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Hi everyone,
As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.
When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.
Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.
Unfortunately, the new software version doesn’t support importing the old site’s styles, so for now, you’ll see the XenForo default style. This may change over time.
Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.
Thanks for your patience and support!
main jet for 77" 250 cr
- Thread starter dumpbear
- Start date
Ron
Husqvarna
AA Class
I have 77 250CR with a 38mm Mikuni with Boyesen reeds. I'm still working on getting the jetting dialed in, but here's where I'm at now.
I ride mostly around 4000 ft elevation, so you might have to compensate a bit.
Main jet = 430
Needle jet = R-2
Needle = 6DH2 (clip 4th from top)
Pilot jet = 40
Slide = 2.5 cutaway
The bike starts and idles good with the 40 pilot, air screw 1-3/4 turns out and good throttle response with the 2.5 slide cutaway.
When I raced at the Elsinore Gran Prix last Nov 2012, I had a N-8 needle jet with a 6DH2 needle (clip in the middle). I should have tested the main jet, but the bike seemed to run good, although the plug color was a little bit light. I took a chance and unfortunately, I seized the piston on a long steep uphill.
After I put in a new piston I was thinking it was lean on the main jet. I tried a larger main jet but that didn't seem to make any difference. Then I tried a couple more larger main jet sizes and they didn't make any difference either. That's when I realized I had a restriction in the needle jet/ needle combo.
The last time I rode the bike I tested an R-0 needle jet in it, but it still wouldn't let me get on to the main jet (the bike will rev's to full throttle with the main jet removed). I didn't have an R-2 with me at that time.
I now have an R-2 in it and that should be big enough. I may have to switch to another needle maybe 6DH3 and move the clip around to fine tune the mid-range, but I haven't had a chance to ride it with the R-2 yet.
I've had a 430 main jet all along, but since I had a needle/needle jet restriction in the past, I may have to go smaller main jet.
I think this should be a safe (rich) place for you to start though.
Make sure you check what slide size you have (it's stamped on the bottom), before you change too much. If you have 2.0 or 3.0 your jetting needs to be different then the
guide lines Ron provided. You did mention how the bike runs? If runs good up til 1/2 throttle then it's more then likely the main jet & as Ron mentioned your bike will run
without one, til you sort out the rest.
Husky John
dumpbear
Husqvarna
AA Class
Tom
Ron
Husqvarna
AA Class
Go ahead and run it with the 440 main jet. Just don't hold it wide open for any length of time until you can do some plug readings.
It's not rocket science, just takes a little patience and time. Trouble is your friends are all riding, while your fussing with your carb.
