Safe revs?

Hello Paul, looking good for a young man, grin. That RGS issue, was there the possibility of hydraulic fuel compression when the rod bent? Off the cuff question, has been an issue, the liquid fuel into the inlet tracts, as you know.

Like you, made ( good ) use of Wolfgang in the day, built me a hooting motor around a 1200 motor that had wrecked two complete top ends in succession, when i got the motor, noticed it had that idiotic tap hole to lube the primary chain drive, chains ok, lets oil starve the top end valve train, and it did, twice...

Of tacho's, which i called guessometers, one famous owner down here, "ignition is cutting out early" yes it will do that when your over 8250, "but the Tacho reads 5,000"....indeed it does... that motor was well reved prior to the iis fitment. Regards to all...

BTW the iis had an electric tacho test feature, motor not running. Test mode invoked, the tacho will chronometricaly step from 1000 to 10,000 rpm in 1000rpm stages on the tacho, pretty much restricted to the RGS style motors or 180 with electric after Tacho. Non linerity can be seen at a glance, plus watching this feature was very new in the day, not so much now with uP driven instruments/clusters.
 
Agree tachometers were bought in as off the shelf items from Nippon Denso,the 6500-7500 redline probably being the closest most suitable unit available although early units had the Laverda logo included on the face so you would have thought if they went to the trouble of doing that they could also have shifted the red line section up by 1000 rpm for the triples as well....
Contemporary Jota road tests with "megaphone" exhausts (presumably factory 3 into 1`s) quote 90 bhp at 7600 rpm.
I would think if you keep it spinning free and easy between 5 and 8 grand (tops) and change the oil every 1500 miles as Laverda recommend things should be ok.
For me I found a few missed gearchanges now and again resulted if anything in bent valves rather than the crank or rods going AWOL.
 
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Take no notice of the red band on the tacho. Like Paul says, it's probably a carry-over from the 750 twins.

A stock 180° triple 3C(L) or Jota will reach max power at around 7500 rpm, with max torque is a bit lower than that (give or take a bit depending on the camshaft spec). There's nothing to be gained by revving it beyond 8000.

Vince, I'm not sure exactly what you mean by hard or soft rev limiter. There's a range of ways you can set up an Ignitech to limit revs.
You can simply program a RPM number into the "Limiter (rpm)" box in the "Miscellaneous" tab. I'm not sure exactly what that does. Maybe it just cuts the ignition. The programming documentation is unclear on exactly how it works.
Another approach is to program a limit into your advance curve by dropping the advance back to base advance at your limit RPM. That has the effect of cutting engine power without shutting off the spark. Maybe that's what the rev limiter actually does. Who knows?

The Ignitech also has a switchable rev limiter. There's a box labelled "Start limiter (rpm)" just below the rev limiter box on the Miscellaneous page in which you can set a second rev limit that's activated when a pin on the ignitech box is earthed. I'm not sure what they had in mind for this function, but you could use it for different rev limits for track and street modes by flicking a switch on or off. Or maybe different rev limits for different riders (flick a secret switch to lower the rev limit if you let Cosi ride your bike ;)). I suppose you could do other stuff with it, like limit the revs when the neutral light is on, but I'm running out of ideas. Perhaps (as the name suggests) it's intended to limit the revs while you have your thumb on the starter button. If anyone has any clues as to why they'd build this feature into the system I'd be curious to know.
 
In all the youtube videos I watch everybody used the rev limiter as a warning device, instead of a HORN. I was speaking to Marty and he called it THE "Middle Eastern Nationality of Hot Harley Rider". LOVE CALL. Made me laugh. Seems a bit destructive doing that on a Laverda with a perfectly good horn right there. Another definition of rev limiter I have heard is what effect it has if your leaned over in a bend and it activates. Having a big effect wouldn't be a good thing in that case.
 
Dellortoman said:
The Ignitech also has a switchable rev limiter. There's a box labelled "Start limiter (rpm)" just below the rev limiter box on the Miscellaneous page in which you can set a second rev limit that's activated when a pin on the ignitech box is earthed. I'm not sure what they had in mind for this function, but you could use it for different rev limits for track and street modes by flicking a switch on or off. Or maybe different rev limits for different riders (flick a secret switch to lower the rev limit if you let Cosi ride your bike ;)). I suppose you could do other stuff with it, like limit the revs when the neutral light is on, but I'm running out of ideas. Perhaps (as the name suggests) it's intended to limit the revs while you have your thumb on the starter button. If anyone has any clues as to why they'd build this feature into the system I'd be curious to know.
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Perhaps useful as a speed limiter in pit lane of the race track.

cheers,

bazzee
 
Start limiter is a simple form of launch control, holds the engine at some inbetween # revs (usually peak torque). Not sure how it's meant to be implemented in the Ignitech, but there are inputs for both start limiter and clutch master. Some combination of that would allow you to have a rudimentary launch control and flat shfter. Drag cars used to call this sort of thing a 'two step', as you'd have a staging limit and a run limit.

We tried out the flat shifter on the ICR racebike (never told anyone!). I had the kill switch on the left side because of the ginormous Domino fast action throttle getting in the way on the left. It was one of those early Fireblade ones with a start button, so I wired the start button to the ignitech input and set it as 'clutch master'. You could preload the gear lever and with throttle still WOT hit the button it would cut ignition briefly and change gear. So we had a totally invisible flatshifter, although the big metho pop and bang was a bit of a giveaway. The main objective was to try to reduce false neutrals, as Drmsby was much faster than the gearbox was. :) It worked well but turned out to be just enough to overload the clutch (especially 4th > 5th where I had a bigger than ideal ratio drop) and cause slip so it only got used rarely. I didn't try the start limiter as that would have been pretty obvious and flying a bit too close to the wind in terms of leaving one open to protest.

