PHF32s/gearing

[czakky82]

Sorry for blowing up the forum lately. I’m on vacation pondering my V7 Sport  .

I’m through the break-in and have played enough with jetting. The bike is basically stock with a lightened flywheel and an HMB 8.1 (torque) cam.

Throttle response is great and 1-3rd gear run right up to 7k. 4th requires a bit of extra throttle up any hill but does it. 5th gear will very slowly pull, I’ve gone from 80-100mph and it happens just not too quick.

I’m contemplating going to PHF32 carbs as I have manifolds that I could use and it would give me an excuse to update the throttle.
Would this have much effect?

The other thought would be to throw in 7/33 gears.
I don’t plan on doing any high speed racing with this bike and think that this gearing would make sense.

Any thoughts?

[czakky82]

Gearing charts
7/33




8/33



Stock

[Frenchfrog]

Amedeo at Raceco UK told me that the optimum sized carbs for the small valve heads was 34mm and he used to bore 30 's out to that diameter.It's not as easy as it would seem though.Plenty of folk go to 36's and seem very happy with the results.

[80CX100]

I have nothing for you re the carb swap, if it wasn't a lot of trouble more gas couldn't hurt idk.

I don't do the highway/4 lane thing unless I have to. 99% of my riding is on mostly back country roads, fyi.

Over the years, I've read many times that the Tonti 5 speed is happiest if you treat it like a 4 speed with an OD.

I'm slow to get with the program and only recently started riding like that; I only use 5th on long downhill or long straight level stretches of road, the rest of the time I leave it in 4th.

The sages were right, the engine & drive train are much happier, the bike feels like you're in the groove as opposed to one gear above it. 

fwiw ymmv

[Antietam Classic Cycle]

Gearing charts
7/33




8/33



Stock

You should have kept that 8/37 rear drive you sold me. 

[czakky82]

@ACC, I needed a starter waaay more!
I’m not sure that small amount of lower gearing would’ve been enough for what I’m after.

I’ll probably keep as is until December when I get bored.

[Canuck750]

Last week I sat down with Wolfgang Haerter of Columbia Car and Cycle in British Columbia, ( laverda@lightspeed.ca ), the `go to guy`for all things Laverda and an all around Italian bike mechanic with 40+ years in the business. Wolfgang set up the Dellorto PHF 36 pumpers I got from Bevel Heaven with new needles and atomizers to suit the Ducati 860 motor, (Dellorto sells the PHF 36 carbs set up for a Moto Guzzi 850 LeMans). The Ducati ran much, much better with the replacement atomizers and needles.

I could not find PHF 32`s to replace the stock Ducati carbs and opted for the 36 pumpers, I SHOULD HAVE CALLED WOLFGANG! he has in stock new 32 and 36 Dellorto carbs set up for either a Guzzi or Ducati. Talking with Wolfgang he explained there is nothing to be gained from the 36 carbs except on wide open throttle and even then the 860 motor will run better on the stock 32mm carbs.

I wanted to swap my VHB 29`s on my Eldorado to a round slide 30 or 32 Dellorto cars but Wolfgang talked me out of it, instead I flat sanded the manifold to head surfaces as well as the pair of thick gaskets and eliminated any air leaks no matter how tiny, the Eldorado now runs better than it ever has.

I also talked to him about my 750S with VHB 30`s asking about round slide 30 or 32 Dellorto replacements, he recommended against it telling mew the `best`carb for the Guzzi 750 and 850 pre Le Mans are the VHB carbs.

I agree that 5th gear on a V7 Sport or 750S is an overdrive, keep it in 4th and rev the heck out of it. I remember Mike Harper telling me could ride a V7 Sport in 1st gear to 50 mph! I was complaining about the pick up riding my 73 V7 Sport and he told me I was shifting way too soon and not letting it rev, he was right!| (on that and many more things he told me about Guzzi`s)

[huub]

After the vhb of the v7sport wore out I fitted Phf 36.
Those were too big, midrange suffered , without much benefit on the top end.
I did a couple of dyno runs , but no way I could get them to fuel properly.
After that I fitted Phf 32, those are great, solid midrange , and it does not limit the revs like the vhb did.
Recommended...

[czakky82]

@canuck, thanks for weighing in and sharing the wisdom of yours and another master.

@huub, ditto!

 I’m likely to be caught in a moment of weakness and do it all!

Either way I couldn’t ask for more from the forum, thanks again.

[czakky82]

I like the idea of fitting 7/33 rear drive to the Sport.

I know that the drum brake rear drive bikes need a spacer to fit newer disc bikes. Is there any easy way to fit the newer disc rear drives to older models?

[Antietam Classic Cycle]

I like the idea of fitting 7/33 rear drive to the Sport.

I know that the drum brake rear drive bikes need a spacer to fit newer disc bikes. Is there any easy way to fit the newer disc rear drives to older models?

Swap to a disk brake swingarm (T3, Convert, etc.) and weld a tab on for the brake torque rod. You'll also need the larger u-joint from the same models.

[czakky82]

Well, I’m out!

Thanks for the info