1973 V7 Sport Cylinder Relining Millennium

[Richiez22908]

Suckers popped right out, thankfully.

Now. Want to measure the pistons and make sure they’re good before sending to Millenium with the cylinders. Like a dumb#%€I forgot to keep track of which piston was which when I was taking the rings out. I’m assuming they will have to measure for the rings, etc anyway and and will match based on size. Fingers crossed.

So… what am I measuring on these? I found some great Italian in the book and some long division on a diagram, lol. Also found ring slot height clearance but that’s with the rings in. I took them out. Any guidance or hard numbers here would be appreciated.

[Richiez22908]

Do you have a shop manual? https://www.thisoldtractor.com/mg_manuals/workshop_manual_v7sport_750s_850t.pdf
Piston specs are on (pdf) page 21 of 135, paper manual page 19. The drawings of how to measure and dimensions is on 98 & 99 of 135.

Thanks for this.. but unfortunately I took the rings out already and the measurements on page 21 seem to refer to rings still in. I guess I can put the back and measure but is there an overall measurement I can check since the rings will be replaced anyway?

And on pages 98&99... excuse my ignorance, which measurement might be the right one? None seem to be right if I'm reading it correctly, which I am definitely not.

Basically.  how wide should each of the ring channels be? And aside form that and the overall diameter of the pistons, which look fine, what else do I need to measure? Not concerned with ring gap, again as Millennium will be installing new fitted rings.

Thank you so much for your help!!

[Tom H]

If your sending off the complete sets, they should check the measurements. You might want to give them a heads up to make sure they do it. When you get them back, then you could measure the ring groove clearance.

As low a miles as your bike has, I would think the pistons are in very good shape. Just like I would do, I think your over thinking this.

They will probably check the pistons and find they are fine. Then plate and bore them to the pistons.

If they send the pistons back without the rings installed. There is a top, this way up, to the rings. If they do not include instructions, ask them!

Tom

[Richiez22908]

Ok yeah I believe they said they’d do all that. I’m sure they’ll let me know if anything is out of whack. They Thanks. Gonna get them in the mail this week and start pulling the rest apart and see if there’s and damage from the chrome.

Thanks and have a great evening!!

[Canuck750]

Harpers has V7 Sport ring sets in stock, worth fitting new rings if your going all in with the Nikasil coating.

https://www.harpermoto.com/deves-piston-rings-for-v7-sport-mc151.html

MG Cycle has the gudgeon pin circlips, they should always be replaced when a piston is removed from a conrod.

https://www.mgcycle.com/index.php?main_page=product_info&cPath=68_129&products_id=1345

and a whole other option is to go with these kits from HMB Moto Guzzi in Germany, 855 Euro / $892 USD and get new pistons, rings, pin, circlips and cylinders, might work out to be cheaper than the replating route.

https://hmb-guzzi.de/Engine-upgrade-V7-V7-Sport-750-S-750-S3

[Richiez22908]

Harpers has V7 Sport ring sets in stock, worth fitting new rings if your going all in with the Nikasil coating.

https://www.harpermoto.com/deves-piston-rings-for-v7-sport-mc151.html

MG Cycle has the gudgeon pin circlips, they should always be replaced when a piston is removed from a conrod.

https://www.mgcycle.com/index.php?main_page=product_info&cPath=68_129&products_id=1345

Thanks... was thinking I'd do new rings... then broke one removing it so... yup.

I shot Millennium an email to see if they have them or if I should source elsewhere... and will grab a set if so. Do you know if that set you linked to is for both cylinders? I see these for only one:

https://www.dlastore.com/e_store/piston-ring-set-for-moto-guzzi-v7-sport-750cc-motorcycle-82-5mm.html

https://www.stein-dinse.biz/product_info.php?language=en&products_id=177950

https://moto-renzo.biz/Tecnical-Goods/Engine-Spare-Parts/cylinder-piston-rings/Piston-Rings-V7-Sport.html?language=en

Any better or worse than the other?

Thanks!!

[Canuck750]

Thanks... was thinking I'd do new rings... then broke one removing it so... yup.

I shot Millennium an email to see if they have them or if I should source elsewhere... and will grab a set if so. Do you know if that set you linked to is for both cylinders? I see these for only one:

https://www.dlastore.com/e_store/piston-ring-set-for-moto-guzzi-v7-sport-750cc-motorcycle-82-5mm.html

https://www.stein-dinse.biz/product_info.php?language=en&products_id=177950

https://moto-renzo.biz/Tecnical-Goods/Engine-Spare-Parts/cylinder-piston-rings/Piston-Rings-V7-Sport.html?language=en

Any better or worse than the other?

Thanks!!

I used the Harper’s rings on. 750S3, no experience with the others.

[Chuck in Indiana]

And on pages 98&99... excuse my ignorance, which measurement might be the right one? None seem to be right if I'm reading it correctly, which I am definitely not.

Basically.  how wide should each of the ring channels be?

That is what it is showing. 2.03 is min, 2.05 is max.
Edit:
If you don't know.. there is a ring expander for use in removing rings. Hopefully you didn't scratch the pistons taking them off (and breaking one).

