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General Category => General Discussion => Topic started by: 850brian on November 11, 2023, 05:42:45 PM

Title: 75 850t Cylinder
Post by: 850brian on November 11, 2023, 05:42:45 PM
Hello all, I have recently acquired a 1975 850t that was my Grandfather's. I have been in the process of getting it back up and running for the past week or so since it has been sitting for 15ish years. I was unaware of the chrome cylinder issue and have started thr motor a handful of times while tuning the carbs and doubt they have been changed to another material. All of that being said, what should I look for in the motor to determine the amount of damage If any I have done by starting the motor and where can I find some resources or tutorials on changing the cylinders using a kit. Thank you.
Title: Re: 75 850t Cylinder
Post by: moto-uno on November 11, 2023, 07:00:07 PM
  I think we'd be pretty surprised if there wasn't any damage in the cylinders . If you had access to a bore scope you'd probably
be able to see , but since you only need 4 or 5 tools to take the top end off ~ . And it's pretty much a given that cylinder damage
will be there ,either now or very soon . Not an "if", but a "when" kinda thing . Good luck, Peter
Title: Re: 75 850t Cylinder
Post by: 850brian on November 11, 2023, 07:14:30 PM
I guess what I meant to ask was would i be able to determine if me starting the motor a handful of times did any damage elsewhere in the motor. I fully intend on replacing the cylinders.
Title: Re: 75 850t Cylinder
Post by: cliffrod on November 11, 2023, 08:06:41 PM
If there’s missing chrome, it went somewhere and probably did something along the way.  Whatever it did won’t be good…

You can check it all and fix it now -aka spend the money once- and know it’s properly fixed so you can enjoy the bike without any angst.  Or you can do the minimum now, cross your fingers hoping everything unknown is ok and see what happens.  It may be fine or you may learn that you should have left no stone unturned in the first place.  It won’t be any cheaper to fix properly in the future.
Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 11, 2023, 08:17:37 PM
I doubt that you've done any damage just starting it a few times. But, there could be damage from 15 + years ago. The good news is the chrome usually flakes at the tops of the cylinders first, so a lot of it may have been blown out the exhaust port. Being a '75, your 850-T may have an oil filter, which will help catch flakes that do get into the oil.
Title: Re: 75 850t Cylinder
Post by: Don G on November 11, 2023, 08:54:48 PM
Damage likely already done, buy a Haynes, Clymer if you have to  a Chilton's manual as well as down loading a free factory manual and a copy of Guzziology(not free) these will show you the way to repair your cycle. Also consider changing out the rod bearings if required, timing chain and spring loaded tensioner and an overhaul on the cylinder heads if required according to condition and mileage, if it is high mileage expect to remove the engine and do an in-depth re-furb as well as the whole drive train as its old and used and nearly 50! Sometimes its not as simple as just getting it going cheap, my motto is: just cuz it works, don't mean its right, riding something that needs maintenance to make it safe and correct can hurt you and your wallet.                                       
  If doing basic maintenance, check your top end oiling circuit, it may be plugged with debris, especially the rocker arms and banjos. DonG



DonG
Title: Re: 75 850t Cylinder
Post by: 850brian on November 11, 2023, 09:48:45 PM
Thank you for the reply! Surprisingly it only has a whopping 17000 miles on it so fingers crossed for a straight forward road to recovery! I am a fireman so I won't be able to drop the pan until Monday since im at work, but I will post an update with my findings.
Title: Re: 75 850t Cylinder
Post by: fotoguzzi on November 11, 2023, 10:00:25 PM
There is a lot of real good info here,
https://www.thisoldtractor.com/moto_guzzi.html
Your T is a Tonti frame so look in that section.

I have a 1975 Loop frame,(motor nearly the same as yours) here’s what the bore might look like.. slight flaking near the top rim..I found nothing unusual in the oil/sump so assume the flaking was blown out the exhaust.. I’ve not gotten any deeper into it yet.

