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Discussion Starter · #1 ·
I wanted to clean up the wiring around the carburetors and would like to remove the carb heater and TPS wires. I know that the carb heaters are pretty worthless in Southern Arizona with our 5% humidity and blazing temps.
I guess what I looking for from the collective knowledge here is whether the TPS are really needed and will it adversely affect my ignition timing? I know that when people switch over to other carburetors that a lot don't have the throttle position, and they haven't had problems.
Input appreciated.
 

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Thats a tuff call with stock carbs on the bike.Mike has done some good work with the tps hooked up.I dont run one with the flat slide carbs and dont need one.Iran them unhooked when my bike was stock and didnt see much that they did.They could help at heavy load low rpm though I guess,but i dont do much of that so cant say.As far as wot haul ass mode they do nothing.
 

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i agree with sweat. if it ain't broke, don't fix it. what are your reasons for wanting to remove them, aside from 'cleaning up' around the carbs? some here have stated that the bike runs better with the carb heaters removed. i tried this and never noticed a differrence so just put them back on and just leave it. if having the TPS sensor and carb heaters are really annoying you get a set of CR carbs, or go big and get some mikuni's. you probably wouldnt like the FCR's though because eventhough they dont have carb heaters they do have a TPS sensor.
 

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Discussion Starter · #5 ·
Thanks for the info. I know it's just a visual thing of seeing all the wiring there. I'll take the good advise and leave well enough alone.
 

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The fcr are way better carbs then the cr carbs you can run them with or with out tps .In fact the they just started putting the tps on them lately people ran them for years with out it.The tps on race carbs is just put on there to sell carbs lol.flat slide carbs dont need a tps.
 

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The fcr are way better carbs then the cr carbs you can run them with or with out tps .In fact the they just started putting the tps on them lately people ran them for years with out it.The tps on race carbs is just put on there to sell carbs lol.flat slide carbs dont need a tps.
Mike, you have said many times that the flat slide FCR are much better than the CR35S round slides... Granted, I know you are right, but I chose the CR35 for a couple of reasons. I like the looks, (Amal kind of) price, and no TPS wires... So it is true if I went w/ FCR in the future, no wires.... Cool!
I hate wires. Derby has seen my re wire job and it looks so clean...
Hey, also what's the fuel mileage difference?
Are people getting better mileage w/ the 39's? If so and why? What about Mikuni's? That would be a consideration in the long run as I ride a lot...
Thanks...
 

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When i had a stock motor with stock carbs and went to the 42mm carbs my over the road curse milage was about the same.Now if you open them up they would burn more but they made more power.
Mike to be dead honest and I know you have done lots of testing with tps maps.I have yet to see any facts that make me beleave on a set of flat slide carbs set up right that the tps helps any at all.It might help on vac slide stock carbs because the slides are worked by vac and it may make them work better.It may help someone that rides aroundunder heavy loads at low rpm,but people that build there motors dont lug them around.my 42s run smooth as glass , have no flat spots,have more low end torque then you will ever need with out the tps. So let me ask you why do you think you need the TPS on mechanical carbs?
 

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Mike, you have said many times that the flat slide FCR are much better than the CR35S round slides... Granted, I know you are right, but I chose the CR35 for a couple of reasons. I like the looks, (Amal kind of) price, and no TPS wires... So it is true if I went w/ FCR in the future, no wires.... Cool!
I hate wires. Derby has seen my re wire job and it looks so clean...
Hey, also what's the fuel mileage difference?
Are people getting better mileage w/ the 39's? If so and why? What about Mikuni's? That would be a consideration in the long run as I ride a lot...
Thanks...
I dont think mpg will change much from any well tuned carb on the same motor because mpg is mostly about less then 1/4 throttle( the bigger the carb the less you open them to get the same rpm. What does change is the wot wow factor.with well tuned flat slides its like you got hit in the butt.very quick rpm rise.And yes the bigger the carbs the more gas they burn at wot.people dont beleave it till they ride one of these bikes with well tuned flat slides.Not everyone knows how to tune flat slides,thats why one would be ahead of the game to buy them from someone that does even if you pay alittle more for them $100 or $200 saved on price of carbs might cost way more on wrong gets dyno time and labor to get them right.
 

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Tps

Un plug them & see? I did mine when new & seemed to run alkittle better? If you unplug- can always reconnect!
 

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tps

search on husaberg dot org and you'll find many have removed the tps with no problems, as have I. Many were found to be set up wrong from the factory at the start.
 

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Wait wait wait - it seems like (and I can be wrong) that people are saying the tps helps the carbs. It does not and has nothing to do with the actual functioning of the carbs. The TPS takes the position of the throttle, reports it as a voltage and sends that info back to the ignition module or ecu (if fuel injected) which then changes its signal to compensate for throttle.

This is how it works on FI systems so I don't see why it would be any different here. Now obviously it doesnt do a ton because anyone running the bigger carbs don't seem to use a tps but I think that is because of the mechanical slides.

