2011 Season preparation...

Details from another post for Derek :-

My 2011 race prep is going slowly - due the cold weather and not going outside.
My to do list
001:- Cycle Parts. -Rebuild front wheel with lighter gauge spokes(butted too if a weight saving). New Tank seat and fairing to fit.
Engine. -has had a re-vamp (greater port timings,higher compression).

003:- Cycle Parts. -Rebuild rear(lightened hub)wheel with 10gauge spokes. New seat and fairing to fit.
Engine. -was new last season and features 1 large exhaust port and 2 small auxillaries,4 transfers and a large and lower inlet port (no tonsil needed). It has two water inlets into the water jacket one on the left side another on the left which ends up on the right inside the jacket. This I asked for because I felt the water was short circuiting out of the top of the head with minimal flow to the right side of the cylinder. Also features water cooled engine packing rings?? (like BTW circa 1990) This motor has had a pre-2011 revamp too -lower port timings/higher compression. Need to mend gearbox problem(3rd attempt coming up).

I intend to use which ever bike can produce the quicker lap times!

With regard to engines I think Water-cooling is not required bearing in mind our races are short and BTW barrels so good, I only want them because I have run boilers since 1985...

Hi Mike

very interetsing on the water jacket details mike,

Ports why single and auxilaries on exhaust port, and why you reducing the port timings.?

on the wheels blimey does having lighter spokes, make that much difference ?, can you actually tell the difference between wheels, when riding, or is it just the weight accelleration or is it the unsprung weight argument.?

What a Topic - the aircooled / watercooled argument ! was it Mick Scutt or was it George Harris who did a thesus on this subject, in one of the mags in the late 70'or 80's saying only needed for the TT, I'm sure others have said fair more on this subject/ and possibly more to say.

so is water cooling really needed to get HP out of a bantam to compete with the front runners, looking at peters bike as an example, his bike is aircooled but I think may have been watercooled as the ex Martin Parmer and always very quick, before it was sold to Nick Turner! I think as aircooled to nick who sold it to Pete on his return to the class about 12 months later early 80's ? from memory, it would be interetsing to hear Pete's and or Ted's view on this subject - air cooled or water cooled, subject.

not sure if others, have views on these subjects, I would be interetsted to know what others think on this. ?

regds Derek

Hi Derek you must be the only bantam tinkerer interested in things technical! Here are your questions with my answers:-

Q1 "Ports why single and auxilaries on exhaust port, and why you reducing the port timings.?"

A1 Can get a larger port area the auxillaries are for quicker opening. Reduced port duration to try and get a torquer motor (not so peaky).

Q2 "on the wheels blimey does having lighter spokes, make that much difference ?, can you actually tell the difference between wheels, when riding, or is it just the weight accelleration or is it the unsprung weight argument.?"

A2 I don't know? but I'll tell you when I've done it.

Q3 "What a Topic - the aircooled / watercooled argument ! was it Mick Scutt or was it George Harris who did a thesus on this subject, in one of the mags in the late 70'or 80's saying only needed for the TT, I'm sure others have said fair more on this subject/ and possibly more to say." and "so is water cooling really needed to get HP out of a bantam to compete with the front runners?

A3 Water-cooling not required...

Mike

In addition to Mikes comments,
I agree with Mike on the reduced port timings, but when you do this there is a bit of a fine line to draw between ridability and what you can get speed wise, higher port timings equal greater revs, but tighter powerband... If you can cope with slipping the clutch then you can cope with a higher ports!! But its a swine at tight circuits.
I prefer lower ports and easy riding as you concentrate on actual riding and not on what the clutch is doing.

As for water cooling... There is too much complication in my book, and far too many things to go wrong, and the short races we do its little problem to stay air cooled. I have gone down the deliberate route of keeping the BTW barrel as long and intact as possible to provide the largest heat sink, this is to try and keep the heat out of the crankcases as much as is feasible, however if you go down the route of high port timings then the slipping clutch increases the crankcase heat massively, which is another reason why a torque motor is more reliable! and also the crankcase water cooling motors that are now sneaking out into races.

Think heat management and you will not go too far wrong.

Just an opinion!
Alan

bettsd wrote:

on the wheels blimey does having lighter spokes, make that much difference ?, can you actually tell the difference between wheels, when riding, or is it just the weight accelleration or is it the unsprung weight argument.?