(https://photos.smugmug.com/Eldorado/i-fQWZ3Rg/0/442085c2/L/2023111121570202--320758685637202090-L.jpg) (https://fotoguzzi.smugmug.com/Eldorado/i-fQWZ3Rg/A)

Title: Re: 75 850t Cylinder
Post by: Scout63 on November 11, 2023, 10:19:51 PM
This will sound silly, but it’s almost easier to pull the heads than the sump.  I’m kidding but not a lot.  I would lay out a clean towel on a bench and pull the heads.  Then inspect the cylinders carefully.  If no flaking of the chrome, then no worries about the bottom end. You can have your cylinders replated with Nickel Silicone or source replacement cylinders. Guzzi top ends are wonderfully simple and right there for the access.  Best of luck.  This forum talked me through my first Guzzi rebuild.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 11, 2023, 11:57:04 PM
Thank you for the Info and picture, I will probably just pull the heads to start after sticking a magnet in there and hope I get lucky with it sticking. Anyone have the grocery list of parts that I will need for when I bite the bullet and replace the cylinders?
Title: Re: 75 850t Cylinder
Post by: chuck peterson on November 12, 2023, 05:22:51 AM
MGCycle is only one source..currently out of stock

https://www.mgcycle.com/index.php?main_page=product_info&products_id=2129


(https://i.ibb.co/ZYpTf2y/IMG-0779.jpg) (https://ibb.co/ZYpTf2y)


Harpers Moto Guzzi

https://harpermoto.com/products/c-cyl-850-t-t3-13060162


Stein Dense (spelling?)

https://www.stein-dinse.com/en/

Title: Re: 75 850t Cylinder
Post by: 850brian on November 12, 2023, 08:06:16 AM
Great thank you! Has anyone heard about the knock offs from the Crusty Cycle?
https://www.crustycycle.com/products/moto-guzzi-cylinder-complete-83mm-850t-t3-eldorado-850gt
Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 12, 2023, 08:34:18 AM
Great thank you! Has anyone heard about the knock offs from the Crusty Cycle?
https://www.crustycycle.com/products/moto-guzzi-cylinder-complete-83mm-850t-t3-eldorado-850gt

I wouldn't call them "knock offs" any more than I would use that to describe Gilardonis. The Crusty Cycle kits are from Stein-Dinse and the same kits old by MG Cycle I suspect. I've installed them in two customer's bikes and they work just fine, quality is on par with the Gilardonis.
Title: Re: 75 850t Cylinder
Post by: guzzisteve on November 12, 2023, 08:42:43 AM
If you do some research you'll find you can send your stock cyl's to Millennium in WI for replating  in Nic, using your stock pistons. Low mileage on your pistons, they may be fine. Better than having to balance all involved.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 12, 2023, 08:59:23 AM
If you do some research you'll find you can send your stock cyl's to Millennium in WI for replating  in Nic, using your stock pistons. Low mileage on your pistons, they may be fine. Better than having to balance all involved.
I will look more into it, it seemed around the same price as getting a new kit but I could be wrong. Why would you recommend that over getting the new kit or is it just for keeping it original?
Title: Re: 75 850t Cylinder
Post by: guzzisteve on November 12, 2023, 09:18:51 AM
To keep motor balanced like original. Any kit should be checked for balance, weight of pistons, pins & rings. Manual will give you specs on differences allowable so as not to vibrate.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 12, 2023, 09:40:10 AM
To keep motor balanced like original. Any kit should be checked for balance, weight of pistons, pins & rings. Manual will give you specs on differences allowable so as not to vibrate.
Great thank you! I will check the wear on the internals and post an update with which direction I plan on going with them!
Title: Re: 75 850t Cylinder
Post by: John A on November 12, 2023, 10:02:15 AM
I consider it important to clean the sludge trap in the crankshaft. Unfortunately the crank has to come out for that because it is a plug facing forward that is staked and loctited in place. When it is removed it opens into the crank pin where you will find heavy black crud laying in there. Scrape it out and reinstall the plug if you haven’t butchered it when it’s removed. I smooth the threads that I can get to so it doesn’t rip the the aluminum plug threads as you wind it out. With the engine at that stage of disassembly clean and seal the cam plug on the back of the engine because the flywheel will be off. I’d replace the rear main seal and consider new clutch plates.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 12, 2023, 10:14:32 AM
I consider it important to clean the sludge trap in the crankshaft. Unfortunately the crank has to come out for that because it is a plug facing forward that is staked and loctited in place. When it is removed it opens into the crank pin where you will find heavy black crud laying in there. Scrape it out and reinstall the plug if you haven’t butchered it when it’s removed. I smooth the threads that I can get to so it doesn’t rip the the aluminum plug threads as you wind it out. With the engine at that stage of disassembly clean and seal the cam plug on the back of the engine because the flywheel will be off. I’d replace the rear main seal and consider new clutch plates.
I will add this to the list, thank you.
Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 12, 2023, 10:23:24 AM
I will look more into it, it seemed around the same price as getting a new kit but I could be wrong. Why would you recommend that over getting the new kit or is it just for keeping it original?

