ESE's works engine tuner

[guyhockley]

Thanks a lot. Interesting stuff.

[F5 Dave]

Well I've finally managed to get some time again and dynod the RZ350 (+7mm crank and CPI barrels 496cc) with the 8 plate clutch. And after, ahem, tying it down a bit tighter, got some readings where it actually peaked without spinning up and losing the trace. But all is not rosy. Its got a decent hole in the power. 6 transfers but ducts aren't marvelous.

So I took the fuse out of the ypvs control and you can see it fills the gap from 6200-7200. I'll have to sort that with a new controller or go Ignitech. But the dip from 5500-6 stays. I take airbox off and that really helps the rest of the curve, but ran out of jets to see if that's just mixture. A jet leaner without doesn't help that area appreciably. And that 5-6 dip remains.

First pic PV locked low vs opening but too early. Click 3 times.
2nd pic without airbox.

Bearing in mind this is a roadbike and I chose 35mm pwk to try bolster lower revs. I was rolling it on to full from just below 5ish.

Thoughts?

So I could try cranking in a bunch of advance at 5-7 and see what happens, but its not without its risks on unleaded with a 2D map as on the road it will spend a bunch of time part throttle near those revs cruising.

[FastFred]

.

Don't do it ...... or part throttle deto will ensue.

Somewhere TeeZee has a post about the results when he tried that.

[F5 Dave]

Im thinking I might have to ditch the zeeltronics and go ignitech so I can 1. Control the PV better, 2, buy and RGV TPS so I can make a 3D map. But only if that would help fill the hole, at least at full.
Wob, have you had this issue on CPI barrels to try fill in? Or perhaps your pipes were understandably better suited. Any ideas appreciated.

[wobbly]

There are three suspects.
1 - how much advance have you got at the rpm where the hole is - with the PV down at that rpm a bunch of advance at part throttle isnt going to detonate.
2 - seeing as the PV fills in the huge hole, I wonder if the blade is down far enough and or is it sitting at more than 0.5mm away from the piston when fully down.Any more than that and its leaking like a sieve and doing jack shit.
3 - The end of the needle may be too thin, as you said you were rolling on to WOT just below the hole. The mixture at WOT when at low rpm is set by the needle/tube annulus area, and this may simply be way too rich
as it hits full throttle.Try rolling on slower so the needle isnt fully up till over 7000,this will show whats going on with the fueling.

[F5 Dave]

26@5000 down to 24#7000. Was trying to be conservative on pump gas.

Yeah needles do need some more work, what I was running trying to tune around that porous cylinder isn't right now.

I matched the (flat) blades you got made real nice to the first barrel. They aren't as well matched to the current one. Maybe I should readdress that.

Thanks for the ideas.

[F5 Dave]

Er. . no.2. Surely if the PVs were leaking badly. Leaving fuse out holding them down, surely that would have little effect?

[richban]

Er. . no.2. Surely if the PVs were leaking badly. Leaving fuse out holding them down, surely that would have little effect?

Well I can vouch for the igntech PV control removing big holes in the curve of the 300 Honda's. Turned mountains into mole hills.

[F5 Dave]

Yeah, so I tried it opening as late as the dip switch modded Yam controller would allow (supposedly 7000 but seems like earlier) and then with it held closed. Closed till almost 8 wins.

[G Jones]

The 250G cylinder has much more modern transfer ports and ducts than anything previously.
Thus you could do the mods as per the Eckerold cylinder but using waisted studs allows the inlet to go even wider ( with a bridge of course ) allowing two extra boost ports
and you then dont have to add an Exhaust bridge as going 3 port is easy.
Turning the cylinder around is also easy and this makes the pipe headers straight, and then the inlet becomes dead straight onto the reed blocks with the carbs sitting horizontally.
The 350 period engine going into the LSR streamliner is as above, but uses a Banshee 58mm crank/115 rods with 61.5 Kawasaki pistons, making it a not so big overbore and close to square.

