Resurrecting a '75 850T

[RevDave]

This past weekend I purchased a 1975 Moto Guzzi 850T from a neighbor, who explained that it's been sitting in his garage and hasn't run for 10 to 15 years.  The bike is dirty as can be, and the inside of the gas tank looks like an EPA Superfund site.  (Frankly, that's the least of my worries as I've cleaned out and re - phosphate coated more than a few rusty motorcycle gas tanks over the past few years.)   And while I've owned and worked on dozens of bikes over the years and done everything from minor tune-ups to major overhauls, I've never worked on a Moto Guzzi before. 

The bike is complete, except for the headlight, as the previous owner had mounted a Vetter Windjammer fairing, which I do not plan to use.  As a result, I'll need to find a headlight and shell to replace the missing unit.  the bike also included a set of Krauser luggage with the racks already mounted on the bike - the fate of which I'm not too sure about at this point...   But the most amazing part is that the bike has a total of 4,458 miles -- and no, that is correct...  (Not 44,580 or some other number, but 4,458 total miles since new.)  The bike even came with two sets of keys and a ton of paperwork dating all the way back to the year of it's purchase in 1978 - apparently from the original owner, as well as the original 0wner's Manual and a Haynes Shop manual.

My primary questions are as follows:

1.  What pitfalls or weird issues specific to this bike am I likely to run across?

2.  I'm aware that these bikes had chrome cylinder bores that are subject to failing and that if they are flaking, the chrome plating can get into the the bearings and otherwise wreak havoc on the bottom end.   With that in mind, I haven't cranked the engine at all, and was contemplating pulling the cylinder heads to check the bores before doing so.   As for the bores themselves,I've heard mixed opinions - some saying that they're usually OK and that failures were actually pretty rare.  Others say that it's a major and very common issue and that it's not worth messing with.  They seem to encourage replacing them - perhaps with a big bore kit, or removing them and having them re-plated with Nikasil, or having cast iron liners fitted to the existing cylinders.  A big bore kit is appealing, but the cost seems pretty high, and apparently using one may also require re-balancing the crankshaft - something I'm hoping not to have to mess with.  I've also wondered about re-using the existing pistons, possibly with new rings in the re-plated Nikasil or cast iron lined cylinders.

Everything else on the bike seems to be in pretty good shape (aside from needing a good washing and polishing).  I was frankly amazed to learn that apparently these bikes came without any meaningful air filter, but would plan to fit either the individual K&N filters, or the single K&N that serves both carbs.    And of course I plan to change the engine oil as well as the transmission oil and rear end lube - and flush and bleed the front disk brake. 

Once I get it up and running I may also be interested in upgrading the front brake with either a second disk and caliper or at the very least, a smaller bore master cylinder and stainless brake lines, as from what I've read, the original brakes were ok - but nothing to write home about.  Any thoughts on that modification would be appreciated as well.   

Finally, any thoughts as to the best place to find new and/or used parts would be appreciated, as it doesn't appear that much if anything for this bike is still available from Moto Guzzi. 

Thanks in advance for any thoughts and suggestions you may have!

Dave

 

[Brilig]

Hello Dave and welcome to the sight.  You will find many people on the sight with a wealth of knowledge and a willingness to share it.
I am presently rebuilding a 79 SP1000 and I was lucky to find it has cast iron cylinders.  Try removing the spark plugs and insert a magnet that will reach the cylinder wall.  If it sticks good you probably have cast iron cylinders.  If not you probably have the Nigusil.
Good luck! you will enjoy the Guzzi.
Post some photos too!
Mark

[Two Checks]

Ts had chrome cylinders. Sitting like that its a good bet the chrome is lifting.
Late 75s had oil filters. If so equipped the sump will have four 10 mm hex head bolts in the middle.


Sitting for so long I would be concerned with transmission bearings being rusty.


Imo K&N filters are little better than no filter.


Parts? One word.
Harper's.

[Scout63]

You should enjoy working on the Guzzi. I started on a 79 V1000 full tear down project this year and found the bike to be robust, easy to work on and very well put together.  Also the drivetrain is so pretty it belongs in a museum.  I highly recommend buying a copy of Guzziology to supplement your shop manual.  Best of luck and please post pictures.

[wirespokes]

Welcome to the forum, Dave!

Sounds like you've done your homework. Good questions.

I can't really say on the chrome, but I'd replace them, personally speaking. The stock pistons will work, but I seem to recall the T having four wide piston rings, which might be a problem.