I cant remember the exact percentage but I read many moons ago that a reduction in live weight (any moving part of the power source) was several times more beneficial than a reduction in dead weight.
So reducing the weight of the rear wheel by one ounce would not only reduce unsprung weight but would also be several times more beneficial than reducing one ounce from the frame.

Hi Mike,
I also love the technical aspects of bantam racing, its a shame i havent yet cracked the code for reliability ! I tend to think that air cooled motors with BTW cylinders are fine for our race duration could be a bit different at a red hot Snetterton. Totally amazed about Petes motor just shows how diverse things are in our class.

Cheers Nick

You're right Ned...

Unsprung weight (wheels tyres brakes lower suspenion)is the most important part of a bike to shed weight from.
Reason being - handling!

Quote from Clymer Yamaha book :-

"While total weight reduction will improve performance, reduction of unsprung weight produces the greatest improvements in handling performance. A light wheel reacts more quickly to bumps than a heavy wheel and transmits less shock to the rest of the bike. Therefore, it has less effect in altering the primary(forward) direction of the machine and contributes less the rider fatigue."

I've weighed wheel rim's in the past and was surprised the find flanged 'borranis' to be the lightest!!

On my bikes i've used Gt185 hubs(like 002 when you raced it) as they are small and light, with a 12mm spindle, 10gauge spokes, a small(ish) 260mm brake disc and altered forks to accept a caliper without an extra mounting bracket and no front mudguard! - Every little helps.....

Mike

To reply to Derek.

I did buy Nick Turner's bike off him in late 1983. The engine was removed and along with the front forks and disc, built into my ex Max Ridge D7 chassis. The ex Nick Turner D5 frame plus the old ex Max Ridge long stroke engine was assembled, and sold to one Tim Partington for approx £100. He promptly sold the Oldani front brake for approx £250

However, I have no knowledge or recollection of my bike being Martin Palmer's before Nick's ownership. As far as I can recall, the engine was definitely South West Centre design and build. I am pretty sure Martin Palmer was affiliated to the Eastern Centre.

I am pretty sure its never been air coooled either, although radiator brackets would have disappeared along with the frame

Perhaps someone will come along and confirm / correct.

Nick Turner bought it off Martin Palmer - with cast 175 cylinder, sleeved with reed set up. It was fast then with Martin either winning/second in the inter 50 miler in 81/82? I think the bike was faster than him! He had an official 'South West Centre Beard' with no moustache and smoked a pipe! Looked like a fisherman! Unless I've got the wrong man.....

Mike

A very accurate characature of the Martin Palmer I know. Last saw him about 5 years ago at the South West Centre re-union. Not changed at all !

Chris

HI all

I thought Mike was talking about Nick Turner,? not Martin, it was only when chris replied, I got it !! Hmm
I think Nick went off to race a 250 rotax ? anyway thank you for the confirmation details.

So Pete:- I never new the engine your ruinning now is one you built, I always believed it to be Martins old bike - looked identical, if its not the Martin Palmer one then, his bike must still be sitting in a shed somewhere, a super quick and reliable bantam.

my preparation is going very slowly at the moment - no time, and too cold in the shed just purchased a new heater so that should sort it.

the site is not very active lately - ! everyone hibernating ?.

is anyone doing it differently in 2011- what are you doing on tuning and prep for this year -

!who is trying somthing new in 2011.

I was talking To Tom about transfer/ exhauset timings I was wondering if thigs had changed much so what are you running and what are your port timming. total open period will do - so we can come pare put on long stroke / 125 or 175 short stroke . !

Im curiouse to see if things have changed much, as people seem to be going no faster top speed but just getting there much quicker. ?

I am really sorry to hear about Russel moving on to greener pastures,
mind you Russ at your age im not surprised your not retiring ? LOL !! good luck,
I will miss your shots - "even though you never got me on my return meeting at Pembrey.

Russels shots - loaded straight after each /most meeting - some realy great pic's.

The mosts memorable pic's for me "mike powell - Highside on I think robbies bike at lydden, - Alan T-bone-ing Michael Brown at Lydden, cadwell, and a few others at Anglesea or was it the other way round. !! LOL

Regards

Derek

Hi Derek,
its a shame but it appears everyone currently racing wants to keep all their tuning secrets to themselves. So i'll email answers direct to you and keep my secrets aswell! I suppose some current racers don't know what they have got and how to measure it or change it anyway.

