850T Help Needed

[alacy01]

Hello all and thank you for taking the time to read.

A couple of months ago I purchased a 75 850T.  Thee bike has an unclear history, but originated from NW Indiana.  When I purchased the bike, it ran rich and still had the original cylinders.  After changing all fluids and filters, I did have the opportunity to enjoy a few short rides.  However, recently while riding, I experienced a loss of power and pulled to the shoulder and the bike stalled.  When restarting, there was a scraping sound in the rotating assembly.  It sounded like it the noise was from the left cylinder. It was pushed home.

Believing it to be a broken piston ring, I took the Gilardoni cylinders/pistons that I had purchased for my 72 Eldorado and installed them.  However, when installing the left cylinder, no broken piston rings.. 

Restarting the motor, the same issue.  In fact, whatever is scraping is slowing the rotating assembly and stops the engine.  At this point, I am trying to deduce where to inspect next.  My consideration is that perhaps the timing chain tensioner or main bearing.  I wanted to solicit folks here, as I have to tear back into it, and would like to target likely problem areas. 

I had planned on a rebuild this winter, but my Guzzi's have always had other plans..

Thanks for any insight or advice!

[pat80flh]

  A little shy on information, you need to diagnose a bit.   Some questions...

    Does it still have low power? Do both cylinders fire?  Hold throttle about 1600 and remove spark plug wires one at a time. If there is little or no change, that cylinder is misfiring. If misfiring a compression test would probably be in order, assuming you have spark and plug is ok.

  A loose connecting rod bearing noise will usually change on the bad cylinder when you're testing misfire. How did the rod bearings feel while you had the heads off, did you check the play?


   Does the clutch work normally? Does pulling the lever make any difference in the sound?

   A length of rubber heater hose or plastic pipe or a long screwdriver can be used as a makeshift stethoscope to islate the noise.

 

[guzzisteve]

If you had chrome coming off of stock cylinders it could be the oil pump is trashed. There is no spring in the chain tensioner on a T. Drop the pan & front cover and you'll find it.

[wirespokes]

Not a good idea lifting plug caps while running. It can damage a coil or electronic ignition - the damage might not be apparent immediately, but why chance it? Best to short it out instead. 

[canuck750]

Unfortunately there are a quite a few things that could be binding and creating the metal scraping sound. When you had the pistons and cylinders off did the con rods rotate freely and where you able to spin the crank shaft without the sound occurring? Just trying to narrow it down from the crank mains / big end shells to the timing chain and gears.

[John A]

Just throwing this out there but could the starter be having trouble disengaging ?

[Two Checks]

Later Ts did, in fact, have tensioners. The pieces that wear off clog the rocker arm shaft oil holes. Don't axe me how they got past the oil filter.

[alacy01]

I appreciate the responses and apologize for the delay.  Your help and mental support is appreciated. 

Today I had a moment and dropped the pan and worst fears were met.  Somehow the oil pressure relief valve had come off.  Having starved the system of fuel, the metalic sound was the rod bearing destroying itself.  You can see some of the sizable chunks in the pics.








I understand that this now means that I will have to fully disassemble, clean,  figure out what can be reused, and rebuild the engine.  Being a novice and frustrated, I need to figure out some next steps.  I may need some guidance.

Thank you again.

[alacy01]

Any advice on how to clean out the shavings from the internals, oil galeries, once disassembled?  Any parts that should simply be replaced?

Thanks again.

[John A]

I'd be looking for a different engine. You can find a decent one and then you can repair the old one at your leisure .

[pete roper]

The Guzzi pushrod motor is delightfully simple. For a novice it is a dream to rebuild.

The fact that your engine has a filter is a bonus but there will still be major damage to the crank so it's a full strip, grind the crank pin, (And maybe main journals, you won't know until it's apart.) and close and grind the rods.

Use this as the excuse to do all the niggling little 'Improvements' while you're in there and once done you will likely have an engine that will see you out of this lifetime.

Pete

[alacy01]

Thank you for the responses gents.  I am just a bit deflated at the result.  Having an Eldo torn down for rebuild and now a T.  But I am the guy that will bail out water, even when the ship is underwater.  I appreciate the encouragement Peter.

1. Should I be using gasoline and air to wash out the internals?
2. Can anyone recommend a reputable place in Michigan to assess and repair the crank?

Perhaps I should consider having someone with greater experience do this work.

[Two Checks]

NEVER use gasoline! One spark and.....BOOM!
It appears that engine didn't get regular oil/filter changes.
Find a new engine and put your cylinders on it. New to.ing chain/tensioner and rebuild the heads. You'll be good to go.
Then do as said, rebuild at your leisure if possible.
Good luck!

[s1120]

Have you ever rebuilt a engine before? Ive not done a Guzzi yet...  but they are really pretty basic.. Read some manuals..watch some vids.. Ive seen a few Guzzi engine rebuilds on you tube in the past..  Study up a little bit, and you will be on your way.

[elvisboy77]

Thank you for the responses gents.  I am just a bit deflated at the result.  Having an Eldo torn down for rebuild and now a T.  But I am the guy that will bail out water, even when the ship is underwater.  I appreciate the encouragement Peter.

1. Should I be using gasoline and air to wash out the internals?
2. Can anyone recommend a reputable place in Michigan to assess and repair the crank?

Perhaps I should consider having someone with greater experience do this work.

I would clear the passages with.WD 40 or similar.  Good luck!

[chuck peterson]

Oooohhhhhhh that's gotta hurt...id start to make friends w a machine shop.

Here's an off the wall suggestion..just an oddball view.

Push the whole thing into a corner.