Millennium charges $309.95 per cylinder for replating, add rings ($132.24) and you'd spend $752.14 (and still have old pistons which may be worn) vs. $650 a pair for for kits with new pistons.

The new piston assemblies weigh within 5 grams of the original pistons, so the engine will be just as smooth as before in my experience. 
Title: Re: 75 850t Cylinder
Post by: 850brian on November 12, 2023, 11:01:38 AM
Millennium charges $309.95 per cylinder for replating, add rings ($132.24) and you'd spend $752.14 (and still have old pistons which may be worn) vs. $650 a pair for for kits with new pistons.

The new piston assemblies weigh within 5 grams of the original pistons, so the engine will be just as smooth as before in my experience.
Awesome, it looks like I would need the 2 gaskets and 2 o rings for the cylinders and then some for the exhaust (I already have extras for the carb intakes) any other tidbits I would need to get the cylinders back to normal?
Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 12, 2023, 11:36:21 AM
Awesome, it looks like I would need the 2 gaskets and 2 o rings for the cylinders and then some for the exhaust (I already have extras for the carb intakes) any other tidbits I would need to get the cylinders back to normal?

MG Cycle sells a complete kit: https://www.mgcycle.com/index.php?main_page=product_info&cPath=284&products_id=4788

Use two intake manifold gaskets per side.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 12, 2023, 12:11:46 PM
MG Cycle sells a complete kit: https://www.mgcycle.com/index.php?main_page=product_info&cPath=284&products_id=4788

Use two intake manifold gaskets per side.
Mgcycle looks sold out I think I found the same kit on thr crusty cycle. Thanks for the tip on the intake gaskets!
Title: Re: 75 850t Cylinder
Post by: guzzisteve on November 12, 2023, 02:28:25 PM
You got your answers, unlike the other forum, not a peep. AND you need 12 orings-4 on top 2 underneath on ea side.
I had 2 sets done w/cast iron LA sleeves matched to original pistons. It all works.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 12, 2023, 02:55:36 PM
You got your answers, unlike the other forum, not a peep. AND you need 12 orings-4 on top 2 underneath on ea side.
I had 2 sets done w/cast iron LA sleeves matched to original pistons. It all works.
Already very thankful and happy to be a part of this forum! Thank you
Title: Re: 75 850t Cylinder
Post by: John A on November 12, 2023, 03:06:44 PM
You may want to do the sludge trap at a later time, it’s a good bit of added work.
Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 12, 2023, 04:13:09 PM
Mgcycle looks sold out I think I found the same kit on thr crusty cycle. Thanks for the tip on the intake gaskets!

The top end gasket kit is in stock at MG Cycle.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 12, 2023, 05:03:28 PM
The top end gasket kit is in stock at MG Cycle.
Is that all the gaskets I would be replacing during the cylinder job?
Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 12, 2023, 06:32:05 PM
Is that all the gaskets I would be replacing during the cylinder job?

Yes, plus the intake manifold gaskets.


