Thoughts on this much carbon in a KTM 65 SX?

[xrocket21]

116 hours. Did a top end last night, seems pretty full of carbon to me.

[Paul_E_D]

That's been generally running rich, but dirtbikes are tricky to read. The reason is that nobody ever rides them wide open all the time. Jetting richness varies widely across the rev range. burbling around will often show rich.

[xrocket21]

That's been generally running rich, but dirtbikes are tricky to read. The reason is that nobody ever rides them wide open all the time. Jetting richness varies widely across the rev range. burbling around will often show rich.

He generally doesn't burble around, he is a brapper, but it was winter riding recently, which I thought would be lean from the cold. I just hadn't seen internals THAT crusty before.

Thanks for your input!

[typeone]

ugh, reminds me i need to get on my top-end work ... +1 to Paul ... gauge where in the rev range he's riding most, then try a jet tweak. rich is better than lean, of course. we ran the Nihilo jet kit in our 65, maybe give it a shot and see. i don't remember what i was looking to tune out back then.

[xrocket21]

By ear, it seems to run pretty well, it sings.

https://youtube.com/shorts/C4Ud8ulUm...4HR1uzWXst73RR

Ill just tell him to ride harder.

1 month till the season starts!!!

[xrocket21]

Also to note, we added the pipe and muffler, FMF said it needed no jetting change, but I would have thought that would have leaned it out?

[boosten lebaron]

Might be your mixture is a bit heavy. Some 2t oils call for reducing the ration but you wouldn't know that unless you talked to them. A few of the motuls are like that.

[xrocket21]

I always follow the manual.

His 50 was 50:1, this 65 is 60:1, his sister's 85 is 40:1.

60:1 seems pretty light on oil to me. But also the 40:1 seems pretty heavy. I bet hers is awful with the increased oil and she doesn't ring it out like he does.

[Paul_E_D]

It's probably fine as is. Richer = torqueier, Leaner=revvier. most dirt riders want the torque.

[typeone]

+1 ^

[RandyO]

back in the day, we just sprayed water in the carb, steam cleaned the inside

[xrocket21]

Well, it's running like a scalded dog so we're good!

[breakdirt916]

send it

Paul - didn't you say it's best to just tune it proper throttle response? as long as it runs right, then there is no "correct"? oily plugs don't mean much unless it was a new plug with WOT run followed by a throttle chop and kill switch

As long as it runs run, send it like crazy angry chainsaw from hell that it is, and hold on

[jimmycapp]

send it

Paul - didn't you say it's best to just tune it proper throttle response? as long as it runs right, then there is no "correct"? oily plugs don't mean much unless it was a new plug with WOT run followed by a throttle chop and kill switch

As long as it runs run, send it like crazy angry chainsaw from hell that it is, and hold on

I feel like throttle response is pretty accurate, especially with a 2 stroke. You can hear and feel the lean bog with throttle input. Coming on the throttle going slow in second you can really feel it. Never really ran into high end lean bog, because I mostly ride in the woods. If it's 4 stroking it's rich. I haven't blown one up yet, but YMMV.

[jimmycapp]

I feel like throttle response is pretty accurate, especially with a 2 stroke. You can hear and feel the lean bog with throttle input. Coming on the throttle going slow in second you can really feel it. Never really ran into high end lean bog, because I mostly ride in the woods. If it's 4 stroking it's rich. I haven't blown one up yet, but YMMV.

Tuning by plug sucks. It's so hard to be accurate.

[Kurlon]

Tuning by plug sucks. It's so hard to be accurate.

It requires your fuel to be super consistent and not be using additives that throw the color off too... good luck with that out of the pump.

[xrocket21]

Makes it tough when I can't ride it to see what's going on. He is getting better at vocalizing what the bike feels like thiugh

[jimmycapp]

It requires your fuel to be super consistent and not be using additives that throw the color off too... good luck with that out of the pump.

The whole process is awful. Run at target throttle open. Shut off and coast while holding that position. Pull plug (after it cools). Use new plug if it’s not ideal. F that noise.