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 Heavy Crankshaft....

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john bass

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Number of posts : 1728
Age : 88
Localisation : Bensberg, Germany
Registration date : 2006-12-06

PostSubject: Oldest what??   Mon Nov 07, 2011 1:54 am

I joined the BRC in 1968 -- late `68 -- too late to do anything meaningful.

<<<< ---Just look at that dreadful heap -- Icarus-1 -- no skirt and funny forks, I ought to be ashamed...!!

So I am not the Oldest member -- although probably the other thing -- what happened was that as a yokel from the Essex countryside I had the fantastic luck to be awarded a Scholarship, started a family and retired from grass track and things motorcycle, except for riding down to Bristol Uni from Barking on my old iron-engined 500 BSA that handled like a drunken camel which I gave to a copper when the studying venue was back in Essex....

9 years of no racing and no motorcycles and She said, "You need a hobby why don´t you get yourself another motorcycle?" I don´t think She meant a Racing Bantam -- and come to think of it, neither did I!!!

Oh! get behind me nostalgia.

Far too heavy to race Bantam -- just ride it... and now I wish I´d taken more time
on engine matters because I am learning lots & lots on here and think I could build
a reasonable racing Bantam engine with lots of secret goodies -- if only I had a workshop -- boo-hoo!

Iza Hasbinn the 3rd!





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mjpowell

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Number of posts : 1074
Localisation : Lincoln England
Registration date : 2006-12-09

PostSubject: Re: Heavy Crankshaft....   Mon Nov 07, 2011 9:00 am

Trevor ref ccr and 360 inlet timing - have you managed this with
1) a hole in the piston skirt.
2) connecting passageways between inlet and transfer cavaties.
3) large piston cutaway and a deep inlet port floor.

I've done it previously with 1) on the Phil Betty motor(002) and my (001) reed motor.

And whats your thoughts on ccr and reed motors?

Mick, I remember Ian's bike going on to Avgas as I was the test pilot at Mallory that day, Ian wasn't availible
I had my clutch hand ready but had 25? trouble free laps before putting it away and stop wearing it out!


Regards Mike

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Derek

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Number of posts : 1065
Age : 56
Localisation : worcestershire
Registration date : 2007-06-15

PostSubject: Re: Heavy Crankshaft....   Mon Nov 07, 2011 10:42 am

HI Mike I had thought you had lost ur P.C.!

Anyway you were not far away the other day, a good guess, about ten miles from the castell you spoke of, that's not spelt wrong its welsh for casel !.

what you planning for next year, with your new engine, a new exhaust /ports carb tell us how thats been going, seems at the the theory is small is good !!

regards Derek


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john bass

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Number of posts : 1728
Age : 88
Localisation : Bensberg, Germany
Registration date : 2006-12-06

PostSubject: Hi Derek!   Mon Nov 07, 2011 12:31 pm

Hi Derek -- Sorry! I suddenly realized what you might have meant "....putting it in layman´s terms..."

I am assuming everyone -- but everyone and his brother -- knows what a P-V diagram looks like. I was weaned on PV diagrams and of course if you haven´t had PeeVee for brekkers, dinner & tea you wouldn´t know what the cock I was on about. SORRY!

I cannot send photos, pics nor diagrams on this paraffin-PC of mine -- you´d more likely get a picture of my Mum circa 1926 riding Dad´s 2.5hp New Hudson motorbike... or Uncle Walt circa 1913 illegally shooting a moose in Alberta!?

The P-V diagram has cylinder pressure on the vertical Y-axis and engine´s cylinder volume on the X-axis.

The P-V diagram makes the thing clearer and perhaps one of our other friendly native posters could put the diagram up on here for us -- so´s we can proceed.

Also the index of the compression stroke, pressure curve which is known as "Gamma" (1.41, 1.35 & 1.27) -- I cannot show either.

However, I am able to show X² and X³ where the little 2 and little 3 are the squared and cubed index of X but I cannot put numbers like 1.41 & 1.35... -- I have spoken of in the same manner.

Where´s Trevor? -- playing wuith his aeromodel I suppose!!!


Cheers!

PS. Before the invention of "The Force of Gravity" by Isaac Newton not many other people than camel drivers knew what it was....JB.


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Trevor Amos



Number of posts : 863
Registration date : 2010-08-13

PostSubject: Re: Heavy Crankshaft....   Tue Nov 08, 2011 12:43 am

I`m here John , keeping an eye on you !
My software has a facility to depict P-V diagrams , the Bantam profile looks pretty good , untill , that is
i superimpose the RSHonda on it then the Bantam engine is put firmly in it`s place and reality takes over!

