The very latest and no technical two stroke tuning topic !

just spotted johns post

i agree with john I just can not keep pace with all this extra tech stuff on here latley ? but would help if a little bit more background was forth comming. - Just two comments on this, it must be me, but I seem to be doing a lot of a)assuming -b) guessing, on what people are saying
just joking john - hope ur well, did the earth movement for u or your bike, hope ur ok down there from what I here , a seriouse peek. ?

Mike come on !! bhp and FTLBS ? I like ur style, I do this in a meeting it usually opens peoples eye's or ears!.

I thought Robbies's bike looked quite quick. !

regards Derek

More assuming and guessing for you!? This is the right side crankcase of my new 'Evo' engine, study it carefully and you should have a few questions to ask? (I copied Evo from Harley not the Ducati 848Evo, Ian/Tom refer to his new motors as 'ironclads' think it coz they weigh the same as an 'anicent portculis')

WoW pictures paint a thousand ?--- Great Picture like to see the other side too !

- have a number of questions, but first, I'm actually looking forwards to the season start. More importantly has anyone had regs yet>? was wondering when we would get them.?

Alan could you please post on here or mail me about the bellmounth work you spoke about, I now you have some really interesting comments to make on this, hope you well and the recovery it still on course, not heared from you in a while.

Planning to dyno my bike again first thing sunday morning, so hopfull will have some technical stuff to post about. On the dyno you asked about, we have same set up as last time, all bar- some smaller jets- a new belmounth to try, a mock diff pipe-bogged made from two, once I get a good design, I will re-make properly, enjoy doing this myself, will show results, also due to overheating, we have reduced the comp ratio again. somthing wrong here ? ?.

out of interest you 125 riders what head volume are all you running, Im on 15cc volume, is this big now, I had assumed avgas could afford a lower volume, as we bought the jetting down the temp went through the roof, its air cooled so don't want to distroy the thing, lifted the head looked ok initially, under closer inspection, slight det on front side piston exhaust edge. we are assuming its either breathing well or has a hot air leek, as when cold its fine. losing 2 psi in hrs.

Mike on your photo. mine engine been in the frame a few months, ? your leaving it a bit late ?.
1)On that very interesting shot of the transfers "two, as you previously said, i see no screws below barrel, are these D7 cases?.
2) interesting full size? / larger diameter flywheels ?.
3) no packing rings ? no screws, "why" I understand this is not needed on a reed valve. ? your PISTON PORTED please elaborate.
4) Bearing diameter those are not large bearings ? what size, shaft size looks large but not the o/d - 22/47 ? I assume it leaves the cases with a thicker material round the bearings after boring, please elaborate your theory?.
6) welded in? gearbox plate lower needle or ball bearing . our is screwed in. ?
7) The rear selector plate looks thick, sorry made of a thicker material is it or what D10/14 std ?
!!!!!!!
I'm clearly missing a few points, anybody spot anything else. ????????.

I'm even more confused, and in pain, so please relieve my pain/assumptions.!


regards Derek

Hi Derek ref your post-
Forgot to take a picture of the other side when it was apart on Monday... when its apart next?
Leaving it late - No.... I've smashed a hole in the cases before in practice,replaced gears,filled hole with plastic padding and gone out and won races 2 and 3! So its never too late...

Regs not out yet. Will ask at committee on Wednesday.

I'm interested in anything on bellmouths? and inlet tract lenghts Alan if you have something pls tell.

Head volume mines 10cc and 11cc... I think your ignition is too advanced or your exhaust bleed pipe is of to small a diameter.
Ref head volume/compression ratio/squish band:-
Fixed timing say 18/20degrees needs low C/R 11:1
Retard ignitions needs C/R 13:1

Is your exhaust bleed pipe smaller than 19/20mm? Its just that a low comp motor should not be detonaming...

Pressure test? mine go from 10 to 0 psi in about 3minutes...

Ref my pic... don't want to comment just yet want to see other peoples assumptions first? Then I'll tell ya...

