Triumphrat

Cyclops116 · 06-01-2012, 12:29 PM

What exactly does the Baffle do? And do Carbed Bonnies have them?

Forchetto · 06-01-2012, 12:50 PM

Quote:

Originally Posted by Cyclops116

What exactly does the Baffle do? And do Carbed Bonnies have them?

Yes, carbed bikes have an identical device.

For a long time it was thought to be some sort of intake air speeding-up device to improve cylinder filling and low down torque.

The likes of Pieman at Triumph Twin Power and others did a lot of testing and found that it does nothing for torque, in fact on the dyno there's no difference until 4.5k rpm or so when the absence of this device makes a difference (about +3 bhp I think).

It's really a sound control device. Manufacturers are ever more constrained in the levels of emissions and noise that they're allowed. Intake noise is a very important part of the overall sound produced by a bike.

It should be called a Resonator rather than a restrictor really, although it also acts like a restrictor.

You get similar devices in exhaust systems. Here's a detailed explanation of how they work as fitted to an exhaust system, with a nice animated GIF:

http://auto.howstuffworks.com/muffler4.htm

Cyclops116 · 06-01-2012, 01:14 PM

WOW! Never really knew how mufflers worked. I actually thought they had insulation inside that absorbed the sound. So motorcycle mufflers are mor like glasspacks than standard car mufflers?
So this baffle, and mufflers for that matter, work on the same concept of the baffles in a tanker truck. In a tank they compartmentalize the water, with offset holes in the baffle walls, to keep the waves from getting too large and tipping the truck while it's moving.
Would I need to Re-Jet if I remove the baffle.

STW · 06-02-2012, 12:54 AM

great pics Thruxton155. thanks.

Good to know it's a resonator, and for sound control. thanks Forchetto.

AlexBB · 12-05-2012, 11:15 AM

Hi Guys,
Well even though this is an old thread I thought I would add my (recent) experience to it.

I used this thread as a basis to remove the baffle on my 2006 790cc Carb Bonnie, and I have to say it was really helpful. Well to start.....

I say that as in the end I decided to remove the rear wheel and remove the complete air box from the bike. I will explain later.

It is possible to remove the baffle without removing the air box as in the thread above, though very hard without removing the battery and lowering the box and moving it backwards..... BUT on a 6 year old bike that brown gunky glue that Triumph used to seal the air box side had stuck like S**t to the proverbial blanket

... it was really hard to remove and very difficult with the air box in place on the bike.

So I gave in, removed the rear wheel & mudguard, then removed the complete air box from the bike.
I also removed the left hand side cover and the carb rubbers (velocity stacks) and cleaned everything up, gave it all a good soak in hot water and washing up liquid and then scraped and picked off all the old glue. There are rubber seals in the gasket groove and I removed these and also soaked in hot water and dish wash liquid to soften the glue and remove it....

I spoke with the parts sales guy at my local Triumph dealer and he said he had come across this before, (apparently a guy with a scrambler had flooded the air box and needed to remove and strip it to clean it out) he had checked with the factory at that time and they had said they use any sealer they have to hand to seal the air boxes, he advised using the black silicon from Kawasaki (Kawaseal) or the one Yamaha do, they use the Kawasaki one at his dealership as Triumph don't stock one...

So anyway...
When all was clean and dry I re-assembled it all using automotive black silicon sealer on the gaskets and to seat the rubber carb connectors (velocity stacks)..

All round it took about 2 1/2 hours from getting the rear wheel out to getting it back in again and doing a test run (not including going out to fetch the silicon sealer) and I have to say I am much happier with the result

Also the other upsides with doing it this way were;

It was easier to remove the float bowls and fit the new #120 jets
I had easy access to the centre frame tube and rear of the gear box etc.. to give it a clean
It was real easy to refit the air box screws and ensure they were all snug

Well I hope my experience helps someone else out... If I were to do this job again I would without doubt plan to remove the air box from the start...

PieMan · 12-05-2012, 12:06 PM

Alex, as you've removed the AB baffle, 120 mains will likely be too small unless you've left the snorkel in place and are using factory silencers.

AlexBB · 12-05-2012, 01:18 PM

Hi Mike,
Thanks for the heads up on the #120's...

I have TOR silencers and K&N filter with the snorkel and baffle removed.

I have followed the Jenks tuning guide and Version 6a Feb 2007 lists #120 or #125 with a 40 pilot, 2 1/2 turns on the pilot screw and 1 shim with the stock NFCD needle.

Its not an exact match to what I have in the table of the Jenks guide as the #125 are listed for 'Free Flow' exhausts, not the TOR's, so I thought I would start with the #120 and see how it goes..

PieMan · 12-05-2012, 03:24 PM

Much of the jetting in that guide was extrapolated from a few dyno runs, much more in depth work has been carried out since. You may be better starting at 128-130 mains with 40 pilots and one 0.5mm shim under the needles.

luckyduck · 12-05-2012, 03:31 PM

I have snorkel removed, baffle removed, and inlet enlarged. I'm running 135 mains.

AlexBB · 12-05-2012, 06:24 PM

Looks like I will ordering some larger jets then!

The jump from the #110 stock jets seems big from what I have done in the past on other bikes but guess the Bonnies must be really strangled when stock...

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