb, put it in second gear , rock it back and forth a couple times then kick. Works like a charm. I would try this for jetting base line:

40-42 pj
CEK #2
172-175 MJ
#7 SLIDE

Well, since starting is by in large dependent upon the PJ, I would think the 40-42 I had in before would have made a difference. But to show my appreciation for your advice and to keep my sanity I'll try it again this weekend. Though this time with a JD red as it is close to a CEL which is slightly richer than a CEK; #7 slide, and 172/175 MJ.

FWIW as I have a 300, the CEL works best in either 2nd or top slot and gives better power than the JD red.

Agreed the CEL is better than the red. I was just giving a good "SAFE" starting point. The JD red per JD is real close to a CEQ

I tried the following yesterday afternoon:

42 PJ
CEK #2
175 MJ
#7 Slide

No improvement, other than I learned when keeping the throttle fully closed it started; this is my first 2 stoke to do this - all others required a slightly-opened throttle. It idled okay for as long as I cared then died after the choke was turned off. Needed throttle to keep idling with no choke. It would bog off the bottom like before, under load. I went up on the pilot one size, then another to no change in the bog.

I'd change to the recommended CEL and CEQ but those are leaner. Since changing to a richer pilot does nothing to cure the bog, shouldn't I rather go CEJ/CEH (richer on the diameter) which is the part which takes over from the pilot?

If it doesnt run with that jetting I would start looking at something else. Compression good?, Reeds good ? electrical connections good?

Oh it runs now (thanks!), just not off of the pilot into the mid without bogging.

Yes: compression feels real good - it takes almost as much force turn it over as my low-hours 360: the mutha of compression this side of a Yammi YZ400/426/450 in their early days (pre-cam compression release).

Reeds look new; seat perfectly and no fraying.

Electrical connections? How would I test those? As there is spark - enough to run, and run well mid- to top-RPM (neighbors must hate me); if it were an electrical problem then that would be more difficult to troubleshoot. How to?

How many turns on the airscrew?

Just thinking have you checked the power valve to sure that its opening and closing properly. that to can causing boging and make the bike feel like a 50cc weed waker.

1.5 turns on the AS. No setting makes much diff.

I removed the pipe and looked in the exhaust port. The power valve is fully closed. I can force it open with a wrench handle, then when released it snaps back.

Check your needle and seat in your carb, could be worn

Carb is is good, used condition - ran well on my prior RMX.

Though I remember when looking at the piston, admiring the machine marks on it and cross hatching on the cylinder, thinking wait a minute: what are those two ports on the piston doing on the exhaust side? I believe the piston is installed backwards. Yep: that's it. This is a piston-port-timed designed. Now this is something to laugh about.

I looked on Hall's site, and it shows the exhaust side should be like all other 2 strokes - no holes. Their diagram does not show the carb side but I'm pretty sure the holes go on the intake to charge the bottom end upon TDC.

let hear how it runs after you get if fixed

Okay Troff - runs pretty good now. Thanks. It's a bit lean on the pilot but one or two sizes richer ought to fix that; air screw all the way in now. This sucker will be easier to manage than my former 360.

what did you end up with for jets?

42 PJ but will go to 45 or 48
CEK #2
175 MJ
#7 Slide