ESE's works engine tuner

[F5 Dave]

Time to add that injector for closed throttle application. Only problem is it still needs to be fed from the same 24mm aperture.

[husaberg]

Time to add that injector for closed throttle application. Only problem is it still needs to be fed from the same 24mm aperture.

24-2-4 Engines must be derived from non-competition motorcycles. Motocross, Road Racing,
Enduro and Go Kart motors and transmission parts are not permitted. There shall be no
restriction on the make, type or design of carburettor, ignition, exhaust, piston, cam, valve
springs or cooling system except for class eligibility. All engines must be normally
aspirated except F4 4 stroke engines of less than 100cc capacity, which may be turbo or
supercharged.
F4 2 stroke engines over 104cc are restricted to carburation equivalent to a single 24mm
carburettor, F5 4 stroke engines over 53cc are restricted to carburation equivalent to a
single 20mm carburettor.

I have said to TZ for a while that i think not all the air has to flow through the carb. So not sure the rules define this.
It says the carb must be eq to a 24mm. Not that all the air has to go actually through it.

But anyway it has been written that one dodge to lower the risk of ring jamming that may be either thermal or as a result of piston rock is to machine the lands a tiny amount 0.02-0.04mm was mentioned. Yes the amount is tiny and the pistons are not round but i believe it can be effective.

[Ocean1]

It says the carb must be eq to a 24mm. Not that all the air has to go actually through it.

Wouldn't be the first to develop a persistent and strangely consistent vacuum leak.

[Frits Overmars]

The engine did not seize on full throttle running flat out, but after several down changes, when the throttle had been closed for a bit, maybe the cooling was marginal and when the cooling from the MJ fuel stoped, the engine stoped.

Then don't close the throttle .
The old 100 cc kart engines with direct drive were notorious in that respect. They were air-cooled, iron-sleeved and they revved over 20,000 rpm. When you cut the power at those revs, chances were that the con rod would quit; it needed the help of the compression pressure to stop the piston from going through the roof. So you had to brake first and then cut the power.
Common practice was to put a hand against the carb bellmouth and blip the throttle occasionally during braking to get some fuel through the engine. But more than one rider forgot how close the chain was to the carb, and had to remove his right glove with a finger tip still in it...
My solution was to fit a brake light switch to the brake pedal and connect it to the ignition cut-out wire. Then you could keep both hands at the wheel, saving your fingers, and keep the throttle wide open during braking. I would not advise you to copy this 100%, but think about mounting a kill switch and using it....

.....what to do? an alloy sleeve with large tripple ports, not for power but for better thermal reliability ..

And if the triple ports would raise the power by coincidence, you wouldn't object too loudly, would you?
But sleeve and thermal reliability are another set of words I would not use in the same sentence. OK, an alloy sleeve is better than a cast iron one, but there will always be a thermal barrier between sleeve and cylinder body. Even with the best shrink fit, oil will creep between the sleeve and the cylinder; that oil will char, and gone is your heat path.
Believe me, I know; you cannot come up with a single mistake I haven't already made decades ago (there is a fancy word for it: experience).
All in all, I guess the triple ports may outweigh the disadvantages of the sleeve. But couldn't you make the ports without using a sleeve?

[bucketracer]

couldn't you make the ports without using a sleeve?

TeeZee has hand sculptured a set of auxiliary exhaust ports into a cylinder, but with an offset exhaust the effort makes it difficult (impractical) to replicate in any qty, I hear Speedpro has suggested a different approach to him for getting more blow down STA.

Below is TeeZees triple port which will get a proper tryout with Wobs pipe on the dyno after the Easter meet at Kaitoke, the plenum might get a run too. The plastic sleeves are mock-ups made by Chambers, note the modified verniers he uses for measuring the port heights.

