John's ex Lionel Howell 125 watercooled motor

As requested my Mike and Nick a little history and detail of my motor.

It was built in 1980 by the late Lionel Howell in 1980 as a 54 x 54mm short stroke.

I think that#29 is him.

He broke his back in an accident at Snetterton that year and his son Richard carried on with the bike after he retired.
Getting 12th place in BRC Championship in 1981, 2nd in 1982, ? 5th in its last year of 1983.
It had a number 2 plate on it when I bought from Lionel in 1988, he showed me a lot of his photos and I seem to remember him telling it came second in a 50 Mile race.
When I started racing the porting was too wild for me and we put the original 1980 liner with BRC manual porting back in. Later the porting was increased and 4 years ago a new liner made with a 56mm bore, as I ride in an <250 pre65 class. It originally had a 34mm Mikuni carb, even though the inlet port is only 32mm, It has run for 23 years now with a 32mm Amal Mk2 power jet for our BEARS type regulations.
It has a 96mm crank with pattern TZ250 rod, which Dave grinds oversize pins to keep a tight fit. RM125 ProX piston



Port timings are Exhaust 196 with 38mm port, Main transfer 132, Auxilary 133-134, Inlet 170










Gearbox is pretty standard BRC modified setup, with 25/22 top gears I had made, needle roller layshaft bearings.

Clutch has 4 hardened metal plates and the usual radial roller bits.

Ignition was Motoplat, but I fitted an experimental Rex Caunt system like Alan Brown had used, it broadened the torque curve, but stator coil has gone down, so I might fit an Electrix world system.



CR is 15:1 using AvGas.

As I am not a fast rider and don't have a lot of spare time I have kept it basic, reliable and had a lot of fun.

An early Dyno run with 1980 pipe and an RS modified pipe (too short):

Hi John,
a nice insight into your bike, thanks for the post. The motor looks very nice just out of interest do you keep a race log or
is it a case of strip and measure for your rebuild and maintenance schedule.
all the best Nick

Hi John

good of you to post your engine details, thanks

I'm not familiar with that piston - what is the hole above the gudeon pin for ?

You mention this was an early dyno run - have you managed to raise the power since then ?

Mick

Yes Nick since starting racing Bantams at Snetterton in 1985, 3 BAntam racers later, i have kept extensive race logs in wee notebooks I take in toolbox to meetings and later enter data into my modification of ye olde BRC "Essential Data" and "Routine Check" sheets.
My maternal Grandfather was a pattern maker at the BSA and when I was a little tacker, regailed me with many stories, the boring old fart- I thought, now I realise all that social history has gone, unrecorded.
So I have deligently noted many conversations with some of the great characters like Ron Warrior, Terry Betts,Tom Miller, Bert Flood and Ginger Molloy, I have met printed out many e mails etc
but.......SWMBO has just banned my huge collection of ringbinders from the recently redecorated study/office ! So now I am forced to sit out in the garage aka "Man Cave" with a cold one, listening to Acka Dacka, to mull over the masses of info. Well its better than Coro St or Neighbours!!!

Mick, those dyno runs were done a while ago when Scott (my engineer mates son) built F3 Kawkers. Sadly he sold the dyno and I have not had near access to another since. So still using 1980 pipe at short circuits:

Ken got a new tailpipe and silencer made 2 years ago when he rode it, I suspect the 19mm ID is too small.

The cobbled up RS derived pipe, was one of Scotts 125GP rejects, that works better than either of the Computer Simulated/designed pipes people have done for me. Reasonable for long fast Pukekohe circuit, but judging by your figuires still too short to the middle section. Each works well with the two Caunt ignition curves chips.
So with big hospital clinical work load, department admin, keeping young fellow busy, I have not developed it much nor derived anymore power. if the old barrel and cases are worth preserving I really need to get on and get a better modern pipe made. But I also have numerous other projects: cast iron barreled 185 and a 4 speed BTW/TM alloy top end, not to mention 2 bantam and 1 TY trials bikes, to get on with. But I would really relish getting past a few more heavy old C15s and NSUs if I could get it upto 20Hp

JB, I would be interested in your thoughts on burn pattern of my piston?
Warren incorectly marked it, numbers are to rear
.

My cylinder head always runs really clean since using synthetic oils.
My water inlet is left and below exhaust port and exit top/back of head.
The black smudge happened after Motoplat back plate came loose and outer crank seal got heated up and marmalised.

Mick,
I ahve no idea what the reason for piston cavity is for. It does not go right through. Maybe part of a boost port system.
I used to use Wiseco RM pistons, but my new tuner/helper prefers ProX and this one was avaialble locally sitting on shelf.
Having ridden Alan Browns bike in the Parade at Lydden in 2005 (yup I was the wally that shot up inside you and Pete, before ground looping in the kitty litter at Paddock Bend!
) I realise that one can get a lot more torque than I have, but it takes a lot of know how and work on the dyno.

