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 The previous version was outdated and no longer supported.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

Adjusting the TPS TB position on Mikuni EFI

OlderHuskyRider

OlderHuskyRider

Husqvarna
Pro Class
MotoMarc36 said:
If you are at wits end with the bike, place some marks on the TPS and Throttle body to mark roughly where it is and to use as a movement gauge. The tps is in line with the throttleplate shaft. Tweak the tps A LITTLE in the SAME direction that the throttle shaft moves when you open the throttle. Does that make sense? Ride it, decide if it improved it, and go from there.
Click to expand...

Marc has been kind enough to give me a tip which I have been wanting for 2 years: how to incrementally lean out my FI mechanically, without a computer. I asked around for a 310/250 injector thinking they would flow less and I could just swap out injectors, like jets, that's real attractive to me. But Marc's tip above is even better: leaning out the entire system by 'tricking" it with an altered position on the TPS.

My question: has anyone manually changed the TPS mechanics, under the little cover on the left side? On the butterfly drum, there appears to be a plastic cap with the magnets embedded that maybe slips onto the drum, maybe that plastic cap slips off and then can be slipped back on at a different position?

HuskyTPSinnards2.jpg
 
You are on the right path OHR. Unfortunately it looks like that TPS is not slotted for adjustment, probably because of that plastic pin on right. Your idea on the plasic cap is solid but I would urge you to PROCEED WITH CAUTION!! My experience has been that those kind of parts are not available as replacement spares, and damaging one beyound use could result in the need to purchase a whole throttle body:eek:.

That plastic pin appears to be a intake air temp sensor, or is there a separate one of those in the airbox/airboot? You may have options there, too, by making the bike think the air is warmer than it really is , equalling a linear leaning.
 
MotoMarc36 said:
You are on the right path OHR. Unfortunately it looks like that TPS is not slotted for adjustment, probably because of that plastic pin on right. Your idea on the plasic cap is solid but I would urge you to PROCEED WITH CAUTION!! My experience has been that those kind of parts are not available as replacement spares, and damaging one beyound use could result in the need to purchase a whole throttle body:eek:.

That plastic pin appears to be a intake air temp sensor, or is there a separate one of those in the airbox/airboot? You may have options there, too, by making the bike think the air is warmer than it really is , equalling a linear leaning.
Click to expand...

I have already buttoned it back up, and will think about it, I am pretty sure I will not try and pry that plastic ring off of the butterfly drum.

I also think that the plastic pin that inserts into the TB is the air temp, and the part at the front of the assembly may be the air density measurement piece, it has to be lined up as well as the plastic pin, thus removing the ability of using the housing as the rotatable adjuster.

I have noticed that I got better gas mileage this past summer when it was 90+ degrees, and on a trail ride the other day in the 50-60s, I got about 28 mpg and almost lost my lunch!

What if I pipe some exhaust air into the airbox?
 
It will run richer because you are displacing some oxygen with spent gasses which will not be combustable. By adding a resistor in-line with the wiring for the IAT sensor, the ECM will see that as a warmer temperature than it really is and will lean the motor in a linear fashion. It is harder to do than tweakin a TPS but looks like the best option for a non-computer tweak of the EFI. It would involve testing the resistance of the sensor at 80deg, 60deg, 40deg etc and duplicating the difference between a temperature step in resistance, with a resistor from radioshack or some source.
 
MotoMarc36 said:
....By adding a resistor in-line with the wiring for the IAT sensor, the ECM will see that as a warmer temperature than it really is and will lean the motor in a linear fashion. It is harder to do than tweakin a TPS but looks like the best option for a non-computer tweak of the EFI. It would involve testing the resistance of the sensor at 80deg, 60deg, 40deg etc and duplicating the difference between a temperature step in resistance, with a resistor from radioshack or some source.
Click to expand...

That just MIGHT be within my technical capabilities, although the amount of patience it would take is probably outside my limit....
 
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