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 returning to bantam racing

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Derek

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PostSubject: returning to bantam racing   Mon Jan 11, 2010 11:10 am

Hi all,

I have been considering an intention to return to racing in 2010 for some time, but having thought long and hard, since after a day off work while up north - and a trip to croft in 2007, it put me off.

The considerations I have gone through, am I too busy/rusty/age !.

Do i realy want to do this, I remeber the long, long midnight hours in the shed, the cold, stress, hassel, cost! and head aches.

so I have considered all these, and made my mind up, I am going to have a go in 2010.

Now! what does/should a new/returnee consider,

Type of enging -short stroke 125 or 175, what changes have taken place since the last time I rode, regulation, transport to and from meetings, tools /knowledge required, time available from work, do I still have the spirit, want!, need, the hassel.

the simple answer is "yes".

I am very busy reading my old notes on what I "should/should not be doing".

I will need help/advice on contacts, the first one is what do i need to do different to the last time I rode, scrutineering, noise regulations/changes.

the next is configuration engine do I return on, my main priority must be to return with a reliable? Bantam Racer if there is such a thing,- period.

I do not wish to embaress my self, otherwise she who must be obayed will bring a swift end to this return, so I feel reliability is the key to any new or returnee having some fun.

i hope to post some pic of the bike and engines progress soon.

regards

Derek Betts
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alan
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PostSubject: Re: returning to bantam racing   Mon Jan 11, 2010 8:40 pm

Hi Derek,
A big change in the 125 class is the electronics, many different types are being tried out, but a good reliable electronic unit is needed to get the best result. Most other things are pretty much the same, but I am sure you have worked that out! If you have plenty of machining facilities then a 125 is the way to go and you will need a short stroke, I have stuck with 54mm stroke as it is very easy to get 54mm pistons for, and the choice is endless! plus some of the best 125 GP bikes have stuck with this arrangement, and the factory boys can not be that far wrong..
Watch out for the sound regs that are now in force, it is easy to get the noise down as long as you use soft Aluminium for the body of the silencer and have a good fat section, the small silencer fitted on mine last year works wonders! and no alteration at all to the engine settings was required.

As always the devil is in the detail...
Cheers,
Alan
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Derek

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PostSubject: Returnee   Tue Jan 12, 2010 4:36 am

Hi Alan
Many thanks for the sound advice.
Why have I decided to return to racing on a Bantam ?? a good question. believe me I ask this.
I did other forms of racing and sprinting after racing bantams, I still have my 1981 mk4 Honda 125 a super quick and reliable bike, I never really got the same enjoyment out of it, and while for sure bikes built for racing are much more reliable, there was never the same personal statisfaction of building and racing your own bike/engine.

I dont have access to engineering shop machinery anymore. So for now Im sticking with simple std set of cases, and using a maico rod, small en40b nitrided flywheels, the rod is 125mm, std size main bearings, and a 22x29 big end from an rd250 silver plated cage, with a hardened steel bush in the little end. The drive side shaft is worn tapered, causing it to rotate in the fly-wheels, a std bantam replacement has been sort and pressed home, the crank is just about ready to be pressed back home.

When I moved house, I threw away so many things, what a great decision keeping my little lathe has turned out to be, although its taking me time to learn how to use it again painfully!.

I have been busy over the past few months making bits/pieces, rather than comming home from work and veging in front of the tele, trying to
de-stress, I have been going out in the shed/ garage, its turned out to be quite theraputic.

Tom Miller kindly agreed to help me with a selector mechanisum and modify the gearbox layshaft to roller bearings. I still have to sort an exhaust pipe, a frame-modified for sprinting to re due, so a welder and some tubing is required, other bits and pieces like reg cycle parts, front forks, wheels, and tyres, are still to be sorted, but its comming along.

I believe current bantams race on avgas, some advice if anyone can help with how I can find out if this is available in Worcester !anyone help!.

ignition - I will be starting with a simple straight line ignition unit, electronics add compexity need lots of know-how and developing, while I am sure these work and are very effective as you all seem to be going so much quicker. I dont want the complexity of try something new "when I'm trying somthing new", if you get my drift.

I dont think we ever stop learning, so I will be going back to basic. I will be paying particular attention to the simple things that I can do like friction and drag, seals, bearings, air flow, gear box, and exhaust pipe. in that order, I need to keep things as simple as possible.

Reading the threads on this site about weight, I found most interesting. I'm at least 2/3 stone up now compared to when I last raced.