Hi John you have a great amount of torque from this motor, I would of expected it to be
a fair bit lower. Does your gearbox mod use shim's to get the layshaft in the right place?
Brass coloured shim in press on gear? Did this cylinder have ports put 'on' or is it using
std cast ports plus a few mods?

Cheers Mike

Mike,
Yes and sort of both.

The layshaft is located by phosphur bronze washers that basically replicate the flange of original bushes.

The transfer ports utilise the original outer wall and exhaust side of original casting to feed a standard sized main cylinder opening. With a brazed on rear box to make the base appeture wider towards the inlet and to feed the auxillary transfers.
I think another mod would be to put a splitter in like yours.
But the old barrel is getting leaky and often needs another Devcon bandaid.
Me crankcases are looking at bit sad too, so now weighing up its longterm prospects.
Given time, my dream is to build a 4 speed, short stroke 175 with an alloy watercooled barrel !

I was interested Mike, by your comment about adequote torque.
When Aidan Bent rode it he reckon it was easier to ride than his bike, didn't rev out quite as high and had around 20Hp.
My vague memory of 002 at Cadwell was that it revved out much higher
He was doing 1.34 - 1.37 a lap [90mph ish] round Pukekohe first practice, which is a bit faster than I ever did.
But then I have a few extra Kgs (sorry Ted and JB, even the butter we sell you is 0.55Kg!) to carry.

Hmm, any suggestions where to look to shorten lap times ? other than funny fuel.

Hi John Mike makes a very interesting comment on torque 12 is a lot for a bantam a v/good Rs will only produce 18.

I can see why your 22/25 works well, great for the 175 - not sure how they get on without a set.

I would look for a 21/26 slider set from the trials set up, were 13,000 made, You would need to convert the layshaft dogs to go with the close ratio 1st gear,

but if you run it through that excellent piece of work you did on ratio/calcs formula,spread sheet, you will see with your torque you should be able to pull a much taller gear,and not have issue when changing between 2nd and Top ( please post that formula spread sheet again, as I can not find it)

Regards Derek

This is something I asked about before and didn´t get an answer: the JohnS ... dyno curves have similar fluctuations as had the Jimmy´s power curves which Mike showed some time ago. Jumps and drops of 1/3 to 1.5 hp over 50 and 100rpm increases -- just unbelieveable??

I realise now what it possibly is (not undamped stylus...) and have lost the excitement first felt -- I´ll not criticise the dyno operator just ask if it is OK to construct a curve using all the peaks where there seems to have been a struggle to get the WOT (Wide Open Throttle) conditions steady... Jusz not used to seeing dyno curves drawn this way.
Cheers!
.

Second thoughts on the JohnS... dyno curves:
-- a bump at 5,000 followed by a dip to then bump again at 8,000rpm on one of the curves harks back to Jaguar yonks ago making a similar -- winning -- GP car do that by tuning the air intakes...
hmmmm -- Must look it up...

Looked it up -- it was Coventry Climax and they got the double max torque hump by "tuned exhaust"
so I guess it was down to exhaust pipe, JohnS...

... But WHY?

With a resonant pipe, are we always using the first reflected wave? I´ve often wondered about 2nd harmonics or are smaller reflections cancelled out??? -- I know little about what goes on there -- just used the formula that my engine man gave me that originally came from Joe Ehrlich ....??? and with the ABS 250 the measurements Andy Boyle gave me....

Just seen your note, JohnS..., about the burn pattern on the piston -- it seems to me there´s some useful expansion combustion pressure going out thro´ into the exhaust ... -- pipe or exhaust timing?? plus the squish band (bump clearance, piston crown to head) is uneven. I´m only guessing. Why does the head look so clean -- except for where the squish looks uneven ?? If the bump-clearance is less than 40thou the piston crown clearance can actually reduce to almost zero at full load max revs....

Avgas? 15:1 compression ratio means a methanol or doped fuel of high octane number should be used -- in my opinion -- surely that´s allowed over there ... ??!!

I like the one ring...

If anyone can help to tell me how I can insert an Excel Spreadsheet ?

Hi John is that RM piston pegged at the back and on the centre line as std?

I assume its a plus 2mm o/s of a 54 piston?

I think the number we can read is a batch? number? The part number is the
one we can't read in the middle of the crown.

I believe Wiseco no longer do .25 .75 1.25 etc o/s only std .50 1.00 1.50mm.

Holes above wrist pin - I think its a forged piston think! removing ally so it does
not expand quite so much when hot...

Mike

My apologies, despite past and present tuners disparaging comments about Wiseco pistons, one bought it the other fitted it !

It is indeed a forged Wiseco RM125 1989-1999 Prolite 641M056 00
They do seem to vary 0.1 -0.3 thou when new, but last 30 hours with out shrinking - despite the rumours.
Yes, Mike 54 +2mm, single ring at 5 o'clock rear, high up so covered by "tonsil" on liner

Thats a shame, looked like a good piston, was hoping it was pegged on centre line.
I see Wiseco do a flat top piston pegged on centre line, but can't find a pic. Chances
are front and rear skirts won't be wide enough