(https://i.ibb.co/B6v3SLV/1402kitb.jpg) (https://ibb.co/B6v3SLV)
Title: Re: 75 850t Cylinder
Post by: jrt on November 12, 2023, 10:04:58 PM
I'll add two more points-  one is obvious, I hope.  Label your Left/Right, Intake/Exhaust parts.  Don't mix and match.  And- when you do take out the sludge trap, use an impact driver.  It is less likely to strip out.  I suggest just buying a new plug- they are very cheap. 
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 03:34:53 AM
I'll add two more points-  one is obvious, I hope.  Label your Left/Right, Intake/Exhaust parts.  Don't mix and match.  And- when you do take out the sludge trap, use an impact driver.  It is less likely to strip out.  I suggest just buying a new plug- they are very cheap.
Great thank you!
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 08:52:11 AM

(https://i.ibb.co/4dKCHRZ/20231113-085237.jpg) (https://ibb.co/4dKCHRZ)
Update: just got off work and am in the process of removing the cylinders. I was able to get one of the spindles out but the other one isnt budging. Any tips?
Title: Re: 75 850t Cylinder
Post by: John A on November 13, 2023, 09:33:50 AM
If it’s not on top dead center on the compression stroke there may be spring pressure on it. Will the pushrod spin with your fingers? It’s an exhaust valve so it could be on the exhaust stroke with the pushrod pressing on it, even with the adjuster backed off. Otherwise it could have the spring on the rocker shaft caught on a wear mark on the shaft in which case I would take a screwdriver and rotate the shaft back and forth a little while pushing on the shaft .
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 10:14:31 AM
If it’s not on top dead center on the compression stroke there may be spring pressure on it. Will the pushrod spin with your fingers? It’s an exhaust valve so it could be on the exhaust stroke with the pushrod pressing on it, even with the adjuster backed off. Otherwise it could have the spring on the rocker shaft caught on a wear mark on the shaft in which case I would take a screwdriver and rotate the shaft back and forth a little while pushing on the shaft .
It will not spin in my fingers, easiest way to verify TDC?
Title: Re: 75 850t Cylinder
Post by: guzzisteve on November 13, 2023, 10:53:52 AM
Easy way would be rotate back wheel forward till you see intake valve go down & come up then you are on compression stroke, when piston gets to top is TDC.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 11:11:08 AM
Easy way would be rotate back wheel forward till you see intake valve go down & come up then you are on compression stroke, when it get to top is TDC.
Maybe I'm just really dumb but nothing seems to be moving when I spin the wheel.
Title: Re: 75 850t Cylinder
Post by: John A on November 13, 2023, 11:11:56 AM
Rotate the engine and watch the pushrod actuate the valve. Depending on the state of disassembly you have to be careful the pushrod doesn’t come out of its socket  and get bent. I would just rotate the engine until the pushrod goes down relieving the pressure. Always put it at tdc compression stroke before disassembling to make it easier but it’s not necessary now. Generally I pull the plugs and valve covers,rotate the engine clockwise viewed from the front and watch as the valves operate. After the intake starts to close put your finger over the spark plug hole and you will feel air pressure. That’s the compression stroke. The exhaust will be closed at that time. If you put a straw down the hole you can feel the piston come up and when it stops you are near tdc. There is dwell at the top and the crank can be turned slightly back and forth without the piston moving. In the middle of that movement is tdc which should correspond with timing marks on the flywheel through the hole in the bellhousing.  Be careful of jamming and bending a pushrod as you rotate the engine in a partially disassembled engine.
Title: Re: 75 850t Cylinder
Post by: John A on November 13, 2023, 11:15:03 AM
Maybe I'm just really dumb but nothing seems to be moving when I spin the wheel.



