Manifold Rubbers with & without restrictors
 

What is it ???????
VTR1000 Manifold Rubbers with & without restrictors :
http://www.dynobike.com/vtr1000_tips.htm

Do you think I will have to rejet the bike in case I have it and decide to remove it ?

Is it the way honda restricted my 2001 french model ?
:roll:

Absolutely not.

Re: Manifold Rubbers with & without restrictors
 

:roll:
absolutely not ... what ?
The fact I have to rejet it or the way Honda restricts the bike to 106 Hp ?

Re: Manifold Rubbers with & without restrictors
 

One theory here for the manifold intake :

http://www.bluepoof.com/motorcycles/1202/121302.html

Re: Manifold Rubbers with & without restrictors
 

You don't have to rejet. I'm not calling you a liar. (That would make me quite the ass, don't you think? :wink: )

Re: Manifold Rubbers with & without restrictors
 

Thanks ;-)
Then, do you think I will benefit supressing these restrictors without rejetting or would it be just another chance to get into problems ? :roll:

Re: Manifold Rubbers with & without restrictors
 

The reason why the european models after 2001 have 3 HP less is because the PAIR system and the EVAP system was installed.

The intake restrictor is a restriction that germans VTR have or had. They are restricted at 100 Hp (engine Hp)
I thought rejetting was not needed. I'm not sure!

Re: Manifold Rubbers with & without restrictors
 

I thought Pair system is working only on decceleration ...
And Evap is for California type only ...
Sounds like the restrictors exist on Australian models too ...

Do I miss something ?

Re: Manifold Rubbers with & without restrictors
 

I'd pull them out and see. Chances are you won't need to do anything else but enjoy the benefits.

If you do create any sort of lean condition, you'd just jet to the USA specs. A lean condition presents itself as a hesitation then recovery when you roll on the throttle. There are three circuits where it might exist: just off idle (idle jets,) in the midrange (needle circuit,) and WFO (on the mains.) A rich condition, btw feels like a burble (sort of like clearing your throat.)

When you open the throttle, these circuits correspond to roughly under 2500 rpm, 2500-5500, and higher but thats not the most accurate way to understand them.

Re: Manifold Rubbers with & without restrictors
 

Thanks ;-)
I think I have to check if I'm really restricted for my model and think about removing these restrictors if it is confirmed ;-)
Any US or other countries models has been detected with these restrictors ?

Don't you think circuits are simply related to "throttle open" ?
I mean :
zero throttle : most used : idle jet (engine at idle or decellerate)
1/3 to 2/3 open : most used : needle (light acceleration or cruise at mid speeds)
2/3 to full open : most used : main jet (full acceleration until limiter cuts ;-) )

The tests you're speaking about is at neutral or riding the bike ?

Yes, that's a better explanation. The bike needs to be ridden to reveal the condition or run on a gas dyno if you can.

Re: Manifold Rubbers with & without restrictors
 

OK I could be wrong,

but where does the newer moddels loose the 3 HP? Nothing else is changed, I thought.

Re: Manifold Rubbers with & without restrictors
 

have seen :
So, suppressing these restrictors would drive me to more carb backfires that I already have ?

We may be confusing the stalling problem with a lean condition. I hope I can explain this well enough.

All fuel is pulled by the air in a carburator. The jets are actually flow restrictors affecting the mixture of air and fuel. But it is the venturi effect of the passing air that pulls the gas into the mix. If there is no air velocity, there is no gas. If there is too little air velocity, there will be a corresponding decline in gas.

(A little gravity fed gas will dribble for a second in the absence of air. A tiny amount)

The only way to have a lean condition is if the jet (restrictor) is too small to allow enough fuel for the amount of air volume in the mix. Too little air will not cause leaness. But it will cause stalling.

Re: Manifold Rubbers with & without restrictors
 

So the previous theory for restrictors fixes a problem of stalling at idle, not deccelerating nor blipping throttle ?

Do you believe in this theory ?

In 2000 the SH got a necked down intake boot in an effort to increase minimum air velocity.

Does it work? I don't know but it doesn't seem to have eliminated complaints about the stalling problem. However it does make more sense than twisting the vent tubes in a different direction.

I don't actually think the problem is fixable.

Re: Manifold Rubbers with & without restrictors
 

after removing air filter, I checked the manifold rubbers thru the trompets with a spot light, I didn't notice restricting metal pieces.
There are stamped MBB-G. (my VTR is a 2001 european model)
No restriction in there I think.

No but it was worth a try I suppose. I've reduced mine greatly by upping the idle to 1300.