I have my notes from 1990 telling me this engine was set up with a HDA go-kart 125 reed valve, in a home cast alloy reed block bolted to the rear of D1 iron barrel, the top fins where removed to allow welding the exhaust port, two fins where then made from solid alum billet and shrunk on, this barrel has two std transfer ports beautifully crafted by dad circa 1960's, never been touched again. I added a third at the rear from the inlet port, after we fitted a reed valve. it ran 92 deg exhaust 64 trans 89 inlet approx, However I can not make out if I was using a hole in the rear of the piston, mice or squirels in the loft played with my notes.

if Jeff Bridgeson is reading this - can you ring me jeff or make contact please.
Any other comments, advice, help would be very welcome.

Derek Betts
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alan
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PostSubject: Re: returning to bantam racing   Wed Jan 13, 2010 2:44 am

Hi Derek,
You are doing all the right things and you will get there! I amy be able to help with some patterns if you have an exhaust design, or if you really panic I can knock up a straight expansion box and then you arrange to get it fitted around the bike?
Possibly be able to help with advice as well but you do seem plenty capable!
Have fun
Alan
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Derek

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PostSubject: big end interference   Wed Jan 13, 2010 7:47 am

Thanks for the very kind offer alan but all I need is the info, the exhaust silencer stuff is very helpful thank you.

pushed the crank back together and aligned last night, just one small problem. I'm concerned about how easy it pushed together. Im using the same pin and put 3 tons on it to seperate and push the flywheels apart still had 2 tons after it moved, so seem ok, the interference fit was approx .0015 to 2 thou, I was given and advised to use a white grease, very slimy stuff, never used this before, told this is the thing to use when pushing cranks together. However it went back together so easily, seemed too easy, I'm concerned its not right, and it was also very easy to move during the alignment process. A slight knock with the copper hammer to move it. I'm unsure this is the "super duper" white grease or just not tight enough interference on the crank pin. If it was a hollow pin this would be easy to correct, however its a solid pin so I can not plug the ends.

Before I push it back appart, any advice or comments on this anyone.

Derek
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chris



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PostSubject: Re: returning to bantam racing   Wed Jan 13, 2010 8:18 am

hello alan,do you make your own pipes or experiment with different types if so can i pm you
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alan
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PostSubject: Re: returning to bantam racing   Wed Jan 13, 2010 9:04 pm

Hi Derek,
I do not use grease on my cranks when assembling, but the interference you quote is OK, I do like a tighter tolerance of 1.8 to 2 thou but do not expect it would make that much difference. Put together dry, my crank has done 3 seasons with no ill effects and all still seems to be well. It will be stripped after this season and checked out for wear but I only expect to replace the big end and pin with its side washers, and always throw the small end away for good measure! but I avoid removing the piston as much as possible after fitting, so as not to disturb the small end and circlips.
Hope that helps.
Alan
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nigel breeze

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PostSubject: avgas   Thu Jan 14, 2010 5:05 am

hi there, if your birmingham side of worcester i would think that your fairly close to bobbington (stourbridge roughly). i googled avgas and im sure its available there as im hoping to get hold of some myself. im in halesowen..
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nigel breeze

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PostSubject: avgas   Thu Jan 14, 2010 5:45 am

oops, sorry ignore my last post it seems thet avgas is only available there for aircraft only, ive just been told it is the LAW...
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Derek

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PostSubject: Re: returning to bantam racing   Fri Mar 05, 2010 8:44 am

yes you are quite right, nobby I went along to said air field and sadly the law is air craft only, good job a frend of mine kindly offered some used stuff from his Microlite !.

Up to this date there has been little progress the new gears have just arrived, what a cracking job they made too, all Im waiting for now is the clutch "Dad"!, There has been no movment with the frame as work has taken front seat for the time being, but a few more weeks and this should be sorted. I'm already thinking about which meeting I going to start, quite exsiting realy. I see the technical stuff has come to a stand still on the site ? looks like theres a lot of cock measuring goin on! about how many you rode LOL or busy with prep for this weekend ?.

I hope to get time to attend during the morning test day to say hello etc.

Alan If your attending the practice day, I will make a point to bring along those paper articles we spoke about, you can have them to copy but I want them back, may be we can grab a cup of tea together.

Mike's always got the kettle on I'm sure he keeps it for his bike! another one of those top secrets !! ?.

I was realy saddend to hear that John spencer (raced Bantams) had lost his life at the Island some time ago, I was informed only recently about this. I new John and his dad realy well, they lived local to me and often came over in that three wheeler contraption on a weekend. I remember the first time we met john and his Dad, both very nice guys. I saw John at olton Park some years later, he had moved on to much bigger and quicker things, and was realy progressing his racing career, he was never too busy to say hello and have a chat, its always sad when you hear about things like this.

Derek Betts
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Derek

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PostSubject: Re: returning to bantam racing   Thu Mar 11, 2010 8:53 am

Just got the clutch back from Dad what a great job, also took time out after Mallory to collet some high speed bearings, so now all I need is a window of opportunity to start the assembly process.

