New Builds - Learners

Hi Derek,

Considering that your son is gonna possibly be racing at some point, are we gonna hear about why he wants to do it, what mods have been done, possibly pics or is this what all of your goodie hoard is gonna be used on?


Eddie

HI Ed

Not sure I understand you correctly!,

I, - we have a very modest set up, very basic - short stroke, Tom miller has been very helpful and converted the selector mod, and the layshaft to roller bearings, I have re model'd the ports timings and directions, we still have a liner/exhaust and many items to finish, and will not be rushing out for the sake of just racing, we will however be keeping things modest to start, we did on our way manage to badger the hell of a very good friend for a barrel and and got agreement by all to use this, so its sad we have run out of time,

The liner is very special item, and its taking a little time, to set up, taking a little longer than expected, so Ed's is off for the weekend, and his bike will be ready to race when its ready, but we are hopping it will be on a dyno before the end of year, time willing.

regards

Derek

Hi Derek,

Sounds interesting, what frame setup and brake route have you gone down for your son?


Eddie

now come on ed, you should know we like the "original look" all these disc brakes may well as be a bunch on honda's so we have currently a drum brake but seriously this may change, dependant on what he wants.

hope you enjoyed the sunday as much as we did,

we have at last found the problem, we have been suffering, so we should be able to correct this to move forwards.

regards Derek

Hi Derek,

Yeah i know you do like the original look, we really enjoyed it and was good to have a chat to people, also was good to finally meet Colin and Nobby.


Good to hear that you are moving forward, lets hope all the new builds get sorted ready for next season!


Eddie

Ed! I don´t want to get the name of a busybody pedantically nitpicking but I saw something
in your first picture that worries me a bit.
Just behind the rear engine plates is where the down tube enters the swinging-arm-lug.
During twice times of scrutineering I found the down tube in two different Bantams to have
cracked there. Looking at this place -- in your first pic -- I see what looks like a bit of brazing
that hasn´t been done all the way round. Just a thought -- is there a crack just there?

What I did on both my Bantams was to put a 1/8th thick, triangular plate in there which was
was brazed on the center-line of the saddle-down-tube at where that upper bracket is and
at the ends of the swinghing-arm lug.
Not necessary according to a lot of people yet in my 2 times of scrutineering I found two with
cracks just there....

Just a thought....

Hi John,

Dont worry about saying anything as i dont mind, to be honest i dont know is the answer. When i get home tonight i will have a look and report back.

Good Observation.


Eddie

Hi John,

Well the first thing i did when i got home was checked, its not a crack but you are correct it is just brazed shortly on one side and other. Dad says its better for people to comment and find things that we may miss along the way then for it to go wrong during racing.

Kind Regards



Eddie

I Forgot to say that with Johns eagle eye hopefully the casual approach can be reduced!




Eddie

Ed!
I wonder if it was brazed because a crack had started?
I also wonder if the reason for no reported incidents
of cracks at this (lugged tube) point is associated with
the introduction of fairings.
Halt! Another JayBee joke there -- that fairings
hold the frame together!!!! -- might it be true??

Many years ago I spoke of it with a well-known frame welder
who reckoned such a failure should never occur because
the process of brazing factory made frames was a controlled
heat process and fracture cracks at that point are probably
the result of overrheating causing grain-growth which severely
weakens the tube material.

So keep an eye on it -- in case a crack appears.

Final thought for the day: proper brazed joints are very strong
-- frequently stronger than welding in situations like tube-in-lug
because of deeper penetration but frequently in the hands of
amateur welders the braze is only a pretty piece of show --
a´ la Mike Powell´s clip-on as we saw earlier on here when he
abandoned ship at Mallory....

Well today started with good intentions, thought we would try and start the red one to make sure it ran and then move it to make way to get the blue project on the bench and moving forward. Well didnt start off well as she decided to rebel and tried to make a break for freedom unaided up the driveway, nothing major broken on it.

Went to start it again and felt locked solid, back on the bench and checked clutch and gearbox which were fine. Took off the head and one of the gudgeon pin circlips had decided to come out and jam in the opposite side.

Wrecked barrel and piston, Bantam 1 - Pickering's 0

That´s tough Ed. Circlips should not spring out -- was the groove
at fault?
But I was more interested in the picture that showed a Greeves.
Couldn´t help thinking that the work area doesn´t look like a garage
-- more like a kitchen?
Now, that is what I calle enthusiasm.
Maybe if things go well I might bum a ride on that Greeves, next year
-- 3-gear-Bantams were always difficult for me to ride.

All the best!
Cheers!

Hi John,

Well these things happen and atleast no one was hurt, doesnt appear so but have taken pictures of it all, maybe cheap springs.

Yes that is a greeves, you are right it is a kitchen and it doesnt end there if im honest.....

Eddie

Pictures Moved To Engine Opinions

Wonderful photography Ed -- but what a disaster!

Circlips should stay in -- also not break. I discovered one broken in two pieces
in a Colchester lathe, of all things, which rendered the lathe almost useless.
Circlip cost was one in a packet of 30 different sizes for Òne & Three´ (One shilling
& three pence) which meant a halfpenny circlip cost us a pile in having a useless
lathe until it was repaired.
But your trouble looks to be worse than that -- and much more costly.

Don´t give up!!.

Good Evening John,

Thanks for the compliments on the photo's, well it could of been worse. It does only take something as small as that to create a problem and it was from the other side!!

Main thing is that it didnt happen on track and no one was hurt from the process, as for cost well these things happen and you push forward!



Kind Regards



Eddie

Hi Derek,

Thought i would move back to this thread, with regards to bottom end issues we havent looked yet, only got as far as digging out another barrel and piston.



