Power Band - Triples

1200 JOTA

1200 JOTA

Senior member
Location
Australia
With limited experience on my 1200 which has recently returned to the road ... just wondering - where does your bike 'start to take-off'?

It's been posted before that lumbering at lower revs. is not the thing and that it'll sing in the right range - so what is that range?

Mine's got Mikunis and an Ignitech and needs ~ 3200 rpm to get comfortable. That's with a fairly flat curve from 8 deg. to 34 deg. and seems to be quite sensitive to a curve from 8 to 32. Possibly 32 is a better max. advance.

Anyway .... discussion item only.
 
Depends (among other things) on what cams you've got in the engine, what compression ratio and what exhaust system.

Ignition timing is sensitive to compression ratio. Higher CR generally needs a little less advance on the spark.
 
Dellortoman said:
Depends (among other things) on what cams you've got in the engine, what compression ratio and what exhaust system.

Ignition timing is sensitive to compression ratio. Higher CR generally needs a little less advance on the spark.
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Yep ... just wondering where everyone's kicks in. Specify cams etc. if you wish, but I'm just interested to hear how 'other' bikes perform. I'm standard timing (roughly) with A11's and my open bells (50mm) will affect it too.
 
.... and this one has the 3 - 1 exhaust that definitely doesn't work low down!
(choked to 50mm from ~ 65mm but with a pretty standard header diameter)
 
My RGS was completely original when I got it, it hated running below 3-4k, fantastic above 6k.
Now has sachse ign and will run quite happily at 2k, but is still fantastic above 6 ;)
 
For a start, 34° BTDC (if that really is accurate) is too much advance, even for a stock engine. 32° at most, more compression can lead to less advance.

The stock cams should allow you to trundle along at 1800-2000rpm in 4th or 5th and just by opening the throttle, you should have smooth, steady and reasonably rapid acceleration to 3500, where a second wind kicks in. With A11 cams, this will not be very dramatic, but can certainly be felt. C4 cams almost give you a kick in the arse around there... C7 start to fly at 5000.

For a wider power band, fit a stock Jota header/collector system with silencers of your choice. Obviously, "Jota" cans will aid performance, up to you if you put up with the associated noise and aggro.

"Choked to 50mm from 65mm" ... that's how 3-1s work. Google "venturi effect".

piet
 
120 jota, A11 cams, likes to sing between 4500 and 6500. Will keep spinning up happily, but I try and keep the piston speed down, original motor, original conrods.
3C Axtell cams, about the same, comes in at 4500. Likes to spin up to 7500, my self imposed limit on this rebuilt crank. You can hear the exhaust note change, starts to really growl at 4500, love that sound..
Jota cams tend to come in higher in my experience, around 5500.
 
now we're on track .... so far I'd agree that 32 is better than 34 and I'm happy with the understanding of running the
3 - 1 (not just for the noise) and also that there is let's call it a sweet spot above 3000 that the bikes like

I chose 50mm bells for the low end instead of (say) 30's which would be better at (say) 6000 rpm

The actual (accurate) advance at ~ 3000 would be maybe 1 degree delta (32 vs 34) ... so possibly not significant (but some) if the curve tops at ~ 6000 (depending on programming)

Thanks for the input ... hopefully others will also chip-in wth an impression of the engine's characteristics.
 
The 6 plugger has a custom cam that Doug developed, pulls hard from 3000, ive stolen its battery for the sf2, might have to recommission it as soon as the lockdown ends, it needs more riding time.
 

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One of these days we must adapt a gear change so you can try my bike, Marty, only fair as I have ridden at least all but the twin of yours. I would love an opinion. I loved my rides of yours especially the twin plug. I am going controversial here, the 120 was ok. Prefer all the 180s and the Guzzi, it was really a big suprise.
 
With my Mirage with 4C`s as standard there was a power step at 5500 rpm similar to a Jota I guess but probably not so pronounced due to lower comp.pistons.
In the lower gears this didn`t seem so noticeable what with all the noise speed and vibration going on but on the motorway in top gear with the engine having more of a load to pull against at about 5500rpm/100 mph you could feel it enter the band ,everything would smooth out and throttle response from that speed up would be instant.
Came across a GS1000 on the M4 near Taunton and the Mirage would leave it for dead when winding it on from 100-110 mph upwards.
Spoke to another Mirage owner once who said I should try standard A11`s in it for the greater spread of power,but I always liked the way the way the Mirage would pull strongly(but not particularly quickly) from lower revs and then enter that power band.
 
My Jota has 4C cams and hi-comp pistons from the Laverda factory (are they Mondials?). It also has a big bore Redax exhaust, Mikuni RS36 carbs and Ignitech ignition. By the seat of the pants dyno, it has useable power from quite low revs and it feels like there's a power surge at around 5000 and is pretty strong all the way to 8000 or more. I think I got to about 8500 on a track day at Broadford while dicing with Tom the Wrecker, but that was pretty much a one-off rush of red mist. I'm usually mich kinder to the poor old thing because it's got at least 100,000km on the engine and still has original Laverda conrods.

