ESE's works engine tuner

[wobbly]

He He, watch out or I will tell No Mates you guys think you are fast - and he will turn up with the 5 year old 29 Hp RG100/RS125, just to put you all in the fence.

[F5 Dave]

. .. sacks of shit called 4 strokes, will be down the dunny along with Hondas corporate masturbation antics - exactly where both belong.

That's a bit harsh, what have Honda ever done to you? You meet the nicest . . .etc etc. .

[richban]

He He, watch out or I will tell No Mates you guys think you are fast - and he will turn up with the 5 year old 29 Hp RG100/RS125, just to put you all in the fence.

Oh fuck yeh, bring it on. I'd like to see that. 205kg of me and FXR don't get put in the fence that easy. We will be waiting all weekend. Have a track all organized.

[kel]

205kg of me and FXR .

So if the FXR is 135kg that makes you 70kg. Is there a fly weight class in buckets?

[kel]

He He, watch out or I will tell No Mates you guys think you are fast - and he will turn up with the 5 year old 29 Hp RG100/RS125, just to put you all in the fence.

Ive heard a rumour that there just might be an apperance at the next round.

[richban]

So if the FXR is 135kg that makes you 70kg. Is there a fly weight class in buckets?

No that would make me 6'2 and 96kg and you can work out the rest.

[speedpro]

Oh fuck yeh, bring it on. I'd like to see that. "205kg of me "and FXR don't get put in the fence that easy. We will be waiting all weekend. Have a track all organized.

Richban @ 205Kg
FXR @ 95Kg
Total @ 300Kg, is how I read it. He goes all right for a fat bastard, eh?

I saw someone who didn't know any better putting the lean on Warwick Snow once. Only once!

[richban]

Richban @ 205Kg
FXR @ 95Kg
Total @ 300Kg, is how I read it. He goes all right for a fat bastard, eh?

I saw someone who didn't know any better putting the lean on Warwick Snow once. Only once!

Thanks Mate. No comeback for the one.

[TZ350]

Well Thomas has come up with the goods again.

Making more power than the 4-Strokes with a peaky 2-Stroker is relatively easy but having a wider effective power spread than the FXR's is something else and has been a goal of mine for a while.

As I see it, having a powerful easy to ride bike with a very wide power spread is the key to beating the FXR150's with a Stroker. As part of the plan I have been looking for a practical variable inlet and Thomas came up with a good idea.



And it could be the answer to lifting the lower rpm power of the GP (blue line) and thereby having a wider power spread than the FXR's (red line).



The way the engine is now, the rotary valve closes the inlet tract 85 deg ATDC. The idea is that its not necessary to have a continuously variable closing point, in practical terms, a stepped closing from 55 to 85 deg ATDC that is opened automatically by something sensing the rpm would work just as well.



With a divider down the middle of the inlet track right up to the rotary valve and a gate that closes one half of the inlet tract the closing point of the rotary valve with the gate closed would effectivly be much earlier, 55 deg ATDC. With the earlier closing and the inlet tract being effectively much smaller this should extend and lift the lower power spread.



By opening the gate you get the full inlet tract and later closing point of 85 deg ATDC for high rpm power.



With a high velocity fuel atomizer region in the carburetor (like we use), the rotary valve and inlet tract divider does not have to extend very far into the carburetor.



I think this variable inlet idea could work equally well with reed valves if the reed block has a divider fitted inside like some modern ones have.

[wobbly]

Have a look at this idea.The Lectron carbs have a venturi behind the slide, so you get high velocity at half throttle, but actually in bench tests they flow more air than the same size PWK when wide open.
Add a 1/2 throttle plate and the flow wont be as disrupted , as it would be with a plane "gate" when inserted.

[TZ350]

Have a look at this idea.The Lectron carbs have a venture behind the slide......

The lectron venture looks a bit like my 24/28 idea.

I would be very interested in where the size of the Lectron carburetor is calculated (measured), is it at the slide or inside the venture? might settle a few arguments about the legality of my 24/28 carb.

[TZ350]

Add a 1/2 throttle plate and the flow wont be as disrupted , as it would be with a plane "gate" when inserted.

Thanks for the post, looks to be a better (and easier) way of doing it, it encourages me to give the idea a go,

I think the FXR's should be afraid, very afraid, this could be the first 2-stroke Bucket with more power and a wider easy to ride power spread than the popular FXR 4-Strokers.

Watch this space, if we can get this to work, home built 2-Strokers could soon be making a comeback .........

[ac3_snow]

Home built Strokers could be making a comeback .........

Well along that tune, with uni holidays at the moment I have had a time to make some progress on my bucket.
so its a TF125, first attachment is the port map for its current state.
This gives me timings of :
Exhaust opens 81 ATDC so 200 duration
Main transfer opens 117 ATDC so 126 duration
and the Piston inlet ports open 74 BTDC with 158 duration.
I'm fairly confident I have the right exhaust width for the necessary blowdown time area.

However after talking to giggles and reading speedpros comments I think I may have got a little carried away on the inlet ports. Might see how it goes and can always put a little devcon in if needed.

Don't get carried away with the piston port intake as the pistons will start cracking and if you don't catch it in time you'll do some serious damage.

Transfer openings/ window seem to have about a 1.5 ratio by my very rough measurments so have not widened them at all will just match them nicely to the cases.
The main transfers have a 126 duration but the secondary trasnfers open about 2 degrees earlier, should I raise them both slightly to increase the main duration closer to 130??

I also plan on copying giggles and Tezees RG50s and cut down the crank case reed and epoxy it in flat to the bottom of the barrel. Then do a little grinding to help the air/fuel find its way into the transfers


The head has far to big of a squish area at the moment and needs almost 2mm taken off to bring it down to 0.9mm.
I have heard speedpro mention previously that a centered sparkplug will perform better than one offset. I don't know if I want to attempt this might be beyond my capabilities and tools.

Its all going into a cbr250 frame.
6 months ago I new less than nothing about 2 strokes, have managed to bluff my way this far can't wait to have it all together and see if it actually goes or not!

[speedpro]

Love the toothpick.
Don't raise the transfers, blowdown is most important on a motor with a single ex port and you don't want to reduce it.
My old TS100 had 200deg duration of intake timing and I devconned over the reed valve to make a nice smooth intake port. The theory was that with the intake timing tuned for 10-11K there was no need for the reed to extend the working revs. I'm not sure why it turned out to be such a nice engine, see the graph green line labelled KR100.

[TZ350]

Its all going into a cbr250 frame.
6 months ago I new less than nothing about 2 strokes, have managed to bluff my way this far can't wait to have it all together and see if it actually goes or not!

It all looks good ........ actually, it looks very good.