Dear KLX forum,

After reading most of the forum over the last few days i wanted to say thanks so much for all your advice... i feel like i know some of you already and am happy to be part of this community.

In any event, i am in need of some recommendations.... I've noticed that the TPS on my 2007 KLXs' stock CV carb has some adjustment and my local mechanic advised not to mess with it... too late.

What was happening was that i was riding along at full throttle and the bike shut down, similar to how it would when it's time to switch over to reserve, although i knew that wasn't it as i had just filled up.

Pulling over on the side of the road i found the bike would start and idle although if the throttle was opened it would stall out... It would run with the choke on, and would rev up if i really flogged it and eventually it would straighten out.

Thinking that it was starving for fuel i had the carb apart several times and once i got the diaphram seated properly it now seems to be Ok... I have since run about two tanks of fuel without incident although i did get a little backfiring on deceleration initially, and have since not really noticed it as much. Nearing the end of the season, i didn't want mess with it since the bike was running fairly well.

Back to the question ... When these issues first started i mistakenly convinced myself that there was something wrong with the TPS... before taking it apart i was clever enough to at least ohm it out before doing so... 800 ohms on one side and 1400ohms on the other... both raising to about 4.9K ohms at wide open throttle.

I am thinking that this advances the timing as the throttle is opened and am wondering how to best set it.

I've tried leaving it a bit loose and rotating it back and forth while revving and don't seam to notice any difference... I've also tried leaving it unplugged and it doesn't seem to run any worse.

I locked it back down towards the middle of its adjustment and have since measured about 600 ohms on one side and about 1600 on the other... I thought later that i should have probably just put it back to the original readings although for 200 ohms i figured it could wait till the next time I've got it apart.

I'm at the point where i'm ready for some aftermarket exhaust and figure that while i'm making breather mods and installing a dynojet kit that i should probably make sure that i optimize the TPS setting as well.

Any thoughts anyone..??

Sincerely yours,
NorthRider

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I didn't get any of that crap on my AUS spec bike and it runs fine. Disconnect it. One less thing to go wrong. It's all about emissions. The USA bikes seems to get an extra portion of that stuff. Best removed and left on the shelf in the shed, the bike 'll thank you for it by running like a champ.

 

Pretty sure I've read on here that when folks switch to the pumper carbs they just disconnect the sensor. So +1 to what W/oz said.
I don't think your problems are related to the tps.
Good luck , Dan

 

I also suggest you disconnect it and forget it. It doesn't advance the timing. Only the ECM could do that, the tps only sends a tiny bit of information to the controller. On this motorcycle, the tps doesn't do anything that changes how it runs.

 

So, what does the TPS do if it doesn't control how the bike runs?

 

On this bike, we've never found that it does anything. Sure, it sends a difference in ohms reading to the ECM. The ECM has a map it follows, this ohms reading is fed into that. Perhaps line itemed into that programming is the parameter that within a certain range of RPM, if the throttle is suddenly yanked open, then the CV would slowly open the slide; and the ECM knows to follow along with the RPM rate rather than the throttle setting. For a few hundred revolutions, IF at the ECM this TPS signal is programmed to do so, it could momentarily change the timing of the spark. Can you tell if it does anything? No. It can't be for anything but emissions standards on this particular bike. I've ridden mine back to back with it plugged in, and without, and you can't tell any difference at all. It's effect is on the emissions.
I've seen it before; different bikes have different ECM maps between model years, because of emission standards changing. One year, the TPS setting doesn't mean anything, and the next, it means a whole lot. My BMW's have been that way.

 

Does anyone know if the 2009 USA version has a TPS? I have had my carb off and didn't notice one.

 

The tps allow's more timing at lower throttle setting/higher rpms. And less timing at bigger throttle settings/lower rpms.

This is mo betta than just a purely rpm based timing because fixed timing would have to be slightly retarded so the engine wouldn't ping when the throttle was wacked wide open at low rpms. With tps at steady cruise (high rpm- small throttle openning) the engine can have a little more advance which helps mpg.

Hpw they program the map is everything though. It could be used as purely an emissions thing targeting a specific throttle setting/rpm where its' dirty. It's also been used as a sound abatement taking some timing out at test rpms which reduces the "crack" of combustion" . It's a good thing if the mapping is performance based.

One of those thing that you just have to try and see. On my kawi street bike I ost mpg with it unplugged, on my honda enduro bike it made it run smoother and idle better unpluged, but took some snap away (good for slick rides).


It's better to use a voltage reading to set the tps running with fully charged battery than resistance unless you just verifing it's "in range". I plug the connector together with some tiny wire shoved in to hook the meter leads to. The range is usually 0-5v on most bike tps I've worked on, check your manual though. Some variation is OK due to battery votage and is allowed by the system. For example the ecm is proabaly only looking for .5-4.5

 

Its been unpluged for 2 years with pumper on mine and no problems.

 

I leave the TPS plugged. Last time I tried with it disconnected, the engine seemed to have less snap when cranking the throttle. But ran fine at a steady cruise.