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V7 820cc 2V Big Bore Kit '09-16

I...


  • Total voters
    15
  • Poll closed .
Sigh... I really need to not spend more money on my bike, but I have a feeling I’ll do this to my V7III eventually....

out of curiosity, does a larger piston size equate to a lower rpm at given speed? I get that it means more power on tap, but I’ve always wondered if it also affects rpm since the gearing isn’t changing.
 
Sigh... I really need to not spend more money on my bike, but I have a feeling I’ll do this to my V7III eventually....

out of curiosity, does a larger piston size equate to a lower rpm at given speed? I get that it means more power on tap, but I’ve always wondered if it also affects rpm since the gearing isn’t changing.

I can’t speak for the v7-3 (and I was never watching my RPMs to closely before), but for me it seems a little bit lower especially on thefreeway, but most importantly power is longer lasting in the range. So where my bike would start to taper out on power at 5500rpm, it’s now at 6500rpm ish. I need to put more miles on before I can say for sure on lower. The bike was already rev happy and now it just sings at 5,000 rpm. I’m holding each gear longer because of it.
 
Like my exhaust from GuzziTech, my biggest regret is that I didn't do this mod sooner. It's really hard to explain the transformation this kit achieves, but it's creates a whole new visceral and intuitive ride.
Funny how many times that "regret" is stated. :happy: -- and I'd say you did a pretty good job at describing it. Thanks for your words here and as a Review on the purchase page(!), and thrilled to have another person on a GTM-ized V7-820! Enjoy!
Worthy of note here is that you also opt'ed for the GTM ported heads. Without them, the kit is decent, but all of the added power at higher RPMs is from the headwork, not just the pistons. ;)
 
out of curiosity, does a larger piston size equate to a lower rpm at given speed? I get that it means more power on tap, but I’ve always wondered if it also affects rpm since the gearing isn’t changing.
No it does not. As you say, that would require a gearing change or taller tire. The V7 III really responds well to the 820cc pistons, and no head work is needed.
 
Quite a few enjoying this kit, and some fun photos posted on IG below. Thanks to those who have stepped up for this kit; https://gtmotocycles.com/products/gt-v7-big-bore-820-2v-pistons

820 Hemi, Quattrovalvole & Heron heads:
View attachment 20790

820 Café & Racer:
View attachment 20791
No, thank you for taking that leap of faith in selling this. I'm still enjoying mine!
Only cons I have are: rear tire goes sooner, brakes are abysmal to the bump in power.
Looking forward to doing that air box delete later.
 
No, thank you for taking that leap of faith in selling this. I'm still enjoying mine!
Only cons I have are: rear tire goes sooner, brakes are abysmal to the bump in power.
Looking forward to doing that air box delete later.
Agree on the tires and brakes. Todd just finished upgrading my front brake and it's a huge improvement in safety and confidence. Another one of those things I wish I'd done sooner.
 
Agree on the tires and brakes. Todd just finished upgrading my front brake and it's a huge improvement in safety and confidence. Another one of those things I wish I'd
My plan is to dump the ABS altogether and get custom lines. brakes feel like wood blocks
 
I've read several sources that claim the horsepower rating of a stock 2010 V7 Cafe Classic is 47/48. However, my engine when stock measured at 37HP at the rear wheel on a Dynojet dynomometer. So, where is the discrepancy? Are the magazine articles quoting bogus numbers based on what the manufacturer has told them? Or what?

Jason
 
The 48 Hp is probably measured at the crankshaft, however that power has to be transmitted through the clutch, gears and driveshaft which all reduce the power to the next component. So the mags are not lying just quoting the best HP figures.
 
The 48 Hp is probably measured at the crankshaft, however that power has to be transmitted through the clutch, gears and driveshaft which all reduce the power to the next component. So the mags are not lying just quoting the best HP figures.

Perhaps, but a 10 HP loss through drive train seems excessive to me.

Jason
 
Hi,

I have heard that 15% is a general figure for drive line loss in automobiles,
Some Dyno setups allow that number to be input so you get a corrected number out of the machine
One that might reflect a number closer to the crank output.

I’m wondering now, if our driveline would indeed be sapping more power than chain drive ?

What those numbers *might* be more usefull for, would be measuring output after a change, air box/filter and Exhaust, ÉCU tuning etc...

You have to ask yourself, “Do you need to get in trouble any Faster !”
I don’t :angel:
 
When was your bike measured, it is now 11 years old and horses escape as the mileage increases. The factory HP figures will be measured on a perfect engine in optimal conditions.
 
I've read several sources that claim the horsepower rating of a stock 2010 V7 Cafe Classic is 47/48. However, my engine when stock measured at 37HP at the rear wheel on a Dynojet dynomometer. So, where is the discrepancy? Are the magazine articles quoting bogus numbers based on what the manufacturer has told them? Or what?
Jason, merged your post with this thread. Please spend a little time with the search function here. Tons of info on topics that have been covered over and over again.
36-39 rear wheel is the norm. Horsepower is given at crankshaft from Guzzi… Without any loss through the entire driveline (clutch, trans, driveshaft and wheel/tire). See the first post of this thread where I personally dyno’ed a heron head V7, and the mods I’ve done to offer here to get them into the 50’s at the tire.
 
When was your bike measured, it is now 11 years old and horses escape as the mileage increases. The factory HP figures will be measured on a perfect engine in optimal conditions.

It was measured in 2011, prior to having an 820CC piston/cylinder kit installed.

Jason
Jason, merged your post with this thread. Please spend a little time with the search function here. Tons of info on topics that have been covered over and over again.
36-39 rear wheel is the norm. Horsepower is given at crankshaft from Guzzi… Without any loss through the entire driveline (clutch, trans, driveshaft and wheel/tire). See the first post of this thread where I personally dyno’ed a heron head V7, and the mods I’ve done to offer here to get them into the 50’s at the tire.

I apologize for not posting in the correct location. I did in fact use the search function and came up with nothing, hence my post. I searched for: "V7 horsepower rating" and "V7 HP". So that I do not repeat the same mistake, please tell me what key words I should have used for V7 horsepower rating.
Thank you.
Jason
 
When was your bike measured, it is now 11 years old and horses escape as the mileage increases. The factory HP figures will be measured on a perfect engine in optimal conditions.

It was measured in early 2011.

Jason
 
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