Dyno runs show that there's no sudden rush of power anywhere. The power builds pretty steadily as revs increase. I dunno what I've done with the dyno charts, but I think it was something like 78 RWHP at 7500rpm.
 
Dellortoman said:
My Jota has 4C cams and hi-comp pistons from the Laverda factory (are they Mondials?). It also has a big bore Redax exhaust, Mikuni RS36 carbs and Ignitech ignition. By the seat of the pants dyno, it has useable power from quite low revs and it feels like there's a power surge at around 5000 ...
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thanks guys ... could someone give me some info. on Reds's big-bore (such as area / dims. of collector and mufflers etc.) as I'm considering reworking mine from the collector back and removing the extractor (kerker style) pipe.
 
1200 JOTA said:
thanks guys ... could someone give me some info. on Reds's big-bore (such as area / dims. of collector and mufflers etc.) as I'm considering reworking mine from the collector back and removing the extractor (kerker style) pipe.
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Hmm reckon you should ask the man himself and donate to the umpteen hours of dyno pulls that they made to get to where it is.
Or just put a set of Jota pipes with big bore collector and then get ya cams dialed in and bob’s ya uncle. ..
 
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2622 said:
Hmm reckon you should ask the man himself and donate to the umpteen hours of dyno pulls that they made to get to where it is.
Or just put a set of Jota pipes with big bore collector and then get ya cams dialed in and bob’s ya uncle. ..
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I get your point, but wonder if he'd want to 'shoot the shit' all the time (maybe just an annoyance).
I'm happy with my headers as is but the muffler / race pipe is a little tinny ... maybe a termi or yoshi should go on?
I thought it was a simple question to ask the forum (see original) and I'm responding to comments.
If I need tractability below the current 'step' I would just put the stock pipes back on I guess.
 
1200 JOTA said:
I thought it was a simple question to ask the forum (see original) and I'm responding to comments.
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Ok, I am a bit late to the discussion, however,,

Back in 2014, I started to share some dyno results I did with my 1978 1200. Called Clyde. The engine was built by Redax Laverda to my scope of works. i.e. Clyde was to be a good work horse, hence the name, not a hot-rod high performance engine and Red gave me a great engine.
It did already have 4C Jota cams so they were used again in the rebuild.
Perfect. Loved it. The best triple I have ridden.
Anyhow, if you can wade through all the drivel and crap I use to type about back then, you may well find something close to a suitable answer.

Dyno performance- actual readings

yes, i am a curious sort of soul. & i 'want' to know. & yes, i really don't 'need' to know. torque & rpm. yes please !! (thumbup) it's been in my blood since i first cut me teeth, up in da cane fields. so i reckon it was time to have a dedicated dyno topic. no, i don't want to turn...
www.laverdaforum.com www.laverdaforum.com
The 'Miss J' bike referred to is my 1981 Jota.

(note to self)> Do some more searching and update the old topic with some of the latest dyno charts since 2015.
And I would like to thank Lothar and others for their helpful comments back then in the original discussion. At the time, I had searched the forum for anything I could find that was previously posted and included it in the discussion.

Have fun.
cheers, Mark
 
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Maybe I can re-focus the thread and maybe I should have called it "ride impressions" (or similar) so let's not go full 'social media'. It was intended as a comment & discussion thread only to share your experiences. Thanks to those that have contributed their "when does the engine settle in and sing" story.

I've had the 1200 for about 3 years and love it. It came to me with a problem in the cam timing (was a tooth out on the inlet side), it was riden for a while with standard pipes .. and I then went to the 3 - 1. The head has been off because it was obvious that the PO had tried to do it and stopped half way, failing to torque it down correctly and with mis-aligned cam blocks. It's been 6 months (off the road) and the valve timing has been corrected, the ignition changed to Ignitech (because I've had really good results from a digital upgrade on prior bikes). The bike came to me with the Redax triple Mikunis and runs the recommended jets. Aside from that, the engine is standard.

I've taken it out only once since and notice that it still lumbers a little below ~ 3200 (in top gear) aside from that it runs very nicely! This seems perfectly normal with the extractors and bell mouths on the carbs. The K&N filters were taken off because they would rattle off due to a distortion of the rubber). As an example of it's overall performance - if I'm in top gear and want to overtake then I'd better change down (to get the revs up) and then blast by. The bike does sing from 3200 all the way up and is a charm.

As to pilfering others' hard earned data ... be assured that I'm not seeking max. BHP figures or trying to compete in any way but simply keep a good example of the marque on the road. I recall from a older post that there was an optimal diameter for after-market pipes (being 50mm) and as my headers are likley standard diameter but collect to about 65mm when I coupled the collector to the muffler, I settled on 50mm which was it's diameter anyway. The 'out' end is about 10% over the combined exit of 2 standard mufflers. The pipe works fairly well (ride impression only) and as I doubt I will ever get the chance to ride another 1000 / 1200 in my lifetime, why not ask "how does your bike feel"?

Interesting to note that the dyno figures rarely dip into the lower RPM ranges.

So again ... thanks to those that have answered in kind to the original thread. I thought there were a few more triples out there.
 
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