MCN's pic of a 8v Griso

[jcbooghs]

This is correct, Paul. But we still have to do it with pushrods instead of desmodromic. That's why I won't see it really happen or there must be a really short stroke like the older 70mm strokes did also get 10.000rpm in racetrim. Don't know exactly how long the engine will keep breathing! In race circomstances this is not really an issue.

[Paul Minnaert]

well pushrods llike in the daytona, it does have an inhead cam like daytona & BMW, that is driven by chain. The pushrods in the daytona are no rev limiting factor.

[Pierre]

well pushrods llike in the daytona, it does have an inhead cam like daytona & BMW, that is driven by chain. The pushrods in the daytona are no rev limiting factor.

Paul, it'll be interesting to see what they've done to get it to spin upwards of 9500 rpm. If they have gone 'big bore, short stroke' then I think we'll see a parallel development of two distinct motors - one a long stroke torquer, and one a "sporting" short stroke mill. The problem I have with going down the hi rev path (ala 1098) is that in the extreme, I think you lose a lot of the motor characteristics that make a twin attractive in the first place.

 

This will be interesting to watch.

 

BTW, would you mind posting the power (in cv) and torque (in kgm) figures of your 1225? I assume the 1225 is strictly a "big bore" approach with no change in stroke. TIA.

[Paul Minnaert]

well the bigbore is 106x73 giving 1300cc.

 

ducati aircooled 1100 are 98 x 71.5

 

ducati 1098 104x64 max hp @ 9750

 

morini corsaro 1200 107x 66 max hp@8500

 

 

My daytona does 115 hp@8000rm at the wheel, also must be 125 at the crank. Torque is 106 nm@6750

 

My bike does not have a high power c kit cam but a milder one so there is power everywhere.

 

Other similar 1225 bikes have 125hp at the wheel. and yes, the 1225 is a 100x78 engine, so stroke is stock.

[Skeeve]

W/ all the discussion about "x HP @ 10k rpm," & bore x stroke numbers, let's keep our eyes on a few simple facts:

 

Guzzi is highly unlikely to use a bore or stroke that they don't already have in production in some other model(s).

 

Their horsepower numbers [as are almost any motorcycle manufacturer's!] have always been highly suspect.

 

The quoted rpm is more likely to just be the redline, not necessarily the h.p. peak rpm. Advertising ginks: you gotta love'em, but they're almost invariably clueless when it comes to engineering!

 

Let's wait & see what the truth is after the unveiling this weekend. I would hope that some enterprising moto rag will have a truckable DynoJet somewhere in the vicinity of Mandello and 'just happen' to make a detour while on a test ride [they will have some for test rides @ GMG, won't they?]

 

[callison]

W/ all the discussion about "x HP @ 10k rpm," & bore x stroke numbers, let's keep our eyes on a few simple facts:

 

Guzzi is highly unlikely to use a bore or stroke that they don't already have in production in some other model(s).

 

Their horsepower numbers [as are almost any motorcycle manufacturer's!] have always been highly suspect.

 

The quoted rpm is more likely to just be the redline, not necessarily the h.p. peak rpm. Advertising ginks: you gotta love'em, but they're almost invariably clueless when it comes to engineering!

 

Let's wait & see what the truth is after the unveiling this weekend. I would hope that some enterprising moto rag will have a truckable DynoJet somewhere in the vicinity of Mandello and 'just happen' to make a detour while on a test ride [they will have some for test rides @ GMG, won't they?]

 

 

The Norge and Sport 1200 have a new crank with a longer stroke than previously used in street models, so MG does "evolve" a tad every so once in a while. With all of the previously after market stroker cranks carrying an 82mm throw, I was surprised when the new 1200cc engines came out with only an 81.2mm stroke.

[Frio]

In the other thread with the close-up pictures the rev counter is clearly visible and it looks exactly the same as the old one, in which the redline starts at 8000 RPM, so the argument about max HP at 9500 RPMs sounds a little unlikely, or not?

 

Frio

[BRENTTODD]

SHOULD BE PRETTY EASY TO DRESS IT UP AND MAKE HER GOOOD

[Skeeve]

The Norge and Sport 1200 have a new crank with a longer stroke than previously used in street models, so MG does "evolve" a tad every so once in a while. With all of the previously after market stroker cranks carrying an 82mm throw, I was surprised when the new 1200cc engines came out with only an 81.2mm stroke.

 

.8mm different stroke? That's just a difference in setting up the grinder for the big-end journal; same crank as the 82mm throw, otherwise. Probably done just because the new pistons [95mm?] would have gone over 1200cc if staying w/ the 82mm throw. Heck, it may all just be an official measurement fallacy: wouldn't be the first time a manufacturer juggled their numbers to make something fit a legal category...

 

EDIT: Dunno where I got the idea that Guzzi had made an 82mm stroke in the V11s; just a little slydexia of the 92 x 80mm numbers? At any rate, adding 1.2mm to the stroke is only .6mm more offset to the crankpin: not a huge change to the existing forgings needed, I'm sure... And checking the specs on the 1200 Sport, it's only 1151cc, so clearly the stroke could have gone longer w/o going past 1200cc, but maybe that would have required too many changes to existing molds/forgings/whatever?

 

At any rate, I'm still willing to wait until this weekend to get some more hard facts before spending more time in idle speculation!

 

But I think no matter what, this weekend is going to be a good one for Guzzistas everywhere! Finally, the promise of the original Griso 8v concept-bike is fulfilled; who knows, maybe the MGS-01 Stradale will be next?

[pete roper]

One of the major limiting factors to increasing stroke on the pushrod motors is that if you do the rods hit the cam lobes!

 

No cam lobes on the dummy shaft? You can certainly increase the stroke.

 

the 850 Griso's etc use the shortest stroke of any 'Big Block' twin at, (From memory?) 68mm. Now if ever there was a two-valver that begged to be blown it was the 68mm crank models! With the 8 valvers I'd think they would be wanting to exploit the better breathing at the top by keeping piston speeds as low as possible, That would indicate super-short stroke and a Huge bore. My feeling is that that will be the 'Next Phase' and the motor they'll shoe-horn into a 'Nuovo LeMans' in a couple of years time. Personally a longer stroke 8 valver will do me just fine. Being honest my 4V Griso does me just fime but I'm such a tart I'll just *have * to buy one

 

Pete

[dlaing]

The problem I have with going down the hi rev path (ala 1098) is that in the extreme, I think you lose a lot of the motor characteristics that make a twin attractive in the first place.

 

... That would indicate super-short stroke and a Huge bore. My feeling is that that will be the 'Next Phase' and the motor they'll shoe-horn into a 'Nuovo LeMans' in a couple of years time.

I sure hope you are wrong.

Still I can imagine it would still be a nicer ride than most 600 fours.

Without shame, I think BMW is the one to follow for power curve design.

I'll bet this Griso will be pretty close to a BMW R1200's power curve.

Personally I like the curve of the R1200S

EDIT

Here are some interesting dyno charts

Kind of interesting how many flat spots are on the R1200ST curve.

http://www.moto-one.com.au/performance/r1200s_st.html

http://www.moto-one.com.au/performance/v11sport.html

http://www.moto-one.com.au/performance/1098dptermihomo.html