v7 lack of power, why?

[erik_w]

Hello!

I have been thinking about the v7 a lot recently, maybe not about buying one, but rather about tuning one as a prerequisite for buying one.

the consensus seems to be 48 hp at the crank and 38 at the wheel - which is quite low for a modern 750. I am interested in the reason for the low power and possibly what can be done to increase it .

for example, looking at older small blocks:
- the v7 sport from 1972 had a claimed power of 70 hp, which is more than  20 additional ponies at the same displacement!
- the v65 from 1985 has a claimed hp of 50, which is the same power at a 100 cc disadvantage.
- the v50 from 1982 has a claimed power of 45 hp, which again  is roughly the same at a 250 cc disadvantage!

what is going on here? it seems to me that the engine design  has an inherent potential of at least 70 hp ( 40 years ago!), so the same power should be possible today even in a detuned state!

I've also read about tuning the v7, such as tinkering with the exhaust and fuel mapping and even a compression increase seems to bring it up just a couple of hp each.

so, what is the reason that the 1972 v7 sport was able to pull of 70 hp while the 2015 v7 (racer, haha!) can only pull off 48?

[twhitaker]

The V7 Sport is not a small block and the claimed 70 hp is just that, claimed. Those claims are at the crank while they are now at the brake.

[rocker59]

First of all, the 1972 V7 Sport was a big block.

Secondly, the 70hp of the V7 Sport is "brochure horse power".  Not real world.

Thirdly, the small block's Heron Head design limits power, but 820cc kits are available that can help.

Fourthly, this horse has been beat to death over the past six years, or so, since the V7 Classics were released and began to generate lots of new interest in Moto Guzzi.

All it takes is money, and the Small Block can be much more than it is.  Just look at Chuck in Indiana's transplant of a Guzzi aero engine into his bike.

[Cam3512]

 Take some time to use the search function here, and do some reading. This topic has been beat to hell.

[sib]

Let's ask a more important question:  what is the appropriate horsepower for a 400-lb street bike that has to be reliable, have a long lifetime, not be fussy, not require a lot of servicing, and be suitable for riding by newer as well as experienced riders?  Seems to me that the newer V7's are spot on.  If you're looking for something different, there are lots of choices out there.

[rocker59]

Let's ask a more important question:  what is the appropriate horsepower for a 400-lb street bike that has to be reliable, have a long lifetime, not be fussy, not require a lot of servicing, and be suitable for riding by newer as well as experienced riders?  Seems to me that the newer V7's are spot on.  If you're looking for something different, there are lots of choices out there.

I'll be spending my money on suspension.  More power would be nice, but in all honesty, the V7s need better suspension before more power.  I'm not a drag racer and live in the mountains, so suspension shortcomings on any bike can be glaring.

My V7 Special is quite a ways from being a comfortable peg dragger.  Both ends need attention.  Until then, more power would not be enjoyable to realize.

[Perazzimx14]

I think the biggest thing the OP is missing is while the V7 is currently produced it is far from a "modern" design.

 

[Chuck in Indiana]

I think the biggest the OP is missing is while the V7 is currently produced it is far from a "modern" design.

Ya think? 

[Perazzimx14]

Ya think? 

I said it before and I'll say it again.... I would bet 90% or more of the motorcycling population can't use all the power the Ninja 250 puts out but insist on buying motorcycles well over a 100 HP.

Oh well to each their own

[Doppelgaenger]

Let's ask a more important question:  what is the appropriate horsepower for a 400-lb street bike that has to be reliable, have a long lifetime, not be fussy, not require a lot of servicing, and be suitable for riding by newer as well as experienced riders?  Seems to me that the newer V7's are spot on.  If you're looking for something different, there are lots of choices out there.

This is the answer. You can get a lot more horsepower from 750ccs, but at the cost of longevity. Hell, you can get 5000 horses from a nitro fueled drag car, but the engine life is measured in minutes.

The V7 is unintimidating performance for the real world, the 750 engine offers torque instead of power which lets you have fun without having to break the speed limit.

After saying all that, I still bought an 1100 because while the 750 made me smile, the 1100 made me grin. Or laugh like a maniac....

[pyoungbl]

The current V7 engine is a nice, simple, dependable mill with good torque.  That Heron head design is inexpensive to make and works well enough for real world riding.  Oh, and it's easy to work on.  Yes, you can get more power out of the V7.  Any gains are going to be at great expense (relative to the cost of the bike) per hp gain because that head design will always limit how well the engine can breathe.  You can't do much to increase the compression since the head is already flat, you'll have to mill the jugs or change the pistons...then balance the crank.  As Rocker has noted, changing the suspension will give a much more pleasant riding experience and probably have you going faster to boot.

Peter Y.
V7 with stock engine but upgraded suspension.

[Kev m]

I just got back from a 100+ mile loop on my ~40 rwhp V7, followed by my dear wife on her ~68 rwhp M696. There were quite a few times I had to completely roll of the throttle and coast for a couple of hundred yards so she could see me again. She loves that bike....I really prefer the V7.

