.................*NICK BRAMLEY'S 186CC ENGINE*.............

Good Morning Trevor,

Thank you for the Great input for more power!

I had not realised we could take advantages in that area!

I just measured our actual test piston crown height and it measures 3.965mm

We did not use the original as it required a much more accurate crown shape (comes as cast)!

https://2img.net/h/s6.postimg.cc/8nst1hu1d/BANTAM_20_BHP_ENGINE_DATA_Page_4.jpg

As you say lots more "free" horsepower available!................

By the way,Debb stumbled in the garden Saturday morning and broke her neck!

She will be ok with a 12 week rest period and we are working on solutions to cope with it!

Keep up the Good Work!

All the Best!

Rex

Oh dear, so sorry to hear of Deb`s miss-hap in the garden it does sound rather nasty, please give her my best wishes for a full and speedy recovery. Sounds like you may have to be "mum" for a while now!

Trevor

Rex , give my best wishes to deb, hope she is as comfortable as possible.

Hi Trevor and Nigel,

Thank you for all your Good Wishes for Debb!

I just brought her home from Leicester Royal Infirmary and she thanks everyone for their kind messages!

Have a peaceful night!

Rex

Good Morning All!

Time for tea and more information!

Below is a drawing of Nick's prototype silencer as raced!

The packing was fibre glass strands gently packed!

It was very close to the maximum DBA so a future one would be a slightly larger body diameter!...

The actual stinger bore is 23.4mm.

Have a Great Weekend!

Rex

More top-notch technical info from Rex, no excuses now for marginal decibel reduction!

The most effective silencer I ever saw and heard was for a 125cc kart, it had a length of 400mm, an outside diameter of plastic tube of 80mm and a core diameter of 35mm with a high perforation count.

A large diameter core exposes the exhaust wave fronts to more of the packaging material surface area, thus reducing noise.
A smaller exit pipe than the core will increase wave amplitude and make MORE noise!

When the original, elementary silencing set up was removed from the w/c exhaust and replaced with the tail pipe and silencer set up from an RS Honda we experienced a small and unexpected performance increase. Quieter and quicker, a real double plus!

Trevor

ive just started o use a tz350 silencer , and Mallory was the first time I've passed in the 1st visit to the meter man !  96db

Oh dear Dan.... the noise testing at Mallory was done by the local environmental health dept ( or under their supervision)....and fortunately/unfortunately depending on your view point they set the test gear to rapid instead of slow mode hence all noise reading were effectively 10db low so your 96 is really 106 just over where as my 93 would in reality be 103db...funny old game this racing...

that figures!

How was the test done? Not drive-by surely with those high figures.

At race tracks it always seems a bit suspect -- to me -- holding a no-load speed constant -- etc... etc... I saw a stationary test at Lydden (2005) where the tester was standing at about a 1/2 a meter from the tail pipe -- the engine obviously running under no-load. The rider was having difficulty at keeping his motor running at a constant speed....!
There seem to be a confusing number of different tests these days. I remember it was -- for commercial vehicles -- a drive-by test and the limit was 80dBa with the accoustics tester at 7.5m from the vehicle passing at some constant speed (forget now ...?)

KHD -- my old German parent  company had a special room for engine noise with knobbly bits all round the walls  and on the ceiling. At one time -- in the early 70s -- running the engine at the engine rated power on the dyno 90dBa was the limit but I think think this has been changed since then.

In Montreal in the winter we used a frozen lake with flat land all round to test out bare engine screaming at no-load and a truck with our engine installed doing pass-by test. The lake must have been 5 miles long by 4 miles wide and we bravely criticised our HQ´s methods saying they had 3 dBa more than they should have had `cos we had done the testing proper like ... That argument went on for decades....

The dBa scale is logarithmic which means 3 dBa at the top end is not the same amount of noise difference at lower readings and since a typical Canning Factory was 101 dBa we had that on a tape-recorder. which we used to play alongside our dead engine  before doing  the engine test. Such püroduces a difference of attitude in the testers. Perhaps such should be tried at race tracks.

Great fun!

Cheers!

Good Morning Trevor, Dan, John and All!

Debb thankfully is getting on well and has accepted the compulsory 12 week recovery period!

There appears to be no nerve damage at all and a full recovery is forecast!..

That is indeed a Blessing!....

Now it is tea break time and a Great chance to offer some more technical on the "Low Revver" 186cc!..



This is the 2-stage diffuser pipe Nick ran at the June 2014! Mallory meeting!



This one shows some technical spec. and Nick's comments were.. "Ok but could do with an extra 500 rpm "rev-on".

When we checked, the tacho recall read 8340rpm --More work needed!....

It is always encouraging to get feedback that backs up the theory, but we stay ready to learn any new twists of 2 stroke development!..........