"o yes" I need some help with magnets with holes in, for the gearbox, to collet the metal bits comming off the clutch, who has some or where can I get them from, do I have to find a company or can some one help.
in which case can some one identify the correct company to contact.

The chassis is still no further along just needs a weekend or two to get it moving. Im running out of time.

I did manage to find a formula exhaust from the old shed, it looks about right, my notes say I used it previously, witha a 30mm carb bored to 34mm, but I also remember using a 38mm on this bike, my notes are a mess on this page so I may stick to a smaller size to start.

One point I was paying particular attention to at mallory was exhausts tail pipe diameters, although difficult to say exactly. Most look around 25mm and quite large, except one who's was much smaller and about 20mm.

now assuming everyone is using avgas, I can not understand these bigger sizes as the gas temp must be lower. ? or may be not.

Derek
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alan
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PostSubject: Re: returning to bantam racing   Thu Mar 11, 2010 9:24 am

Hi Derek,
You can obtain the magnets from Radio spares very easily, or RSonline just "google" them out, they are easily obtainable, and often used on magnetic reed switch arrangements.
Be careful with the internal tail pipe diameter, if you drop below 23mm you are at increasing risk from engine overheat and siezure, 23 mm is reliable and as good as it gets! affraid
Good luck with the build.
Alan
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Derek

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PostSubject: Re: returning to bantam racing   Thu Mar 11, 2010 7:47 pm

Hi Alan

Again what sounds like sound! advice on the tail pipe diameter.

Looking around I had assumed a smaller size, I was guessing at approx 21.5/22 as the inner diameter, I know this can have a considerable effect on under crown temp/piston temp, but I had assumed because of the use of avgas this would not be a problem. I will heed the advice though thanks.

I will be starting on approx 23/24mm with the facility to change the S point diameter with washers.

Thank you for the magnet info - great, I will check out the RS site today,
out of interest where exactly do you bolt these in the clutch side and in the base of the gear box or at the back of the gear box, some advice here would be great.?

I have put them on the clutch cover previously, but never on the gear box side always worried about the consequences of one comming lose ??

Regards Derek.
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alan
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PostSubject: Re: returning to bantam racing   Thu Mar 11, 2010 9:45 pm

Hi Derek,
Don't waste too much time on the washers lark! the difference isn't enough to spend hours messing about! stick with 23mm and you will be safe regardless of the fuel. Note the smaller size I believe you saw was from Nick's bike, and yes it siezed due to that exact problem!!!!

I have my magnets at the back of the clutch outer case, they seem to catch plenty of swarf and get cleaned every time I take the case off (after every meeting).
The gear box ones I put right in the bottom corner of the gearbox casting, and after locktighting them down I run resin across the top of the lot! the resin gets refreshed every season and the magnets stay put! Of course when the motor is stripped it goes without saying that they get cleaned. The main purpose being to collect any nasty bits like a broken tooth from a gear, rather than it flinging about the box creating even more havoc! and yes it does work better than not having a magnet at all...
Good luck
Alan
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Derek

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PostSubject: Re: returning to bantam racing   Sun Mar 14, 2010 4:25 am

Thank you Alan -
Engine assembly!!!!
I have plenty of crap clogging the shed, because of the bad weather etc not quite got enough room to do an engine rebuild, so I going to try assembly on the kitchen table, ?? see if I get away with it!!!.

longer term I think I need the lower half of a frame to make an engine work station out of, heared of others doing this- Brian White use to transport his spare engines to/from race meetings in one, a very simple and effective idea, unless anyone has any better or other ideas for this assembly process.??

Been tryin to get some pictures loaded of the engine clutch, gears etc. bits'n'peices, but to no avail.

anyone help with this Tony Davis I hear your a wizz with this so "come on" how about giving me some assistance.

regards Derek
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PostSubject: Re: returning to bantam racing   Mon Mar 15, 2010 8:26 am

Hi Derek

I host pics on

http://photobucket.com/

If pics are on your PC then upload once registered and then click IMG code in the share this image box below pic then >control V to paste into your post on here then hey presto a pic will appear as below




me sprinting the green Bant or trying to remove my eyeballs as some commented Shocked
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Derek

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PostSubject: Re: returning to bantam racing   Tue Mar 16, 2010 3:37 am

He'y Tony.

Looks a great front end on that there bike, mind you Tony was this pic taken after christmas"?? I'm on a strict diet trying and lose a bit of weight LOL, but I just can not break throught the 14 stone bracket, I think its too much REV"JAMES.

Now talking about eye's and balls's, I just got a nice front set up, WE fitted a drum twin leading to it and gave the fork's to an engineereing company to reduce the station length- Blimy the damping stuff inside looks like clock inners, anyway they have re-thread the ends 65mm shorter , i have reduced the springs by the same amount, they are the "eye balls" charged me fifty notes for the pleasure.