A higher gear will make it easier to turn the engine but it will turn faster
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 11:16:47 AM
Easy way would be rotate back wheel forward till you see intake valve go down & come up then you are on compression stroke, when piston gets to top is TDC.
False alarm. I got it and I'm really dumb
Title: Re: 75 850t Cylinder
Post by: guzzisteve on November 13, 2023, 11:47:59 AM
Un-Experienced , not dumb
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 02:22:56 PM
Update: right cylinder
(https://i.ibb.co/6NH9sK5/20231113-142048.jpg) (https://ibb.co/6NH9sK5)

(https://i.ibb.co/CzGPHVc/20231113-142100.jpg) (https://ibb.co/CzGPHVc)
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 02:35:16 PM

(https://i.ibb.co/k3YJWx7/16999076303567494188196276329928.jpg) (https://ibb.co/k3YJWx7)

Looks like I only have o rings on 3 of the 5. Should I remove these as well?
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 02:49:41 PM

(https://i.ibb.co/Jt1nZ5S/16999085351619087728835349989819.jpg) (https://ibb.co/Jt1nZ5S)

Additionally is there any tricks on getting these buggers out?
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 03:17:10 PM

(https://i.ibb.co/cYGGpFs/20231113-151423.jpg) (https://ibb.co/cYGGpFs)

Realizing #14 and #16 were not on the short stud and the short stud on the right cylinder came off with the sleeve nut. Should I purchase 2 new washers?
Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 13, 2023, 03:58:50 PM

(https://i.ibb.co/Jt1nZ5S/16999085351619087728835349989819.jpg) (https://ibb.co/Jt1nZ5S)

Additionally is there any tricks on getting these buggers out?

No tang to grab hold of on the piston pin clips? Not factory - installed by a previous owner. If you can find the end, you may be able to wedge a pick under it and remove the clip.


(https://i.ibb.co/cYGGpFs/20231113-151423.jpg) (https://ibb.co/cYGGpFs)

Realizing #14 and #16 were not on the short stud and the short stud on the right cylinder came off with the sleeve nut. Should I purchase 2 new washers?

14 is an o-ring and is likely still stuck in it's groove on the underside of the plug. 16 is a washer, most often stuck on the cylinder head. Fish a magnet down the hole - if it grabs hold of something, the washer is stuck in there.

 
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 04:31:28 PM
No tang to grab hold of on the piston pin clips? Not factory - installed by a previous owner. If you can find the end, you may be able to wedge a pick under it and remove the clip.

14 is an o-ring and is likely still stuck in it's groove on the underside of the plug. 16 is a washer, most often stuck on the cylinder head. Fish a magnet down the hole - if it grabs hold of something, the washer is stuck in there.
I got the circlips out. I believe the part is called the gudgeon pin
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 04:33:53 PM
I got the circlips out. I believe the part is called the gudgeon pin
Also you were correct on the washer and o ring thank you.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 05:22:53 PM
It looks like I have to press them out but I'm not exactly sure how to do that while they are still connected to the rest of the engine
Title: Re: 75 850t Cylinder
Post by: John A on November 13, 2023, 05:34:52 PM
I use a rubber coated pliers handle to cradle the piston against two studs so I don’t put any side load on the piston. It’s curve holds the piston in place so it’s not flopping around like a fish.Then heat piston so it’s hot to the touch. I use an oak dowel to push and tap on the pin. It should come right out without much drama.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 05:43:13 PM
I use a rubber coated pliers handle to cradle the piston against two studs so I don’t put any side load on the piston. It’s curve holds the piston in place so it’s not flopping around like a fish.Then heat piston so it’s hot to the touch. I use an oak dowel to push and tap on the pin. It should come right out without much drama.
Thanks for the reply John I will attempt  this in the morning. I am assuming you have to use a blowtorch to heat the piston? Also if I bought an aftermarket kit that comes with new pins is there any harm in using a socket to tap out the original pin?
Title: Re: 75 850t Cylinder
Post by: Tom H on November 13, 2023, 05:47:29 PM
What John A said. All you need is a heat gun, maybe even a hairdrier will work.

