The very latest and no technical two stroke tuning topic !

message for john senddle just spotted your gearing suggestion for 22/25 top gear long fast tracks, what is this john a 125 or 190

most 125 pulling 10,000 i think Iread earlier your 125 pulls to over 10,500 so at 15x49 would be doing 109.8mph, do you agree with my calc's on this ?

Hi Bantam Fanatics,
As a fellow W. Australian I was interested to read your letter from Dave King. I remember seeing his machine in use at Wanneroo race track many years ago and at the Round the houses racing at York even longer ago( on which occasion he was having great difficulty starting it)
Nice to know you are still trying, Dave.
My question is. Why are Disc valve engines not allowed in Bantam racing in the UK. when Reed valves and multiple ports are .
All of this is purely academic in my case as my tuning methods are quite basic, with no fancy add-ons.

Mike.

Derek,

I have 25/22 top gears in my shortstroke watercooled 125, 24/23 in longstroke 185.

Top speed really depends on what tyres you are using and their outside radius.

With my rear wheel set up, 15/49 at 10,500 gives 95.3mph

fowl fellow wrote:

My question is. Why are Disc valve engines not allowed in Bantam racing in the UK. when Reed valves and multiple ports are .
All of this is purely academic in my case as my tuning methods are quite basic, with no fancy add-ons.

Mike.

Hi Mike. It goes back to the early regs for formula Bantams. The original rules were set for low cost and simple garden shed engineering. It took many debates at AGMs before fairings or reed valves were allowed.
Incidentally the main reason for allowing fairings was not for added speed, but to encourage more youngsters to join the club by making Bantams look more modern.

Interesting comments Derek... Don't know what others thinK?

I was interested in saving weight to increase performance/handling of bike, not having heavy bantams (they are all heavy) made heavier..

I noticed Lightweight Peter Tibbits won this year..

I think Peters giving me a 3 or 4 stone advantage but i think i'm giving him a 5bhp advantage..

I think things/rules should remain unchanged, i think people race bantams because they like bantams... admitedly the low power output of a bantam favours the smaller rider... but we all knew that before we started..

What do people think of a minimum Rider/Machine weight?

I agree with Mike,
We have had the overall weight rule idea banded about many times, and it will end up making no difference at all! anyway who is going to stand around with a set of bath scales after every race??
The rules seem to work well, and allow the home brew racer to develop his machine in the shed, and it is possible to get to the front of the races if you get down to the work required, but as in all racing, it ain't easy! the easier class is the 175 for beginners, the "fairy" class where the real development takes place is the 125 take your choice....

Never had so much fun with a chicken
Cheers
Alan

ok - I think this is a really interesting subject - clearly many differences of opinion, its a healthy subject to debate, as is other subjects like the crank inertia /carburation, gearboxe's /lightweight wheels, and tyres plus all the other really interesting stuff been on here recently.

All these subjects allow us to help each other to ride faster, more reliably and safer. I feel its important to review all topics like these, even the one's we prefer not to. - Makes our site interesting, beside what other forum do you see debating tuning topics like these. Its also a good marketing stratergy to cover these topics, especialy one's where there are differences of opinion. if we all agreed it would be boring.

Now "my opinion" is that a low weigtht rider does have an advantage, "a big advantage" ? on excelleration, so how big an advantage is big? -
Does anyone really know!! , who amongst us has done the sum's ? , can some one do or show the sums, I bought it up because its a big disadvantge for me, as I'm struggling to lose weight, I'm 50 this year, I returned last year, its my intention to stay, I really enjoyed my return however I want to compete, its not easy to be at a disadvantage because of your weight, in 125 British BSB and the minimoto racing world it became an issue, but was resolved fairly, also in Karting and F1, So i dont believe we should dissmiss this subject too early.

Actually I think Ian made a good responce, a very good suggestion about rider weight, I dont think he was acurrate with the weight, however I would say closer to 13/13.5 stone is a more realistic figure.

