• 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 The previous version was outdated and no longer supported.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!

Runnig Leaner With a Bigger Jet

D

DGA

Husqvarna
AA Class
Hi,

I have a peculiar situation with my '07 SM610's jetting. Got the bike used about a year ago. It was well taken care of has bunch of stuff on it including the Leo Vince can and they guy, second owner, tells me that the previous owner bought the bike off the showroom floor with the pipe and jetting already done from Bill's in Salem, OR. Bill confirms that if that was the situation they'd bump the main up to an 185. Strap the bike to the dyno and it's lean, about 15:1. Disassemble the carb, the jet was a 175. No problem, the tuner suggests a 195 main (a very reputable local tuner). I throw in a 195 main, 45 pilot, wire the accelerator pump together, time it, fuel screw is two turns out, unplug the TPS, and put in the recommended iridium spark plug. Bike starts easily, idles great, certainly feels better on power, and rides much smoother. Put it on the dyno again, it's running even leaner, about 16:1. Huh?! Everything looks great till it gets on to the main jet.

My thinking is and I've not had the time to confirm it is that the main jet I got, not a genuine Keihin one, is not machined correctly. Aside from replacing it again with a genuine one, what else could it be? Carb is very clean, no debris or deposits to be seen anywhere.

Before I tear into the carb again, for the 20th time, I wanted to see if any of you have an idea of what I should be looking for.

Thanks,
D
 
The issue is exactly what you thought it was: the real jet size is way off on most jets. I recently bought a 10 pcs set of genuine dell'orto jets, got them measured just to see a claimed 56 being more than 80 when measured, just to mention one. For peace of mind, take the fake 195 and get it machined to spec. For future reference, always get your aftermarket jets (regardless of brand) measured before you install them.
 
I ignore the a/f numbers when tuning for peak power. If you have access to a dyno, take a variety of jets and see which one makes the most peak power. Start small and go up until the bike looses power. The bike is jetted correctly on the main jet at that point irregardless of what number jet or an a/f probe says. The bigger the main you end up with, the more you may need to drop the needle for midrange/cruise. If you have confidence that the a/f meter is accurate, it can be useful for setting the needle height for midrange/cruise. I've had difficulty getting consistent a/f feedback on thumpers.

Good luck!

.
 
Thanks all.

I have a genuine Keihin 190 sitting around somewhere and as soon as I get some time I'll get that one in and see what happens. I need to find a place that will check and drill them out, otherwise I'm just going to stick to genuine Keihin stuff. But that is very interesting MG', that far off seems pretty odd to me.

You are right about tuning for power, add gas while you are still making power, go back as soon as you taper off. Pretty much how you would tune a FI motor. This was just a few dyno pulls at two different times to see where the mixture sits to satisfy my curiosity. I'm more concerned about her running right and not melting a piston. Good point on the needle though and something worth fiddling with this winter. With the wideband I really wanted to see what my A/F ratio is at on full load, other parts of the power band I'd tune based on seat of the pants and how she takes to it.

Again, thanks for the suggestions.

-D
 
You must log in or register to reply here.
Back
Top