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Author: Subject: Do i need tps?
Eviljohn

posted on 1/8/17 at 06:58 PM Reply With Quote
Do i need tps?

Hi all. Hope you are well. I am part way through a bike carb conversion on a 1983, 1043cc polo. I'm using the carbs from a cbr400. They didn't come with the tps sensor. I've been reading a little about them and wondered if anyone could say whether i actually need the tps or not.
From what i've read, and feel free to correct me if i've misunderstood, before tps, or other similar, the two things engines used to correct fuel/air mix were vacuum advance and centrifugal weights in the dizzy.
I actually have vacuum advance in use on my engine. Would that mean i don't have to use a tps system or i have i misunderstood it?
Thanks for stopping by and any guidance you can give.

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rayward

posted on 1/8/17 at 07:02 PM Reply With Quote
if your running carbs , you would only need TPS if your running a 3D mappable ignition system (such as megajolt)

hope this helps

Ray

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cliftyhanger

posted on 1/8/17 at 08:37 PM Reply With Quote
If you have a distributer, then fine.

If running something like megajolt/nodiz or whatever, not using a TPS or MAP sensor means you will lose torque and economy at cruise.

MAP sensors do the same thing as TPS (in fact are often better, long story!) in that they alter the timing according to manifold pressure. So effectively work in the same way.

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Eviljohn

posted on 2/8/17 at 06:53 AM Reply With Quote
I have refurbished stock distributor. When i had it refurbed, had it converted from points and condensor to electronic ignition. But does still have vacuum advance unit fitted.
Thanks for advice gents. Very much appreciated.

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Jenko

posted on 2/8/17 at 07:40 AM Reply With Quote
quote:
Originally posted by Eviljohn
I have refurbished stock distributor. When i had it refurbed, had it converted from points and condensor to electronic ignition. But does still have vacuum advance unit fitted.
Thanks for advice gents. Very much appreciated.


All the TPS does is feed back throttle position information to an ECU. The ECU can then decide what ignition advance to give and what fuel to inject (if it were on a fuel injected car). If you don't have an ECU controlling fuel or ignition, then there is no requirement for a TPS.





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redturner
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posted on 2/8/17 at 08:14 AM Reply With Quote
I run my Zetec with R1 carbs on Megajolt using the MAP sensor. I could have used the TPS but I found it more convenient to remove it and connect the throttle cable to that end.....
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mcerd1

posted on 2/8/17 at 08:36 AM Reply With Quote
quote:
Originally posted by Eviljohn
I have refurbished stock distributor. When i had it refurbed, had it converted from points and condensor to electronic ignition. But does still have vacuum advance unit fitted.

^^ as above you don't need the TPS - its only for ECU controlled sparks (in place of the vac. advance or MAP sensor)


but to get a good vac. signal for the dizzy you will need to connect up a vac. line from all the cylinders into a chamber bid enough to smooth out the individual pulses from the cylinders - then take a line from this chamber to the dizzy - without this the pulses from 1 cylinder will potentially bounce the spark timing all over the place


the other approach is to modify the dizzy to remove the vac. advance completely (suitably locked at a fixed advance) - this effectively make it a 2D ignition map which is simple, but will give poor economy and less throttle responce

[Edited on 2/8/2017 by mcerd1]





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SPYDER

posted on 2/8/17 at 10:37 AM Reply With Quote
quote:
Originally posted by mcerd1
... you will need to connect up a vac. line from all the cylinders into a chamber bid enough to smooth out the individual pulses from the cylinders - then take a line from this chamber to the dizzy ...



A lot of people use one of these. Myself included. Mine's a large one.




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redturner
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posted on 2/8/17 at 01:02 PM Reply With Quote
I fancied that idea but thought that 4 separate pipes into a small manifold then 1 at other end to go to the ECU would be better...
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Eviljohn

posted on 2/8/17 at 05:12 PM Reply With Quote
I kept the vaccum hooked up to the new manifold. Drilled a hole and attached a little take-off. Hooked it up as it was when the stock manifold was in place.
Not sure how that affects the running at the moment as it's running poop anyway. Have to move the fuel pump and see how that works so will probly be back for more guidance after that!
Thanks for guidance so far. Very much appreciated.

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mcerd1

posted on 3/8/17 at 11:33 AM Reply With Quote
^^^ sounds like you'll need to connect up all the cylinders

like this: (MAP sensors need connected the same way as your mechanical advance )



[Edited on 3/8/2017 by mcerd1]





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Eviljohn

posted on 3/8/17 at 05:27 PM Reply With Quote
Just to make sure i understand it:
I attach a vacuum hose to each inlet pipe/runner and hook all 4 of those up to the vacuum advance, with a fuel filter after the last runner?

[Edited on 3/8/17 by Eviljohn]

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David Jenkins

posted on 3/8/17 at 05:33 PM Reply With Quote
quote:
Originally posted by Eviljohn
Just to make sure i understand it:
I attach a vacuum hose to each inlet pipe/runner and hook all 4 of those up to the vacuum advance, with a fuel filter after the last runner?



Or 4 pieces of hose, 1 from each inlet, into a small cylinder (like the fuel filter) then on to the distributor. Whatever's most convenient.





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