Regards



Eddie

ED
If i were you !! I would get a bogg std 175cc barrel, set it up off the bantam tuning magazine transfer ports from the 125 of Dave Hunter ports should be close to 50/50% ratio, I feel, but take no notice of the widths, as these on a 175cc make them 60% of the bore diameter, The port heights I would make the exhaust 50% of the stroke and the transfers 50% the height of the exhaust port. The direction should not target the rear wall, but cross a point about 12/15mm infront of the rear wall, a D14 or D10 barrel stay away from D7.

I would not suggest anything larger than a 34mm carb, "to start with" although others will suggest much larger, you will get less issues with a smaller carb, we have moved to a much smaller carb on our 125 and have incorporated less issues however we are getting on top of the set up issues and the bike has become much more tractable as a result of the smaller diameter, now that we have found the issues creating other problems, we are hoping to be able to see progress over the winter months, we are not stripping and waiting till next year, we have tests planned, as soon as Ed's bike is finished.

At cadwell a number of people spoke to me about arranging a meeting with local Midlands Bantam racers. , not sure if you all still wish this but (midlanders) up for this, I would suggest a pub along the m42 to M5 south B.ham corridor, I have been offered a hallway to aloow us to bring bikes or engines, for discussion, we may even ask for guests to attend. to discuss topics of tuning, and devlopment, i would need to know who is up for a mid week venue or a weekend venue. - any views please to my private post, I will correlate and respond once I have numbers any other ideas or potential locations,

my view is within 30 minutes travelling time,is ideal mid week, or 50 mminutes needs to move to a weekend for travelling.

regards Derek

Hi John



"How do you know a good circlip from one of low quality?

With difficulty, of course, but checking that its free-size is larger than the groove intended for it -- is one... another is comparing the free diameter of an old one with a new one (obviously of same dimensions of course) and feeling the springiness
of the clip when entrapped in the circlip pliers. Again, that is a "Feel" situation that comes from experience. If when fitted, the circlip can be pushed along (say with a scriber point...) in its groove it is obviously the wrong size (too small) or has relaxed its spring strength from its original diameter which could be attributable to poor tempering or over-use...
Any doubt and a dubious circlip should be flung .... Using only once might be considered going too far but I have known people who insist on the procedure.

Sorry! if that hurts Ed...."


To be honest it was more than likely inexperience and as you say used more than once when checking, all a learning curve and no i havent taken offence at all, opinions is what makes things go forward with us.

I have a cunning plan though, when we go to rebuild it i am going to find out what terry's favourite biscuits are to go with his tea and he hasnt seen the presses dad bought years ago, i can see him laughing now.....


Kind Regards


Eddie

Good Evening Gents,


Just been look back at my photos and the barrel and noticed a part missing that is unaccounted for, for safety sake so no more damage is done we are gonna check the bottom end. Does anyone have any tips or suggestions with regards to splitting the crankcase's so that the surfaces dont get marked.


Kind Regards



Eddie

Hi Ed
great quote ED "Opinions is what makes us go forwards" -

I think I will try this"new PMA" (Positive Mental Attitude)

there are a number of ways to split the cases, the best way will depend on how your crank fits into the mains.

If I were you I would follow this strict routine
1) you first must make an apple pie - stick it on gas mark eight for about 20 minutes, then go out in a the garage
2) get a big hammer and flat head screw driver, put them both away, never to be used for this operation again.
3) you need some plate alloy tap some screws and holes.
4) Remove the crank drive sprocket
5) drill some 1/4 holes in the plate on the same centers that line up with the two large clutch cover screws next to the crank outter drive side boss and one of the outter front case screws,
5) drill tap in the plate for a larger diameter bolt, that when screwed in, pushes on the end of the crank.
6) remember to remove all the crankcase screws, first before you try pushing the crank out out, the sameplate can be used to pull the crank in and help assemble the engine when your crank is a tight fit on the main bearings.
7) The most important call me and invite me round to eat that apple pie

I'm feeling faster already carnt wait till next year, all this positivity, I will be flying.

regards "Flying" Derek.

Hi Derek,


Thanks for the information, cant believe you made me put away a technicians primary tools!


Kind Regards


Sensored Cradock

"Quote"

Hi Ed!
Funny things happen with stored engines. I had one where the rings were rusted to the bores because of condensation rust. Just thin lines of rust had it locked solid.

We had a golden rule when reconditioning car & truck engines which was to identify bolts, fasteners and clips as, "Use once only from new ..." and circlips, flywheel bolts and bigend bolts were among those of top priority.

All circlips have a tendency to relax spring tension -- so they should be thrown straight in the rubbish bin...

Those round wire type -- the ones with long ears for the circlip pliers -- tend to move in the gudgeon pin groove because of the cocktail-shaker effect (of the piston) on the long `ears´ causing rotation which has the clip riding the groove-edge and going over the edge...

Round wire type should only be used in slow-moving linkages.


Ahhh(yawn)men!


Hi John,


I think you probably hit the nail on the head, circular and too many time taken out = lost spring tension.

Interesting you saying about stored engines, i sure this was freshly rebuilt (not by us) yet my period project which hadnt started for years only had a carb clean out and fresh juice and battery and literally started on the second go.


Kind Regards


Eddie

Depends on the weather Ed -- shut down a hot engine and store it away may have the bad luck of high-humidity during the day bringing condensation in the cylinders during the night.
I had another form of it it, happen with a Bantam. Long term corrosion between the spark plug and its alloy head was so locked solid that the threads stripped in trying to take out the plug -- but that Bantam was twenty five years in storage....