I remeber James cook put some detail on here about the weight he was planning to lose, would be equvalent to an extra 3 BHP ?- how did he come obout this figure.

it would be good to tabulate, QTY of weight to BHP?.

Now one final issue, I do need some more help, does anyone know where I can get some slimming tablets, im not planning on taking them all at once though !.

regards Derek

Derek my feelings are,
yes being heavier is a disadvantage but i think their are other more pressing areas if changes had to be made, one being to keep interest and grid numbers as high as possible.
my opinion on the weight issue is that you will always have someone lighter or heavier than yourself. Yes you could ballast every bike but in reality its virtually impossible.all our bikes are different so where would we mount the weight.some riders would need alot ?
how would it be policed? time is always tight on race days.
It would have to meet acu regs? i could go on but hope you get my drift.
I think that the only way to win is to have the complete package and have seen lets say larger guys win many races ,yes small capacity classes do suit small riders but steve rides real good and he isnt small .
keep plugging away your get up the front if you really want to.Just to let you know i still consider myself as a newbie at bantam racing and think its one of the harder forms of racing to make your mark in.My problems are as follows;reliabilty,handling,gearing,jetting,ability but my weights ok.so weight aside loads of areas for improvement . If you have a good package then ride fast & your win races.Easy.

best of luck to everyone this year Nick

Derek

Should say I agree with Nick entirely, my weight was not an issue last year because I couldn't resolve my gearbox issues, have to finish races first and then put everything else together.

I did have a great race at Lydden with Mr Bramley and pinched it at the line by a hairs breadth despite the fact he weighs about as much as my left buttock weight is just one of the many factors.

That said the benefit here is its cheap to do and has value both on the track and off and I can improve power to weight without putting extra load on the engine.

Anyway its just simple maths

Bike max bhp / total weight = power to weight ratio

so Bike and rider weigh 100kg each bike makes 25 bhp

25/(100+100) = 0.125

Rider slims down to 80 kg

25/(100+80) = 0.139

A quick bit of formula transposition and we can work out the total bhp required for our 100 kg rider to achieve the same power to weight ratio in this case its 27.75bhp

27.75/(100+100) = 0.139

So in this case a rider shedding 20kg (thats a lot, but can come off the bike as well) has the same gain as if they found another 2.75bhp at least in terms of power to weight ratio.


James

Hi Nick met you at mallory last year practice for first time, some interesting comments agree with the reliability stuff, James love the maths. ?based on your maths (I recon Im between 50 to 60 kg heavier bike rider combined than others) meaning I would need to find 8BHP more just to excellerate at the same rate. Anyway looks like this subjects been throttled enough, although I do agree on the reliability, gearbox, and the rest as being just as important.

would like to pick another subject to discuss with others found this last one really interesting, like nick and james said reliability is a great subject. and one for every one.

Mind you, you never see Peter Tibbitts suffering break downs or reliabilty issues, Mike's is also very good, but Peters is what can only be discribed as an amazing record for reliability. I have only been whatching again since 2007, but when I was racing many years earlier, Peter reliability record was simply unberlevable, I can only remeber one insident the 1989 50 miler where peter did stop while comming off the line, I think some one told me he had cracked a piston skirt, after the race was stopped and re-started, if my memory serves me correctly.

be interesting to ask Peter to comment on what he feels are the main topics and issues for discussion on the reasons other than merticulaus prep- so Peter what are the main reasons for this record, Is it a routeen for checking /is it knowledge / ability to spot a problem before it causes a break down, most of the top scorers milage parts, but this can not be the reason for Peters trully remarkable record of reliability, is it he changes more often, or is it down to meticulaus prep in certain areas, combined with his knowledge, - I can not be drawn to believe luck has anything to do with it.

a trully amazing record.

regards Derek

Hi
Mike/ Allan do you think we could pursuade Peter T, to post a responce on ? - it would be great to get a responce or his thoughts on this last post, but better still if he would tell us his routeen's. ?
1) post race day, checks
2) during meeting checks
3) after meeting checks ?
if he is trying a new exhaust what does he look for / if he is trying new jetting what is he looking at or for. ?
Any process of checks imeadiatly before /after races and meetings, either before he leaves to start his journey, ?or during this could be on, tyres / jetting /plugs / cleaning routeen ? anything that may be usfull for us to follow. o and the weather ?

would be good and I'm sure, helpful to all others contemplating, as it appears we have a few more comming out the wood, we never new who are building Formula Bantams to race.