Charlie: The upper cylinder stud, the one covered by the sealing plug. Have you seen a washer on that stud? I normally see the lower and the 4 inners with washers but never that one, just the allen head nut.  Enquiringly minds need to know :smiley:

Brian, the 2 O rings at the base go on top of the base gasket. Put gasket on, then the top and bottom stud get an O ring. Then the cylinder goes on, then the head. Put O rings on the center 4 studs, then the rocker blocks. Oh..and don't forget the piston :wink:

Tom
Title: Re: 75 850t Cylinder
Post by: Tom H on November 13, 2023, 05:49:09 PM
A socket is what I use. IIRR a 14mm, maybe 15mm, pick one that fits inside the pin hole in the piston.

Tom
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 06:10:04 PM
A socket is what I use. IIRR a 14mm, maybe 15mm, pick one that fits inside the pin hole in the piston.

Tom
Great! Thank you tom!
Title: Re: 75 850t Cylinder
Post by: Pescatore on November 13, 2023, 07:02:00 PM


Quote from: 850brian on Today at 06:22:53 PM (https://wildguzzi.com/forum/index.php?topic=119919.msg1870677#msg1870677)
It looks like I have to press them out but I'm not exactly sure how to do that while they are still connected to the rest of the engine


I use a C clamp, without forcing, to avoid the side banging.
But as people already said,  heat is required. It might even slide out by pushing with your finger.

Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 13, 2023, 07:18:01 PM
Charlie: The upper cylinder stud, the one covered by the sealing plug. Have you seen a washer on that stud? I normally see the lower and the 4 inners with washers but never that one, just the allen head nut.  Enquiringly minds need to know :smiley:

Yes, I find a washer on that stud more often than not. But as in my previous post, they usually stuck to the head very well and only come during cleaning and media blasting. The only way I know if they're in the hole is a magnet sticks (or not). 
Title: Re: 75 850t Cylinder
Post by: BigDen on November 13, 2023, 07:19:12 PM
See the various DIY tools for pulling piston pins (wrist pins, gudgeon pins) in this article from Greg Benders This Old Tractor Site.

https://www.thisoldtractor.com/moto_guzzi_loopframe_wrist_pin_puller_tool.html
Title: Re: 75 850t Cylinder
Post by: 850brian on November 13, 2023, 08:10:44 PM
See the various DIY tools for pulling piston pins (wrist pins, gudgeon pins) in this article from Greg Benders This Old Tractor Site.

https://www.thisoldtractor.com/moto_guzzi_loopframe_wrist_pin_puller_tool.html
Thank you for the article, I will give this a try after work tomorrow. Fingers crossed!
Title: Re: 75 850t Cylinder
Post by: Tom H on November 13, 2023, 08:40:16 PM
I have never had a washer in that hole as far as I could tell. Always thought there should be one. Never had one fall out like the lower hole washer does. I shall check for it more closely in the future!! So that I can be sure to install it!!

Thank you!!!!!!
Tom
Title: Re: 75 850t Cylinder
Post by: n3303j on November 13, 2023, 09:07:46 PM
Never had to fight a piston pin out of a Guzzi. Maybe a touch with a heat gun but no more than that. Then carefully slide the pin out with finger pressure.

It is most important that there are no burrs caused during circlip removal. A burr will hang the pin. The pin is a gage fit. The whole path for extraction must be undamaged.
Title: Re: 75 850t Cylinder
Post by: John A on November 13, 2023, 10:16:18 PM
I have never had a washer in that hole as far as I could tell. Always thought there should be one. Never had one fall out like the lower hole washer does. I shall check for it more closely in the future!! So that I can be sure to install it!!

Thank you!!!!!!
Tom




Like Charlie, I make sure one is there and often a magnet is the way .
Title: Re: 75 850t Cylinder
Post by: Scout63 on November 14, 2023, 07:07:02 AM
I have found a washer under the hidden nut. The parts fiche shows it as a spring washer, part no. 16 here. I have to fish it out with a skinny magnet.


