curious question

sideshowBob said:
I just reread jaydaniels results...the voltage reading prior to adjustment on his was way too high, the opposite of mine!!! I will go back + check my procedure again and report if its different. Our set voltage numbers are approx the same.
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Sorry, I'm going form memory here but maybe it was .07. For some reason I was thinking it was higher not lower. Either way, I had to rotate mine almost fully counter clockwise to achieve the desired results.
 

just looked at mine for the halibut. mine appears to be or almost be fully clockwise, there could be a little slot left under the screw head but i didn't pull one to see, nor did i check readings since i wont be using these carbs on my new setup, but if i get some spare time maybe i'll do a reading just to see
 
staggs65 said:
just looked at mine for the halibut. mine appears to be or almost be fully clockwise, there could be a little slot left under the screw head but i didn't pull one to see, nor did i check readings since i wont be using these carbs on my new setup, but if i get some spare time maybe i'll do a reading just to see
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Just keep in mind that this test procedure does not work unless your idle is set properly.
 
sideshowBob said:
Just repeated all the tests again basically same results although I was more attentive + recorded all the exact readings + updated the previous post accordingly.[carbs were cold from the shop last night...have been in the house so slight changes on readings this morning]
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Test should be done warm,right,but yea looks like you did it right manual is pretty vague on the procedure but if that's what you came out with go with it,still hard to believe it could be off from factory like that,but no matter it only controls mid range cruse timing where most time trail riders are at so to get best performance and fuel economy you would want it close to spec.

thnaks for your post should help others...
 
jaydaniels said:
Well, for starters I know mine were touched because the bolts were all rounded off where somebody used vice-grips to loosen them. As for the procedure it was followed as per the manual. The exaact output voltage of your power source is not really that important (within reason) because what your are checking is actually a precentage of that. First you check the open circuit voltage and multiply that by the variable to determine the final voltage reading when the sled is at idle. If you have 4.7 volts x .136 = .64. This is what you should read at idle when checking voltage through the resistor/rehostat. If you have 4.5 volts open circuit x .136 = .61. I measured mine and it was something like 1.7 volts(not sure though) when rotated fully clockwise. Rotated fully counter-clockwise and got a reading of .64. So as far as I can tell, mine needed adjustment. When your throttle rotates it turns counter clockwise looking at it from the clutch side. Turning the TPS sensorfully clockwise would have the same effect as the throttle being opened just a bit. Basically the TPS sensor would be acting as if you are at low to mid-throttle when you are actually only at idle. Clear as mud eh!!
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Yeah, after reading the procedure I see it's self correcting for the various voltages the homemade power supply could produce.

As I said earlier, mine appears to have never been touched including the white paint/cert. mark on the screws...it's cranked CCW. I bought it new.

I would expect the voltage (as measured between signal return and ground)to increase with throttle opening like most automotive 5v reference systems.

But Bob is saying he sees a decrease with throttle opening from .65 to .07 yet you were seeing 1.7 misadjusted/part throttle?

I'm confused.
 
snomofo said:
But Bob is saying he sees a decrease with throttle opening from .65 to .07 yet you were seeing 1.7 misadjusted/part throttle?

I'm confused.
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I think the 1.7 was just an error in his memory of the readings.
The first time I did it I also was not recording the readings as though they were going to be posted as a baseline. The second time I repeated the test I recorded everything accurately.
I would be very interested in someone elses finding because I expected an increase in voltage for throttle opening as well!
 
sideshowBob said:
I think the 1.7 was just an error in his memory of the readings.
The first time I did it I also was not recording the readings as though they were going to be posted as a baseline. The second time I repeated the test I recorded everything accurately.
I would be very interested in someone elses finding because I expected an increase in voltage for throttle opening as well!
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Gosh darnit Bob, you're going to make me check mine aren't you?

You were supposed to be wrong!

On the good side, it's very likely they're supposed to be closer to CCW and it appears yours and others were misadjusted. It'd be interesting to see any improvements in part throttle fuel economy.

Or could misadjustment be a contributor to part throttle deto burndowns???

Enlightening.
 
sideshowBob said:
I think the 1.7 was just an error in his memory of the readings.
The first time I did it I also was not recording the readings as though they were going to be posted as a baseline. The second time I repeated the test I recorded everything accurately.
I would be very interested in someone elses finding because I expected an increase in voltage for throttle opening as well!
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That is correct I was going from memory and wasn't 100%. I didn't pay attention too much to that reading as it is the calculated reading at idle that was important. I just adjusted the TPS until I had the correct results. I'll check mine again tomorrow evening and post the results.
 
snomofo said:
Gosh darnit Bob, you're going to make me check mine aren't you?

You were supposed to be wrong!

On the good side, it's very likely they're supposed to be closer to CCW and it appears yours and others were misadjusted. It'd be interesting to see any improvements in part throttle fuel economy.

Or could misadjustment be a contributor to part throttle deto burndowns???

Enlightening.
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I'm curious on this as well. There are a few things I've noticed on my 00 SRX vs my 98 which had no TPS. The 00 is harder to start and is harder on fuel. Not sure if the TPS improper adjustment could have caused this but I really hope so.
 
jaydaniels said:
I'm curious on this as well. There are a few things I've noticed on my 00 SRX vs my 98 which had no TPS. The 00 is harder to start and is harder on fuel. Not sure if the TPS improper adjustment could have caused this but I really hope so.
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Not knowing the advance curve and it's relation to throttle angle, misadjustment might improve both F.E. and/or reduce detonation.

