New G5 Project

[Antietam Classic Cycle]

Should still look brand new at only 18k 

I opened up the valve covers and was greeted by this happy sight:


Looks worse than it is, the grime/sludge wipes away without too much effort. Everything moves as it should. Methinks the PO (however many) neglected oil change schedule. Will clean it up as best I can and run frequent oil changes.

I also cleaned up the intake manifold threads. RHS threads looked great after running a tap through them. LHS have been abused. There are some threads left but I may have to helicoil them.

It does look new - there's still paint marks on the rods and crank that were applied at the factory.

Run Shell Rotella T (now called T4) for a while and it'll clean all of that out. Really does wonders on neglected old engines.

My Convert has some thread issues in the same location as well. There were 30 mm long socket head cap screws, when it should have had 35 mm long. When you have two manifold gaskets and the knee guard plastic isolators to go through, that 5 mm is important.

Opposite situation with rocker cover screws - had 30 mm long (which stick out through the head casting and drag rust and other crap through the threads every time they're removed) when it should have had 25 mm long.

You probably already know this, but there are o-rings under those "cover plugs" up between the pushrods. They get hard and compressed over time and then don't seal, oil gets by and dribbles down looking like a leaking head gasket. 

[Groover]

You found black oil, if you lived in TX you'd be rich!

[Groover]

Black gold is what I meant...   

[Antiquar]

Run Shell Rotella T (now called T4) for a while and it'll clean all of that out. Really does wonders on neglected old engines.

I was planning to use that oil; it's nice to hear it will help clean out the gunk. Really a great oil, especially at the price.

I've been blessed that my previous Guzzi and BMW bikes have had trouble free final drives, so I am not too familiar with diagnostics.
I am revisiting my bevel box now, how can I check its health (to some extent) without disassembling it? I feel no play in the pinion. Pinion and wheel drive rotation feels nice and smooth. The oil showed no fragments when I drained it. Crown gear looks good, as far as I can tell, when peering through the filler hole.

[Antietam Classic Cycle]

I was planning to use that oil; it's nice to hear it will help clean out the gunk. Really a great oil, especially at the price.

I've been blessed that my previous Guzzi and BMW bikes have had trouble free final drives, so I am not too familiar with diagnostics.
I am revisiting my bevel box now, how can I check its health (to some extent) without disassembling it? I feel no play in the pinion. Pinion and wheel drive rotation feels nice and smooth. The oil showed no fragments when I drained it. Crown gear looks good, as far as I can tell, when peering through the filler hole.

It's usually fairly easy to pull the whole pinion carrier out of the rear drive housing, it just slides out. Sometimes it can be stubborn though. Pulling that out will allow you to have a look at the pinion teeth. They're more likely to show wear or damage than the ring gear teeth. There's also an o-ring in between the flange and housing that would be good to replace.

Guzzi finally got it right with that rear drive design - they seem to suffer relatively few failures if maintained properly.

[Groover]

My final drive also looked good from what I could tell, and I decided to only replace the large seal #45 and the one (out of two)#34 o-ring (the one that meets directly with the swing arm). A few thousand miles later, my final drive started dumping oil from the final drive all over the wheel and that's when I parked it last season. It was my final hurray ride that was a little longer than usual and that's when it blew. It's starting to get warmer now, and I'm just about to get into it this weekend or next to replace seal #45 again. If by any chance it's seal #25 (internal) that failed this time, do you guys think that can be replaced without removing the actual drive box from the swingarm/frame, or does the whole thing need to come down?

Final Drive Diagram:

[Antiquar]

It's usually fairly easy to pull the whole pinion carrier out of the rear drive housing, it just slides out. Sometimes it can be stubborn though. Pulling that out will allow you to have a look at the pinion teeth. They're more likely to show wear or damage than the ring gear teeth. There's also an o-ring in between the flange and housing that would be good to replace.

Guzzi finally got it right with that rear drive design - they seem to suffer relatively few failures if maintained properly.

Thanks for the advice. I will pull the pinion carrier and examine the pinion. I think I'll also flush with mineral spirits and give the box a good clean, finally replacing the pinion carrier o-rings and big seal. Any tips for pulling the big seal?

My final drive also looked good from what I could tell, and I decided to only replace the large seal #45 and the one (out of two)#34 o-ring (the one that meets directly with the swing arm). A few thousand miles later, my final drive started dumping oil from the final drive all over the wheel and that's when I parked it last season. It was my final hurray ride that was a little longer than usual and that's when it blew.