I think the biggest thing the OP is missing is while the V7 is currently produced it is far from a "modern" design.

He's also not comparing apples to apples on a bunch of those numbers... crankshaft vs rwhp, claimed vs. reality.

Ya know, I almost brought this up last week when I got my copy of MCN but figured we'd beaten this dead horse so badly there was nothing but entrails left... but here we go.

September 2015 MCN

2015 Kawasaki KLR 650, 651cc, 433# wet, 36 rwhp and only 32 ft. lbs. of torque

This is a pretty popular bike.

It weighs about the same as the V7, makes LESS hp and a good bit less torque (MCN puts the V7 at 41 ft. lbs.).

Seriously, buy what you want, but I suspect most people who bitch about the V7 wouldn't use all 40 ponies it comes with anyway, so why do they need more?

After saying all that, I still bought an 1100 because while the 750 made me smile, the 1100 made me grin. Or laugh like a maniac....

...which is fine, but I'll add after saying all that, in the past few years I've SOLD 2 1100cc Guzzi big-blocks AND a 100 rwhp Buell... and look what remains in my fleet!

 

[redrider]

Horsepower is a rating, not a real thing. Torque is what engines "make".

[Arizona Wayne]

Horsepower is a rating, not a real thing. Torque is what engines "make".

Torque is for acceleration, HP is for top speed.

[jackson]

If Guzzi hadn't made V7's (the modern ones with fuel injection), I would still be riding a BMW airhead.  The Guzzi V7 is the closest thing I can find in a modern bike to compare to an airhead and I REALLY liked airheads.

[erik_w]

Ok, sorry about that, I thought the v7 sport was a small block due to displacement - my bad!

I do understand perfectly well that the v7 is a very old design that goes back, well not quite, to the original v7 of 1968(?). That why I was comparing the specs to the older bikes...

I also understand that HP is not all there is to it, and that if you try to pull a truck using a UJM with 200 HP it would simply disintegrate while a Harley with a HP of 45 would pull the truck all day. But I do think it is a relevant measure to guage an engines performance.

Anyway,

Seems to me like the v65 is the closest, same claimed HP ought to translate into the same RW HP, so the 1985 v65 gets the same HP despite being 30 years senior and having 100 cc less.

The Heron heads are the biggest culprit? What about the older small blocks, did they have a different head design?

Can somebody point me to a thread regarding a succesfully tuned v7?

The bike I ride today has a claimed hp of 36, so I am not a stickler for specs, this is more out of curiosity!

[Antietam Classic Cycle]

The current "small-block" 750 goes back to around '77, starting as a 500. The V65 didn't have to meet as stringent of emissions or noise standards, so less hp loss to that. All production 2 valve per cylinder small-blocks have Heron heads.

Moto Morini 250, 350 and 500 v-twins (and a few late singles built from the twins) also have Heron heads, though they seem to have done better with it. Guzzi could have learned a few leassons from Morini IMO.

[Vasco DG]

The small block engine design, basically unchanged apart from bore and stroke differences, was launched in the late seventies in 350cc and 500cc forms. The earlier V Twins were all big blocks.

[Kev m]

Not to mention, I'm not sure I believe the V50 or V65 "claimed" crank hp. So between that and lack of emissions strangulation, what's the point again?

[SmithSwede]

I don't think you can really rely on the accuracy of the published horsepower figures for the older Guzzi small blocks.   Therefore, I doubt there is any mysterious "difference" that needs to be discovered or explained.   And even if there were some difference, that would be like Army privates arguing about who has the higher rank. 

The older small blocks were probably a bit weaker than the modern small blocks--i.e. that's what you would see if you put them both on a dyno side-by-side.  I think the small blocks have always had the Heron heads.  The older ones would have had lower compression and probably less precise fueling compared to modern fuel injection.   

Jackson is pointing in the right direction.  Think of these small block Guzzis as being closely akin to a BMW airhead--except you can buy the Guzzi brand new with a warranty and fuel injection.  The BMW 750 and 800 cc airheads made about 45 to 55 horsepower--just like the very similar Guzzi small block did back then . . . and still do today.

No doubt there are various things one can do to hop-up a small block Guzzi.   Just like you could hop up a 750 cc BMW airhead.  But for most people, there's little point in doing so.   

I'm with Jackson, Kev M, and others here.   I like the V7 precisely *because* it's so much like an airhead. 

Heck, I also own a "modern" BMW 800 cc twin cylinder bike, an F800s with about 85 horsepower--liquid cooled Rotax, overhead cams, 4 valves per cylinder, etc.   Nice bike--but I enjoy the Guzzi just fine and don't worry about its horsepower.   

If you are inclined to worry about horsepower, then I suspect you will never be happy with a small block, even after pouring thousands of dollars into the engine to chase a few extra horsepower.   And your souped-up Guzzi 750 would still not be in the same horsepower category as a modern 750.   

