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2 stroke jetting, cold temps & lower elevation riding

Greg

Greg

I run a tight ship... wreck
Admin
Location
Grand Junction, CO
So with the upcoming ride in St George, I want to make sure I'm prepared for any needed jetting changes with my KTM 300 XC. I realize how important the right jetting is for a 2 stroke and how elevation changes can effect it.

The bike has been jetted for 4,500' and up, I haven't had a problem with the jetting as is. Since we'll be riding in St George, the bike should be running richer... looks like the elevation is closer to 3,200 ft. On the other hand, the temps will be cooler with highs in the mid 50's, which would mean denser air and a bike running more lean.

I think I'm just going to leave it as is and see what the bike likes once we get there. Adjusting the pilot circuit is easy enough if there's a bog... I just don't want to run it lean and burn it up!

Anyone want to weigh in on this?
 
Caleb

Caleb

Well-Known Member
Location
Riverton
Just take the JD kit with you. That way you can adjust if needed, but I doubt you'll have nay problems as-is. I never had that bike in low elevation, but all the way to the top of AFC I never really noticed a change/need to adjust.
 
Greg

Greg

I run a tight ship... wreck
Admin
Location
Grand Junction, CO
Caleb said:
Just take the JD kit with you. That way you can adjust if needed, but I doubt you'll have nay problems as-is. I never had that bike in low elevation, but all the way to the top of AFC I never really noticed a change/need to adjust.
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Yeah, I was going to take it just in case. I felt the same way, the jetting has almost always been fine.... the last time I rode out at Rabbit Valley was in the rain, in 50* weather. The bike had an off-idle bog, turned in the pilot a bit and it went away.
 
anderson750

anderson750

I'm working on it Rose
Location
Price, Utah
Most of the riding you are going to be doing will be mainly off the needle. If you think you are going to be to lean by going down in elevation, I would just raise it (lower the clip) one position. If you go to Sand Hollow to play, I would pay closer attention to maybe richening up the main 1 size.
 
Greg

Greg

I run a tight ship... wreck
Admin
Location
Grand Junction, CO
anderson750 said:
Most of the riding you are going to be doing will be mainly off the needle. If you think you are going to be to lean by going down in elevation, I would just raise it (lower the clip) one position. If you go to Sand Hollow to play, I would pay closer attention to maybe richening up the main 1 size.
Click to expand...

Thanks Paul, I appreciate your input!
 
Rot Box

Rot Box

Diesel and Dust
Supporting Member
Location
Smithfield Utah
I would install a new plug and check it everysooften but I really don't think you have anything to worry about. Elevation can change around here several thousand feet within a short ride. Like stated above the pilot can be tuned in with the fuel screw so you're good there. I'd pack a few main jets and if you do adjust the needle make sure you have some spare clips. Those are impossible to find in the sand trust me :D

I like to carry a magic marker/sharpie and write all the adjustments I make on the swing arm or ignition cover. If you're old and stupid like me you forget what size jet you installed before you can get the carb put back together :eek:

Wish I was coming with you guys!
 
Greg

Greg

I run a tight ship... wreck
Admin
Location
Grand Junction, CO
Rot Box said:
I would install a new plug and check it everysooften but I really don't think you have anything to worry about. Elevation can change around here several thousand feet within a short ride. Like stated above the pilot can be tuned in with the fuel screw so you're good there. I'd pack a few main jets and if you do adjust the needle make sure you have some spare clips. Those are impossible to find in the sand trust me :D

I like to carry a magic marker/sharpie and write all the adjustments I make on the swing arm or ignition cover. If you're old and stupid like me you forget what size jet you installed before you can get the carb put back together :eek:

Wish I was coming with you guys!
Click to expand...

Thanks Andrew! Some great tips & pointers!

Kind of makes me think about making any carb changes on a tarp, just in case I drop a clip! :rofl:

Sucks you can't make it, I'm looking forward to an off-season ride for sure.
 
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