Derek, thanks for your concern; I was at work in Palmerston North oblivious to the earthquake down south in Christchurch. Yes, it is very serious, my daughters home is a mess inside and unrepairable, but they are all safe.
High tech manufacturing things are what we have actually done. Still puzzling about set ups though. My short stroke wc bike goes well what ever I do to it. CR 15:1, Avgas, 17 degrees advanced on old Motoplat (Rex Caunt stator coil gone). But my 175, big flywheels, CR12.3:1, 19 degrees and shortened Betts "Sprint" pipe is more difficult to get going well. Nothing below 6K, hard to get on pipe, then goes like a raped ape as the EGT shoots up to 1400-1600 F. 108 needle jet in Amal MK1.5, plug and piston look good ?

Mike, sorry your Evo has dissappeared ?

john where are you measuring EGT, sounds very hot, im only measuring under plug temp ,

"if"- u can measure EGT accuratly, its a better method, than what i am doing.

derek

Picture back online wish i knew how to operate computers aswell as bantams...
Glad you are all ok in the turmoil down there.

Technical tell us about your 4speed c/r boxes - not that our rules allow it!

Derek hope your rolling road session went well today. Looks like your questions are the only ones... there have been a fair number of views though.. so hopefully people are getting some ideas etc..
Answers:-

1. Yes D7 sandcast
2. Well spotted fullsize crank chamber on this case
3. No packing ring - but Primary comp is average 1.3/1.4:1
4. Bearing is large just look smallish in full size case
5. its a 6205 52mm o/d 25mm i/d
6. Screwed in bearing retainer plate running a 6001 bearing on the layshaft
and a HK1212 needle roller on the other end
7. Gear selector plate/parts must be late D7/3sp D10 they are beefier!
Auto jumbles the best place to find these..
4spD10/D14/D175 are compleately different...

Hope this makes everything clearer?????

Hi Mike
hope that gearbox mod that tom done for you works as he has done mine yesterday
could not find anything wrong with gearbox
but wen I was at brands could not get into 2nd gear from 3rd

hi rob think i have an idea what this could be - !

wait for it - Try pressing the gear peddle in the opposite direction. LOL


Mike - u sure this is a A D7 it looks home made to me can see the hammer marks or has it been modified - distance holes changed.

you really running large diameter flywheels ?

Derek

Derek definately std unmodified selector parts no brazing or welding or hammering! I think that ragged edge you can see on the notch and flag plate was done by BSA in manufacture. Has the Tom mod of a 7mm pin and tensioned bantam clutch spring. My pin was to slack in the holes (in the fixed and moving plates) so now has a 7.15mm pin - works on the bench..
Rob - Have you got a bespoke pin in your box now too??

This is the other crankcase half from the outside(motor built).... I think it gets more interesting?

Yes mike tom has made me a new pin too lets hope that fixes it

Hi Mike -
Its been a long day we just finished.

mike have to take my hat off to you, had me going there,!! actually believed you!!, full size flywheels, ? tut.

Can not believe others are not commenting on this, we had a good day extracted some additional information, should be more for us to use come season start, hoping this will be enough for me to hang on to those just in front, who were pulling away from me at cadwell and Pembrey.

Mike on the photo's - I can see two feeds for water so your not running full size crank wheels ? tut- as you first agreed you were ??!! tut tut,

Anyway with my assumptions, dad said he like's the way you have seperated the flow between tansfers starting in the crankcase mouth.

I' on the other hand' really can not see how this would make a difference, what is the theory behind this, and does it make a difference.

I would like to see the other side of the timming side in last photo, anyway well-done to you for getting this on, looks like my assumption was wrong.

Anyone spoke to Alan recently, not heared from him in a while, hope he's ok, sent him mails off line hotmail - with no answer.

anyone else got interesting photo's we could look at.

regards

Derek.

Hi Derek glad you had a productive day and gleened some info..

My new motor is basically Tom's creation but with input from his many contacts and a couple of requests from me.
As you know Ian Scutt rode the first test and development motor (in my 003 chasis) in 09 and last season Ian's motor was housed in his own 008 and my new Evo motor in 003. Unfortunately it only did 180miles - so still early days. Thx to test riders Michael Brown and Andy Checkley.