[husaberg]

Then don't close the throttle .
The old 100 cc kart engines with direct drive were notorious in that respect. They were air-cooled, iron-sleeved and they revved over 20,000 rpm. When you cut the power at those revs, chances were that the con rod would quit; it needed the help of the compression pressure to stop the piston from going through the roof. So you had to brake first and then cut the power.
Common practice was to put a hand against the carb bellmouth and blip the throttle occasionally during braking to get some fuel through the engine. But more than one rider forgot how close the chain was to the carb, and had to remove his right glove with a finger tip still in it...
My solution was to fit a brake light switch to the brake pedal and connect it to the ignition cut-out wire. Then you could keep both hands at the wheel, saving your fingers, and keep the throttle wide open during braking. I would not advise you to copy this 100%, but think about mounting a kill switch and using it...

I guess that was not with pumper pulse carbs because they would still pump gas on overun. no air though or not enough anyway.
I believe this was the major problem Cagiva had, as the fuel injectors would still pump gas into the cylinders on overrun. when the throttle was opened nothing would happen (BOG City) then it would fire up suddenly again, once the build up of fuel was expelled. High-sides anyone.
As i have said before, i once rode a pumper carbed MB100 that did exactly the same thing.

You GP125 already has the capacity to pump fuel using the pumper set up, has an ignitech, you can rig up a TPS. Wobs shown how to do the truth table. So a wee play and Bobs you mothers Brother. Fuel on over run when the throttle is closed and only when the revs are high. Shit you could probably go it gravity with a solenoid fuel control as long as it was post slide? Not as simple as the Frits solution though.

TZ wasn't there a plan a long time ago tho adapt a RGV cylinder.
If you were to use one of those you could have liquid cooling.
In fact if you went with a late model VJ23 wob suggested you could have auxillary ports and a wide ex port and liquid cooling and a power Valve.
but yes only 100cc but you could then run any carb you would like. Yes the stroke will need a bit of work as well.
Failing that you could always put a NSR250 cylinder one top of that Suzuki Honda made GP bikes to you know they went ok as well. So i am told.

Have just found out that the Suzuki VJ23 cylinder is a T port ( like the older models and also Aprilia RS250) but it has sub ports as well.
This may be an even better choice for sitting on a RG bottom end and sleeving to 50mm.
Anyone got one I can look at.

Posted the Cagiva stuff before but i don't care it suits my POV

[jasonu]

So what to do? an alloy sleeve with large tripple ports, not for power but for better thermal reliability ...

No, build a water cooled 100cc motor equiped with ANY size carb you want.

[Yow Ling]

with your ignitech could you run 2 maps, both identical but one having a revlimit of say 4k, when you brake it changes maps.would sure get you off the brakes on fast corners. You can get cast iron liners nikasiled. Rg150s inject oil into the barrel just beneath the exhaust port and RH main bearing only , petrol goes in raw, not affected by throttle position except in the pump

[twotempi]

There is a silicon paste which is used for thermal conductivity with alloy heat-sinks on electronic circuit-boards.

This may have an application between sleeves and the outer cylinder muff during assembly.

I don't think it is petrol soluble either.

Just a thought.

[Grumph]

There is a silicon paste which is used for thermal conductivity with alloy heat-sinks on electronic circuit-boards.

This may have an application between sleeves and the outer cylinder muff during assembly.

I don't think it is petrol soluble either.

Just a thought.

I've used something very similar seating heating elements into dies...given enough heat cycles it turns to dust. Maintenance on the dies consisted of redoing the paste application regularly.

[husaberg]

Ian Cramps 500 twin as i have said before the inlets were ugly but he was trying to fit it in a tz250 frame so the exhaust under the seat would not work.
i always did like the overlapping cranks though. As well as the 3 part crankcase which were clever.

This is his Website a few interesting bits and pieces http://www.iancramp.co.uk/journalism.html

[2T Institute]

Anything ever come of it?

