DAMN Riders - No rules, Just ride!

Was busy this weekend. Got a new bigger pilot jet in it and it'll kickstart! Replaced the rear brake line, rebuilt the front master brake cyl, and bled the clutch while I was at it. Put a new spoke/nipple in the rear wheel and welded up the clutch lever I broke into a shorty (dropped the bike earlier )
This thing might be ready to go soon.

Having tuning problems. Once running I'm pretty satisfied. Did the o-ring/safety wire mod to the accel pump lever and it eliminated most of the quick throttle twist bog.

Cold start: takes a little choke but once running likes it off.
Running I've backed out the fuel screw ~4T and the RPMs keep increasing as I do. That indicates a lean pilot jet (or air leak) and I need to go up one more size. But...
Hot start: You CANT touch the throttle or it bogs and wont start. You have to kick and kick (or crank and crank) and it tries and tries to start but often never quite makes it. That indicates rich

I have more luck kicking it when hot than using the e-start. Spins it just a little faster I guess. I hear the old e-start systems are pretty marginal but its not kicking reliably either. The battery is getting weak and doesn't last super long cranking so I'm going to put a lithium in it to get more CCA - can't hurt.

I could double check the valves again. There are within spec but not perfectly in the middle of the range. I understand them being off a little can make it harder to start.
I could be suspicious of the alternator output but it seems to measure ok. The windings look a little brown but not burned or anything. I do wish the ignition ran off the battery.

I hope to see this bike in action on Saturday!

Sounds like you're hot on the tail of the jetting issue. I assume you've gone through the carb already. Floats/ needles need love too.

If all else fails, I've found JD jet kits to be spot on. But I'm no carb tuning pro. They always seem to be worth the money IMO.

My buddys 07 250sx-f required 10kicks when cold like clockwork.


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Yeah, I've rebuilt the whole carb bottom half. It was spotless inside when I started though so don't know that it helped much. Didn't replace the needle but since I'm only at idle and the needle is fully seated, it shouldn't be doing anything. Though if the needle or main nozzle is corroded, it might not fully be blocking off flow from the main? Eh, its something to check! JD is just going to give me different jets and a needle. I already have all the spare jets. I have had some luck w/ JD in the past. I might call them and see if I can just buy the needle they recommend.

I have done some reading on KTM's e-starts in the carb'd thumpers were always marginal to begin with. Apparently in the later models the starter peak power was improved and the gears redesigned to spin the motor faster. I've also read that some 4-strokes thumpers are notoriously hard to start when hot. Plenty of Honda/Yam/KTM/etc owners complain about the same thing online. So maybe its normal? My DRZ used to restart hot fine (though that had a CV carb at the time.) All the EFI bikes start right up hot

I double checked spark today and it looks really good.

I just put the OEM lithium batt that came in the 2020 500 in the 250. It definitely cranks faster now w/ the lower cell resistance. Just fiddling w/ it this afternoon seems 'better' but still not 'great'. I might at least be able to figure out a hot start procedure that is more repeatable now. Will still go through all the other stuff to double check. The true test will be @ Phil's place on Sat.

Update: Bike wouldn't hot start @ Phil's a couple weeks ago. Its still too rich @ cranking and I've now discovered I have a bad regulator/rectifier too.

I replaced the R/R.
I rebuilt the carb again w/ a new 'mid gasket' (not sure why they don't include this w/ the regular carb gasket set )
Still won't hot start
I put a 42 pilot in and can cold & hot kick it. Cold is 3-4 w/ a little twist of the throttle at the bottom of the kick. Hot is more finicky, can be 1 to 10 kicks w/o touching the throttle. Crappy but its still progress! Its popping on decel so I know the pilot/fuel screw are too lean but I'll take that any day to be able to hot restart it. I do wish the 250 carbs had the hot restart lever like the 450s got.

Now onto the e-start. I understand between the starter gearing and the low power of the starter these early KTMs don't e-start well. They just don't crank fast enough. So I did what the high compression ratio 2-stoke 150s do (they have a TINY scooter starter) - run higher voltage. Since I fly RC I have a ton of different batteries. I grabbed a 5S Lithium (~20V) and jumped it direct to the starter. Yeah, it cranks faster now! But is still SUPER finicky to e-start I don't understand why kickstarting works but the e-start doesn't

I'm wondering if I can change the starter jet to something TINY and use the choke lever as a hot restart (lean) lever. It not only opens up the fuel passage from the starter jet, it opens an air passage around the throttle. This is to give a higher idle and more fuel when cold. I can always crank the accel pump a few times in cold weather. But if I restricted the starter jet, pulling the choke lever should lean the bike out w/o extra fuel.