Transfer ports - I've no idea why they are split in the cases, i'll ask Tom?

Cases - rightcase no packing ring. leftcase a water cooled packing ring ???

I think your still guessing ??? lol

Hi Mike

Yes thank you - had some interesting results -indifferent from the last run, but all the same we seem to be making progress, identifying the issue stopping progress, one such issue found by chance, "tail pipe - causing over heating - gone and able to reduce exhaust /plug temp drasticall. Allowed us to come down to sensible size main jet - the power gone back up, planning head comp ratio increase, ran ot of time,

on the other issues I will decide when a get some quiet time what to do.

"now" on your own evo-evo-evo 008 and / new or was it old evo 003 in the 007 frame or was it 002 frame in 2007, all this OO is very confusing, I think a trip down the pub is in order this evening, it sounds to me like a story of a guy who was moderating your speed down a back straight in order to hide your true top speed surprised him on the last lap !!

On the Guessing "NO" Mike i'n not guessiing anymore, why don't you be brave and do the full monty. !!!

besides we and all can not see but only measure what a tru difference is, when we hide things we hide the design, but its all been done before.

I feel its open and good for the forum, makes it interesting for others looking to see what your doing from time to time, if its the same old thing week after week then it not so interesting, its the same in retail the guy next door to a show room, changes his window every week - just so people will look in to see what the diffference is, the theory is when they have the time or it comes to a point they are in the market they will choose him first to shop/try, its the same theory here, "so try telling me and others all we need to know so we can beat you" !. LOL

Now this new guy from Australia sounds interesting, 20 years racing and tuning bantams, dad had some guy send him photo's some time back of a 175 watercooled bantam with a rotay vale in the drive side and ingnition on the same side, no seal on inlet side just a plate, ? not a typical Bantam racer.

i will ask if he still has the shots.

kind regards

Derek

Perhaps I've got one big crank wheel (for added inertia) and one small.....

Mike, I did have a good look at your pictures, very interesting.
Could see most of the same comments that Derek made.
Went cross eyed trying to count gear teeth numbers, 23/24 ? I still reckon 25/22 good for long fast circuits, using 15/49 gearing.
Did wonder if they were die cast cases, but fewer screw holes than my D10 ones.
Agree about D7 selector plate and bracket.

I had some big pins made, Dave thought the plate should just rotate, but Bantam mechanic - Captain Bain thought it needed to sway, move out and rotate on pin. Seems if you have too much clearance, the plate moves up and down.

Thoughts on clearance and pin size ?

Clutch spring on top ???

CR, seems you guys are going up and down. On previous and RS125/GP tuners reco I have got 15.5:1 in WCSS motor. On 100 octane. 22mm tail pipe.

Still not sure about water temp at head. TM suggested 65 degrees C, needs 3 runs of duct tape over radiator in cold, 65-70 in hot summer, Bultacos going 75ish.

Derek,

Measuring EGT 150mm from piston face as recommended by tuner and manufacturer

Mike still work in progress.

My secret weapon against the NSUs and C15s in the 250 < '63 class ! So I can get off the line easier.

I got some 27/20 top gears from Frank Perkins whom I met at Lydden in 2005.
Reckoned we could get some 20/27T mainshafts and first gears made, using 25/22 and 22/25 second and third would give same ratios as 3sp CRs with a 1.83:1 lower first gear. Can send you my Excel chart of all different combos.

Then Trevor Amos told me what they used in the Todd/Amos 185 4 speed. That would be a good set with slightly lower second.

So we are getting some 27T first gears cut and standard mainshafts modified with some 20T gears splined on.

Still dreaming of building an aircooled short stroke 175 (64x54) a real weapon me thinks ?

Hi John

Thanks for the reply can you elaborate on this subject, EGT and instrument the manufacturer can you tell me who it is, or is it a home made afair, are you checking oxygen content, all I seem to remeber is gordon gennings book was great if only i could find it.
Bosalgnia also specifies this in his Kart tunning book, I find it laboriouse, also you need a personallity transplant to read it.