Have a Wonderful  Day!

Rex

Rex,
     Shorten the rear cone, lengthen the diffuser!

The pipe has two major functions, one to return a plugging pulse of sufficient magnitude to forcibly return escaped mixture that is contained in the exhaust duct, back into the cylinder. Second, to produce a pressure differential of sufficient length and depth to suck mixture from the case into the cylinder. The pipe has to substitute for the lack of adequate case pumping. However, if you can arrange for a pump prior to the pipe working in the power range it is designed for you might just get the best of both worlds. The pump becomes a resonator when engine revs are into the power band!
One thing I forgot to point out was that the parallel section produces no wave reactions, and only `times` the two cone reflections, the longer it is the less effective the other two phases will be.

What happens to the mixture when it is in the cylinder is quite another matter?

Trevor

Hello Trevor and All,

I must say you have some interesting points on the pipe there and considering the limited development time on this setup, Nick reckons it already has promise for the novice!

To me it is only a fast road tune..............

His intention was to build a 175 to the formula on the KISS method and see how it fared with other ones?

There are still many avenues to explore (including exhaust testing), in line with our company's aim to have powerful (in Bantam terms!),reliable, easy to ride equipment available to any one in the world who might be interested!

By the way, how does our crank BMEP compare with the other Bantams?

Nick says track top speed on 17/49 sprockets is around 90 Mph

Have a Great Day!

Rex and mending Debb!..................

Rex,
Let me say at the outset how much I applaud and admire your support of the Bantam Racing cause and your efforts at keeping the project within reach of the newcomer`s pocket and abilities. Include also the wealth of priceless technical information, which is of so much assistance to all Bantam enthusiasts, that has been posted here on the Forum.

Nick is a very fine and experienced rider and his judgement and opinions are to be respected, indeed given the right machine there are more championships awaiting him! But do we have a conflict here, on the one hand Nick is a racer and as you suggest, you regard the thing as a road bike?

Up to as much as 50% of the power of a well sorted Bantam is attributable to the design and function of the exhaust system. As a single entity, no other design feature has such a fundamental impact.
It costs no more to make a good, ball-park pipe than one that clearly falls outside of that parameter. Looking at this from another perspective, the pipe can only capitalize on what the remainder of the engine spec gives it in terms of wave energy. From the instant the exhaust port cracks opens that energy is being consumed, you cannot allow that energy to dissipate too much without using it to advantage, and that omission will be reflected in track performance.

I would think that the BMEP generated by your engine is comparable to that of most of the other 175/186 runners, the best of the 125 engines will better this, and the 22rwhp area is where most engines are.

For a fast road bike, 90mph sounds pretty impressive to me!

Don`t forget Rex, that racing is not about being fast, it`s about not being slow…..anywhere!

Relieved to hear that Deb is feeling somewhat better now and on the mend, a convalescence of 3 months cruising the Med should do the trick!

Trevor

Good Evening Trevor,

Nick and I welcome your valuable input on his 186cc efforts!

No conflict here - only massive co-operation!

Part of the brief was to consider its potential as an excellent starter race Bantam and also as an excellent fast road tune kit!

His words spelled it out--"Rides like a road bike with grunt everywhere!"

Mick Grant heartily agreed after a road test of 25 minutes on the Leicestershire lanes pre Nick's race efforts!

Not many words, but masses of smiles, with a proviso of a slight rich spot at 1/4 throttle!

Plenty to keep us all fired up!......................

All the best!...........Rex

john bass wrote:

How was the test done? Not drive-by surely with those high figures.

At race tracks it always seems a bit suspect -- to me -- holding a no-load speed !

John when question methods it's worth knowing how noise testing came to be. It wasn't the government it was the ACU that introduced them.  Those of us that considered the crackle of an open exhaust as music to our ears thought the ACU bosses were clueless boring old farts. The reality was they had envisaged the noise abatement society and do gooders either banning or enforcing serious restrictions on the sport. So they introduced tests with levels that were fairly easy to obtain to show the powers-that-be ours was a responsible controlled sport. So I don't think they were too fussed how tests were done as long as they were seen to be doing right. There was even talk in the early days of having different levels for two strokes and four strokes because the sound of one traveled further than the other !

Well done Ned -- still with us and making the right noises. I never really got to understand noise as a scientific
subject -- to me it was a new regulation we in engine development had to comply with. Nowadays tyre noise is
frequently more irritating than exhaust as cars rush by with their revs at barely 2500rpm. Its the rat-a-tat that got so many agitated -- what a beautiful sound it was from Icarus-1 at 0700 hours of a cool crisp morning. There was some twit at Llandow who did it at 0330hrs who I would gladly have murdered. Scuffling of feet, batt-atatt-plop-plop -- poof-poof and dakk-dakk-dakk bweehowee-- rat-a-tatt ... Something like that! Then total silence when I was thinking back to sleep Joihn-Boy -- but oh no! the whole ruddy thing happened all over again plus a few barrack-room inflectives from others try to kip.