I mean those mechanical slides operate as a direct funtion of twist instead of engine vacuum which can take a time to build up and is variable.

I might be wrong here but seems logical to me.
 

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Wait wait wait - it seems like (and I can be wrong) that people are saying the tps helps the carbs. It does not and has nothing to do with the actual functioning of the carbs. The TPS takes the position of the throttle, reports it as a voltage and sends that info back to the ignition module or ecu (if fuel injected) which then changes its signal to compensate for throttle.

This is how it works on FI systems so I don't see why it would be any different here. Now obviously it doesnt do a ton because anyone running the bigger carbs don't seem to use a tps but I think that is because of the mechanical slides.

I mean those mechanical slides operate as a direct funtion of twist instead of engine vacuum which can take a time to build up and is variable.

I might be wrong here but seems logical to me.

+1 on this.

My understanding is that the TPS tells your ignitor where in its 3D map it should be operating...disconnecting the TPS puts you on the WFO map all the time. If the part throttle ignition map has any value, then using the TPS is the only way to take advantage of that ignition timing variation....

Now, whether the part throttle ignition map has any value or not is the question you need to answer. That is beyond my knowledge...

Regards,

--Rich
 

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Hey...I just had a thought. Is there any implications with me disconnecting my TPS? (as in, does it plug in and out w/o needing some fancy positioning?).

Reason I ask is that I'm headed over to the dyno later today (about an hour to be precise) and I can do a pull with the TPS disconnected to give some real data on where it helps make power with stock carbs. Anyway, post a reply real quick if you know the answer.

--Rich
 

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If you take off the right hand side panel and follow the cable from the TPS unit on the right hand carb your should find a connector tucked under the horizontal frame tube. Mine was partially hidden and I had to remove a cable tie to pull it out so it could be unplugged so I could remove my carbs. Unplugging the TPS does no harm, removing the unit screwed to the side of the carb is not advised! I unplugged mine as an experiment once and can't say I noticed a huge difference in the running of the bike. N.B. on EFI bikes the TPS is moved to the other side of the bike and is screwed to the left hand "carb" body.
 

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Wait wait wait - it seems like (and I can be wrong) that people are saying the tps helps the carbs. It does not and has nothing to do with the actual functioning of the carbs. The TPS takes the position of the throttle, reports it as a voltage and sends that info back to the ignition module or ecu (if fuel injected) which then changes its signal to compensate for throttle.

This is how it works on FI systems so I don't see why it would be any different here. Now obviously it doesnt do a ton because anyone running the bigger carbs don't seem to use a tps but I think that is because of the mechanical slides.

I mean those mechanical slides operate as a direct funtion of twist instead of engine vacuum which can take a time to build up and is variable.

I might be wrong here but seems logical to me.
That is how i see it .The tps might help with vac slide stock carbs because it might change the advance map in away that makes the vac to the slides work better (more stable) to a degree you can advace timing and pick up vac under some engine loads.The way Iunderstand it with it unpluged it controls advance by rpm just as it does at wot.On a 790 if you unplug it at idle you get more advance (it will idle faster)The 865 box does not seam to do that or at lest not as much.One thing Ihave done that seams to make my bike start and run alot better ,I took the pick up coil and opened the mounting screw holes up so I could move the pickup and advance the timing a few deg.Any of you runing pro com boxes it will cure the hard start troubles they have.Its worth playing with and dont cost a dime if you dont mess up the alt gasket.
 

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Calliway is correct, what type of carbs makes no difference. The TPS is measuring the engine load and feeding that information back to the igniter.

Without the TPS in circuit you have a 2 dimensional ignition advance curve that advances the spark depending on the RPM, no matter what the load, similar to points and centrifugal weights of yesterday.

With the TPS in circuit you have the 3rd dimension. Now the igniter knows if the engine is under hard acceleration, cruising, slowly building speed or decelerating when it cross references with RPM. This is important as the speed of the flame front in the combustion chamber changes as the load on the engine changes and in turn the timing of the spark needs to change in line with the flame front to produce good ignition at the point of maximum chamber pressure.

Not using the TPS certainly won't hurt your engine as the igniter reverts to the 100% throttle open ignition map. If it doesn't have a TPS input, you have an ignition system similar to the electronic ignition Meriden Bonnies of 30 years ago. But you are losing out as the spark timing will be constant at any particular RPM no matter what the engine load/flame front speed and thus you are not taking advantage of performance/efficiency at any part throttle openings. This is why all modern vehicle ignition systems use an engine load sensor of some description and also why Keihin have gone to the trouble of incorporating a TPS on their lovely FCR39's.

This also explains why we have seen the comment by many owners "I disconnected mine and didn't lose anything". If you disconnect the TPS, full power WOT will be the same as with it connected. Also a one or two BHP gain is very hard/impossible to detect on WOT unless on a dyno, so a one or two BHP gain on part throttle is definitely impossible to detect, but in everyday riding it'll make a difference.

Mike, I have no problem with you being a ludite, I'll forward a set of points to you in the post. :p
 
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