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KB Article #4 - Throttle Position Sensor

Old 06-06-2010, 09:59 AM
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I'll add my experience. Just did the adjustment. I took the tank and airbox off, left everything else in place. The TPS was at 907 ohms, and I could only twist it to 670, so I took it off (I just touched the multimeter leads to top two prongs, no need for wires and connectors).

Taking it off was pretty easy with a dremel, but I do have a pencil extender, which I think is necessary unless you pull the carbs (I left the carbs in place). I first tried to chisel the bottom bolt loose since it's a tight fit even with the pencil dremel, and I was NOT hitting it that hard, but the plastic "wing" with the bottom bolt going through cracked right off when I hit it. So be very gentle as the TPS can be brittle (mines 12 years old).

I thought I was screwed, but I got out the JB Weld as a last resort, and it worked to put it back together. I love that stuff.

As has been said before, small adjustments make a huge difference. I had to drill out the holes and got it to 540. Took it for a test ride after putting everything back together, and I couldn't tell a difference honestly. My bike ran pretty well before though, so I don't know what I was expecting to feel.

So my advice would be to do this adjustment if yours is running poorly at low rpm, but otherwise it might be wiser to just leave it alone.
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Old 06-06-2010, 09:57 PM
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I was thinking the same thing, leaving it alone. My bike also runs fine no hesitation at all throughout the rpm range, so I'm just procrastinating for a period.
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Old 06-07-2010, 03:48 PM
  #63  
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Ok well I ended up doing mine today. Used a sharp flat-head and a hammer to knock them sheer bolts counter clockwise. Mine was set at 855 ohms I brought it down to 624 because it wouldn't turn any further, but heck I could immediately tell the difference on my bike, so much smoother in the lower powerband. Very noticeable and I for one am
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Old 06-20-2010, 02:13 AM
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Here is a photo of the TPS removed from the carburator. You can see the metal bottom tab that may need to be bent slightly to get the proper adjustment

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Last edited by residentg; 06-21-2010 at 01:44 AM.
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Old 06-20-2010, 07:04 AM
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FYI, you can do it without bending. I took out the inserts in the housing and used a round file to extend the slots. Replace the inserts and rotate until you get a low enough reading.
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Old 06-20-2010, 03:18 PM
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Originally Posted by thetophatflash View Post
FYI, you can do it without bending. I took out the inserts in the housing and used a round file to extend the slots. Replace the inserts and rotate until you get a low enough reading.
I did it this way too, very easy. I tried to bend that top tab in the pic above, but it's a 90* bend and didnt do anything. I bent it pretty far too, didnt really make any sense to me.
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Old 06-20-2010, 10:15 PM
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Originally Posted by residentg View Post
Here is a photo of the TPS removed from the carburator. You can see the metal top tab that may need to be bent slightly to get the proper adjustment

I believe you mean the bottom, left, rear tab needs to be bent slightly.

Originally Posted by thetophatflash View Post
FYI, you can do it without bending. I took out the inserts in the housing and used a round file to extend the slots. Replace the inserts and rotate until you get a low enough reading.
that's an ingenious method. We have some creative people here. Good thinking.

Last edited by nath981; 06-21-2010 at 07:45 PM.
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Old 06-21-2010, 07:52 PM
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Originally Posted by nothing View Post
I did it this way too, very easy. I tried to bend that top tab in the pic above, but it's a 90* bend and didnt do anything. I bent it pretty far too, didnt really make any sense to me.
yeah, because you bent the wrong tab, but i like the way you ended up doing it better. Actually, if you bend the rear tab, it's only a slight bend to get it into spec.
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Old 07-01-2010, 08:20 AM
  #69  
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^oh I get what you mean now, makes sense. I just stuck with the non-bending of things


Question, does anybody know if this TPS adjustment is an alternative to the ignition advancer thing from factory pro? Aren't we in theory advancing the timing with this TPS adjustment just like the factory pro item does? Or can we gain more with the factory pro piece in addition to the TPS adjustment? 98 timing vs 02 timing?
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Old 07-16-2010, 09:09 AM
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Has anyone done this mod, and ended up having some major hesitations at low RPMS? My bike was having some major issues with surging at low speeds, and rpms. So, I did the mod, which fixed the surging, but now it seems to not want to rev up at low throttle, and low rpm. So, when pulling away from stop, I almost have to rev it up higher then normal to get it to go, so that it won't stall out. Also it seems to be doing more carb backfires. I thought maybe it had something to do with jetting, so I tried pulling on the choke while riding, and it made no difference at all. After the mod, it didn't start as good, idle went down from 1200 to about 800, so I turned that back up. It still runs almost exactly the same everywhere else in the power band. Just has nothing at very low rpm, and hesitates to the point of almost stalling when I just give it a tiny bit of throttle when it's standing still.