Sadly sold my sprinter, to some guy - he's taken it to where the sun shines.

thanks for the info, now where did I save those pic's !.

regards Derek
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Derek

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PostSubject: Re: returning to bantam racing   Fri Mar 19, 2010 8:12 pm

Hi Mike
thanks for the info, will be bringing my old bike with me to mallory, want check for noise and scrutineering, but sadly this bike while it will run it needs a liner as the interference is too small, unsuitable to race, the other is almost there, so we will see, I will be looking possibly Pembrey but hopfully before, one of my favorite circuits and get some testing done at mallory before hand.

Tony very sorry, given up with the photo stuff, ! its just too long a process ! frustrating". I use to do this sort of thing years ago. its surprising what you lose when you stop(get old). some one said it like riding a bike, you can always get back on, but sorry its not!
I know you travel to nottingham on a regular basis if and when your passing how about popping by and showing me how. if your going to any of the meetings I,m sure we will catch up, send you my number by private post.

no replies to my questions about best methods for holding the engine steady while you go through the assembly process,

so "come on" if you do your own - "how do you do it" and what do you use as an aid on the bench ? "please no jokes"?

regards - Derek
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Tim Cornish

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PostSubject: Re: returning to bantam racing   Sat Mar 20, 2010 6:01 am

Derek, have you tried getting the bottom half of a main-loop? Just standard bolts and you have a stand for your engine. I did that for mine. Simple to make but works a treat! Very Happy

Tim
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PostSubject: Re: returning to bantam racing   Mon Mar 22, 2010 7:58 am

Pembrey Derek! thats nearly the end of the season! Try to get out earlier if you can?
Engine stand - I use a D3/5 loop that been cut off above the engine mounts welded to two bits of angle iron!?
It came (in the spares) with Ricks ex-Richard Harris ex-Ken Rees South West Centre 50 x 56 bantam in 1980. Rick won the novice and inter enduro in 1980 on it! That bike was sold to Peter Stoke's and became known as the clone (of Pete Tibbits Bantam). It when to Elaine Gillingham and was then lost to the club ?? It must be somewhere......
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Derek

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PostSubject: Re: returning to bantam racing   Mon Mar 22, 2010 10:10 am

Hi Mike, interesting stuff - the last I remember being told the bike you call the clone was broken down the engine was sold off seperatly but im not sure who to - Peter may know, Colin dials in occasionally, Ive been communicating with him on here by mail, he's been giving me some technical assistance on liner details, but due to lack of time, I've now asked brian to make a liner for my air cooled GT piston port Alum barrel, It's going to be quicker I think.


hope it works


Last edited by bettsd on Sat Jan 21, 2012 7:10 pm; edited 1 time in total
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PostSubject: Re: returning to bantam racing   Tue Mar 23, 2010 5:25 am

Wow Derek!! A picture tells a thousand words!! Frame looks good! A bit scarred by the rear michelin TF23(last made 1986) on the rear of bike with yellow seat not to mention the michelin PZ2's circa early 80's. But did notice the water cooled crankcase reed motor and the number of teeth on the brand new top hat gears?? Very interesting! You must of kept all your best bantam bits....
Regards Mike
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PostSubject: Re: returning to bantam racing   Tue Mar 23, 2010 8:16 am

Edit


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Tim Cornish

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PostSubject: Re: returning to bantam racing   Tue Mar 23, 2010 8:44 am

Wohoa! Looks neater than the day it left the factory. Wink Gear cluster looks in really nice condition. Just as a question, Derek, what rear sub-frame arrangement are you using? Looks pretty simple. Might try myself if that's okay?

T
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Derek

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PostSubject: Re: returning to bantam racing   Tue Mar 23, 2010 9:38 am

Hi Mike all gears in picture are 24/23 "count again", and like you "I found them at an auto jumble" last week, I could not believe it when I saw them on some guys stall !.

The crank reed motor, has a big problem with the barrel/liner, can never be raced again just distroy's it's self, but it is a cool piece of home engineering. if I knew then what I now know it would have been a very different story, May be one day we will try again, if all things are fun, and we get the bug, and will deff ask for help.

Tim thanks for that - The Fame is/was a materpiece, designed and made/welded on a weekend trip to Micky Nashes place, in his jig, I think its a copy of the frame Mike Readhead has, but with suttle changes. Mick was a great ambasador and did many good things for people in bantam racing. This was something he helped me with, It was a fantastic handling machine, like it was on rails. but we all make mistakes, and we changed it! not to make it better, but for CRMC and classic sprinting/racing regs. "what bloody mistake" after it handled badly and eventually we gave up with it and built a special, very low rigid-end sprinter frame.

As you can see I'm seriouse about returining.

I think I have answered all. and thanks for the positive comments.

regards Derek
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