ESE's works engine tuner

[wobbly]

Something seriously wrong there then.
The reed 1st resonance should be around 11 to 12,000 for peak at 14,000.

[Lightbulb]

Attachment 332386Attachment 332387

Ages ago to increase the airflow through a class legal 24m carb I came up with the idea of a 24mm venturi section in a 24mm carb that had been bored oversize. The idea was that the larger front section acted like a flow straightener and by eliminating turbulence it would allow the venturi to pass more air. Whether it really worked like that I don't know but it did allow Team ESE to make much more power with the old air cooled 125's than people thought possible for the class.

Attachment 332384

Recently on an inspired whim I brought an old Kilt pumper carb from Ebay Japan. And found it had a larger bore with a 24mm venturi at the engine end, just like my modified carb.

Attachment 332383Attachment 332385

The 24mm venture can be seen at the engine end of the Kilt carb. Seeing that Kilt have also done this leaves me feeling really vindicated and in good company.

It is not everyday that you find one of your original clever ideas was also one of the big boys tuning secrets...

Attachment 332389

Kilt make real flash pumper carbs for Kart racing.

My experience of venturi for a restricted class, is to have the venturi point a s far forward as possible, with almost the longest possible total venturi length that the rules allow. Often with a restricted class is a plenum volume as well.
Neil

[schutten]

Thanks for info.
I´m just sold to the stability of PVL, solid like a tank, never fails.(well, not yet)
And the curve seems to fit my engine just perfectly now after activating the exhaustports.(had them locked open before).
I have a perfect flat torque powerband that´s about 3500rpm wide.

And by that i want to give the PVL 458/4000 some more chances.
I dunno, but i ordered some silver sparkplugs just to minimize losses in spark.
Maybe a pluglead with silvercore could help also.
Dunno if even exists thou.

Rgds.
Patrick

The PVL coil is a CDI and coil in one, and there are no different winding ratios available.
One magnet on the rotor supplies the power to the CDI the other activates the trigger.
There are various stator windings available,and the more turns ( like 4000 ) the greater the retard available but less " power " at the plug.
I got 5000 turn coils made years ago ( no plastic covering ) to use on Banshee quads as the kick start hardly turns the thing over and the high ratio
winding gives a fatter spark at kickover ( also more retard as a bonus ).
But anything other than a pretty much stock engine and the plugs would misfire at higher rpm.
The kart stators are the lowest number of turns ( 50 ohms ) and have no trouble at all with high speed high power engines, but that has a useless dead straight ( flat ) line ignition curve.
They do run best with no resistance, in the cap or the plug, but sadly there are no trick rare earth plugs available with no internal resistance - that would be the best case scenario.

Edit - TM sell a Brisk plug with no resistance that does work well with the PVL - part on box is L08S Silver 1827

@Wobbly

Many drivers use here the NGK R7282 plug with the NGK TRS1233A plug cap, this is a total resistance off ~9 kohm.
TM advice no resistance in cap or plug,what are the pros and cons Of this combi, s ?

[JanBros]

regarding squish : it is agreed that a minimum of 1% of stroke is safe. I suppose this is the limit for "normal revving engines" - by that I mean for example +/- 14;500 for a square 125?)

but what can be considered safe for an engine that hit's only about half it's "normal max rpm" ? talking about my Sky-MX (39x41.4) moped : tuned for max power at 7.500-8.000 rpm, and I don't think at a race it will ever reach 9.000, so that's about only half of the "normal max rpm" for 50cc.

Is my simple thinking correct that a squish of 0.4mm is over-safe and that 0.2mm would be ok (very simple thinking : half rpm's, half stretching/bending, half squish needed) ?

[lohring]

Our solution was to drop the head button in small increments until marks appeared on it from piston strikes. Then we increased the clearance a little. Of course that's easier to do on a 34 mm bore cylinder.

Lohring Miller

[SwePatrick]

regarding squish : it is agreed that a minimum of 1% of stroke is safe. I suppose this is the limit for "normal revving engines" - by that I mean for example +/- 14;500 for a square 125?)

but what can be considered safe for an engine that hit's only about half it's "normal max rpm" ? talking about my Sky-MX (39x41.4) moped : tuned for max power at 7.500-8.000 rpm, and I don't think at a race it will ever reach 9.000, so that's about only half of the "normal max rpm" for 50cc.

Is my simple thinking correct that a squish of 0.4mm is over-safe and that 0.2mm would be ok (very simple thinking : half rpm's, half stretching/bending, half squish needed) ?

Don´t take the 1% rule as certain.
I have 61mm stroke and piston touches the head with 0.8mm.
I run at this point 1mm and can rev upp against 14000 without touching.

137mm rod 61mm stroke and 66.4mm bore.

Rgds

[JanBros]

isn't your engine 211 cc (and a dragbike) ? and wouldn't it be fair to say that a 211cc revving to 14.000 is slightly outside the "normal max revving" capabilities ?

[SwePatrick]

Oh yes it is.

But i just mentioned it so one can se that 1% doesn´t need to be the complete truth.

[wobbly]

Schutten - the combination of plug and cap with 9K Ohms is what is needed for a digital ignition to reduce the bad RF created by the coil voltage "ringing ".
In the PVL analogue setup this is not necessary at all as there is no digital control of the ignition curve.
All the testing I have done with PVL shows that a " better " spark is gained by using cheaper,non rare earth plugs, with no internal resistor, as well as simple clip on caps.
All the latest rare earth plugs have internal resistance,and good results are had with these ( like the NGK shorty type ) and the ridiculously expensive matching cap,but that only
works on the kart type straight line PVL version.
Much cheaper is to use a R7376 with a clip on cap and this gives the same performance for 1/3 the cost.

[SwePatrick]

How about those bosch silver plugs?

[wobbly]

Never seen Bosch silver - only Brisk, that is what TM sell.
But those have a silver center electrode, not a rare earth ground strap, thus only half the advantage of less voltage requirement and less shrouding.

[TZ350]

.

Just so us 2T boys know what we are up against.



Some time ago Richban and the GPR boys dropped in for a dyno session. Richbans FXR150 pulled 23.9rwHp (red line) which was pretty impressive. The blue line is my air cooled 125 2T, being air cooled it would lose its edge after two or three laps.



I think this is the 20th Team GPR bike and I expect they may have improved the power output a whole lot more, they are looking dangerous.

You have to admire those GPR bikes.

[TZ350]

I was traveling in the South Island this week and made the pilgrimage out to Grumps place. Where he was working on his latest project, the twin cylinder 150 made from cutting down a four cylinder engine and crank.



Even though the original four cylinder motor looks quite bulky it is much lighter than I thought. The half crank is very light and the primary drive and gearbox is much lighter than comparable FXR150 parts.

But the best part is that the twins RPM ceiling is about 18,000 rpm while the FXR150 is about 12,000. There is big performance possibilities in that extra 6,000.

[TZ350]

.

The two stroke team need to get busy........ or the four stroke boys are going to give us the 4T salute....

[mr bucketracer]

.

Just so us 2T boys know what we are up against.



Some time ago Richban and the GPR boys dropped in for a dyno session. Richbans FXR150 pulled 23.9rwHp (red line) which was pretty impressive. The blue line is my air cooled 125 2T, being air cooled it would lose its edge after two or three laps.



I think this is the 20th Team GPR bike and I expect they may have improved the power output a whole lot more, they are looking dangerous.

You have to admire those GPR bikes.

thats rob , hope to have good results , got to get me a tread mill to fix me lol