Aluminum absorbs water like a sponge. If you've ever heated it up, like for expanding it so a bearing will drop in, you've seen the surface get all wet from the moisture coming off. What happens when the bike is run after sitting so long, is that moisture turns to steam and presses against the chrome causing it to flake. Bad deal!

A K&N properly set up filters well. These bikes don't seem to wear out very quickly and probably last longer with a K&N rather than no filter the way they came. I'd go with a filter that joins the two carbs rather than the individual pods.

[fotoguzzi]

  If not you probably have the Nigusil..

um, no. Guzzi and everyone else started using Nigusil about 1980.

The 850t had the chrome bores. And early T's didn't have oil filters either.
My first Guzzi,

[Turin]

Some T's have oil filters, some don't. With that mileage, you can probably send the cylinders to millennium tech https://www.millennium-tech.net/ for nikasil plating and re-use the pistons.  Chrome bores are a mixed bag, I'd err on the side of caution. My T started delaminating at the top of the cylinder. 32,000 original miles.
I like a 4 piston caliper with a stainless line for the front brake.



I've upgraded to double discs with two 4pots and the master works great.
A headlight that will work can be found at MG Cycle or Harpers Moto Guzzi ( Harpers might have an original ). Moto Guzzi Classics in California might also have some stuff.
I love mine.

[Two Checks]

Its not some have and some don't have filters. Late 75 Ts had them after a certain serial number.

[s1120]

Seems to me, that a bike thats sat is more likly to have flaking chrome liners that one used all the time. Sitting is never their friend, and with such low miles, shes sat a lot. I would plan for replating myself.

[Markcarovilli]

Dave

I went with Nikasil plating on my old chrome bores and reused pistons with new rings.  Harpers can help with that.

for all parts try Harpermoto.com and mgcycle.com this should get you started...

Mark

[Furbo]

Dave,

I'm guessing that what you'd like to do is get this thing running and see if you dig the Guzzi vibe.....so I'll keep it simple.

Engine - yep, may have issues. Pulling the top end on a Guzzi is only a 2 beer job. You could inspect the bores carefully, make sure the rings are free after all that time sitting, lap the valves as they've been sitting open for some time, and most importantly, replace gasket and O-Rings which will begin leaking about 30 seconds after the first start up! If the bores need work - I'd go with Nikasil plating. Big Bore - just don't - unless you're going to buy new cylinders. Yes, you'd need to rebalance the crank and frankly the round fin Guzzi 850 is just a very well balanced engine.

Seals - Assuming you replace the oil o-ring seals in the top end, the next will be the Rear Main. It's usually not a big deal, yeah, gets some oil on the clutch but wont cause problems for a good while. The thrust bearing seal on the rear of the tranny will prolly weep a bit as well.

Carbs - VHB's are one evolutionary step above a lawn mower carb. Clean'em and you'll be fine. I prefer UniFilters over K&N's.

Cables - if you can get - or better make - some teflon lined cables you'll find this a much more enjoyable ride.

Drive line - assuming you'll remove the wheel to mount a new tire - pop off the rear drive and make sure there's good grease on the splines at both ends of the drive shaft. fortunately the 850T has a cush drive (as I recall..), but still. 

Ignition - lotsa folks hate the dual point dizzy. It takes a bit to master but it's not that big a deal. I set the gap and static time - but really depend on a dynamic timing check at 4K RPM. I balance the carbs with Carb stix at the same RPM. If you're gonna spend $$ on ignition, keep the points and buy the Dyna coils.

Weaknesses - one really - electrics. Weak alternator output, highly questionable relays, poor ground connections. If you're familiar with BMW's or Laverdas early triples you understand the limitations of the Bosch alternator. You cannot run the headlite around town. Instead of using relays, the lites run directly thru the handlebar switches and all the jiuce but the starter flows thru the ignition switch. These are generally locally sourced components and many are simply bizarre.   If you fall in love with this bike, which you well may, there are fixes for all of this. 

Ok, well. Have owned a 72 Eldo for 32 yrs now. Hope you like the T!

[Testarossa]

There are several threads on T rebuilds, some profusely illustrated with good photos of the process.  This guy Shiskowd did a beautiful job: https://wildguzzi.com/forum/index.php?topic=102453.0

Here's mine, not so beautiful but a great rider: https://wildguzzi.com/forum/index.php?topic=96442.0

The 88mm Gilardoni cylinders are said to be gone for good, so plan to send yours out for rebore and replating or have iron liners installed.