[Kev m]

If you are inclined to worry about horsepower, then I suspect you will never be happy with a small block, even after pouring thousands of dollars into the engine to chase a few extra horsepower.   And your souped-up Guzzi 750 would still not be in the same horsepower category as a modern 750.

THIS!!! If you are that concerned with hp you can buy a faster bike for less, or a mind numbingly fast bike for about the same.

I didn't because I value many other traits more.

[BRIO]

I just got back from a 100+ mile loop on my ~40 rwhp V7, followed by my dear wife on her ~68 rwhp M696. There were quite a few times I had to completely roll of the throttle and coast for a couple of hundred yards so she could see me again. She loves that bike....I really prefer the V7.

He's also not comparing apples to apples on a bunch of those numbers... crankshaft vs rwhp, claimed vs. reality.

Ya know, I almost brought this up last week when I got my copy of MCN but figured we'd beaten this dead horse so badly there was nothing but entrails left... but here we go.

September 2015 MCN

2015 Kawasaki KLR 650, 651cc, 433# wet, 36 rwhp and only 32 ft. lbs. of torque

This is a pretty popular bike.

It weighs about the same as the V7, makes LESS hp and a good bit less torque (MCN puts the V7 at 41 ft. lbs.).

Seriously, buy what you want, but I suspect most people who bitch about the V7 wouldn't use all 40 ponies it comes with anyway, so why do they need more?

...which is fine, but I'll add after saying all that, in the past few years I've SOLD 2 1100cc Guzzi big-blocks AND a 100 rwhp Buell... and look what remains in my fleet!

 

My KLR feels as fast as my Norge up to about 40mph. A lot of it has to do with gearing and drive train losses in the shaft drive. The KLR runs out of steam over 60 where the Norge still is very powerful. This is a good demonstration of torque vs horsepower.

The low geared KLR has a lot of torque but runs out of total power early. The Norge soldiers on above 60 which is where you would wish for more with your V7 I'd assume.

[Kev m]

The low geared KLR has a lot of torque but runs out of total power early. The Norge soldiers on above 60 which is where you would wish for more with your V7 I'd assume.

No, it doesn't run out of steam at 60 and no I don't wish for more, which is why I sold the Guzzi big blocks, and the Buell, and shun the M696 in the fleet.

I've been on a 180 rwhp bike and wished I was on something like a V7, but I'm rarely ever on a V7 wishing the opposite.

The ONLY exception to that is IF my riding was going to be 80+ ALL DAY, yes, I'd probably be more comfortable on a Norge or B11... BUT that's not the type of riding I prefer to do all day.

I should add I rode a little 120+ mile loop yesterday which included the NJ MGNOC lunch. That loop also included two higway stints of about a dozen miles each and the V7 had no problem with 80+ (I'm not going to say how much plus but at one point it was not insignificant)..

I doubt from your description that the KLR would have kept up.

[Guido Valvole]

If you think a new 750cc smallblock is slow and wimpy and has no power, try an old V50. 

Otoh, it's more fun to ride a slow bike (relatively) fast than it is to ride a fast bike slow and never get beyond third gear without serious possibility of incarceration... And on narrow and twisty roads the small bike is hardly at a disadvantage. Interstate? Sure, but that's for cars or Hondabagos/Hondapotamuses.
cr

[Penderic]

Just like boats. If your boat isnt capable of doing 100, why even bother?

[tiger_one]

These threads always go the same direction.  Someone wishes for info on tuning for higher HP.  Most owners say it doesn't need anymore.

Two different threads, very confusing to a new guy.  I don't know what a Heron head is, and doubt he does either.  I do know it is flat as a board and the piston is dished to make the combustion chamber, very poor design for power.  But as the other camp (owners) say, a easy motor to produce (cheaper) than a hemi or wedge shape head with flat top pistons or raised pistons.

With a hemi or wedge head, you can mill some off the head and get higher compressiion ratio, but with a flat head nothing can be done to the head.  Also far as I know there is no aftermarket cam to liven it up (maybe the drone engine). 

I'm in the camp that wants more HP for the V7, but I know it is not coming from the current engine design, so we wait and grow older!

[pyoungbl]

Here's a link to an article about the Heron head...the good and bad:
http://www.italian.sakura.ne.jp/bad_toys/heronhead/


Peter Y.

[SmithSwede]

Dang it Peter.   I went to your link, and it rekindled my long standing desire for a Moto Morini 3 1/2.

[bad Chad]

No v65 ever rolled off the line making 50hp, not even at the crank.  I have a pretty cherry v65sp, with less than 10k, I have never bothered to dino it, why polish a turd?  But seat of the pants, I'd say somewhere between 25-35 rwhp.  It is what it is, but it an't 50hp!

[O]

You can bench race and speculate all day.  Much better though go take a test ride, and see if you actually like the bike.  If you're just looking for impressive specs on paper, Guzzi is not the brand for you.  However, if it's a unique and enjoyable riding experience you're after, on great looking, great sounding, lightweight machine, the test ride might just lead to a new Guzzi in the garage.  Go ride one!