[Frits Overmars]

And now for something completely different: the glorious new Moto3 Grand Prix class that will make us all forget those damn two-strokes.
I proudly present the Honda Moto3 price list: http://www.fim-live.com/fileadmin/al..._version_1.pdf
The above document shows the prices for the standard parts. Honda kit parts tend to be 'a bit' more expensive. But let's stick with the standard prices for now.
A standard piston sells for 1644.60 Euro; today that's NZ $ 2660 (and Honda will make you wait 4 months for the privilege).
And did you notice the price of a piston pin? 342.90 Euro ($ 555). Now who said Honda has no sense of humour?

[F5 Dave]

HUmina humina!

Well that's brought the prices down for the punter. I hear these 2 strokes were getting too expensive.

Oh well, the engine parts should last a long time being a 4 stroke.

[husaberg]

Anything ever come of it?

Missing a few installments but yes. It was finished in time for the rule change that effectively made it ineligible for most of it potential customers

LionHearthttp://www.iancramp.co.uk/design%20&%20development.html
A project undertaken in Japan was the design of a twin-cylinder 2-stroke 500GP engine (the “LionHeart”), the crankcases for which are modelled here by the sponsor’s PA. Completion of the engine unfortunately coincided with the Japanese decision to abandon a national 500cc class and go to Superbike rules instead.

I think this may be installment 4.
I have a few more but missing the last one i had when he went of to Japan to work and finished the engine there.
There is some information a a couple of pictures about it on his website but not much.

Those of you familiar with the Britten V twin will realise the team had a far easier method of constructing the patterns

http://www.iancramp.co.uk/Word%20Docs/WRITER'S%20CRAMP/GP%20Engine%20layout.docIf you want small and light, the V2 is the way to go. Or is it? Something which I hadn’t realized until I started designing the Lionheart is that having a narrow engine doesn’t do you any good once you get below a certain width, because the rider’s knees are going to be wider anyway. Even the lankiest rider, with his legs clamped tightly together, is going to measure more than 350mm across the knee area by the time you’ve allowed for a few layers of leather, some padding, and knee-sliders. So why make the engine any slimmer than that? Also, in the racing crouch position, the rider’s elbows will be in front of his knees, and you can’t get your elbows any closer together than your ribs. The width across the elbows will be pretty much the same as the shoulder width, which is quite large these days because of all the body-armour carried in that area.

http://www.iancramp.co.uk/Word%20Docs/WRITER'S%20CRAMP/honda_design.docWhen did Honda start designing their twin-crank 250 engine to replace the double-throw single crank one in their GP bikes? Well, it was just about the time that the first drawings of the LionHeart (with its twin cranks) were printed in FB. Ironic, really, when you consider how dog-slow the 98 works Honda engines were, but I did warn them - I wrote that LionHeart would have been a double-throw crank if I could have afforded it, but it was much easier (ie cheaper) to make two single cranks rather than one double. .......The more I looked into this, the more the deja-vus were hitting me. I am the longest-serving FB scribbler (for my sins), and anoraks out there who keep every issue of the comic going back to the year dot will be able to find a photo of me racing my highly modified, fuel-injected Honda RS125 long before Shinichi Ito was first seen testing the fuel-injected works HRC bike (and before the V-Due was ever thought of). Indeed, I think that I was the first person to race a two-stroke bike with electronic fuel injection ever, and while I admit that it needed a bit of sorting, it was certainly a lot better than the V-Due and could have been better still had I not been limited to spending about 0,1% of the time & money that factories have to sling around.

The other top secret HRC works trick of this time was water injection into the exhaust pipe. This, I admit, wasn’t on my RS125 - but only because I had abandoned it ten years before after a few races with it fitted to the Villiers 210 engine on my kart. I found that this type of injection (designed to increase the width of the power band) worked well on the dyno, where I used water piped from a cistern in the lavatory next door, but on the track I had to carry such a big water tank to make it work that the gains were not worth the weight penalty. HRC also abandoned this system after a couple of races, for pretty much the same reason.........but where did they get the original idea? Could it be that we are entering, not so much the twilight zone, but.........the toilet zone?