That's what I'm worried about, but I suppose there's no real way to know for certain until the bike is back on the road. Reading the literature makes these boxes seem like a real PITA to open up. Hoping for the best. 

[Antietam Classic Cycle]

My final drive also looked good from what I could tell, and I decided to only replace the large seal #45 and the one (out of two)#34 o-ring (the one that meets directly with the swing arm). A few thousand miles later, my final drive started dumping oil from the final drive all over the wheel and that's when I parked it last season. It was my final hurray ride that was a little longer than usual and that's when it blew. It's starting to get warmer now, and I'm just about to get into it this weekend or next to replace seal #45 again. If by any chance it's seal #25 (internal) that failed this time, do you guys think that can be replaced without removing the actual drive box from the swingarm/frame, or does the whole thing need to come down?

It's usually pretty easy to tell if #25 is leaking because the inside of the splined hub the whole back to it will be wet with gear oil. You'll need to remove the rear drive from the swingarm to replace it. Everything has to come out to replace it basically. The outer race of the needle bearing #27 and the thrust washer #26 need to be removed to access it. It may be necessary to heat the housing in an oven (or at least on a woodstove, with a heat gun or propane torch) in order for the outer race to drop out. Sometimes they're loose (although they shouldn't be) and you can pull them out by hand - in which case it'll need to be reinstalled with Loctite 609 (or 608? can't remember which and I'm not in the shop at the moment) Retaining Compound. 

Thanks for the advice. I will pull the pinion carrier and examine the pinion. I think I'll also flush with mineral spirits and give the box a good clean, finally replacing the pinion carrier o-rings and big seal. Any tips for pulling the big seal?

That's what I'm worried about, but I suppose there's no real way to know for certain until the bike is back on the road. Reading the literature makes these boxes seem like a real PITA to open up. Hoping for the best. 

It's easiest to do the big seal with the flange (#41) off of the rear drive housing of course, but to do it without opening up the rear drive it might be easiest to (very carefully!) drill two tiny holes in the face of the seal, thread in some screws and pull the seal out by grabbing and pulling on the screws. There are also commercial seal remover tools (some look like paint can openers, others a bit more sophisticated) that will pull the seal without scratching the hub or flange where the seal fits. That's the most important thing of course - making sure neither of those is scratched, pitted or otherwise damaged, otherwise the chance of leak is pretty good.

I prefer to pull the rear drive completely apart so that I can chuck the ring gear and hub assembly up in the lathe and polish the surface the seals run on with Scotchbrite.

Ambassador:


Tonti rear drives are a little harder to disassemble due to the fact that the flange is usually stuck pretty good in the housing. Even with all the bolts removed it might not budge. I've resorted to using a 3-jaw puller with the "points" of the jaws facing outward to catch a slight ridge on the splines and pulling the flange out.

Seals: the normal blue colored small seal, #9040 3850 seems to work fine, but for the big seal I prefer the "updated" brown Viton seal that Guzzi used starting around 2003, #9041 7085:
http://www.mgcycle.com/index.php?main_page=product_info&cPath=79_234&products_id=2853
It costs 4 times more, but seems to be worth it for a leak-free rear drive.

I've actually had a test fixture made that bolts onto the rear drive that allows me to pressurize it and check for leaks.


I'll be doing my Convert rear drive soon and will shoot some photos along the way. 

[antmanbee]

I've actually had a test fixture made that bolts onto the rear drive that allows me to pressurize it and check for leaks.

How much pressure do you use?

[Antietam Classic Cycle]

How much pressure do you use?

5 psi is all that's necessary.

[Antiquar]

Wow, thanks for that incredibly informative post Charlie. When this bike is back together I will have to send you a bottle of whiskey 

Today I installed new steering stem bearings/races and the bottom yoke into the frame. No photos as my phone/camera broke. I haven't documented it here but I have also painted the frame over the past couple weeks, it looks pretty good.

Will try to get more photos up soon.

[Antietam Classic Cycle]

Wow, thanks for that incredibly informative post Charlie. When this bike is back together I will have to send you a bottle of whiskey 

Today I installed new steering stem bearings/races and the bottom yoke into the frame. No photos as my phone/camera broke. I haven't documented it here but I have also painted the frame over the past couple weeks, it looks pretty good.

Will try to get more photos up soon.

Whiskey would be wasted on me - I don't partake of "adult beverages". 