On my injected bike I set up and played around with both launch control and flatshift. With the ECU it was a lot more sophisticated including being able to run fully automated since it knew your speed and gear etc. I could have even set up an inclinometer and had some form of wheelie and/or traction control just for laughs but never got around to that one. The flatshifter worked really nice with a sensor in the shift rod and tuneable fuel/ignition cut depending on which gear it was. I had some great fun playing with all that.
 
Hard and soft limit refer to how aggressive the rpm limiting strategy is. John alluded to how much thought and effort he put into how the limiter worked on the IIS, there are plenty of pitfalls. Depending on the sophistication of the ECU there may be different strategies, eg a missed gear requires a much more aggressive cut to control the revs than just running up to the limiter under load in a high gear. Remember when Rossi blew his motor while leading at Mugello some years back? That was due to a loss of RPM control at full revs and WOT when going airborne over the hump in the straight at full speed. They had shaved the settings a bit too tight when trying to eke out every bit of top speed from the gutless Yammie, and it over-revved just enough to damage things, the limiter was not fast enough to catch it.
There was an interesting article on motomatters.com about Frankie Morbidelli's bike in 2020 where they had to run almost the entire season on two engines due to Yamahas technical whoopsies that year. He described avoiding the hard limiter as absolutely essential, as it's very hard on the motor. They tuned the soft limiter to act a little earlier to give the rider a bit more warning of the need to change gear. Also sticking in my mind from that article is he said the engines got fresh oil every single time they started, he said they went through a lot of the sponsor Petronas' oil that year! :)
 
iis_iis said:
Hello Paul, looking good for a young man, grin. That RGS issue, was there the possibility of hydraulic fuel compression when the rod bent? Off the cuff question, has been an issue, the liquid fuel into the inlet tracts, as you know.
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Hi John

yes, a leaky carb float needle was involved with the bent rod on the RGS, very distressing initlaly but gave me the needed excuse to build a larger higher compression motor for the RGS with all sorts of other tricks. I was much more casual then than now about turning off tank fuel taps, now I check them twice to be absolutely sure they are off before walkng away from the bike....

great to see you active on the forum again, hope all is well with you!

Paul LeClair

edit ps: thinking about rev limits, igntion cuts, etc., the quickshifter feature on my Kawasaki H2 SX SE is magic both upshift and downshift. Unbelievable how the supercharged motor exhaust sounds especially clicking through upshifts near redline. Other than the power, the quickshifter is one of my favourite things about the bike!! The bike also has launch control, but I have not yet felt the need to try that out
 
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The first few times I heard Sashas K1300 BMW quickshifter for a second either a gunshot or explosion. Bloody unnerving when close by.
 
helicopterjim said:
So what's the redline of a 750 with Smiths tacho? Is it possible that the Smiths equipped bikes made more power (assuming they had a higher redline)?

Jim
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The best rev limiter is the riders right hand with a brain behind it.

There is no redline on the Smith's instrument.
You don't need a redline to ride the torque curve which has fallen off way before the red line.
A red line is no doubt useful on the track.

Paul
 
Don't know if it's true, but I'd heard the original ND tacho brief was for the 650 American Eagle, hence the low red zone. By the time the clocks arrived the Eagle had died. The Logo clocks were then used until the contract ran out and the cost-cutters opted for the plain ones.Original Revcounter Red Zone.jpgRevcounter Higher Limit.jpg
 
I think that the eagle was well before ND instruments. Came on the first SF the "zero" didn't they. The red is definitely a carryover from the twin though.
 
The ND instruments were fitted to the 72 SF, sold as from Autumn 71. After the Eagle twins by far.
The red line on the triple was a left over from the twins.

Paul
 
Paul Marx said:
A red line is no doubt useful on the track.
Paul
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a red line on a Tacho is not worth jack shit on a race track, if the rider is staring at the Tacho to see what is happening he/she is not riding the bike to its potential
Far better set up on a Track/Race bike is no Tacho at all but using two shift lights, one Yellow light set at 1,000 rpm before desired shift, next Red light set at 500 rpm before shift, the visual sight of a pair of actual lights coming on is far less intrusive then the rider having to keep watching his/her Tacho

Besides, the rider should be far more in tune with the engine and what it is doing in regard to shift points than to have to rely on a mongrel Tacho that may or may not be reading correct

changing our race bikes to two shift lights plus a Speed Angle dash recording lap times and piss off the Speedhut Slappo (useless piece of shite)
 
redax5 said:
a red line on a Tacho is not worth jack shit on a race track, if the rider is staring at the Tacho to see what is happening he/she is not riding the bike to its potential
Far better set up on a Track/Race bike is no Tacho at all but using two shift lights, one Yellow light set at 1,000 rpm before desired shift, next Red light set at 500 rpm before shift, the visual sight of a pair of actual lights coming on is far less intrusive then the rider having to keep watching his/her Tacho

Besides, the rider should be far more in tune with the engine and what it is doing in regard to shift points than to have to rely on a mongrel Tacho that may or may not be reading correct
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Did that on the Team Moto Witt 883 H-D Sportster, back in the mid-90s. Michael quickly adapted to the row (3 or 4, iIrc) of enormous LEDs poking in his face and went even faster. Over-revving the big lump was not a good thing, the mandatory stock rev-limiter was set a bit to high and non-adjustable, the shift light turned out to be a huge bonus.

piet
 
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