Maybe I'll try to do some A to B comparisions this year and see if anything shows up in EGT. Since I'd be moving the sensor around, I couldn't use it to duplicate consistent throttle angles... perhaps a lever stop block taped to the bar.

Or perhaps a Yamaha calibrator could pipe in and tell us what to expect???
 
It cant reduce detonation because there's no knock sensor like the DCS sleds have. guys don't over think this,i've read about dyno runs on adjusting TPS and it doesn't do a who lot in that respect,only mid range cruse timing is adjusted and by only a few deg. for better throttle responce, your not going to gain anything by adjusting it,set it and forget it.
 
daman said:
It cant reduce detonation because there's no knock sensor like the DCS sleds have. guys don't over think this,i've read about dyno runs on adjusting TPS and it doesn't do a who lot in that respect,only mid range cruse timing is adjusted and by only a few deg. for better throttle responce, your not going to gain anything by adjusting it,set it and forget it.
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It can't reduce detonation on demand or detect it but I would think it would have an effect on it since it does advance/retard the timing by a couple of degrees. In most engines, a TPS advances timing as RPM increases. Would this be true for the SRX as well.
 
jaydaniels said:
It can't reduce detonation on demand or detect it but I would think it would have an effect on it since it does advance/retard the timing buy a couple of degrees. In most engines, a TPS advances timing as RPM increases. Would this be true for the SRX as well.
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correct, but it could also hamper it,deto is happening but its adding timming,not good.

thats the theory of a throttle sesor telling the CDI,ECM etc where the throttle is at what % of opening. we dont know how it's efective on these
 
I'm not looking to gain performance or mess with adjustments but am curious as to how this system works. Someone on here must know if the TPS advances the timing as the throttle is opened and rpm increase. One thing I noticed is that the voltage and resistance readings constantly change as throttle position changes. This kind of indicates that the TPS has an effect throughout the entire throttle range, not just at low-mid throttle positions. Anyhow, not to beat a dead horse but it is kind of an interesting topic. I've done a search and haven't found much more info on this.
 
jaydaniels said:
I'm not looking to gain performance or mess with adjustments but am curious as to how this system works. Someone on here must know if the TPS advances the timing as the throttle is opened and rpm increase. One thing I noticed is that the voltage and resistance readings constantly change as throttle position changes. This kind of indicates that the TPS has an effect throughout the entire throttle range, not just at low-mid throttle positions. Anyhow, not to beat a dead horse but it is kind of an interesting topic. I've done a search and haven't found much more info on this.
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no there's not much on the topic because there's not allot of people that mess with it,one never has any problems with it.

the service manual is very vague about it it says "wile slowly pushing the throttle check the TPS resistance", and gives a resistance range but doesn't say if it suppose to increase with throttle or decrease or just stay in a certain range. like i said book is very vague.

my gut is telling me it just stays in a certain range and thats it.
 
daman said:
It cant reduce detonation because there's no knock sensor like the DCS sleds have. guys don't over think this,i've read about dyno runs on adjusting TPS and it doesn't do a who lot in that respect,only mid range cruse timing is adjusted and by only a few deg. for better throttle responce, your not going to gain anything by adjusting it,set it and forget it.
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I'm not suggesting any gain or reduction. What I'm saying is that if it's misadjusted, is the engine seeing one or two degrees more advance at a curtain throttle opening (and the corrisponding needle position) when it is calibrated to see a lesser spark advance.

In other words, Let's say for argument sake that a properly adjusted TPS adds two degrees at 25% throttle opening (and it's corrisponding needle position). And lets say an improperly adjusted TPS adds two degrees at 20% throttle opening (and it's lesser fuel delivery with the lower needle position).

I'm not arguing for or against misadjusting the TPS. What I'm asking is could the added or subtracted degree or two at the wrong throttle opening (and possible different fuel delivery circuit) put combustion temps near the melting/deto point?


I'm not sure how else to explain it. Am I making any sense to anybody?
 
snomofo said:
I'm not suggesting any gain or reduction. What I'm saying is that if it's misadjusted, is the engine seeing one or two degrees more advance at a curtain throttle opening (and the corrisponding needle position) when it is calibrated to see a lesser spark advance.

In other words, Let's say for argument sake that a properly adjusted TPS adds two degrees at 25% throttle opening (and it's corrisponding needle position). And lets say an improperly adjusted TPS adds two degrees at 20% throttle opening (and it's lesser fuel delivery with the lower needle position).

I'm not arguing for or against misadjusting the TPS. What I'm asking is could the added or subtracted degree or two at the wrong throttle opening (and possible different fuel delivery circuit) put combustion temps near the melting/deto point?


I'm not sure how else to explain it. Am I making any sense to anybody?
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No i hear what your sayin,i do....and i agree thats why it should be set per specs.

thats why unless one is a yamaha designer of the system we just dont know for sure....
 
I don't know how sophisticated the CDI with its 3D mapping is but the TPS may do nothing more then tell the ECU where the throttle is and then the CDI uses that info to calculate/adjust the timing in comparison to the Engines RPM!?? That would make the timing variable not to just the throttle position but actually engine load at a given throttle setting!!!
For example, full trottle 8000 rpm would have more timing advance then full throttle 6500rpm.
That would explain why at full throttle and high RPM, on the Dyno, there was no observed timing variance by moving the TPS around!?

Thats enough for me now on this topic...I have mine adjusted to factory specs and will now let the Yamaha engineers look after the rest!
 
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