(https://i.ibb.co/gzYGRnr/IMG-0108.png) (https://ibb.co/gzYGRnr)


I really like this thread. Nice work so far 850brian. You are hitting all of the same issues and asking the same questions that we (or at least I) did our first time pulling apart the top end.
Title: Re: 75 850t Cylinder
Post by: Moparnut72 on November 14, 2023, 09:17:07 AM
Get the piston good and hot with a heat gun. I use a socket that will just fit in the hole on an extension so you don't burn yourself and push the pin out. I do my old Mercury outboard piston pins this way.
kk
Title: Re: 75 850t Cylinder
Post by: 850brian on November 14, 2023, 09:32:53 AM
Get the piston good and hot with a heat gun. I use a socket that will just fit in the hole on an extension so you don't burn yourself and push the pin out. I do my old Mercury outboard piston pins this way.
kk
I appreciate the info. I will try it with a hairdryer and if I don't get any luck with that I will grab a heat gun! New cylinder kit and gaskets should get here in a few days. I will post an update then!
Title: Re: 75 850t Cylinder
Post by: Moparnut72 on November 14, 2023, 10:16:50 AM
Get a heat gun they come in handy for a lot of things. I use mine for all kinds of things. They are pretty cheap, Harbor Freight has a decent one for very few dollars. I am not a fan of sending more money to China but sometimes.......... ....  In the airplane shop we went through them like water, we got a Makita which was still working when I left.
kk
Title: Re: 75 850t Cylinder
Post by: 850brian on November 14, 2023, 01:11:19 PM
Get a heat gun they come in handy for a lot of things. I use mine for all kinds of things. They are pretty cheap, Harbor Freight has a decent one for very few dollars. I am not a fan of sending more money to China but sometimes.......... ....  In the airplane shop we went through them like water, we got a Makita which was still working when I left.
kk
There have been plenty of times I wished I had one and didn't so I guess it would be a good time to check them out.
Title: Re: 75 850t Cylinder
Post by: n3303j on November 14, 2023, 03:29:37 PM

(https://i.ibb.co/kQMXknV/LS-Master-Appliance-Listings-HG-501-TKV-51979.jpg) (https://ibb.co/kQMXknV)

https://www.masterappliance.com/products/heat-guns/master-heat-guns/?utm_source=google&utm_medium=cpc&gad_source=1&gclid=CjwKCAiA0syqBhBxEiwAeNx9NzoZaBHqQT2acSR8LVuhNgdHtTTAY44O5yTWfkoGjPr56SLgmnffuBoCY78QAvD_BwE
Don't have to send the money to China.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 14, 2023, 04:07:18 PM

(https://i.ibb.co/kQMXknV/LS-Master-Appliance-Listings-HG-501-TKV-51979.jpg) (https://ibb.co/kQMXknV)

https://www.masterappliance.com/products/heat-guns/master-heat-guns/?utm_source=google&utm_medium=cpc&gad_source=1&gclid=CjwKCAiA0syqBhBxEiwAeNx9NzoZaBHqQT2acSR8LVuhNgdHtTTAY44O5yTWfkoGjPr56SLgmnffuBoCY78QAvD_BwE
Don't have to send the money to China.
That's what i like to hear!
Title: Re: 75 850t Cylinder
Post by: Don G on November 14, 2023, 06:33:01 PM
While your there and have the base gaskets off, pull out the lifters one at a time and inspect their faces for pitting or dishing, replace back in their original positions if found OK. Wouldn't hurt to apply some assembly lube to prevent damage from dry start up.  DonG
Title: Re: 75 850t Cylinder
Post by: John A on November 14, 2023, 06:58:17 PM
Here’s a tip on heat, I got it out of an old Dodge manual. It was for judging automatic transmission oil temp. If you can touch it and leave your fingers in contact, it is 180F or less. If you have to take your hand off it right away, it is more than 180F. It’s gone by the wayside with the advent of cheap infrared temp guns but it’s fairly accurate with exceptions for welders. I’d heat the piston to around 180 and try it.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 15, 2023, 07:51:15 AM
Here’s a tip on heat, I got it out of an old Dodge manual. It was for judging automatic transmission oil temp. If you can touch it and leave your fingers in contact, it is 180F or less. If you have to take your hand off it right away, it is more than 180F. It’s gone by the wayside with the advent of cheap infrared temp guns but it’s fairly accurate with exceptions for welders. I’d heat the piston to around 180 and try it.
Awesome thank you.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 15, 2023, 05:19:40 PM
New cylinders have arrived anything important to note on the install or is it pretty much just the reverse of the uninstall?
Title: Re: 75 850t Cylinder
Post by: jrt on November 16, 2023, 10:22:25 PM
Great thread- I love hearing all these tips.  I've been through a couple motors, but I always learn something new.