A used guzzi of any sort year, make or model that will replace the T can be had for a very reasonable $2-$5k. If you choose right your scrap will become a parts bike for the new used one. Motor rebuilds at a true machine shop can cost you that much. Many here can suggest a rebuild, but that's actually fun for many of us not having to make a living at it and we aren't paying for shop time.

Do you want to ride something more than rebuild something? Or do you want to be rebuilding a motor?

Got really good micrometers? Really good torque wrench? Clean work area? Storage for possibly years? Space? Friendly knowledgeable advice?

Just an outside idea to think of...tough choice I know. I had a scorched motor in a Convert....I was lucky to make it okay without a major intervention. Then, I loved the bike so much I would have done anything to fix it...but now I'd look for a decent replacement motor instead of a machine shop

But if I'm thinking of that expense, I'd look for another used bike...there are great used guzzis from that era that are going begging...check out the SP 1000. Bits and pieces from your scrap T might work as a parts bike...

Good luck! If it's not fun don't do it, whichever way you go...it is a recreational sport

And consider this...1996 Cali in great shape just broken in at 97000 miles! $1800. From a member here, too...I'd grab that in a heart beat and I don't know the guy

https://wildguzzi.com/forum/index.php?topic=100998.0




wordsworth i wandered lonely as a cloud summary

[Chuck in Indiana]

I'm sorry, but you are in over your head here. Bailing while under water water won't help.  A proper rebuild is *not* for the novice. As mentioned above, find a good used engine and put your new cylinders on it. It will be much cheaper and less frustrating in the long run.
*Ask* before installing the new cylinders, too. Some things aren't immediately obvious if you have never done it before.
Good luck!

[Antietam Classic Cycle]

I have a complete 850-T3 engine, just needs the chrome bore cylinders replaced AFAIK. $400.

[Idontwantapickle]

I have a complete 850-T3 engine, just needs the chrome bore cylinders replaced AFAIK. $400.

So there ya go alacy01! 400 bucks and needs the parts you already have! Do that and you're back on the road. 

Hunter

[chuck peterson]

I believe you've just found your answer...

Motor $400
Cyl and Pistons about $400-$500 I think, 4x con rod bolts, gaskets all around
Machine shop check interference fit on the wrist pins, check the con rods, install rings, insert in Pistons, etc...$400?

So $800-$1200 budgeted for a rebuild...in that light, I'd consider that EV...for $1800. But you go be you...just making options for you to think of..

I'm sorry your new bike imploded on you...I hope that wasn't someone trying to get rid of a problem

[Two Checks]

He already has Gilardonis. They only need be transferred from one block to the other.

[Antietam Classic Cycle]

I believe you've just found your answer...

Motor $400
Cyl and Pistons about $400-$500 I think, 4x con rod bolts, gaskets all around

Gilardoni kits are more like $800, but he already has those, so $0. Gasket set is $54. Con rod bolts? Why?

An "$1800" EV will likely need all of it's fuel and breather hoses replaced, most do. Quickly becomes a $2500-3000 bike unless you want to tackle that nasty job yourself.

He apparently has a BMW and Indian to ride, so it's not like he needs another bike to ride right now. 

[John A]

For general parts cleaning I use mineral spirits in the parts washer and in a small sprayer and in a compressor operated siphon sprayer. About 9bucks a gallon at menards. Won't hurt plastic and rubber , gaskets and seals.

[alacy01]

Hey all, thanks for the feedback. 

I am fairly inclined with some types of work, have most of the necessary tools and was in the process of rebuilding my Eldo motor.  However, once you get into the machine work, clearances, etc. Yep, I am rational enough to admit, that is out of my depth.  It had been my plan to do a mild build over the winter (cam, lighten flywheel, etc).  I do believe I will still rebuild this original motor, but my main concern is getting all of the shavings out and having a more knowledgeable person check the crank.  I want to do the work and learn, but Guzziology and forums are my only knowledge sources.  No mechanical mentors. 

That said, I will give Charlie a call Monday.  That is an opportunity for me to get back on the road with my son.  That means more than my stubborn attempts at mechanical mediocrity.

Thanks again all.  Many thanks Charlie! 

[alacy01]

John A, Exactly the information I was looking for.  Thanks!

[Matt Story]

This company reground my crank and sized my connecting rods a few years back.  They were recommended by a friend.  I double checked all dimensions afterward and all were in spec.  Motor is reassembled now, but not yet running.

Shannon's Engine Services Inc
Engine rebuilding service
Montrose, MI
(810) 639-2033

[T4halo]

Tim at TICO’s did my heads and has a very nice engine shop.

He is in Moscow MI

T4

[chuck peterson]

Do the Eldo cylinders and pistons fit the push rods angle of an 850T head?...wasn't there some scrapping issue? Clearance or angle issue between the two? Pushrods rubbing on gaskets?

[Antietam Classic Cycle]

Do the Eldo cylinders and pistons fit the push rods angle of an 850T head?...wasn't there some scrapping issue? Clearance or angle issue between the two? Pushrods rubbing on gaskets?

The Gilardoni replacement cylinders have oval pushrod holes, so work for Eldos, Ts and T3s. It isn't the head that dictates the pushrod angle - it's the rockers fitted. Ts have the same rockers as Eldos, T3 have different rockers. Any "mechanic" worthy of the title will check pushrod clearance to make sure there isn't any interference.

[Rusnak_322]

Not a good idea lifting plug caps while running. It can damage a coil or electronic ignition - the damage might not be apparent immediately, but why chance it? Best to short it out instead.

From the 850T manual - it literally says to pull the cap with the engine running at 1,200 rpm when adjusting the carbs idle speed screw.