[Antiquar]

Whiskey would be wasted on me - I don't partake of "adult beverages". 

Fair enough. I suppose sending a fine vintage of Rotella T would not be quite the same, would it? 

[Antiquar]

Did a bit of work on the bevel box today. Replaced one pinion carrier stud (that came out with the nut on disassembly) and flushed the box twice with mineral spirits. I also did a bit of cleaning, but the wheel side of the box needs a lot more attention. I also have yet to replace the big seal.

Here's a video of me spinning the box. There is some noise that can be heard when spinning the box quickly. Some vibration can also be felt with a hand on the right side of the box when spinning quickly. I feel a touch paranoid, as I believe this is probably normal, but wanted to get the board's opinion.

https://www.youtube.com/watch?v=tI9yVzgkxtc

[Groover]

Hmm.. good test for reference for sure. If that's after flushing with mineral spirits, I'd say it's probably normal. Have you tried adding a bit of gear oil back in (even just a little) to see if it still does that? Even brand new bearings sound a little bad when they are completely stripped from lubricants, add gear meshing to the equation and you might get that sound - but then again, don't listen to me.. I'm having final drive issues right now on my G5 

I'm curious to hear what others have to say on this.

[Antiquar]

Hmm.. good test for reference for sure. If that's after flushing with mineral spirits, I'd say it's probably normal. Have you tried adding a bit of gear oil back in (even just a little) to see if it still does that? Even brand new bearings sound a little bad when they are completely stripped from lubricants, add gear meshing to the equation and you might get that sound - but then again, don't listen to me.. I'm having final drive issues right now on my G5 

I'm curious to hear what others have to say on this.

That video is actually with some gear oil in, though not the complete volume. Maybe 100cc. Certainly was quieter with some oil than none. It makes sense that it would make some noise without the full amount of oil and operational load on the drive.

The truth is that I have never given any of my rear drives much scrutiny, outside of regular maintenance, so I'm not completely sure what is normal, and am likely overthinking it.

There's no evidence that the drive was having problems before I stripped the bike down (no evident leaks and the bike rolled well), so I will put it on back on the bike barring contrary advice from the board.

I replaced the big seal and orings this morning, anyway. Both the old seal and new seal went out/in without protest. The sealing surfaces were smooth and unmarred.

[Antiquar]

Back in the frame


Today I plan to do work on the wheels--replacing bearings and tires. I opened up the rear drive hub and the cush rubbers looked good, so they will be staying.

[Antietam Classic Cycle]

 

[Scud]

Allright!!! We've got a roller.   

I like that dark green lower frame rail.

[Groover]

I see some stance shaping up with those handlebars. Looking forward in seeing the full concept!

[Antiquar]

Thanks all!

Allright!!! We've got a roller.   

I like that dark green lower frame rail.

The plan is to continue the black/green pairing on the side panels and tank. Not sure of the specifics yet. I will probably channel some 1000S influence, as that is a gorgeous paint scheme. I also have a Lemans-style aluminum tank coming from a manufacturer in India. It is a gamble but reviews were good. Will take some photos when it gets here.


As to the work yesterday, new wheel bearings and tires were spooned on. Both the old bearings and tires were incredibly stubborn, but the bearings succumbed finally to a slide hammer setup and tires to a three main spooning team.

I've got a leak from the rear of the clutch pushrod aperture, so it is likely I nicked the o-ring on installation. I will have to replace it, hopefully without removing the swingarm. I don't really want to pull it apart again.

Up next is to get some brakes working.

[SED]

Cool project - thanks for all the info and pictures.

[Antiquar]

Took apart the carbs this evening.


 I removed all the bits, cleaned passages (though they seemed already clear), and jets. I also installed new flipper-top chokes, adjustment screws, and gaskets.





Unfortunately both accelerator pumps are wrong--both missing ball bearings and one has a wrong spring. The RHS carb's float was mangled, pin slightly bent. I will also have to replace float valves on both carbs. So looks like I'll be placing another order from mgcycle.

Question: Mgcycle carries these replacement floats (http://www.mgcycle.com/index.php?main_page=product_info&cPath=62&products_id=4761), but they of a lesser weight than the originals. Does anyone happen to know the correct float height for the replacement floats?

[Antietam Classic Cycle]

I've not had very good luck with the white floats - most fill with gas shortly after installation. What weight float do you need - 10 or 14 gr.? I have a few good used ones around.