I know this mod changes the timing a little, so I'm wondering if my timing could be out? or can it be?
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Old 07-16-2010, 10:24 AM
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did you sync your carbs? you don't have a signature at the bottom of your post so we can't tell what's been done to the bike. Are you certain you got the TPS at the right settings? Did you have to bend the tab or elongate the hole? Give us some info here so we're not shooting in the dark.
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Old 07-16-2010, 01:39 PM
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Fixed signature for you. Yeah, positive TPS is set correctly. I got it to 497 ohm, but had to bend the bottom tab very slightly to get it there. Haven't sync'd carbs yet, still stock exhaust, but just put in the K&N. Two bros pipes on order, so I plan on rejetting then and removing PAIR at that time. The bike doesn't even have 2000 miles on it yet, so it's very new. I live at about 4000 ft above sea level, so jetting here is very different then most settings. I'm getting more carb coughing, or up drafting then before TPS mod, and K&N replacement. But bike runs great when I'm on the gas. Pulls smooth from low RPM as long as I give it enough gas. It's only having issues under low throttle input, or sitting at idle and bleeping the gas. It's stalled on me a few times, and coughs back at me a lot when doing this.

Not sure how much more info can help.. Anything else specific you need to know?
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Old 07-16-2010, 01:41 PM
  #73  
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You know it helps if this discussion stays in one thread... It makes all of us a lot less confused... But it's up to you where... Just pick ONE!
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Old 07-16-2010, 04:43 PM
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Originally Posted by dustinwild View Post
Fixed signature for you. Yeah, positive TPS is set correctly. I got it to 497 ohm, but had to bend the bottom tab very slightly to get it there. Haven't sync'd carbs yet, still stock exhaust, but just put in the K&N. Two bros pipes on order, so I plan on rejetting then and removing PAIR at that time. The bike doesn't even have 2000 miles on it yet, so it's very new. I live at about 4000 ft above sea level, so jetting here is very different then most settings. I'm getting more carb coughing, or up drafting then before TPS mod, and K&N replacement. But bike runs great when I'm on the gas. Pulls smooth from low RPM as long as I give it enough gas. It's only having issues under low throttle input, or sitting at idle and bleeping the gas. It's stalled on me a few times, and coughs back at me a lot when doing this.

Not sure how much more info can help.. Anything else specific you need to know?
Was the K&N in there before the TPS mod? If the K&N was installed at the same time as the TPS mod, try reinstalling the stock filter and see what happens.
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Old 07-18-2010, 09:30 PM
  #75  
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Yeah, did them both at the same time.. So, yeah I'm going to try and put the stock filter back in and see what happens. Either that, or I'm going to put my slip ons on when they come in, and try to mess with the jetting a little, after doing a carb sync, and PAIR removal..
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Old 02-19-2011, 05:20 PM
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Looks like there's lots of pics here, but I'll throw mine in as well:

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Old 02-20-2011, 04:39 AM
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great pics moore. a couple questions/comments.

what caused that round mark on the slide(22-23)?

your supposed to pull those rubber lines out of the holes between the carbs for a reason I can't recall offhand (i think it's because they look too orderly all tucked away like that. haha). may cause a stumble i think and you wouldn't want to stumble would ya? what would your friends think?haha

why did you drill out the tps holes when you did such a great job slotting the rivets? I would have left the metal inserts in there and reused the rivets, but no big deal though.

did you remember to insert a fitting and rubber tubing into the bottom of the front carb for the quick carb sync which you will need to do shortly?

did you put a #48 pilot in? If you didn't, 8541hawk is gonna punish you boy. haha

just food for thought in case you may have missed something you didn't know about. great pics

You're gettin close to launching that rocket huh!
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Old 02-20-2011, 05:02 AM
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Well, since it's winter up here and my beloved VTR is hibernating away in my garage (and I recently finished re-doing the jetting to run an open airbox as per the specs kindly forwarded by VTR guru Roger D), I decided to tear into it again last night and readjust my TPS down. While my first experiment (a few years back, with the engine mostly stock) with dropping it down to @ 500 ohms had been largely inconclusive (actually, make that negative, as it seemed to soften up the engine response at low speed), my reading through various threads led me to try it again, especially as my engine is no longer stock (muahahahahahah). I opted to tune it down to 435 ohms (or as close to 430 as I could get it) based on various posts, including one by Greg (who recommended between 410 and 450 or so ohms) as well as the claim by (former member?) CTS moto that 430 was the magical number, based on the dozens of VTRs he had tuned.

