Switch for TPS

92 replies to this topic
  • Alternative

Posted March 04, 2009 - 08:55 PM


I think MaxPower has the only WR that does not do the 'stutter'. No amount of jetting changes improved mine. James Dean has done exhaustive work too in an attepmt to 'jet away' this to no avail. Using an oscilliscope, the erratic ignition pulses were recorded. A Vortex CDI was installed and even with it, on certain engine maps, the stutter remained. On one map, the stutter went away. Disconnecting the TPS (vis a switch) will not make go entirely way but improves it somewhat. The stutter is never noticed off road, only on road at steady throttle.

I must be really lucky then, my supermoto WR426 doesn't stutter at all. When I got the bike it did it a little bit but after jetting it correctly and adjusting the TPS (not disconnecting it) it was completely gone. This was when I had the original CDI as well, I only got the Vortex cause the original crapped out. Maybe it's a bigger problem on the later models?

  • DrzDasher

Posted March 04, 2009 - 10:04 PM


what are the cons to just disconnecting like on the drz fcr?


Posted March 04, 2009 - 10:33 PM


what are the cons to just disconnecting like on the drz fcr?

Disconnecting is fine but "switch on the fly" would be better:thumbsup:

  • William1

Posted March 05, 2009 - 03:10 AM


The CDI on a DRZ is not as sophisticated as the WR one. On a DRZ, the CDI/TPS communication is emissions related. No TPS signal, the ignition runs advanced, a WR is the opposite, more or less. The net effect is on a DRZ, the idle is a little less steady but full performance. On a WR, you get a great idle but less performance. With a DRZ, it is just two mappings (idle and not idle) , with a WR, the map gets tweaked based on the TPS, RPM signal and varies across the rev range.

  • MaxPower

Posted March 05, 2009 - 11:01 AM


[COLOR="DarkGreen"]Really William? I thought there were other WRs that didnt have this problem.Im not being sarcastic.Good for me then.I usually have a weird problem that no one else has and no one has ever heard of it before.[/COLOR]

  • William1

Posted March 05, 2009 - 02:11 PM


LOL, I am not aware of a survey done on all WR's. I also suspect there are many who have the problem but never notice it. I also think there are riders who have experienced it but chalk it up to poor jetting. I only am aware of it during steady state riding. My WR is plated and from time to time, is ridden without constant throttle movement. Before I put the switch on the bike, I have to run a test to see if it makes enough of a difference to go through the trouble. Being I only want this for on road riding betwwen trails, if the trade off is a littler performance hit, that is Ok. It is the guys that have SM'd their WR's that will not have this luxury (if it works). I just need the snow to melt......

James Dean has done some exhaustive work on this issue. Using a scope, he was able to confirm it is an ignition issue. With a TTer, they acquired a Vortex CDI. Apparently, the problem was still there on many of the maps but one in particular did not exhibit the issue.

  • Summit Seeker

Posted March 10, 2009 - 10:37 AM


Upon further ivestigation I think making up a wire harness so when you switch the tps off, the output voltage from the cdi loops back to the input voltage.

  • William1

Posted March 10, 2009 - 10:50 AM


I still have not done anything more for this mod. I cannot find that darned switch, I know it is someplace.

Your thinking is to have the switch connect the yellow and blue together, fooling the CDI into thinking you are at WOT? Hmm, does make sense, why not get the most out of it for the on road steady state duty. Be sure to post your results.

  • Summit Seeker

Posted March 10, 2009 - 02:05 PM


I still cant find connectors in Canada, to buy them from the USA would be a small fortune. Woke up to minus 21 f. and still 3ft of snow, finally warmer weather on the way for the weekend.

  • William1

Posted March 10, 2009 - 03:43 PM



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  • Summit Seeker

Posted March 11, 2009 - 04:47 AM


Thanks William1, I guess I have no choice but to order them from the states.

  • Summit Seeker

Posted March 13, 2009 - 11:56 AM


I ordered the connectors several days ago, I will let you know when I get them installed on the bike. Thanks again William1. :)

  • William1

Posted March 13, 2009 - 01:27 PM


I'll be real interested what you decide to do and if it is worth it. If you can, try the following temporally before you go permanent. Also, I want to know what the improvement is on steady throttle. Would be nice to know also the perceived loss of response/power.
Yellow/Blue connected?
Yellow or Blue to the Black?
Or a disconnect?

I still cannot find my switch, I may really have to do a detailed search. Sort of hard to moto-vate with it sleeting out.

  • Summit Seeker

Posted March 23, 2009 - 04:14 PM


I have Received the connectors today and I will let you know in a couple of days how I make out, I went out for a ride yesterday it sure felt good to get back on the bike again. still have 2 ft of snow. Dale

  • odlaw19

Posted March 23, 2009 - 09:11 PM


I'm considering ordering a set of connectors for the TPS. I'm in Australia an wondering if anyone else is interested in getting the connectors. It just as easy to order 10 as it is to get 1 set.

I'm not in a hurry, let me know.

  • Summit Seeker

Posted March 24, 2009 - 12:48 PM


Well I went for a quick ride with the TPS disconnected and had a Jumper to fool the CDI into thinking it was WOT. Now without the switch this is not conclusive, slow throttle response, small bog at the start of jet needle opening but very little if any surging. until I get the switch installed and it warms up a bit,(plus 40) today I cant do an accurate analysis. Dale

  • William1

Posted March 24, 2009 - 02:45 PM


Hmmmm sounds like the switch very well might do what I'd like it to do. I knew there'd be a performance hit. But if it smooths out steady state running, that'll be fine by me.

TPS engaged, get up to speed, hit the switch, disabling TPS, cruise to the next trail head, hit the switch and re-engage TPS.

I still cannot find my spare switch. The missus has been making me do spring yard cleaning the last two weeks, no time for fun.

  • Summit Seeker

Posted March 25, 2009 - 04:08 AM


I am having trouble on how to hook up the switch so when in off position the CDI still thinks it is WOT.

  • Chas_M

Posted March 25, 2009 - 10:00 AM


I am having trouble on how to hook up the switch so when in off position the CDI still thinks it is WOT.

With the TPS disconnected or switched off, the CDI will automatically 'think' it is WOT, i.e. the advance curve reverts to the built-in factory default advance curve.

  • Summit Seeker

Posted March 26, 2009 - 07:07 AM


I installed spdp switch for now, still cant figure how to have the return voltage back to the CDI work with that switch. It is to cold outside to do any testing. William1 let me know if you come up with any ideas.


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