Restrictor Plates in Intake Boot

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thunderbolt
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Re: Restrictor Plates in Intake Boot

Post by thunderbolt »

cybercarl wrote:You have started already..... First and foremost is the timing and Valve clearances. I believe carb farts occur during the Valve overlap period and the scavenging effect causing intake reversion. More of a problem with bigger carbs at idle speed/low down revs.

The next thing is to move onto Carb tuning. Carbs should be dialled in according to the timing of the engine, including the intake and exhaust systems hence doing the timing and clearances first. Carb farts can often get confused with a lean condition, especially within the Pilot circuit including the correct adjustment for the fuel Mixture (fuel screw adjustment). You will find that a Carb sync/balance, then TPS adjustment and then another Carb balance/sync to finish off will all help.

Fuel Screw/Mixture Adjutsment

How to Adjust the Throttle Position Sensor (TPS)

(:-})
Thanks Carl, I will save these procedures and tips in the appropriate folder for future use.

As you know I already have the carbs off the bike while I am doing other stuff to it. Is there any point in checking the resistance of the TPS while the carbs are on the bench? I notice in the article it said to tune and balance the carbs before doing the resistance test.

Thanks
Cheers
Don
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Bikes:
1977 Suzuki GS550/700 - modified significantly
1981 Moto Guzzi 850 T4
1990 Suzuki VX800
2003 Honda Firestorm VTR1000
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VTRDark
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Re: Restrictor Plates in Intake Boot

Post by VTRDark »

Yeh check and adjust it while the Carbs are off. The only reasoning for balancing first is because this alters the position of the throttle plate which is where the TPS takes it's baseline reading from. It wont make a huge difference not balancing first, not unless it's massively out to begin with.

(:-})
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thunderbolt
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Re: Restrictor Plates in Intake Boot

Post by thunderbolt »

cybercarl wrote:Yeh check and adjust it while the Carbs are off. The only reasoning for balancing first is because this alters the position of the throttle plate which is where the TPS takes it's baseline reading from. It wont make a huge difference not balancing first, not unless it's massively out to begin with.

(:-})
Thanks Carl,

I went out to the shed after reading your post on the TPS adjustment. Slapped the multimeter on the terminals and received a reading of 794Ω as below.

Image

I then was able to reset it to approx. 500Ω without having to file out the slots in the TPS and without having to use the special tool to loosen the two screws holding it in place - replaced them with hex head screws.

Image

It was quite a simple job really, I thought it would be a bit more involved than it was. I cannot do anymore now as I am waiting on the new "O" rings to go in the cylinder head before the valve covers can go back on and start to reassemble everything. I have also ordered a PAIR removal kit from the States - hoping it will arrive soon so it can be fitted as well.

Learnt a lot through this exercise and the willing advice of others on this forum. I am ok at building motors and such, but each bike has it's own uniqueness and there is no-one better to help in these cases that those that already own and have worked on these bikes themselves. Thanks for sharing your experience with me.
Last edited by thunderbolt on Fri Aug 29, 2014 1:26 am, edited 1 time in total.
Cheers
Don
____________________________________________

Bikes:
1977 Suzuki GS550/700 - modified significantly
1981 Moto Guzzi 850 T4
1990 Suzuki VX800
2003 Honda Firestorm VTR1000
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Re: Restrictor Plates in Intake Boot

Post by VTRDark »

You got lucky with such a low original reading there. How big are those croc clips, the insulated one is interesting :lol: The pins are so close together that, not only does one have to be careful not to make contact with the 2nd or 3rd but also the 1st pin that is not required for the reading.

It would have been handy if you posted that post in the TPS thread :wink: I really should take some more pics for that thread. :Stick:

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thunderbolt
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Re: Restrictor Plates in Intake Boot

Post by thunderbolt »

cybercarl wrote:You got lucky with such a low original reading there. How big are those croc clips, the insulated one is interesting :lol: The pins are so close together that, not only does one have to be careful not to make contact with the 2nd or 3rd but also the 1st pin that is not required for the reading.

It would have been handy if you posted that post in the TPS thread :wink: I really should take some more pics for that thread. :Stick:

(:-})
I took the reading off the two uppermost pins, is that correct? You seem to be saying the 1st pin is not required to obtain the reading. Do you mean the lower pin, counting from the bottom up, 1st, 2nd & 3rd - with 3rd pin being at the top with the carbs sitting up the way they would be mounted on the motor.

