Jetting confusion

SS109

SS109

Active member
My bike started acting funny last weekend while riding at a different elevation (4k) than normal (2k). When I would let off the throttle it felt like the engine was actively trying to shut off on me. Give it a bit of throttle and it would come back. I have never played with the jetting of this bike since I bought it since it seemed to run fairly well with a bit of spooge. Here is what I have...

'04 DE250 engine
PWK38AS (with a half-assed attempt by someone to emulate RB's divider only done with sheet metal and what looks like JB Weld epoxy - has been removed)
165 main
40 pj
2.25 turns out idle mix
??? needle - top clip (gold in color - I literally can see no markings on it whatsoever)
BR8ES plug - black at the base (pic below)

So, I cannot even begin to figure out where I'm at with out being able to identify the needle. I do have an older 38mm PWK off of my old KDX250 which has an R1369N needle I can use. If I got it right, that crosses over to a N427-48CGK. Do you guys think it would be safe to start with this needle, and if so, what clip should I start out at? Will be riding again at 4k tomorrow and really need to get this back together.

plug.jpg
 
Well, guess I'll be giving it a shot tomorrow. Installed it at the middle position and installed a new plug. Hope it goes well!
 
Well, put about 35 miles on it yesterday. Mid range felt strong put it was trying to cut out up top. Bottom end felt weaker and by the end of the day when I would come to a stop the bike would die. It would start right back up at least.

Current setup is now...
165 main
40 pj
CGK needle - middle clip
1.5 turns air screw

Thinking about going to a 170-172 main based off of AZRickD's jetting in the jetting guide. Normally ride 2000-2500ft but on occasion ride at 4000ft. Should I change out the pj and needle as well? Thoughts?
 
SS109 said:
Well, put about 35 miles on it yesterday. Mid range felt strong put it was trying to cut out up top. Bottom end felt weaker and by the end of the day when I would come to a stop the bike would die. It would start right back up at least.

Current setup is now...
165 main
40 pj
CGK needle - middle clip
1.5 turns air screw

Thinking about going to a 170-172 main based off of AZRickD's jetting in the jetting guide. Normally ride 2000-2500ft but on occasion ride at 4000ft. Should I change out the pj and needle as well? Thoughts?
Click to expand...

I think you are lean on the main circuit and the CGK may be too lean (length of needle), although I think the diameter and taper should be good. I would try to richen up the main and change clip position to #4 or #5 and see if there is some improvement. I would only make one change at a time.
 
benj565 said:
The Plug in the pic looks very weird indeed.. totally different to the BR8ES plugs ive run forever.
Click to expand...

Sarcasm? Haha! It's been cut away to show a clear view of the ceramic insulator.

Don't have any suggestions re thread as I'm unfamiliar with the older engines, AS1 carbs, and the Sudco needles. I would however agree the main looks quite lean for a 250.
 
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