Mike Powell's 125 Engine...

No I´m not going --- not just yet -- the Last Post is meant to be on this Topic.

Mike never reads more than two lines so where he has said "Um -- any ideas?" with arrow pointing to inlet port I would suggest -- tentatively -- a crack at Variable Length Intake Tube -- I think Trevor mentioned this at sometime or other. Several companies have been successful with simple telescoping tracts and the airbox DOES work....

Over to Trevor.

thank you John

from this I read always consult the head when ever making changes or setting the carb / ignition timing !

John the under plug temp gauge could you also please elaborate on the use of this too.

Derek

Hi John

"They go their best just before they seize!"

Yup I have noticed that and probably said it far too many times !

you also mentioned "the surface was rougher -- sort of sandy texture" and "looks as if a patch had been sand-blasted"

Its pretty certain this is caused by detonation and as you said it means the motor is close to melting the piston crown but if you can control this and not let it get out of hand then the motor is running at its peak hence the reason RS125's and the like use detonation counters and set up the engine to give just a few 'dets' per mile.

Mick

Thanks Mick!

Ey up! I didn´t know that! and I ought to have...with all the instrumentation work I did at Ford Dunton on dyno test... I guess the type of transducer was not available in those early seventies. I used a pressure transducer that ran down the side of the spark plug which could not be used in `normal´ or even race conditions. I wonder where these det sensors are located?

Slick mentioned recently that the computerised (chip) engine management systems have included a sequence where the mixture is weakened off to get the chamber & head temperatures up which gives a boost to the power...

If you can read detonation then carb settings have got be really easy...


Derek! As far as I know of the under plug indicator it is just the spark-plug washer changing colour at levels of temperature. In other words the washer colour shows the max temp under those given conditions.

I´m out of my depth with this -- I think Peter Tibbits could explain that better.

Cheers!

This ought to get a response -- "... direct cooling by air (over fins) is more thermally efficient than water-cooling ..."

This statement can be supported by calculations done by an Auto Engineer of substance in the Auto industry but since my 2012 resolution kicked in I shall only `Bullshine´ Nick -- & others on here -- when absolutely necessary.

What worries me about the above is that Mike Powell´s water-cooled motor is very quick. Not as Quick as Carcreek though -- so what cooling has Trevor made there???

I wonder if -- with Mike´s motor -- it is because the distortions are less -- or MORE!? That latter thought came from the fact that the piston shows cold edges in places where the transfer ports are --and I have said the cylinder head is overcooled -- but the crankcase compression brings the temperature up before the incoming charge gets to the transfers ... and with Mike´s cooling circuit the way it is ....???? Another thought: is it that the cooled tranfers mean an increased air density of the charge rushing thro´the transfer ports???

No! I am flummoxed...!

What if, with the air-cooled barrels the outside of the transfers were clad with thermal insulation -- might it show something ?

OK! so I am senile ...

DoobeeDoobee--efffofff...

John I am confused. Just when I thought I was starting to keep up with your ramblings you throw a curve ball.

john bass wrote:

- "... direct cooling by air (over fins) is more thermally efficient than water-cooling ..."
.

Don't radiators have fins and a larger surface area ?

john bass wrote:

Mike Powell´s water-cooled motor is very quick. Not as Quick as Carcreek though -- so what cooling has Trevor made there???.

If Trevor's motor is quicker than Mikes, is cooling the only deciding factor ? I doubt it.

Yes Ned but water-cooling is INDIRECT cooling and hence less efficient -- what about the fact that you either have to increase the rad´s frontal area or make it deeper to get more heat transfer...?? You know (I know you know) that the cooling fins can be made differently to be more effective -- `cos that´s what you DID.

Has anyone tried using cowlings with air-cooling on a Bantam?

I know this helps more than you realise at first glance. More than I realised at 1st look. Yes, of course, you only have a certain amounts of air rushing thro´. Yet like the water cooling, its the largest amount that can be directed to the right place -- and not be allowed to act in a haphazard, disorganised manner -- like most water-cooled Bantams seem to have that I have seen.
In some multi-cylinder, water-cooled engines the cool water from the rad goes straight to the head and in many it is directed to the top of the bore first then to the head and the bottom of the bore.