Interesting about the gearboxes ratio's - but you can buy all these "off the shelf" - first gear for about £13.5 pounds as you can the press on gear which is cheaper, you can then have them sparked for approx £150/200 for 2 or 3 sets, these are available in two metal types we nitrided ours after machining. I am currently running a brand new set all made like this, I'm sure others must have done this to. The same for top gear that can be repaird when a broken gear available in same or different tooth's -bore gear press on step diameter with face keyway for drive, the only one we have had difficulty with is the slider gear ? on the layshaft, costs for new vary from £350. upwards in volume.

sent you private post on this some time ago you never responded ! specifically on moving top closer to second !.

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Mike inertia is a really interesting subject, on crank flywheel inertia, a lot of the motorcross manufacturers tried this back in the 90's using exterior on the end of the timing side different flywheels for different tracks, all moved to larger fly wheels, they appear to be comming back down again, we tride this on the cluch it allows a little pit more protection for the gear box too, this failed as it caused other issues from my note, we do have a small copper flywheel on the outside end of the crank pressed onto the small sprocket, i could not not tell the difference only it would pull a much taller gear ? if I was honest, dad's idea we did this for CRMC croft race of year in about 2000-pulling 16x52 at 10,100-not sure what this equates to in top speed, we had tried 17x54 a little high- anyway I managed 2nd in the 200 race, thats another tail,- moving on. Mike-my guess base on your photo and elaborations is if your suggesting this now then, your running larger flywheels, this propably means either your about go back to try this or already done it and it never gave you the result you were after.

on the selector i must be missing somthing here, clearance and pin size any clearance allows slider gears to move up and down so affecting location, I think, how much clearance are you allowing, been out too long to make any comment on this, things seem to have moved forwards
in this area with talk of all kinds of stuff going on. should try and get it on here so other can read it. ??

Clutch components- Tom does a mod where he gets rid of the old pin, dished washer and weak spring then replaces it with a ground down shoulder bolt to 7mm(?) as the pin and uses a bantam clutch spring to replace the old sring using a washer and a nyloc nut. I'll take pic's when a have a motor apart (will be post Mallory)

Dave King I'll post some pic's shortly ref clutch stuff (what we do) and more clutch info give me a week...

Derek Cranks- For a Honda RS125 you can get Light, Std and Heavy. Steve Patrickson's site states-
Light - for short twisty circuits
Std (Med) - Everything else
Heavy - long fast circuits....

I've read about crossers having heavy crank wieghts to boost pick up out of corners?

Thing is a modern bike has to have crank weight(flywheel/ignition rotor) or an expensive hi-tech crank honda ones are £1'699? Where as on a bantam you have a lot of space in your crankcase to play about with crank size/weight/ingeria and packing rings.... Food for thought....

Hi Mike been think about the topic you raised some months ago know, having given it a lot of thought I have decided you are right, I agree, I know I did not agree to begin with, but having talked to others about it, its not a fair current state, with some riders 3/4 stones lighter than others.

This is not Discrimination againt the obease !

Light weight riders have too big an advantage, so count me in "a minimum weight should be bought".

not sure how you would police this, but could be simple with spot checks in paddock, by having weights added to the machinery, besides I'm feed up with all this dieting and talk of food and thought.

I therefore forward a motion to have a known std minimum weight with rider and bike inclusive.

regards Derek

How about min weight 9stone???????

Interesting comments Derek... Don't know what others thing?

I was interested in saving weight to increase performance/handling of bike, not having heavy bantams (they are all heavy) made heavier..

I noticed Lightweight Peter Tibbits won this year..

I think Peters giving me a 3 or 4 stone advantage but i think i'm giving him a 5bhp advantage..

I think things/rules should remain unchanged, i think people race bantams because they like bantams... admitedly the low power output of a bantam favours the smaller rider... but we all knew that before we started..

What do people think of a minimum Rider/Machine weight?

Steady Tiger - always new you were an M.P. in the making.

surprised never got more comments to that one, anyway, l like the idea of heavy flywheels for better excelleration out of corners! we must try this one, could make up for my masive weight disadvantage i have to your lightweight frames !.

regards

Derek