Some gearbox info (like i emailed you is now on the site) - tuning info - mikes gearbox page. Will add to it later...

Hope your build is coming along well? Sorted a bike for Ed ?

Hi Mike thanks

I like the gearbox bit well done to you.

I just spent 10minutes typing a repy, but lost it all. ? anyway ed's bike - comming along, I still got to get the btm end to Tom for modifying, what would people like me do without him.!

secrets on transfers ? yes I agree with you.!! - "a little short sited", but i have faith engineers always take a while to respond to questions, its the thinking time, I believe all engineer's need thinking time I know this as I was one a long time ago?. I'm away on holiday next week "long overdue", I was hoping to do some theory and calcs on the transfer port timings subject while away, good to get my memory going again on the subject of breathing, i have been trying to compare it to recent session down the pub and walking home after a few pints, i thinks it very similar subject, a lot of hot air movement. if you close your mouth and run every thing goes blank or stops - if you open wide this is ok but if you open even wider it makes no noticable difference, other than its not as loud breathing in and out, but the air velocity increases with a smaller mouth opening>? , I wish some one would expalin this to di !!

Anyway - I went out in the shed tonight at 10,0! for 30min, even with heater it was freezin,
1) I managed to sort the clutch cover
2) machine the carb bellmouth venture -entrance radii,
3) finish the new mikuni carb all plumbed in now,
so I'm making good progress, just need some jets, i did get some but blimey what a load of rubbish,
also I may well consider asking Alan Brown if he will help me with converting it to a power jet type, as he seems to know a lot about this subject and Mikuni's as he done a great deal of work of late on his own. "What do you think" Allen.?

also Im egerly awaiting my new secret helper /toy, ordered it 2 months ago due last week and late, mind you I got to learn how to get the best out of it first !

regards

Derek

talk again soon

Hi Derek,
No probs if you want help fitting the powerjet, just let me know when you are ready.
I am in the middle of sorting the James Cook 175 engine ready for the season, the gearbox was well crooked last year so hoping to get some sense out of it!
Cheers and contact me soon,
Alan

Hi alan any luck with that picture I sent you for me on here. !

Carb information Thank you, you just got to be a super super star, I have now contacted allens, I can get the kit - online shop, they could not give approx Jet ranges!, so come on what sizes do i need 170/180/190 /200/210 ?, for a mikuni 30mm round bowel slide type, may need some advice here.

for those interested ! I have a mikuni OE part modified float plugged pipe in btm photo's on way, and a new Mikuni 34mm new with pipe comming out of float bowel, I will send you a picture (alan), does your phone accept pics sent via business card or sms ?

Also great to here you so positive about your recovery, its just time.

Mike I really do feel you should publish those jucy bit's, what sent me is fantastic really interesting stuff so common the rest of you ! I always love the ports pipe detailed stuff, so be brave or are you brave enough to show others what we can not see.

is it really that secret, port timings, shapes, is a great subject.

I seen people copy exactly an engine, it never goes the same, there are always so many vairables.

remember we are not just talking to ourselves on here, its about the site being interesting for others to make them want to look in more regular, to stay or have a go. !

regards

Derek

Hi Derek,
Thats your Avatar sorted then!
You should start with 190 main jet and a 90 Power jet and fully expect the top end mixture to be very rich. If not then search for air leaks!! this is the safe way to do it.
Then adjust the balance of the mainjet and powerjet until you get good mid-range and good top end on FULL THROTTLE. Obviously doing the plug chops etc... better still get to the local dyno room and get it checked out there to give you the best overall settings.
Start with the needle in the centre setting, and you will very quickly know if it is weak or rich as the engine warms up whilst blipping the throttle (this is where it matters with needle setting), if you get delayed reaction to the throttle and a zinging feeling, then the setting is weak so raise the needle, if you bog down and wet the plug the setting is rich... so lower the needle.
The air screw setting hardly come into play at all, so leave this at some middle setting for best effect.
If you end up at a needle setting at the end of the needle notches, then buy a new richer/weaker needle to deal with the problem. Speak to Allen's Performance about this if it happens.
Hope this stuff helps!
Cheers,
Alan

just spotted this internet cafe at 2000meters ?

anyway hope the DD goes ok, wish I could be there.

aalan Avatar looks great, and thanks for the info on jetting.

Derek Betts