R1 Throttle Body Question
omega0684 - 27/1/09 at 11:46 AM
not sure if this is in the right section but its about R1 TB's so i've stuck my Qu in here,
i have a set a 2003 R1 TB's on my pinto and myself and a fellow builder have been discussing set ups for them and came across a common query that
we're a little confused about,
when you look into the TB's there is a black platic valve (that covers about 3/4 of the inlet) that is before the butterflies that is controlled
by a diaphram and spring in the top of the TB. now my understanding is that these are vacuum controlled. so as you go faster the plastic
"shutters" lift upwards allowing more air to flow into the inlet? am i right so far?
so here's my question, can these simply be removed? my thinking is that the butterfly also controls the air flow into the cylinders so whats the
point in having 2 controls?
answers on a postcard please 
Mr Whippy - 27/1/09 at 11:59 AM
really I should charge for my web search ability’s 
Rescued attachment 00valve.JPG
cd.thomson - 27/1/09 at 12:06 PM
thankyou Mr Whippy. I had read about this on wikipedia, the valve itself is referred to as a constant velocity carburetor slide.
I can see the need for this on the low torque bike engine. On a CEC are these necessary?
Mr Whippy - 27/1/09 at 12:16 PM
quote:
Originally posted by cd.thomson
thankyou Mr Whippy. I had read about this on wikipedia, the valve itself is referred to as a constant velocity carburetor slide.
I can see the need for this on the low torque bike engine. On a CEC are these necessary?
Sounds similar concept to fords Variable Venturi carb that on paper sounded great but in real life sucked big time. Basically its purpose was to
maintain a high flow rate through the carb at low revs insuring very good atomization of the fuel (often a cause for starting difficulties on carbs
with huge bores) but at higher revs would open up and freely flow the air. Unfortunately the damn VV thing leaked inside like a sieve and instead
tried its best to strangle the engine at any opportunity. Personally I'd leave it alone as if anything its probably going to give you more low
down torque and then get out the way when the revs are up. It's also rather like the vacuum secondary valve on the Weber 32/36 progressive carb,
in that one valve remains closed at low speeds to give you more torque.
[Edited on 27/1/09 by Mr Whippy]
chrisspartan - 27/1/09 at 12:17 PM
The best way to lock them open I found was - take the cover and put a short length of plastic kitchen waste pipe over the flat part of the valve (you
will need to 'ovalise' the pipe to get it to fit. Assuming you have cut the pipe to the right length when you reassemble this will keep the
valve open.
omega0684 - 27/1/09 at 12:26 PM
chris was there any benefit to you locking the valves open?
MikeCapon - 27/1/09 at 12:46 PM
If you want the slides to open more quickly you need to enlarge the hole that passes the depression through to above the slides. This mod worked well
on CBR600 carbs on the offroad racers we have over here and would apply equally to the R1 set up.
cd.thomson - 27/1/09 at 12:51 PM
Speaking for myself, and possibly Omega, I'm really just wondering if they actually do anything functional on a big car engine?
Rather than leaving them/jamming them open/having them operating more quickly I'd be really interested to know *why* I should take this course of
action?
chrisspartan - 27/1/09 at 12:53 PM
Sorry I havent started my engine yet - it was purely a construction suggestion. I went through the same thought process as you but concluded that I
wouln't need them on a CeC. Thats why I opted for the tube mod as I could always reinstate the valve if ever needed by taking the tube out.
Mr Whippy - 27/1/09 at 01:12 PM
quote:
Originally posted by chrisspartan
Sorry I havent started my engine yet - it was purely a construction suggestion. I went through the same thought process as you but concluded that I
wouln't need them on a CeC. Thats why I opted for the tube mod as I could always reinstate the valve if ever needed by taking the tube out.
The pipe you’re sticking down its throat, aren’t you reducing the carbs intake bore? If so, that's not exactly improving the gas flow.
omega0684 - 27/1/09 at 02:46 PM
if you wanted the valves to stay open, would it not just be easier to take the diaphrams out and then push the valves up manually from inside the
inlet and then use some silicone (or similar product) to secure it from the top of the TB where the diapram used to be after removing it, that way you
have not restricted the airflow in anyway and the valve is wide open.
just a thought....
[Edited on 27/1/09 by omega0684]
MkIndy7 - 27/1/09 at 03:12 PM
Nope its much easier to push a piece of pipe down there to hold the slides open, particularly if you may ever want to use them again at a later
date.
As for the slides advantages or disadvantages on a CEC i'm not sure.. We've currently got our wedged open and some pipe reducers to narrow
it down to about 32mm as the low throttle opening and tuneing is a nightmare. On about 20% throttle travel you might as well have your foot to full
throttle as the engine is pulling in so much air and below that you've not got much control. Over the winter we either need to made a cranked
throttle opening arrangement or to restrict the low throttle opening ariflow another way.
They never helped with this tuneing when they were operational and made a very strange noise lol.
chrisspartan - 27/1/09 at 05:22 PM
No I didn't mean put a bit of pipe in the airflow, I meant from the diaphram and spring side you use the pipe to hold the valve back.