Greatly appreciate your experience !
Thinking out loud...- the last of the "normal" TZ250's - I'd forgotten that - wasn't that an odd size piston ? (4A1 ? cylinder) - or maybe thinking of something different...
The banshee +4 crank - I've never been able to find a supplier that lists one that isn't welded - does anyone supply them just pressed up with a separate crankpin ?
I did ask a few of the suppliers a couple of years ago - if they would supply just the wheels - I can put them together myself - but all negative answers...
I'd looked at the Kawasaki pistons a while back too - although in the places I've been looking - can only find pistons for KE175 at 61.5 & the KE175D at 62.5 - although I've a feeling I may have seen KH ? 500 at somewhere around those sizes - not looked recently...

[wobbly]

The PV when held down fills in that huge hole, but just maybe if it was to work " better " it would also fix the hole further down.

Re the 250 G cylinder, yes it had an odd bore size 54.4 I think,but using oversize Wossner H1 pistons at 61.5 diameter this isnt relevant ( 58 by 61.5 keeps it under 350 and doesn't need case trenching )

I build cranks for the RD series engines ( using modified Banshee parts ) and only the center pin is welded.These have Mallory added to the wheels so that
the crank can be balanced correctly for the stronger long rods and the pistons that are much heavier than the oem 250 ones the cranks were originally designed for.
They use rollers on the outside, and a 1/2 clip groove is added to the center main tunnel, as all the engines i do have straight cut low ratio primary gears - needed to achieve
the top speeds and keep normal sized sprockets.

[F5 Dave]

Right gotcha. Will try get back to dyno one night and try different throttle techniques to see if it alters. Will try dropping needles and think already on fat shallow taper but have about 3 other options.

Then will try crank some more advanced just to see if it can be used to change that area.

3rd option take it all apart again and rework or remake the blades.
Appreciate it.

[marsheng]

At Aprilia we never had any high tech equipment, just an EGT sensor.
Nothing else was needed for finding more power!

Please explain. On my Maico, the best I can get is around 500 deg. Does the egt depend on the motor and I assume if my max rpm is 8500, it may never get there.

[wobbly]

If you can only get to 500* then there is a serious problem.
It can only be a few issues that will cause this, way too much compression or timing for the fuel, or severe short circuiting.
I had the short circuiting problem on a 250 MX engine that had the Aux ground around to bore center.It ran just fine but when the piston was changed from a
Wossner to a Prox it ran like shit and would not respond to leaner jetting changes at all.
Finally in desperation I pulled it down ,to discover that the Wossner had a machined hole in the skirt above the small end that did not go around past the centerline.
The Prox had a huge cast in cutout,that was well past centerline and this was seriously joining the Aux and A transfer together as the piston passed over them.
Changing the piston fixed the jetting issue immediately,where previously it would run rich ( 500* ) no matter what jet was in it.
Any engine on petrol should be able to run past 600* in the header without any problems at all, no matter what the cc,rpm or bmep.

[shnaggs]

If you can only get to 500* then there is a serious problem.
It can only be a few issues that will cause this, way too much compression or timing for the fuel, or severe short circuiting.
I had the short circuiting problem on a 250 MX engine that had the Aux ground around to bore center.It ran just fine but when the piston was changed from a
Wossner to a Prox it ran like shit and would not respond to leaner jetting changes at all.
Finally in desperation I pulled it down ,to discover that the Wossner had a machined hole in the skirt above the small end that did not go around past the centerline.
The Prox had a huge cast in cutout,that was well past centerline and this was seriously joining the Aux and A transfer together as the piston passed over them.
Changing the piston fixed the jetting issue immediately,where previously it would run rich ( 500* ) no matter what jet was in it.
Any engine on petrol should be able to run past 600* in the header without any problems at all, no matter what the cc,rpm or bmep.

Wobbly, How close do you run your EGT probe to the port? I noticed on both the new KTM 125/250 MX bikes that I could not see EGT's over 1000*F. leaning it out didn't change much on the temp, but once I heard popping on over-rev, I then came back the other way. I did run the probe about 3" from the face of the pipe, so maybe I was too far away from the port face, making the readings a bit low?