What are lightened flywheel pros and cons?

[amamet]

I installed a v11 10 spring flywheel and ring gear in my 77 lemans.  Engine was completely over hauled. Gilardoni 88mm cylinders, p-9 cam, heads redone, moving parts balanced (all work done by mike rich) bike had all bearing replaced, new u joints etc…basically all moving parts replaced and/or rebuilt.  It runs like a beast. The only thing i have issues with is vibrations and high speed. I don’t remember that when i picked up the bike years ago and drove it from Mass to Ny.  It felt smooth and easy to ride on the highway. While the bike now is super responsive and a hoot blasting around, a 1 hour drive on a highway at 75-ish was very not much fun (numbing vibrations in hands, feet and arse) Was wondering if it was because of the overall effects of a lightened flywheel? Carbs are synced spot on, i trust that mike rich had all parts balanced correctly and the bike put back together properly. The differences between picking the bike up and now are the lightened flywheel, the cylinder kit and all bearing replaced. Granted, I don’t plan on many highway trips but they are unavoidable where i am now.  Just trying to wrap my head around why the bike is now fairly uncomfortable cruising on a highway for any length of time when the first time i threw a leg over it i drove down 95 2 hundred miles and felt fine
Thx
Allen

[guzzisteve]

If you lined up crankpin mark on new flywheel it should all work the same balance. You may feel a bit more vibes but not much. I would make sure timing is on at full advance.

[czakky82]

Valves adjusted?

[amamet]

Valves adjusted, timing set properly. Maybe it’s just me. I remember having it put it together rather quickly because i was moving. Since these bike are so easy to work on, i may just go through everything once more over the winter

[rocker59]

I would think it's an engine balance problem not related to the weight of the flywheel.

[moto-uno]

  It may be worth finding out exactly what balance factor he used . Also is there less vibration at rather elevated engine speeds ?
Was the replacement flywheel assembly balanced with your parts ? Or may it have been balanced from the factory with the heavier
engine parts of the original V11 motor ?  Peter

[bigbikerrick]

When I put the Gillardoni cylinders/ pistons in my 850 eldo, I also noticed more high speed vibration. I took the top end apart, and weighed the forged pistons/ pins ,and they were a bit heavier than the stock 88's. I removed  some material from the inside of each piston, to match the weight of the oem cast pistons, and the  excessive vibration went away.
Rick.

[lazlokovacs]

I'm going to respectfully disagree with my esteemed fellow guzzi enthusiasts. 

I had a lightened flywheel in a fully blueprinted Cal 1100 engine, I then swapped it for a standard one, no other changes. It was definitely smoother when cruising.

I've since re-built the bike as a 17inch wheeled, clip on-ed sports bike (ish).. so the lightened flywheel is probably going back in!!!

 Also, many other things can affect the vibes in the bars, sometimes with a bit of bar end weight experimentation the vibes can be tuned out..

[Texas Turnip]

I've never messed with the stock motor as they always ran good enough for me while putting over 100K on many Guzzis. Speed in a quarter mile, increased HP etc never excited me. Now if someone mentions the town of Beaver, Kansas I have to check it out.

Tex

[Gliderjohn]

Here you go Tex.



GliderJohn

[blackcat]

I would think it's an engine balance problem not related to the weight of the flywheel.

My CX has a lightened Ed Millich flywheel and no unusual vibes at high speed.

I can't imagine that Mike Rich got this work wrong but I would give him a call to discuss what is happening.

[bad Chad]

The question is what are the pros and cons?  I don't know much, just ask those who live with me, but I think a lighter flywheel allows the motor to spin up faster.  On the other side it won't have the same locamotive pull at lower rpm?

[Frenchfrog]

Logically , if Mike had all the parts balanced apart from the new flywheel and it was smooth prior to the flywheel swap, then the flywheel isn't in balance with the rest and this is causing the vibration.
When balancing cranks not everyone checks the flywheel ,or the alternator rotor for that matter.Ideally they should all be done together.

[guido guzzi]

Logically , if Mike had all the parts balanced apart from the new flywheel and it was smooth prior to the flywheel swap, then the flywheel isn't in balance with the rest and this is causing the vibration.
When balancing cranks not everyone checks the flywheel ,or the alternator rotor for that matter.Ideally they should all be done together.

Um... no. Crankshafts are balanced to the reciprocating components: Pistons, rings, circlips, connecting rods and bolts, small end bushings and big end bearings. I have had flywheels and ring gears balanced *to each other* - without balancing any other components - with mixed results...  It makes sense that a heavier flywheel will smooth out the power pulses and store more energy between combustion events.

[MattP]

Whell now you know the cons, what are the pro,s shift faster? It will beat it self and you on the road to  mebeyon the track ok.

[Turin]

I have different variations on the concept with different Guzzi's. I don't have weights on any of these.
My favorite is the lemans flywheel on my 850T. You can see in the pic that not much has been removed. It is a nice compromise for a happy roadbike.