Brakes: If you keep the single front disk, downsize the master cylinder to a 12mm unit. The original round-reservoir 15mm M/C was meant for the two-disk setup. 12mm M/C with steel braided lines and modern pucks gives great braking without the added unsprung weight of another cast iron disk and caliper.

Plan to simplify the wiring loom. Read up on startus interruptus.

The original 14 amp Bosch alternator is inadequate. Upgrade to the 20 amp system that started with the T3, which means updating the rectifier and voltage regulator too.

All these fixes and many more are well described in Guzziology. It's a free ebook download.

[Texcarguy]

Dave,
Congrats on your acquisition.  I too am a recent (4 month) owner of a '75 850T.  Mine was a real fright pig when it showed up, but a few $$ here and there have made it look pretty decent.  The best appearance purchase I made was a VERY complete stainless bolt/screw/nut combination specifically for this bike.  Virtually every visible piece of hardware is included, and amazing how that dresses up the bike... eBay $155:    https://www.ebay.com/itm/MOTO-GUZZI-850T-T3-LEMANS-CONVERT-1000SP-TONTI-STAINLESS-KIT-BOLTS-SCREWS-SET/263228520225?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I too became concerned about chrome cylinders after reading all the horror stories, and confirming with a magnet that my cylinders were indeed chrome.
I purchased a set of Gilardoni 950CC cylinders, pistons, rings, etc from HMB-GUZZI in Germany.  Their pricing beat any dealer in the states AND they actually had them in stock.  $700 US including shipping, and they arrived about 2 weeks after ordering.  The "kit" comes with head and "foot" gaskets, but be sure and order the o-ring kit as well, you will need it and they don't include for some reason (negligible cost), and, if needed (likely) the inlet manifold-to-head gaskets, and a pair of new exhaust pipe gaskets (I think that covers it).

In spite of some naysayers on this forum, I had nothing but stellar experience with HMB-GUZZI.. they are knowledgeable, and respond quickly to questions and guidance, and the cylinders came expertly packed to insure safe arrival.  NOTHING has to be modified on these cylinders to fit the 850.. just bolt them on and enjoy the extra horsepower and peace of mind.  Additionally, I can discern NO difference in engine balance with the new cylinders.. Gilardoni claims these larger pistons are built lighter so as to not effect balance, but what do I know except for the end results.

My go-to parts sources has been mostly MGcycles.com.  I haven't done much price shopping, but they have a great selection, good website interface, quick shipping and reasonable shipping charges (for those inevitable $10 items you forgot to add to your last order).

I currently have 7 bikes in my corral, and purchased the 850 on a lark, having owned and enjoyed a California in the past.  Honestly, I expected it would be a very occasional rider, but I have really fallen in love with this bike, and it is generally my first choice for a quick ride down Texas Hill Country backroads. 

Finally, I must give a shout-out to the best aluminum cleaner I've EVER used.  It's Valvoline Eagle One Mag Wheel Cleaner, available on Amazon.  No telling how many snake oil concoctions I've tried in my 75 years, and this stuff verges on the unbelievable,  It is some serious sh*t, don't get it on your hands.. but if you've got tarnished or corroded aluminum parts (along with, hopefully a pressure washer):  1) mask off painted or polished areas  2) spray this on and let sit for about 60 seconds (Yes, really!), then blast it off with the pressure washer.  You won't believe the end results.  Of course, a bit of brushing mechanical action while the stuff is sitting there can enhance the end results even more, but this stuff is truly amazing.

Enjoy your Guzzi!

[RevDave]

Wow!  Thanks so much for all of the tips and information to one and all.  I hope to be able to begin working on the bike in the next couple of weeks. 

I have removed the tank and begun the process of draining the old gas and cleaning it out.  It sounds like there is a lot of rust sloshing around in it, but from past experience I know that persistence pays when it comes to getting tanks cleaned out.
 
The original petcocks appear to be ok but hopefully i can find some replacement screens that fit over the intake tubes.

I want to see if i can find an original headlight.  I've checked E-Bay, but no luck thus far.  Any ideas as to where I can find one would be appreciated.

i'll post photos as I begin to move forward with the project!

Thanks Again!

[fotoguzzi]

Those headlights are hard to find. Could try Harpers or make a phone call not email to Mark at Moto Guzzi Classics.