My feeling on this is the more the front guys post - you Peter ian allan, post technical the better it is for others contemplating a trip into the unknown, and joining in the fun and heart-acke.

Regards Derek

For me the most important things at a meeting after each time i go out is to. (apart from mods)

1. Clean and check every part of the bike (cracks, broken spokes, Leaks, cables, throttle closure, clutch free play, all bolts in and tight) bits missing or loose make you slower nor DNF.
2. Battery/electrical connections and voltage
3. Plug/ data logger
4. Tyre pressure
5. Fuel
6. water level (bike Dependant)

This is not all i do but the main checks between rides and then barrel off at end of day and CHECK CHECK CHECK. when happy all you have to do is think about racing

Hi Ian

what tyres - you check, do you ever find it different ? what pressure are you running dry ? / wet ? front and rear.

also what voltage - 6 or 12 when do you consider the level drops to a point it needs charging. ?? I know your running EM. does this alter the carburation as your going along, turning off the power jet or just altering the ingnition mapping. ?

you check every bolt after a race or a meeting ? or after each time you go out inc practice. ? or do you check for problem bolts that tend to come lose? from time to time. ?

what fuel you running,
what oil and mixture do you find works best ?


but I think your check list is a great Ian, I have to add one item to mine now.

kind regards

Derek

Ian, whats a Data Logger ?????????

Ian , Derek and I are waiting with baited breath for your answers!!

How heavy is the data logger? Does it look like a log? like with bark?

Mike

Hi Mike did'nt know you were waiting for us two, sorry can you spell it out as not sure what your asking, besides you could be brave like trevor Or Alan and say it the way it is ? ouch!! you asked for it. - Now moving on - Ian what's this data logging thing about as i donn't like the private hidden messages I like to know what is being said, this way I know how to respond like yes or no!! .

Moving on again --- " hey Mike" you seen Trevor's last post ??WOW ??, interesting stuff" far better than all this Testosterone YOUR PAIR KEEP SWAPPING, , Mind you Alan WAY OUT IN FRONT ON THIS ISSUE, on the same wave length, as he told me this, about tail pipe diameter a few weeks ago. ! does anyone remeber this, clearly Trevor is making some interesting posts, I just wish those of you who are responding to me BY PM would just post directly" NO ONE IS going to get upset - we need to remeber this forum is about furthering our cause,


Now looks like we are assebling a Formula Bantam Racing PIPE - so far 38mm front pipe tail pipe 22/23 and from the people that matter and not affraid to tell, besides I always feel he who is open either has nothis to offer or knows everything and is not affraid of losing an advantage beacause he knows his knowledge will always give him an advantage when required.

they already know it. !

Oi Mike "love the pictures by the way" -

Best regards To all those posting - just keep it going - Derek.

Derek are you paranoid?? sometimes there isn't an underlying secret message - sometimes its an art-form called 'talking the piss'! lol.... thou i'm interested in Ian's answers to your questions??

I need a stiff drink before reading Trevors post because to tell the truth its over the top of my head!! But one good thing I gleened was the carboned up pipe bit, my brace of pipes were made by Andy Bacon (ABCON)
in 94 and 98 and never been de-coked? Perhaps there a bhp or two there??

And told you in a post following your rolling road session that your tailpipe was too small ! Where's my thanks?? lol..

Now you look like a man who get heavily into data logging I feel ??

Mike

Hi Mike ( we need to talk seriosly)

I agree with you though but, "did you ever hear of the saying" - "counter taking the Piss" - by taking the piss" by "you go first" - but moviung on, I actually agree with Ian, on this.?

