R3T derestricting

Tripps said:

Would you consider building one for me? (Touring)

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It requires trimming the bottom of the bearclaw an inch or two. I normally only build them for locals or engine builds. But I may get a chance to build a few when we get caught up in September.

GREAT, now I get to build a dozen more.

I would bet at least a dozen!

I have 3 spun aluminum velocity stacks built for the Rocket, and I am not sure how I want to use them, but I bet in a Pipercross somehow would work.

I am open to ideas.

bob

Power-Tripp said:

This really enhances output and response. But they are very time consuming to produce.

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Wayne.

There's a company called RAMAIR in the UK that has taken an interest in building an R3 solution. Colin is going to see the prototype on Monday. They will be moulding in a radius on the base - Foam filter. They have a plenum to get the size and shape right. Might be worth you while speaking with them do you think?

They're even taking about a different outer cover (bear-claw replacement) with air inlets.

Power-Tripp said:

Nox,
Yes, I have mapped all R3 models in various states of tune. Various exhausts and intake systems, all the way to built engines with custom intake and exhaust systems. What do you need?





-Wayne

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Wayne I was just looking for a map that gets the best from a stock Roadster before looking at modifications.

Cheers

I wouldn't care if I left the bearclaw right off!

barbagris said:

Wayne.

There's a company called RAMAIR in the UK that has taken an interest in building an R3 solution. Colin is going to see the prototype on Monday. They will be moulding in a radius on the base - Foam filter. They have a plenum to get the size and shape right. Might be worth you while speaking with them do you think?

They're even taking about a different outer cover (bear-claw replacement) with air inlets.

Click to expand...

There are some basic calculations used for determining plenum volume for specific engine designs. The problem with the R3 is much like many high performance V-twins in that the volume needs to be rather large - bigger than the bearclaw by a long shot. As for ram air, unless you are breaking 148 regularly, it just doesn't compare to what can be had from using cooler/denser air that is not pulled from the top of the engine and behind the radiator.

As a result, a plenum and inlet duct for the rocket would be a very large project, and might be so large as to rival the fuel tank.

Then again, my calculations may be completely wrong.
But I am more than willing to share what I have found.

If one calculates the plenum volume as if the intake system is a tunnel ram design and uses a venturi type inlet into the plenum (just not throttled) you will find the plenum volume needed for the R3 may not be as large as you would think. Once the throttles are open far enough to allow the passage of finite waves, any plenum resonances can be amplified by individual cylinder pulses. Of course resonance effects increase with air density so these designs are most effective at torque peak if partially throttled and again at W.O.T.

Also do not under-estimate the kenetic energy in a fast moving air mass. Too big is worse than too small if one is looking for the highest power average over the engine's operating range. This holds for both intake and exhaust systems.

If there is any doubt as to how powerful the resonances can be, ride your R3 and while slowly accelerating hold your left hand on the stock plastic plenum at the bottom of the bear claw and feel how the plenum pulses (not the vibration transfered from the rubber mounting sleeve but how the plenum expands and contracts) and how the pulses change with rpm and throttle position. Then at home take the bear claw off and see how stiff the plenum is. This will give you an idea of the energy present in those pulses.

The trick is to capture them and then use that energy to your advantage.

Speedy

Their project started based on a Pipercross attempt to make an under-claw single piece filter - Colin did some designs - I think the original went to Scott.

RAMAIR (the company not the concept) seems keener to do something. Time will tell. I'll mention your reply to Colin. Ramair Filters

But if we had something that LOOKED like a bearclaw but was open to the left (outer) side with a NACA duct? That'd cool charge.

Should avoid drawing in off the radiator too.

**** - I'm glad you're back and active again.

I do not underestimate plenum and dust resonance effects in the slightest. A plenum for an individual runnier intake is calculated a bit differently than for a tunnel ram. And the inlet duct length and shape are just as important as the volume and shape. I have built and modified more than a few.

The issue becomes where and how much does it help fill cylinders, as well as where and how much does it hinder output. And does it increase or decrease transient response.

The largest issue with the rocket is the stock exhaust. A highly effective plenum and inlet duct is not going to have the effect that a well designed exhaust system provides. Only then do we need to worry about plenum and duct effect. Cart before horse and all that.

I meant my response as a general response to all readers about the topic and not a criticism of anybody. Wayne, I would hope you are more aware than most and am not questioning your post. However, I think many do under-estimate the energies involved and therefore think "bigger is better," and most often to the detriment of what they hope to achieve.

There is a very fine line between individual runner designs with a common up-stream plenum and tunnel ram designs. Mostly a matter of degree in one area or another and not type in my experience.

Agreed that the stock R3 exhaust is utilitarian. Good for getting exhaust gases quiet and behind the rider, but not much else.

Good throttle response, mid-range power, broad but declining torque curve, and rpm range are what separates a fun and fast street ride from that of throwing a leg over a 70's Kawaski 3 cylinder 2-stroke: great power, itty bitty power band, but useless for anything but full throttle, 1/4 mile, acceleration.