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urgent carb question

Old 04-23-2010, 11:57 AM
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urgent carb question

need an answer fast lol....
does anyone know the purpose of this orifice plate / restrictor in the intake rubber of each carb???
it is 46mm internal diameter - but the carbs are 48mm bore...
need an answer before i grind it away and polish it up to 48mm lol

i'm wondering if it is there to collect fuel on the over-run but seems unlikely.
both intakes are exactly the same, with a slight oval section that goes to the edge, the rest of it restricts the intake by 1mm all round...
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Old 04-23-2010, 12:32 PM
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doesn't matter - i figured it was a restrictor so i ripped them out.

they're in the bin now lol
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Old 04-23-2010, 05:32 PM
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Well let's hope it works. Maybe you discovered something huh? And welcome to the forum Benny.
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Old 04-23-2010, 05:53 PM
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Dunno if they really serve a purpose like that... In some countries they are however "D" shaped to restrict the flow partially... I don't think the difference with them out will be noticable...
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Old 04-24-2010, 05:46 PM
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well im not so sure - the varadero has 45mm carbs and puts out like 85 horse, why fit a 48mm carb and then restrict the inlet to 45mm
(it measured 45mm sorry not 46 as stated earlier.

this is on a 2000 1000f1.
tbh will probably be difficult to tell if it's made a difference cos it's been rebuilt atm and i fitted k&N, dynojet e1185, manual ccts and laser cans.
did have carbon vipers on but trashed the left one when i dropped it!

anyway i opened up the rubbers to the full 48mm and polished out the rim where the aluminium restrictor was - can't see it doing any harm.
one of the lads on vtr1000.org looked at a spare set of carbs and this plate wasn't there, so it isn't essential.

i'll let you know what happens - oh & cheers for the welcome
hoping to have the bike back on the road in a week or 2
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Old 07-21-2011, 08:47 AM
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and?

so what was the result?

i just bought new boots for my 98 and they have the metal plates insert molded in, the originals have no plate, although the ID is the same.

can't decide whether or not to chuck them up and bore that plate out to 48 mm.

thanks
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Old 07-21-2011, 08:58 AM
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I bored that boot out a little when I ported the heads. Figured I would try to maximise flow and reduce turbulence throughout.

I say go for it.
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Old 07-21-2011, 11:53 AM
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The resrictor is there to maintain intake port velocity at low rpm for better fuel metering.
I'd leave it alone since you won't feel the difference up high but you will feel the difference down low.
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Old 07-21-2011, 11:55 AM
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Originally Posted by kai ju View Post
The resrictor is there to maintain intake port velocity at low rpm for better fuel metering.
I'd leave it alone since you won't feel the difference up high but you will feel the difference down low.
That makes sense.
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Old 07-21-2011, 12:20 PM
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Often smaller is better due to increased velocity..
Power News -- Think Fast--Intake Porting For Motorcycles and Cars
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Old 07-21-2011, 12:41 PM
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Originally Posted by lazn View Post
Often smaller is better due to increased velocity..
Power News -- Think Fast--Intake Porting For Motorcycles and Cars
It's called the "venturi effect". Air flows at a faster rate through a restricted area, as does water in the case of river "rapids".
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Old 07-22-2011, 06:30 AM
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that's what velocity stacks help with. i ground down mine so the coupler was one smooth inside diameter.
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Old 03-28-2012, 04:53 PM
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Good Job!

Originally Posted by benny hedges View Post
doesn't matter - i figured it was a restrictor so i ripped them out.

The Man ordered them restrictors to spoil our fun and we defeated him and his main squeeze Hillary. Fight da Man---

they're in the bin now lol
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Old 03-28-2012, 08:03 PM
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Haha, did you just go to a random old thread and hit the "quote" button?
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