We did a subjective study in Montreal on various nasty-noise sources and decided the canning-factory was the most annoying although some other contraptions were positively noisier relative the dBa measurement. Funny thing is that operators of noisy machines hardly ever wear noise protection.

Not so funny was the way Speedway was dealt its death-blow by parents moaning about their kids not being able to sleep. The first court case took a long time getting itself sorted but with the precedent fixed it was not long that others took it up and Stadium after Stadium hda to close down. I can remember going to West Ham, Harringay, Wembley, New Cross, Wimbledon and other London Speedway Stadiums to follow the Hammers -- just after the war .... Sort of silly hero-worship thing....

At the moment we have a civil engineering company installing a sewage filtration plant in the forest about two hundred metres from our flat and no one can stop them with their horrendous noise making during `supposed silent hours´ here.

Cheers!

JayBee....

Then there is the matter of how unsilenced racers affected the riders' hearing. Back in the early nineteen sixties I was blissfully unaware of the damage I was inflicting on one of my precious senses. It took two years to realise that the ringing in my ears was not going to go away. I started wearing ear plugs etc. but it was too late. I have suffered from constant, unabated tinnitus, and poor hearing, for the last fifty-two years.

Sorry about that John ....

Centuries ago we went into Chiselhurst Caves and Lonnie Donnegon   among a lot of others `musicians´ really hurt our ears with their pop renderings....

Interesting thing I heard last year -- with the new F1 regs was that spectators were complaining about the  turbochaerged engines not sounding like racing engines any more. Not loud enough was said on German TV....

Actually with Icarus-1, after I fitted a fairing I could hear rattles and clatterings I´d not heard when Icarus was running naked.

Yesterday we came across a bulldozer demolishing a building and that noise was deafening yet the dozer driver was not wearing ear protection I wonder why the law-makers don´t make the wearing of ear protectors compulsory as they did the wearing of helmets for motorcyclists.

Cheers!

Good Morning Trevor,

Thank you for your valuable input into the Bantam racing scene over the years!

Bantam Racing has come a long way and the potential is now Great for it to Grow enormously with the involvement of key experienced individuals who have been involved with the development of championship- winning machines!......

Would you be interested in building your own 186cc to add another bike to the grid?

If that appeals, we are in a fortunate position to assist with raw materials, say alloy cylinder casting, alloy Todd head, single ring pistons (vast stock), con rod kit (Maico or KTM), clutch plates, primary chain, PVL ignition, Mikuni carburettor, 3 speed close ratio gearbox and other items possibly needed!

If these were available on a no charge basis we could help in a small way if you felt it possible?

The 175 class could certainly become more attractive to future riders with more practical input from experienced tuners?

What do you think?

Have a Great Day!

Rex

PS.................Debb has her eyes on a holiday in Norway to see the Northern Lights in November as a treat!

Hi All,

A quick note in the busy schedule from Sunny Barwell!

Debb is currently working on more health challenges and has eyes firmly fixed on

the cruise!.....

Nick's 186cc engine will be at Cadwell this weekend with Rob Duesbury at the helm!

Have a Great Fun Weekend! .......................Rex

Hi All,

Nick Bramley generously prepared his 186CC engine for Rob Duesbury to race at Cadwell over the Weekend!

The last race on Sunday produced a well earned second place for Rob after being last away at the start!

Well done Rob and Nick for a sterling effort!.......................

Cheers!..................Rex

Thank you!
Wünderbar
The other pics & videos as as well...
Who won what Though?????
Cheers!
JayBee!

the whole seasons results


http://www.theresults.co.uk/theresults/Results/2015/Motorsport/bhr-round6.pdf   cadwell

http://www.theresults.co.uk/theresults/Results/2015/Motorsport/bhr-round5.pdf   darley

http://www.theresults.co.uk/theresults/Results/2015/Motorsport/bhr-round4.pdf lydden

http://www.theresults.co.uk/theresults/Results/2015/Motorsport/bhr-round3.pdf  croft

http://www.theresults.co.uk/theresults/Results/2015/Motorsport/bhr-round2.pdf anglesey

http://www.theresults.co.uk/theresults/Results/2015/Motorsport/bhr-round1.pdf mallory

Hi All,

A Great thanks to all for a Wonderful Cadwell Event!

Nick's motor now apart for checking and some photos for the records!.....









Nick has now suggested to increase top speed on Park Straight from 90mph to 100 mph for next season, so that is now the Goal!............

He wants to continue for us to publish progress and reckons 25Hp should suffice!.....

All The Best!.............Rex