Maintenance & Technical > KX500 Aluminum Frame Conversion (AFC)

HELP w assembly

<< < (14/14)

81cr450:
I've been jetting for days. Between the big bore pulling more fuel & the 50/50 avgas pump blend it's been a challenge. I'm running a Mikuni TMX bored to 39.8 mm so this might not help most people. What I've come up with so far is that I believe the avgas has a different weight , lighter, so it pulls through the pilot alot easier as well. I'm 4 sizes down on the pilot from what I should be on a stock motor, the main is still right where I'm used to it though. It  isnt really building heat though, I'm thinking I'll need to drop the plug to a br7es too.
Is avgas that different?
Runs real strong though. It suprised me on how far off the jetting can be & still run decent, as long as you keep it blown out. I started  with  390 main 35 pilot to be safe I'm now at a 360 main & a 25 pilot Havent messed with the needle at all , 2nd position. I think the mid being right has helped with the other 2 being off.

Rhyno:

--- Quote from: 81cr450 on April 09, 2012, 03:29:19 PM ---.............I'm thinking I'll need to drop the plug to a br7es too.
Is avgas that different?
..................

--- End quote ---

AvGas has lead in it, and of course a higher octane.  Lead is a lubricator for the HOT exhaust valves, but Hippies don't like it.  Some places are different (95-105), but the average octane is close to 100.

I run a BR7xx plug, too.  But it is at partial throttle, trail riding.  If I were WOT more, it'd be too hot of a plug.  Works great at 4500-6500 ft.

-Rhyno

81cr450:
I should have included the elevation 5000 -10000 ft , its pretty mountainous here. If I set the main down at 5000 then ride up to 10000 I'll get the feedback on if it's too rich or not. If I get it to where its on the edge of rideable up top its about perfect in the lower stuff. It is the low range thats loading up a bit, when youre in rock hell & cant wind it out . If I can get stay in the wide open stuff  & keep it blown out it's great. Just a time consuming process dialing it in. 

spinyard:
Dredging up an old post! Any way you could re upload the pics to this thread or email directly? I'm about to embark on your same journey (2004 cr250 frame kx500 motor) after all the broken frame posts I like that you can do this without cutting the y out of the frame!

Navigation

[0] Message Index

[*] Previous page