I will see if I can copy this detail over on to the TPS thread.
Cheers
Don
____________________________________________

Bikes:
1977 Suzuki GS550/700 - modified significantly
1981 Moto Guzzi 850 T4
1990 Suzuki VX800
2003 Honda Firestorm VTR1000
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VTRDark
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Re: Restrictor Plates in Intake Boot

Post by VTRDark »

Do you mean the lower pin, counting from the bottom up, 1st, 2nd & 3rd - with 3rd pin being at the top with the carbs sitting up the way they would be mounted on the motor.
Exactly......you got it. :thumbup:

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thunderbolt
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Re: Restrictor Plates in Intake Boot

Post by thunderbolt »

cybercarl wrote:How big are those croc clips, the insulated one is interesting :lol:

(:-})
Carl, I'm glad you liked my insulation technique :P Thinking of patenting the idea actually :thumbup:

.
Cheers
Don
____________________________________________

Bikes:
1977 Suzuki GS550/700 - modified significantly
1981 Moto Guzzi 850 T4
1990 Suzuki VX800
2003 Honda Firestorm VTR1000
jchesshyre
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Re: Restrictor Plates in Intake Boot

Post by jchesshyre »

Resurrecting this thread rather than creating a new one - hope that's the right thing to do!

I ordered new intake boots, non-OEM but manufacturer unspecified, from wemoto. Turns out they're TourMax which I'm happy with. However, they have the restrictor plates in as shown:
Image

If this is indeed just as per later model bikes and is to improve low-rev running then great. However, they say this on the side:
Image

Does this not suggest that they are restricting the output to 72 kW (96 bhp) or do you think that's just a code which happens to sound like a power rating?!
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Re: Restrictor Plates in Intake Boot

Post by jchesshyre »

Well, answered my own question by going for a ride :lol: They definitely are restrictors and it definitely is restricted to 78 kW. Horrible! Gets weaker over 7k rpm instead of stronger and struggles as redline approaches. Hideous! Out with the Dremel tomorrow!
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Re: Restrictor Plates in Intake Boot

Post by sirch345 »

jchesshyre wrote: Fri Jun 01, 2018 8:54 pm Well, answered my own question by going for a ride :lol: They definitely are restrictors and it definitely is restricted to 78 kW. Horrible! Gets weaker over 7k rpm instead of stronger and struggles as redline approaches. Hideous! Out with the Dremel tomorrow!
Can you not just use your old ones in the new inlet manifold rubbers, that would save you time with the dremel :)

Chris.
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Re: Restrictor Plates in Intake Boot

Post by jchesshyre »

Oh! do they come apart?
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sirch345
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Re: Restrictor Plates in Intake Boot

Post by sirch345 »

I'm pretty sure you can pull them out, although you may need to warm them up first in some hot water to make it an easier operation,

Chris.
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Re: Restrictor Plates in Intake Boot

Post by jchesshyre »

Thanks Chris. They seem very securely held in place and I can't see which way they'd come out, but wil give it a go tomorrow.

Incidentally, a search for TourMax CHH-25 (the part number) brings up this:

98 PS indeed! I will be telling Wemoto about this. They're great but it's not the first time they've sent me something slightly wrong - got a pattern choke cable off them and they were about two inches too short. Nice to know my bike's still making a fair bit more than 100 hp though.
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Re: Restrictor Plates in Intake Boot

Post by sirch345 »

I was really referring to the original Honda OEM inlet rubbers. Thinking about what you said "they seem very securely held in place" I wonder if the Tourmax ones are not so pliable as the original ones would have been when they were new.
I know from experience cheaper rubber motor parts are often more of a plastic type material that doesn't have the flexibility of better quality rubber. Can you not see if you can remove the metal rings from the old ones first :?:

I'm not sure how the ratings of 72Kw and 98PS work, unless 98PS is meant to be 98bhp,

Chris.
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Re: Restrictor Plates in Intake Boot

Post by jchesshyre »

sirch345 wrote: Fri Jun 01, 2018 10:24 pm I was really referring to the original Honda OEM inlet rubbers. Thinking about what you said "they seem very securely held in place" I wonder if the Tourmax ones are not so pliable as the original ones would have been when they were new.
I know from experience cheaper rubber motor parts are often more of a plastic type material that doesn't have the flexibility of better quality rubber. Can you not see if you can remove the metal rings from the old ones first :?:

I'm not sure how the ratings of 72Kw and 98PS work, unless 98PS is meant to be 98bhp,

Chris.
I know what you mean about plasticky parts, but actually they are quite rubbery! I just mean I can't see how or which way you'd bend them and which way the metal part would come out.

Re. the power figures, google says 72 kW = 96.5 bhp = 97.9 PS.
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