Ian we are all interested in this subject, (and Mike- fire your own bullets in future)

Ian we all reget having a dog, as sometimes we need to have it put down, especially when it's in to much pain, so put him/and us out of misery by telling us what he's talking about.

Regards Derek

sorry its been a few days but work comes first.

Derek here goes.

1. Tyre pressures are 26 front and 28 rear in wet and dry
2. anything under 10.5 volts with ignition and pump running gets changed (practice and 2 races)
3. Ignition has 2 curves on handlebar with no electronic power jet yet have tried just not persisted.
4. I check all obvious bolts and nuts after each outing at all meetings and after
5. 100% avgass at 20/1
6. I have 2 dater loggers one is the wife who writes the notes the other is a small white box attached to the fairing mount that can take data from a number of sensors on the bike but only 3 at a time ie. exhaust temp, max revs and water temp shown in a continues graph for 30 mins. Can then see what changes to ignition, jetting/ carb size, exhaust, gearing have done. you get the idea.

Peter can tell you a lot more about loggers he has been using them since i started racing in 98.

Derek,

If youre looking for something cheap and cheerful, the 4 channel Picaxe datalogger is about £30 assembled, work in progress........



James

James,

Interesting bit of kit considering whats on the board and the price, hope it works out for you.



Eddie

Ian, are you sure your not on fuel ratio 25/1? you were early last season....

Oi Mike stop it !!!!!!!!!!!!!


james Ian well were do I start - Ian you posted first absolutley brilliant stuff, well done to you,
1) factual and helpful detail, and brave.
2) informative / "yes absolutely"
3) well put" but with " two Vee's from / to mike" that an't a reed vale either, ? (sorry mike could not think of any other way of putting this. !!!).

james come on tell us more on that picture, as it looks like my son's radio controlled car, without the cover on ?
what does it do
what does it check
next time I going to load a picture of a fox eye to eye with a cobra snake ? see if you all say wow looks interesting for the comming season's opener?

jAMES sorry but both Barrels, against a brave and good post.

rgds Derek

Derek

you could try http://www.rev-ed.co.uk/picaxe/

It is as described a four channel data logger with a couple of built in features like light level and temperature, it has a small memory which is expandable a to d converter etc.

There is also free programming software and as far as I am aware it is widely used in schools electronics so its simple and well supported, a bit like me in my leathers

In terms of Bantams what will it do depends on the sensors you buy and what you want to measure but if you can achieve an output range of 0 - 5 v this device will sample and record

I have so far measured and recorded the temperature and light level in my house overnight, so really is work in progress.

The master plan is to link the output from this device to software (database) I am writing to record the data and cross reference it with design notes.


James

i'm sticking with good old fashioned method of pure tuning, its easier, less complex, besides i have seen all the data you can get from these in other worlds, it is in my opinion not required to build a fast reliable bantam that can compete,
so back to basic's theory, and continuing with my exhaust design formula, and save my pennies for the Dyno.

if your that way inclined must be interesting but the bloke with the current fastest Bantam, and it hasn't got any of these measuring Gismo's, and unless you really know what your doing with the results, as Al says no good having the information if you then dont know what to do with it, or what its really telling you,

so I'm thinking for the new or re/ starter bantam rider tuner, this is too much complexity and more that can/will go wrong.

better sticking with simple practices like the original tuning magazine still very good and all you really need.


for instence "MY" THEORY!!!!!!!!! BASED ON MY WIDE RANGE OF EXPERTISE AND WORLDLY EXPERTISE ON THIS ANY ANY OTHER SUBJECT YOU WISH TO DISCUSS" WHAT FOR IT - power is produced in the cylinder, with a good pipe, and A good rider "unbeatable"
a hard combination to disagree with, and in the over complicated "Gismo's" that I just can not see eye to eye with I feel as with traction control in other sports we need to "BAN THE USE OF THEM" as with enough money they can give an unfair advantage to those who have the knowledge, just like a feather weight rider or wheels ? k


please tell me if you disagree !! anyone !

KIND Regards Derek