Here's to hoping it turns out well this time.........
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Old 02-20-2011, 06:18 AM
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Originally Posted by mikstr View Post
Well, since it's winter up here and my beloved VTR is hibernating away in my garage (and I recently finished re-doing the jetting to run an open airbox as per the specs kindly forwarded by VTR guru Roger D), I decided to tear into it again last night and readjust my TPS down. While my first experiment (a few years back, with the engine mostly stock) with dropping it down to @ 500 ohms had been largely inconclusive (actually, make that negative, as it seemed to soften up the engine response at low speed), my reading through various threads led me to try it again, especially as my engine is no longer stock (muahahahahahah). I opted to tune it down to 435 ohms (or as close to 430 as I could get it) based on various posts, including one by Greg (who recommended between 410 and 450 or so ohms) as well as the claim by (former member?) CTS moto that 430 was the magical number, based on the dozens of VTRs he had tuned.

Here's to hoping it turns out well this time.........
Yeah. I remember you noting that the 500ohm setting didn't help and i really couldn't say for sure relative to mine because i committed the the greatest crime of any good scientist, i.e., changing more that one thing.rot roh The funny thing, or maybe sad thing, is, I couldn't get a reading that made sense on the analog meter I had, so I decided to do it by feel. haha...It ended up that i rotated the TPS in the wrong direction until I could feel tension in the spring acting on the throttle. I thought, this is great, who needs a gage? At this time I also cut the airbox flap and cut out the paper filter(leaving the wire screen) and inserting filter foam oiled as per my dualsport). Of course I set the air mix and shimmed needles, sync mod, etc. Seems weird that so many people have reported difficulty with the K&N filter when the oiled foam works so well in mine and it seems like they would flow air similarly, but I don't know that for sure. So, put it all back together, TPS set by feel, and it ran like a raped ape, i.e., better than ever without a stumble, pop or any dead spots.

Anyway, a couple years later, i was helping Steve29 do his carbs and we discovered that I turned the TPS in the wrong direction and since I had purchased a digital multimeter, we were able to set his correctly. Then we were also able to get a reading of mine and it was over 2000 ohms if that's even possible.haha. So we readjusted mine to correct spec, but it made no detectable difference in throttle response, so who knows WTF is going on for real. Whatever, we know that there is always a real explanation for this type of magic, but i also do know one other thing, it worked flawlessly for two years. thankfully. haha

it'll be interesting to see how yours turns out at 430.
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Old 02-20-2011, 06:53 AM
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Originally Posted by nath981 View Post
great pics moore. a couple questions/comments
what caused that round mark on the slide(22-23)?

I'm trying a trick to get the front slide to open slower as per 8541Hawk's suggestion. There's a recent thread on carb setup that he started- It's explained in there

You're supposed to pull those rubber lines out of the holes between the carbs for a reason I can't recall offhand (i think it's because they look too orderly all tucked away like that. haha). may cause a stumble i think and you wouldn't want to stumble would ya? what would your friends think?haha

You're the second person to tell me no to do that. They're out now! The holes just looked like a perfect hose storage

why did you drill out the tps holes when you did such a great job slotting the rivets? I would have left the metal inserts in there and reused the rivets, but no big deal though.

My TPS was so far off that just bending the tab wasn't enough (no joke, 1190 ohms). I drilled the holes to allow the sensor to be rotated, creating what ended up being 499 ohms. I ended up putting the metal inserts back in after I drilled the slot out

did you remember to insert a fitting and rubber tubing into the bottom of the front carb for the quick carb sync which you will need to do shortly?

Nope- didn't even know this trick. I think I've seen pics of your $5 homemade one (was that you?). I'll go search for that thread later today

did you put a #48 pilot in? If you didn't, 8541Hawk is gonna punish you boy. haha

No local shops had them in stock, ordered a set from hollisterhonda. Pretty much everything is direct from 8541's advice- even the parts venue!

just food for thought in case you may have missed something you didn't know about. great pics

You're gettin close to launching that rocket huh!

It's been a long time coming. Parts are at paint, electrical only has a few more hickups... ohhh man my buddy just got a little Monster and I can't wait to show him the awesomeness of a Honda twin

Last edited by 7moore7; 08-03-2011 at 09:36 PM.
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Old 02-22-2011, 12:07 PM
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Mine is at 862ohms. I'll let you know how it turns out. Going to do it right now. Thank goodness I had a friend who had a ohm meter and dremel. I hate not having the right tools.
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Old 02-22-2011, 01:03 PM
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Originally Posted by nath981 View Post
your supposed to pull those rubber lines out of the holes between the carbs for a reason I can't recall offhand (i think it's because they look too orderly all tucked away like that. haha). may cause a stumble i think and you wouldn't want to stumble would ya? what would your friends think?haha
Well there was a service bulletin in '98 about them. At that time the holes in the carb stays were just a touch undersized and what happened was that under hard braking the rear carb would puke fuel into the front carb.

