ESE's works engine tuner

[TZ350]

Is it just the pic or did you 'miss out' on the opportunity to make a nice radius on the inner side (devcon) of the transfer? (seems wide at the bottom so can't see it getting far more wider inside the transfer?)

Hard to see so well in the first picture. But the devcon comes below the cylinder, as I was trying to form a smooth radiused transition from the inside of the cylinder into the transfer duct. I was also trying to reduce the volume of the transfer duct and have the entry 1.1 times the port window with a big radius right around from the duct entry to the port window.

The inner wall of the duct now looks to thick and has been slimmed down in the top picture. Anyway this triple port cylinder, in spite of having more blow down time area has made less power than the single port so far. And if trimming the devcon in the transfers does not improve things then I probably wont bother on future cylinders and just leave the inner duct wall like Suzuki made them.

[ief]

Guess you went a little overboard there, getting it back to original hight with a better radius then stock... could be benificial... I guess.

That sand linnen stuff used in belt sanders, might be the ticket for the the job, not easy on the fingers tho.

[kel]

The width between the cylinder and transfer where the glue is, is 13mm, it was 16 before, but Kel suggested it might be to much. Before I made these changes the 3ex cylinder made an easy 29hp at the wheel.

Yep thats right I made the leap from test pilot to design consultant with a single crash (hope they realise I took a knock to the head as well ). Whats the saying "hero or zero"?

On a completely unrelated matter, it seems the mighty FXR's have reached their performance/reliability limit - quote Yowling "Yea 4 big ends in 2 weeks,(mat hoogie, hank, josh and bren)"

[FastFred]

...it seems the mighty FXR's have reached their performance/reliability limit - quote Yowling "Yea 4 big ends in 2 weeks,(mat hoogie, hank, josh and bren)"

Then there was that Bike that dropped its inlet valve at the BOB. I am not sure who, but someone on here suggested to Team ESE dropping 2PS or so to improve reliability, the 4-stroke boys might find it worth a go.

[F5 Dave]

Well to be fair (odd as it sounds coming from me) a lot of these 4 bangers are running old parts & at high revs the rods need replacing every-so often. - just people treat 4 strokes like XR250s & just petrol & oil.

That other bike was a GN125 & the best thing that could happen to it. Its been very reliably though (in the garage for 4 year stretches).

[TZ350]

The transfer specs call for a area ratio between transfer port window and tract entry of 1.3:1 (main transfer).



The tripple port cylinder on the right has had the duct entry closed up to a ratio of 1.3, it looks very small to me but the inner radius has a better looking curve to it.

Measured the volumes of the transfer ducts.
Right hand tripple port cylinder with 1.3, 1.2 and 1.1 area ratios
Trans A = 24
Trans B = 16
Trans C = 8
Total = 48cc for all transfer ducts combined.
Left hand single port cylinder
Trans A = 40
Trans B = 20
Trans C = 8
Total = 68cc for all transfer ducts combined.
A lot of the fresh charge must be, being transfered from the crankcase.

Is it just the pic or did you 'miss out' on the opportunity to make a nice radius on the inner side (devcon) of the transfer? (seems wide at the bottom so can't see it getting far more wider inside the transfer?)

I tried to get a more even and better radius like the dotted line with a 1.3 entry area ratio and a nice radius out of the cylinder.



But maybe I need to make it more like this Cagivea cylinder but then I wouldn't have a 1.3:1 entry to port window area ratio ...... I must be missing something.

[F5 Dave]

A reed valve?

[TZ350]

A reed valve?

NOoooooo ...... not a reed valve ...

[TZ350]

Ok ... re visiting compression testers.



This head has a 1/2" reach plug and the compression tester adapter fills it well so no low comp errors there but it would be a different story if this was a 3/4" reach RG50 head, then there would be a big clearance volume error.



140 psi Compresion tested after reassembly, the cylinder was oily and cold.



130psi Tested hot after a dyno session, I expect this is a truer reading as its what the engine would be like when running.

So about 10lb/psi between cold and oily and dried out and at running temperature.