The LeMans 1000 is radically lightened. This was a pro thunder / ccs / bott racebike from the late 80's. Great squid bike, not as fun for touring. you certainly feel the motor.




My Cal III had the lightened flywheel replaced with a RAM clutch before I bought it. This is also a good compromise with the lightest clutch pull I've ever felt on a guzzi. It revs quickly but it's not as vibey. also a very good piece.




My Lemans 3 has the stock clutch and it feels like it takes forever to get up to 6000 rpm.
this bike is getting an ergal flywheel, just cuz I have two sitting here. that and a P-3 cam should make for a nice streetbike.

[huub]

sounds like the engine was not balanced with the new ( heavier) pistons.
usually this is skipped.
a newly rebalanced engine should be absolutely smooth.
the flywheel shouldn't make a difference.

[Frenchfrog]

Um... no. Crankshafts are balanced to the reciprocating components: Pistons, rings, circlips, connecting rods and bolts, small end bushings and big end bearings. I have had flywheels and ring gears balanced *to each other* - without balancing any other components - with mixed results...  It makes sense that a heavier flywheel will smooth out the power pulses and store more energy between combustion events.

I think I have either badly expressed myself or you have missed my point : the flywheel and rotor may  be out of balance.
We agree that the actual mass of the flywheel may be a factor too

[Frenchfrog]

sounds like the engine was not balanced with the new ( heavier) pistons.
usually this is skipped.
the flywheel shouldn't make a difference.

That was also what I thought on my initial reading...

[reidy]

As I understand it, an engine will always have some vibration, or at least that is what my copy of tuning for speed tells me. The vibration you feel is a sum of the engine and its interaction with the frame and motorcycle components.

If you have changed say the handlebars, foot pegs, exhaust or something, that component may be vibrating at a different harmonic frequency to the original and that is what you are feeling.

Have you changed any components on the bike?

Steve 

[PeteS]

My $.02, I had my LeMans Flywheel lightened by Manfred Hecht along with headwork. No increase in vibrations but the engine now winds up like a two stroke.

Pete

[cliffrod]

My $.02, I had my LeMans Flywheel lightened by Manfred Hecht along with headwork. No increase in vibrations but the engine now winds up like a two stroke.

Pete

Yup.  Due to a variety of circumstances, I’ve spent far too little time on my CX100 with seriously lightened flywheel. I know nothing about the specifics of this engine.  So far, no adverse vibration that I’m used to from old singles, etc.   

But riding it back to back against my old V7 Sport makes me think that I’m not riding a Guzzi.  It revs up & down effortlessly, not like my old Guzzi.  To me, it’s a completely different experience. 

[Scout63]

Yup.  Due to a variety of circumstances, I’ve spent far too little time on my CX100 with seriously lightened flywheel. I know nothing about the specifics of this engine.  So far, no adverse vibration that I’m used to from old singles, etc.   

But riding it back to back against my old V7 Sport makes me think that I’m not riding a Guzzi.  It revs up & down effortlessly, not like my old Guzzi.  To me, it’s a completely different experience.

Pros of a lightened flywheel - they are beautiful.  Con is that it is hidden.  Would you recommend a lightened flywheel in your Sport Clint?  I’m not sure whether to reinstall the one in mine or locate a stock one.

[cliffrod]

Pros of a lightened flywheel - they are beautiful.  Con is that it is hidden.  Would you recommend a lightened flywheel in your Sport Clint?  I’m not sure whether to reinstall the one in mine or locate a stock one.

Ben, my v7 Sport engine is all stock specs and so well-sorted that I wouldn’t change a thing.  It isn’t pretty but my video shows how well it starts and runs after sitting for months at a time.  I have no desire to turn a screw.  The way it builds momentum is always a thrill, alway an “uh oh I better quit before I get into trouble” experience every time I really stay in it.  People compare it to a two stroke power band experience.  It isn’t as abrupt but makes me think of when you just drank one more than you should have and quickly realize that there’s no turning back. I love my v7 Sport.

I never liked a bland UJM in-line four feel (including my Benelli 500-4) and as much as I like a Ducati twin, it doesn’t thrill me like my old V7 Sport does every time I twist it.  This lightened flywheel on the CX makes me want to put a heavy stock flywheel on it so it feels like my V7 Sport except I like the idea of quick revs and triple discs as a completely new bend on my Guzzi perspective.  My V7 Sport isn’t a stock resto.  But except for the dyna ignition and k&n filters, the driveline is 100% original and still a blast. After 30 yrs, It is my baseline reference for all motorcycles.

Too bad you’re so far away.  But if you’re down this way, it won’t take a long ride on either of them to feel the difference. Up north, you don’t eat fiddlehead ferns because they are the best tasting culinary delicacy to be found.  You enjoy & appreciate them for what they represent- nature, spring and one more chance to enjoy a new time of life. 

Imho The V7 Sport is the end of the ruler.  It is the origin of all modern Guzzi Vtwin sportbikes.  Appreciate it for what it is and what it inspired.  Modify the rest because none of them came first.

[czakky82]

Well said Cliff.