Perhaps one of you very clever , computer savvy , people out there could run a child`s level tutorial on
getting pictures posted ? It must be simple or i just won`t get it, however , i`m sure i am not alone in this!

Mike , are you asking about the influence that ccr has on reed petal motion and the complete induction cycle,
including , but not mentioned , pipe effect on both ? l,
Cheers for now, Trevor





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john bass

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Age : 88
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PostSubject: My mistake!   Tue Nov 08, 2011 1:54 am

I should not have said I cannot send pics & photos with my PC -- I should have said that when I attempt to send just ONE picture the bluddy thing sends my life story, plus the history of the vikings invasion of Scotland ... etc ... etc ...

Last year my old army college got the lot when I meant to send one picture of me in the desert with an article -- and the bas----ds haven´t stopped sniggering yet.

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john bass

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PostSubject: Please -- abbreviations make me mad!   Tue Nov 08, 2011 3:42 am

Wot´s a ccr?
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Derek

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Registration date : 2007-06-15

PostSubject: Re: Heavy Crankshaft....   Tue Nov 08, 2011 6:32 am

Crankcase compression ratio =ccr

John thanks for that never new a pressure cycle gtaph was called a PV Graph - the x-y's is for one engine cycle, I have seen a Graph before!, way above my knowledge, what is the ideal shape ?.

and thank You

on the reed valves, we are currently making somthing a little different,a single smaller reed block with a shaft that attaches to the reed it has a seal one side and the shaft comes out of the side, attached to it is a small stepper motor, it holds one smaller reed, and open and close it as the revs rise and fall, making but how to test it is another thing, the idea is not new, got it from pitstop buzz, I will post pictures when I get a chance.

Derek
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john bass

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PostSubject: ccr --- reed valve   Tue Nov 08, 2011 6:39 am

Thanks Derek,
A bit clearer now. This mechanical arrangement, you mentioned, is surely getting
away from the reed valve to something akin to the action of a disc-valve .... hmmm --- hmmm?


And another thought? If you have a high ccr -- high crankcase pressure -- the crankcase seals have to be of stronger sealing force against the crankshaft and in the Mackerle book on air-cooled engines that is a friction-loss raiser, he estimates crankshaft seals as 3% of total Mechanical Losses in an engine....?

If we can have a P-V diagram on here -- one cycle of the piston pressure against the piston travel BDC-TDC-BDC I think you will see better what I have been trying to put over...

Interesting question you put there -- what is the ideal shape? of the compression pressure curve? -- it has to be a compromise and that will be easier to see when the curve is shown and we go onto the ignition-combustion-heat release phase which is where things go wrong when using a 95 octane rated petrol instead of
iso-octane (above 100 octane) and rapid, High-pressure spikes spring up before TDC thus opposing piston upward travel thus ruining good performance.

I´ve done a lot of practical work on this too where we had piezo-electric pressure tranducers, at the side and in the spark plug itself and the `pinking´ and inaudible detonation can be seen as icicle-like spikes of high pressure happening before TDC on the visual display monitor...

Cheers!
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Derek

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PostSubject: Re: Heavy Crankshaft....   Tue Nov 08, 2011 7:14 am

Hi John - your very welcome

And yes I saw it done before, its not new but not on a two stroke.

There is a very good picture of one looks similar to our on the pitstop buZZ web site, I never thought of doing it before, never seen the potential until pointed out by a friend

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Edward Pickering

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Registration date : 2007-02-19

PostSubject: Re: Heavy Crankshaft....   Tue Nov 08, 2011 7:35 am

Hi Derek,

Is this "stepper motor" sensor/pulse triggered?



Regards


Eddie
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Derek

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PostSubject: Re: Heavy Crankshaft....   Tue Nov 08, 2011 9:29 am

Hi ed
Actually I got it wrong - after making a call, its a solenoid off a and triggered by a none connected cable that raps arounf the HT lead, it has a small black box that will be connected to a bettery, if the battery fails it will close not sure how as I do not understand it.

We hope to try it out on the dyno soon, it gives an un-interupted inlet for 360 deg between 8500 or 9000 rpm upward.

Hope that explains


Last edited by bettsd on Tue Nov 08, 2011 11:33 am; edited 1 time in total
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Edward Pickering

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PostSubject: Re: Heavy Crankshaft....   Tue Nov 08, 2011 9:50 am

Hi Derek,

That makes more sense from what i understand as i thought it would of been more servo then stepper but thats only from different non related bike experiences.


Eddie
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