So now we know ......

[Drew]

Ok ... re visiting compression testers.



This head has a 1/2" reach plug and the compression tester adapter fills it well so no low comp errors there but it would be a different story if this was a 3/4" reach RG50 head, then there would be a big clearance volume error.



140 psi Compresion tested after reassembly, the cylinder was oily and cold.



130psi Tested hot after a dyno session, I expect this is a truer reading as its what the engine would be like when running.

So about 10lb/psi between cold and oily and dried out and at running temperature.

So now we know ......

I've got a twin though, so either way as long as conditions are the same both sides it's handy for me as a comparison yeah?

[TZ350]

I've got a twin though, so either way as long as conditions are the same both sides it's handy for me as a comparison yeah?

Yes ... I would think so, it looks like a compression tester used intelligently makes a good diagnostic and comparison tool for keeping an eye on the engines health but its a pretty unreliable way of determining a small engines corrected compression ratio.

[TZ350]

Kel came around tonight and gave me a hand with running the Beast up on the Dyno.



Red line is what we had before we lost the ring locating pin. The Blue line is where we are at after chamfering the exhaust port and opening up the transfer ducts. Chamfering the exhaust port from 81 ATDC to 78.5 will have reduced the volume required in the cylinder head from 9.4cc to 9.0.

So three changes:-
Ex port effectivly opens earlier at 78.5 deg ATDC instead of 81 because of the radius.
Corrected compression ratio is reduced because of the change to the exhaust port timing, head needs CCing.
Bigger entry and reduced inner radius on the main transfer ducts.

Right from the start the engine sounded rich and flat. I am not sure what that means. But I will CC the head and the next chance I get to go on the dyno. I will get the laptop out and have a fiddle with the ignition timing and lean the main jet out a bit.

I am not to unhappy as I think the rich and flat response is because of the porting changes and may be a good sign, I expect it will come right when we get the ignition and carb sharpened up.

[Frits Overmars]

This head has a 1/2" reach plug and the compression tester adapter fills it well so no low comp errors there but it would be a different story if this was a 3/4" reach RG50 head, then there would be a big clearance volume error.

There's always a big clearance volume: in the hose. And its effect gets worse the smaller the engine.

... it looks like a compression tester used intelligently makes a good diagnostic and comparison tool for keeping an eye on the engines health but its a pretty unreliable way of determining a small engines corrected compression ratio.

Amen to that.

[Frits Overmars]

Corrected compression ratio is reduced because of the change to the exhaust port timing, head needs CCing.
.....Right from the start the engine sounded rich and flat. I am not sure what that means. But I will CC the head and the next chance I get to go on the dyno. I will get the laptop out and have a fiddle with the ignition timing and lean the main jet out a bit.

Do yourself a favour, fiddle with the main jet and go to the dyno before changing the head volume.
And forget all about 'corrected' compression ratio. It's an illogical and unworkable concept.

[husaberg]

A long while back i said something to Rob about how the 24mm carb need not be as limiting factor to airflow as people think (well seeing as he has got 30 hp. It turns out its not a limiting as i would have thought anyway)

I said something along the lines that i don't see why the carb has to flow all the air flow for the engine, just some of the air/fuel mix.

Well it turns out, as i always suspected, I very rarely if ever have an original idea.

The URS 500
Which Helmut Fath one the 1968 world sidecar championship aboard well at least when in solo form (the sidecar at times had fuel injection i believe) has a duel inlet system with 4 22mm carbs on a 500 four (which is pretty small for a reputedly 85hp four stroke 4 cylinder.) Late MV 500s had 31mm carbs and the late Bennelli 500/4 was 33mm carbs
The diminutive 22mm carbs were supplemented by air slides that controlled air alone. Well they were in the article i read anyway the later ones might have been bigger
I am assuming the additional air inlet ducts only slides only come into play late in the rev range with the air fuel compensation control by rather large mainjets.


If you are struggling to see it look on top of the engine.
So whip up one of these systems over smoko will you Rob


EILE MIT WEILE