[Richiez22908]

That is what it is showing. 2.03 is min, 2.05 is max.
Edit:
If you don't know.. there is a ring expander for use in removing rings. Hopefully you didn't scratch the pistons taking them off (and breaking one).

I did get little scuffs in one, butchered it. Don't even remember doing that but couldn't have been from anything else. The other one is fine. So odd. I should have waited and gotten the proper tool... or just left them on. Definitely got overzealous there and feel like an idiot.

I'll see if Millennium has an issue with anything on the piston. May have to see if I can get it repaired.



Any way to polish that out or should Millennium be able to do so?

[Richiez22908]

Millennium said they'd have to see them in person but should be ok. Fingers crossed. I feel like an idiot.

Ordered rings and will ship off the cyls, pistons and rings as soon as they arrive.

Thanks everyone for their input and I'll let you know how it goes.

[Chuck in Indiana]

Winced (literally) when I saw the picture. Those are pretty serious stress risers..
Here is my antique (naturally)  Spring deringer.

as you close the handles, the jaws close..then as you continue squeezing it spreads the ends of the ring apart so you can just lift it off the piston.

[Richiez22908]

Winced (literally) when I saw the picture. Those are pretty serious stress risers..
Here is my antique (naturally)  Spring deringer.
as you close the handles, the jaws close..then as you continue squeezing it spreads the ends of the ring apart so you can just lift it off the piston.

I went back over them and they look worse in the pics than in person or how they feel... can't feel them at all or get a finger nail to catch... so hoping its ok.

Can I borrow that tool... YESTERDAY!!?? 

[Richiez22908]

Been a while, but rings arrived(from Greece). Packed them in with the pistons and cylinders and handed to UPS today. I'll sleep better when they say all is well and get started with the plating.

Now plenty left to do... gonna take the engine out and see what needs refinishing or replacing.

[s1120]

I went back over them and they look worse in the pics than in person or how they feel... can't feel them at all or get a finger nail to catch... so hoping its ok.

Can I borrow that tool... YESTERDAY!!?? 

I did that before and thought I really messed it up. once I cleaned the piston it was all but gone. It wasn't so much a scratch, but a clean spot. Granted it was a V8 not a motorcycle, but I ran that motor for two seasons in my drag car. Ive been more carful from then on though.

[Moparnut72]

I wouldn't be too concerned about those scratches. I was helping a guy with a fresh out of the box 125 cc Rossi Italian racing outboard. We were setting up the boat for a time trials. We wound up sticking the motor. Some muriatic acid and some fine sanding on the piston we were running again. We got it up to just over 85 mph. Two weeks later he set the world recordat just over 87 mph with the same piston.
kk

[Richiez22908]

Thank you both!

Yeah I'll definitely be more careful.

[Antietam Classic Cycle]

I have an expander like this and it works well:
https://www.amazon.com/Piston-Pliers-Compressor-Expander-Installer/dp/B07YWG6VDR

[Richiez22908]

Ok now that the  cylinders and pistons are shipped off... I guess I need to remove the motor next. Any step by step guides out there?

In the manual this is all it says, lol:
By means of the wrench n. 14927700 (32 i n fig . 6) undo the lockrings of exhaust pipes on cylinder heads and after loosening the screws fixing silencers to frame remove the exhaust pipe-silencer assemblies.
Place part n. 14912400 (10 in fig. 7) under the engine oil sump: remove the rods from rear brake and gear- shift levers; remove the cable from the crutch control
lever on the gearbox; disconnect all electric wirings; then slide off the engine-gearbox unit from the after undoing all fixing devices.
After removing the engine-gearbox from the frame, wash it down thoroughly In petrol before separating the engine unit from the gearbox.

Soooo... do I need that tool/thing to hold the bottom of the motor? Right now its on a hydraulic jack but that device looks more stable.

Also... once the engine/gearbox is disconnected from the frame, electronics, etc... I assume lifting the rest of the bike off it is the only way to get it out?

For those of you at home the have done this... HOW??? lol.

Thanks!!

[Tom H]

Do a search here for Crabbing the Frame and you will find out how to get the engine and trans out.

One place to look:
https://www.thisoldtractor.com/guzzitech.dk/gb_en_complex-technical_crab-frame.htm
You might also want to brows around that site for help with the engine.

You do not need the special engine holder. Once you see what you need to do, some blocks of wood, cinder blocks, scissor jack (platform style preferable), car floor jack will get the job done.

I use an engine puller to hold my frame up, quick and easy. Others remove the front wheel and use various means to hold the frame.  Whatever you chose, do it safely!!!

Tom

[cliffrod]

Guess it’s time to learn about crabbing a Moto Guzzi… Search the forum for the term “crabbing”

Or you can do it from the other end like I did before I ever heard of crabbing it from the back.  Block the engine with some 2x4’s or whatever and undo what is needed to remove front end and other stuff like lower frame bolts, swingarm pivots, etc to lift the frame off the engine/trans unit.   

Just stabilize the engine unit well so it doesn’t fall off. Then take the rest of the bike off the engine & trans assembly.  An engine hoist or even just a rope/strap over a rafter helps a lot.  It isn’t rocket science, just atypical of wrasslin’ a complete heavy engine out of & into a looped frame of any brand.