So the bike would run on one cylinder until the front cleaned itself out.

This condition was fixed in either '99 or '00 so it really isn't that big of an issue on the later bikes.

Though if the bike does run rough after hard braking, then you should pull them from the carb stay and reroute them.
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Old 02-22-2011, 02:19 PM
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Originally Posted by 8541Hawk View Post
Well there was a service bulletin in '98 about them. At that time the holes in the carb stays were just a touch undersized and what happened was that under hard braking the rear carb would puke fuel into the front carb.

So the bike would run on one cylinder until the front cleaned itself out.

This condition was fixed in either '99 or '00 so it really isn't that big of an issue on the later bikes.

Though if the bike does run rough after hard braking, then you should pull them from the carb stay and reroute them.
you mean the holes were constricting the hoses? Mine weren't tight. I guess I could just drill the holes out to the next size and put the hoses back where they were. thanks hawk

couldn't find one on here, albeit they had one on carb spring install:

http://www-odi.nhtsa.dot.gov/cars/pr.../tsbsearch.cfm

Last edited by nath981; 02-22-2011 at 02:45 PM.
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Old 02-22-2011, 04:38 PM
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Yes the holes were a bit undersized and constricted the hoses.
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Old 02-24-2011, 03:35 AM
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TPS mod done. Mine started out being at 860 now it is at 505ohms. Used a dremel to slot the old shear bolts and used a screw driver to get them out. Can't wait to get everything put back together to see how she runs.

Thanks for the info
Attached Thumbnails KB Article #4 - Throttle Position Sensor-dscn0319-400.jpg   KB Article #4 - Throttle Position Sensor-dscn0320-400.jpg  
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Old 02-24-2011, 03:19 PM
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Originally Posted by aaugsbu View Post
TPS mod done. Mine started out being at 860 now it is at 505ohms. Used a dremel to slot the old shear bolts and used a screw driver to get them out. Can't wait to get everything put back together to see how she runs.

Thanks for the info
dude! like when you get that big bitch running, be judicious with your throttle hand or you might find yourself sliding on your backside when that front wheel makes a rapid skyward arc from all that newfound TPS power.
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Old 03-24-2011, 11:15 AM
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Just wanted to drop a quick thank you for all the kb threads. I perform the tps mod along with the pair valve block off plate and WOW! R/R upgrade is next.
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Old 08-03-2011, 09:30 PM
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Okay, so a quick question for anyone who has done this mod....

I fixed the tps and it's set at a nice 507ohm. Then I realized that it was not quite accurate as I just rebuilt the whole set and the idle set was not set. I started it up and it seems to be a lot more responsive but a little bit more backfiring.

So I'm wondering whether the TPS mod should be done at running idle of 1200 or at the stock, closed butterfly and zero set idle? Because even the little tinkering of the idle screw opens the butterfly enough to change my reading by about 105ohms.
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Old 08-09-2011, 01:43 PM
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Originally Posted by bass4dude View Post
Okay, so a quick question for anyone who has done this mod....

I fixed the tps and it's set at a nice 507ohm. Then I realized that it was not quite accurate as I just rebuilt the whole set and the idle set was not set. I started it up and it seems to be a lot more responsive but a little bit more backfiring.

So I'm wondering whether the TPS mod should be done at running idle of 1200 or at the stock, closed butterfly and zero set idle? Because even the little tinkering of the idle screw opens the butterfly enough to change my reading by about 105ohms.
set tps with engine off.
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Old 08-09-2011, 02:47 PM
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Originally Posted by bass4dude View Post
Okay, so a quick question for anyone who has done this mod....

I fixed the tps and it's set at a nice 507ohm. Then I realized that it was not quite accurate as I just rebuilt the whole set and the idle set was not set. I started it up and it seems to be a lot more responsive but a little bit more backfiring.

So I'm wondering whether the TPS mod should be done at running idle of 1200 or at the stock, closed butterfly and zero set idle? Because even the little tinkering of the idle screw opens the butterfly enough to change my reading by about 105ohms.
Well I set mine after I set the idle speed. It took a couple of times because of it changing with each idle speed adjustment.

So it was start the bike and set the idle speed.
Shut it down and adjust the TPS.
Restart and set idle speed.
Shut down and check TPS. If good you're done.
If you have to readjust the TPS repeat the steps of setting the idle and then checking the TPS.

Might be a little overkill but that is how I set mine.
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