I'll save the details but I have been working for two weeks to get out tomorrow and I'm a mcidiot and cant delay gratification so I decided to do the Suzuki needle jetting swap off of a (very good) recommended setting and now the bike runs like aids down low. It's my fault, nobody who's smart would change every jet in their carb at 7 pm the night before riding. So when you finish laughing at me, check out this video and see what you think could be going on. I suspect a lean pilot since the bike tends to run best with the air screw all the way in but I truly and humbly have no idea what I'm doing except how to read the manual and how to physically perform the work.
Watch: https://youtube.com/shorts/4a62y4041iA?feature=share
Aside from the off idle bog you can see and hear, it also "steps" down the rpm. So, if I get on the pipe a little, as it decelerates, it does not return down smoothly. It "steps", or sounds like "ding, ding, ding, ding" as it lowers in RPM. This is coupled with a physical lurching of the bike.
It was smoking a tiny bit out of the powervalve vent.
it will momentarily cut out if you get a handful while moving, then pick up and haul.
If the throttle is eased open and not cracked, the rpms pick up very fast.
Just started using Yamalube 2R and unless it is known to smoke more than 927... it's kinda smoky some how.
Jetting: Suzuki NECJ Needle, third clip, 170 Main, 42 Pilot, 40 Power Jet.
Mods: Boyesen Rad Valve, Shorty.
Bike ran like a pissed off chimp with the stock jetting in it - completely perfect. No mechanical issues.
Paging digger.
possibly an air leak where the carb mounts?
Digger is the one who set me up! I hope he's awake. The combo is awesome I just dont have the skillset to remediate this instantly like some others on here do. I bascially have an hour in the morning to make or break or I'm going to have to save it for later and get to homework (my constraint). I would probably rule that out - Fresh gaskets all around. I'll update the OP with my "mods" simply a Boyesen rad valve and a shorty.
Hopefully he responds tonight. I’m not a jetting specialist, but the first thing I would do it spray carb cleaner/brake cleaner around the carb and air boot while it’s running to see if changes at all. If that checks out, I would go up on the pilot first, next step would be raising the needle a position
Wish It could just be a main.... such a bear to get all that stuff out and get the bowl off. I'll hit it with some spray in the morning I think every one of my neighbors is going to want to kill me tomorrow.
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You should be able to get to the pilot without pulling the whole float bowl off
Go up a size on pilot, then set the airscrew. It should be far too rich with the airscrew turned all the way in.
Why not just run the oem settings?
Obviously lean pilot and lean needle straight diameter. What is stock jetting since I don't know cause I don't ride piece of shit yams.
I've had 6 yz 250s and basically ran stock jetting on them all with zero issues. I had 1 that detonated with a PC pipe and pump gas but that's about it. 35 degrees to 90+
Pull the carb and put the stock parts back in it, it shouldn't take that long.
It's lean on the pilot, put a 45 in it. What is the air temp ?
Put a 45 pilot in?
Yes, it's lean on the pilot jet for sure.
Just saw this, I’m working on it now will report back!
Literally stellar question bro. First, I don’t know. Second, I’m addicted to tinkering with stuff I think. Are you… not?
This is stock jetting.
With a rad valve my understanding is that you can go a bit leaner.
below PC recommendation jetting (bit leaner than stock)
I hope this help.
Good luck!!
Yes, 45 pilot.
Set idle as low as possible after setting up airscrew while bike is fully warmed up. It should barely idle.
Update: i got a 45 pilot in there and it's a little better. I'll upload some videos below this. It is cleaner and now only has a little bog before picking up. It get's better with the air screw almost closed. Also, if I get it up high in the rpms and on the pipe, then coast, then barely open the throttle, it surges back and forth as if someone were kicking the rear tire. If I turn the air screw in to half turn out or less, it will die. I think that means the jetting is close? Day's probably done but man I'm learning alot. Thanks everyone for the help, hope to get some comments back soon. I could still probably get out. It's 50F outside now warming to 60. Would you just go ride it? see vids. It seemed to get better with time as the bike ran more, then stabilized. Partially to do with the air screw tuning I was doing I guess. Yes, it was warmed all the way up.
Pit Row
https://youtube.com/shorts/4X5yHc-DsGQ?feature=share
https://youtube.com/shorts/txhp1zSj4lw?feature=share
Put a 48 in there. I know you like to tinker, but you're pretty close to perfection stock.
Totally bro....it's such a piece of shit that it has went almost 20 years unchanged and is still competitive with the new 2 strokes that cost twice as much....not to mention it has won races and titles in EVERY major series in the US from SX to National Enduro....such a piece of shit though. Face. Palm
Just go back to stock if you're in a bind and need to ride.
"runs like aids" is going in the lexicon
Yeah this takes some punch out of the transition and makes it smoother but if the 48 doesn’t do it I’ll save my tinkering for more consistent weather when I’ve got the time. Semester ends 4/27 I think so should have some time then. We shall see. Thank you for the help too
Just coasting the bike sounds pretty lean. Go up another size on the pilot, or try going down a clip on the needle... Not super familiar with yz250s, but I had an 06 last winter and ran a 55 pilot, 185m, clip 3 (not sure which needle) for deep snow riding. It would only slightly load up in the shop at 60*.
I'd get rid of the Suzuki needle. Additionally, the NECJ is a fairly lean needle in the hierarchy of Suzuki's needles.
I tried a few different Suzuki needles in my sons 2018 YZ-250 and it ran like crap no matter what jet, clip and airscrew combo I tried. For some reason they work much better in the Austrian 300's and 250's.
https://youtube.com/shorts/gWjK7nzpXAc?feature=share
https://youtube.com/shorts/6k20RTO6g5w?feature=share
48 pilot is in and makes some difference. It’s better, I’d say we’ve moved from a bog to a stumble. If I put the air screw at .25 open, it runs just about right. See above. I’m fatigued with it so I’ll probably pull the carb and go back to stock since that was tried and true and mess with this later. Still seems a little smoky but I don’t know about 2R. Is castor just super clean? It’s all I’ve used until I tried this.
This is not a new plug.
Was it running good before and all the sudden shit bed?
Check your float height, run jet cleaner through your jets make sure they aren't clogged.
Check the flywheel side crank seal for any leakage.
Raise your needle(drop the clip).
or you have a bad crank seal.
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