[Chuck in Indiana]

I have a special tool called "The Box."  I have pix somewhere, but it is simply a wooden box just tall enough for the pan to set on.

[Dave Swanson]

Ok now that the  cylinders and pistons are shipped off... I guess I need to remove the motor next. Any step by step guides out there?

In the manual this is all it says, lol:
By means of the wrench n. 14927700 (32 i n fig . 6) undo the lockrings of exhaust pipes on cylinder heads and after loosening the screws fixing silencers to frame remove the exhaust pipe-silencer assemblies.
Place part n. 14912400 (10 in fig. 7) under the engine oil sump: remove the rods from rear brake and gear- shift levers; remove the cable from the crutch control
lever on the gearbox; disconnect all electric wirings; then slide off the engine-gearbox unit from the after undoing all fixing devices.
After removing the engine-gearbox from the frame, wash it down thoroughly In petrol before separating the engine unit from the gearbox.

Soooo... do I need that tool/thing to hold the bottom of the motor? Right now its on a hydraulic jack but that device looks more stable.

Also... once the engine/gearbox is disconnected from the frame, electronics, etc... I assume lifting the rest of the bike off it is the only way to get it out?

For those of you at home the have done this... HOW??? lol.

Thanks!!

[Richiez22908]

This may beyond what I am able to do... we'll see.

Also... at this point the rear of the engine is accessible... but how would you remove it? I'd have to use a hoist to raise the frame? But then why use the crabbing method at all?





I guess instead of tilting it, hinging on that front bolt... I just remove that front bolt and lift the frame off with a shop crane/hoist, etc? Gonna need a bigger garage, lol!

[cliffrod]

Back when I was young & dumb (vs old & dumb now…) and was doing it completely on my own with no internet or nearby guzzi people tell me right from wrong, I simply took my bike apart when it needed to be done.  Never crabbed a bike from the back.  I took front end off, disconnected what was needed and lifted the rest of the bike off of the assembled engine & trans unit.   That approach seemed more logical to me.  Before I had an engine hoist, I used a rope or strap over a rafter to lift the chassis.  I connected it to the steering neck.  When that wasn’t an option, I just took enough off the bike so that I could handle it.

Was it easier or more efficient than an official crab from the back of the bike- don’t know.  It worked for me.  And I did it in borrowed space, on the tiny front porch, etc- always on a short schedule & never in my own dedicated ample space with proper tools.   

Don’t overthink it.  Just be careful not to break anything.  If you have to force it, rethink it to figure out what you missed.  You’ll be fine.  In the end, you’ll know your bike very well.  It’s a simple bike and knowing what & where everything is will make riding it a much more peace-of-mind experience. 

[Tom H]

Crabbing is just about the easiest way to get the trans off to work on the clutch. Can also be used for engine removal.

If you have a helper or a shop crane, you can always remove what is needed to lighten the frame and lift the frame off of the engine. Pull both wheels, fork tubes (leave the triple clamp installed) and swing arm as well as the seat and gas tank and the frame is not very heavy, one person can carry it. To get it on and off the engine, a helper is really nice to have.

Tom

[Richiez22908]

Thank you!!

Ok Millenium says the pistons and cylinders are fine and will begin work. They did ask, however:
 “One is at .0018 and the other is .0024. I need to know what clearance you want to get correct final size. “

Gonna go digging but anyone know what the correct clearance is off hand?

Thank you!!

[Pescatore]

This may beyond what I am able to do... we'll see.

Also... at this point the rear of the engine is accessible... but how would you remove it? I'd have to use a hoist to raise the frame? But then why use the crabbing method at all?

I had never worked on a bike before and four years later, with lots of
help from reading this forum, I fixed my V65 GT.
I hoisted my from the ceiling in my garage. Take a look at my thread.
https://wildguzzi.com/forum/index.php?topic=102352.msg1619257#msg1619257
I'm not sure how similar my bike is to yours, but it will give you an idea of what's involved.
Some of the pictures are motion gifs.

[Tom H]

I feel compelled to mention this. Not all roof beams are made the same. I have hung a frame and the like for painting from the beams in my garage. Would a try to "safely" hang a heavier weight from it, hell no!!!!! Not with my hands/arms in a very compromised situation.

So.....Think it out as to the weight and what you need to hold it for you.

Tom

[Richiez22908]

Thank you all. I found the clearance specs on another thread and also in Guzzilogy. For this interested the V7 Sport is about .0014-.0019”. Later Nikasil bikes a little tighter but .0015 is a good number.

As far as lifting it, I’ll probably grab a crane from harbor freight. Should be able to get what’s left if the bike up plenty night with it. I’ll put the engine and tranny on my hydraulic jack and can lower them. Between the two can probably roll the drive train right out from under the lifted frame.

Exhaust, seat and fender are off. Tranny is drained. Baby steps.

I’ll shoot some pics and updates soon.

[MotoGuzzi750]

What Cam said !!!!

I just noticed the bikes you own, and if possible want to see pictures of your bikes, if you have posted them somewhere.

Thanks.