[Groover]

Maybe I'm missing something, but I didn't think the flat slide carbs like yours have accelerator pumps.. do they? If they do, I am missing the whole concept of the accelerator pumps.

As far as the floats go.. can you straighten the pins/stopper tab? As long as they pivot smoothly and stop where they need to stop, you should be good. I keep hearing bad things about those white ones, and I believe it. I've rebuilt lots of Dellorto carbs (vespas mainly), and anything "white" they started putting in their rebuild bags these days are junk. I once got the filter screens missing the entire screen parts, go figure. I usually keep the stock floats and filter screens as long as they are not cracked or broken.

Also, NAPA sells for about $20 a 1 gallon carb cleaner can (looks like a paint can with a basket inside) that you can soak carb and carb parts. Soak for about 24 hours, and everything comes out nice and clean and de-gunked and works a lot better than the spray cans - just a tip, though may be a little late now since looks like you got them clean now. It's also usable until the liquid turns into sludge basically. After cleaning a few carbs, I designated that can to clean other parts and it also does a good job on those (bearings, and such). It's safe on rubber and plastic too. Ok, I'm done with sale pitch 

https://www.napaonline.com/p/MCR6402

Good luck!

[Antiquar]

I've not had very good luck with the white floats - most fill with gas shortly after installation. What weight float do you need - 10 or 14 gr.? I have a few good used ones around.

Thanks Charlie. I'd be interested if you have a decent spare float. They're 10gr.

Maybe I'm missing something, but I didn't think the flat slide carbs like yours have accelerator pumps.. do they? If they do, I am missing the whole concept of the accelerator pumps.

As far as the floats go.. can you straighten the pins/stopper tab? As long as they pivot smoothly and stop where they need to stop, you should be good. I keep hearing bad things about those white ones, and I believe it. I've rebuilt lots of Dellorto carbs (vespas mainly), and anything "white" they started putting in their rebuild bags these days are junk. I once got the filter screens missing the entire screen parts, go figure. I usually keep the stock floats and filter screens as long as they are not cracked or broken.

Also, NAPA sells for about $20 a 1 gallon carb cleaner can (looks like a paint can with a basket inside) that you can soak carb and carb parts. Soak for about 24 hours, and everything comes out nice and clean and de-gunked and works a lot better than the spray cans - just a tip, though may be a little late now since looks like you got them clean now. It's also usable until the liquid turns into sludge basically. After cleaning a few carbs, I designated that can to clean other parts and it also does a good job on those (bearings, and such). It's safe on rubber and plastic too. Ok, I'm done with sale pitch 

https://www.napaonline.com/p/MCR6402

Good luck!

The old VHB carbs actually do have an accelerator pump setup, you can see them in this rebuild: http://www.thisoldtractor.com/moto_guzzi_loopframe_carburetor_rebuild_-__vhb.html

I'll look into the bath, as these carbs are pretty easy to disassemble, and they won't be going on the bike for a few more days it looks like. 

[Tom H]

I have the Gunk brand 1 gal carb cleaner. Works well.

On the idle jet needles. Did you notice the new ones have a different tip length. I think the long is for a VHB30? Or are they interchangable???? I would like to know why the different tip length since I'm in the need of a set for the VHB30. The 30's have an idle issue that I'm trying to figure out.

Good luck with the bike!
Tom

[Antietam Classic Cycle]

I have the Gunk brand 1 gal carb cleaner. Works well.

On the idle jet needles. Did you notice the new ones have a different tip length. I think the long is for a VHB30? Or are they interchangable???? I would like to know why the different tip length since I'm in the need of a set for the VHB30. The 30's have an idle issue that I'm trying to figure out.

Good luck with the bike!
Tom

The long tipped mixture screws were "EPA", the short tipped are "Euro". Interchangeable, but use in pairs - not one type in one carb and the other in the other. 

[Tom H]

The long tipped mixture screws were "EPA", the short tipped are "Euro". Interchangeable, but use in pairs - not one type in one carb and the other in the other. 

Thanks for that info.

Tom

[Groover]

The old VHB carbs actually do have an accelerator pump setup, you can see them in this rebuild: http://www.thisoldtractor.com/moto_guzzi_loopframe_carburetor_rebuild_-__vhb.html

That's what I love about this place. Always learning something new. I had no idea those had Accelerator pumps. Such a different design than the accelerator pumps in the rounds slide PHF carbs. (the type shown here https://goo.gl/AWKBic )