What about the fact that cooling air-flow picks up heat and then flows adjacent the carb -- that must reduce intake air density -- and that question I had on about, `...should the outside of tranfer ports be clad ...´ ought to have an answer*** -- and then there´s the barrel fins, probably about right, at the top of the barrel -- to get rid of most heat. Lastly there´s an arrangement for the sake of simplicity called, `jet-ejector´ sytem which speeds up the air. Just a tube inside a venturi tube, weighing very little that speeds up the air -- can be in aluminium sheet, bent to the right shape....

Hey! I am supposed to be asleep....

Schnarsh....!!

***even if only a loud burp-blurrbbb!

Under plug temperature gauges are available from Airworld uk for about £35 there made for air cooled micro lites
Bill

Thanks Bill,

Was just one of those things I saw and wondered about.

Hi all

Well It taken me a few hours to write a letter in aid of our cause, to some individual, I hope to raise a few eye brows, with it, but would like to make a few comments about Mike last post.

Mike is absolutly spot on, I'm sure many of you just do not realise, the work Mike does in other areas in order to raise the profile of Bantam racing,
"well he does" - I often disagree with his ways chosing the more jugular method, but I have to say I can not help but respect him and we have the same goal at heart.

so it pleases me when I see a comment like "danglling carrots" responded too, its brave to take head on a comment like this, his comments are spot on.

But if I had my way "at the end of this season I would make it mandatory for any " formula Bantam winning a race" to be stripped and photgraphed for its internals, it would be a rule that would help develop our our cause, it would creat interest, and more importantly keep the doubters mouths shut who suspect the legality, or fairness issues (like me).

Here's to being more open, with more disclosure to come.

I see my Gerabox reverlations have disappeared, or have I missed it but Iys a shame its not been explored!! ?

kind regards to all Derek

Derek please see page 2 of this thread for your gearbox question

this link should take you there

your post is the 4th one on the page

Mikes response is the 10th one on the page

Mick

Hi Mick
your posting again so you must be ready ?

thanks for the reply - "looks like I missed it" ! amazing sometimes, your only off for a day or two and everyone decides to post, end up missing loads of great stuff.

Chris -B did you see this one mate, answers your question.

kind regards Derek

bettsd wrote:

"at the end of this season I would make it mandatory for any " formula Bantam winning a race" to be stripped and photgraphed for its internals,

Unless the rules have changed since my days. You can lodge a protest and have an engine checked. But why should anyone give you the benefit of their labour if they haven't broken any rules ?

I have not deleted the previouse post just moved it to the correct place to, "My return to bantam racing page".

Hi Ned "your missing the point" and I totally disagree, i never said it for the piurpose of calling people cheats, and Im quite aware of the rules for protesting. The point I was making I will repeat using different words for you Ned.

point 1) we need to make sure we are all singing from the same him sheet with regards to what can and cannot be done, if someone has found a better set of ratios that work better, giving a big advantage then this should be made public, ie, as this is a mechanical advantage, yes for sure the individuals using these alternative items have or in doing so have a significant advantage over other who are not aware it can be done. ? hope you find this a little clearer Ned

point 2) keeping secrets yes for sure this is not against the rules - however its important the front runners show engines as Tom & Mike has. It shows us all, were we should be, and what we need to aim for,"BUT" much more importantly, its an open and honest way to show what we are doing, did you see Trevor sleve Gear "Mod" never seen that before, a great idea, simple enginuety ? (I think that's how you spell it) and its this type of thing that creats interest in our class, for like minded people, My point is "who would want to join a secretive bunch of Black cloak racer class"! you get so far then they clam up scared of letting out the informatiion for the whole grid to be on a level peg. Ned for what its worth the added benefit of this is to bring more people to our class, especilly after the first year for new starters, its important for people to understand the information is there and not hidden away what can or should be done.

if I had my way, I would make it mandatory , to have any bike winnning a championship, stripped and measured and the results bublished for all to see, this is a real formula, and I'm not talking about its "bore and stroke". either(im for the masses not the minority).

while I can understand your point Ned- its not worked so far has it ! our grinds are not full, and how many have come and gone! Ive only been back watching again since 2007 I have seen a few, who are no longer with us. "WHY" - frustrated that they just can not compete or do not have the knowledge, we just have to change this, and continue to do so,

although in the last 6 months, there has been some improvments to a better openess, this needs to continue.
ref Mikes 125, but this is still not enough in my opinion, I'm still waiting for PJ engine and Trevor's too.!.


kind regards Derek