Brian- when you push the gudgeon pins out, back the pistons up against something (wood, a rubberhandled pliers) so they don't side-load the main bearings. 

And what did the cylinders look like?  I saw the pictures, but it is hard to tell.  They looked fine to me.  Are they magnetic?
Title: Re: 75 850t Cylinder
Post by: 850brian on November 17, 2023, 06:17:37 AM
Great thread- I love hearing all these tips.  I've been through a couple motors, but I always learn something new.

Brian- when you push the gudgeon pins out, back the pistons up against something (wood, a rubberhandled pliers) so they don't side-load the main bearings. 

And what did the cylinders look like?  I saw the pictures, but it is hard to tell.  They looked fine to me.  Are they magnetic?
They looked fine to me; however, they were not magnetic at all.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 19, 2023, 12:16:13 PM

(https://i.ibb.co/dGJmGzp/17004177219186690473673177425750.jpg) (https://ibb.co/dGJmGzp)

Got one side put back together. How much should I tighten these nuts?
Title: Re: 75 850t Cylinder
Post by: jrt on November 19, 2023, 04:00:37 PM
The locknut?  I've never torqued them.  They just need to be 'tight enough' to keep the adjuster from moving.  Maybe...1/4 turn after they seat? Probably less than that.  I use a small 11mm box end in my palm  so I can't put too much stress on it. 
Title: Re: 75 850t Cylinder
Post by: guzzisteve on November 19, 2023, 05:21:34 PM
I see the rocker pin bolt on the bridge, it is 10mm head and very light torque 4ft lbs, it will strip. Just holds the pin still in place.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 20, 2023, 03:36:51 PM
Update: got both cylinders replaced without a hitch until I broke off the head of the valve cover oil banjo bolt.... and now we wait. So close, yet so far.
Title: Re: 75 850t Cylinder
Post by: Tom H on November 20, 2023, 05:15:31 PM
Years ago I did that. I used a drill press and made my own bolt. Could be done with a hand drill, you just have to go very straight.

Tom
Title: Re: 75 850t Cylinder
Post by: 850brian on November 20, 2023, 05:49:59 PM
Years ago I did that. I used a drill press and made my own bolt. Could be done with a hand drill, you just have to go very straight.

Tom
Interesting! I guess I should have tried my hand at that first.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 24, 2023, 09:39:20 AM
Got it all back together and am about to start it up. Any recommendations on breaking in the new cylinders?
Title: Re: 75 850t Cylinder
Post by: jrt on November 24, 2023, 09:55:20 AM
Ha!  Now you've opened Pandora's box.  Breaking in a motor is like an oil thread....
My (not a mechanic) opinion is keep the revs below 5k or so, vary motor speed and put the engine under load several times to bed in the rings.  I don't remember how many heat cycles (one or two or three), then loosen and retorque the heads.
Title: Re: 75 850t Cylinder
Post by: Don G on November 24, 2023, 08:31:13 PM
Ride it like its stolen, on and off the throttle in an intermediate gear.  Watch a cycle Garden video of Moe showcasing a rebuilt bike, he rides it like its supposed to be ridden, 3 or 4 thrashes like that, if it don't break, its good to go.  DonG
Title: Re: 75 850t Cylinder
Post by: Antietam Classic Cycle on November 24, 2023, 08:45:21 PM
Ride it like its stolen, on and off the throttle in an intermediate gear.  Watch a cycle Garden video of Moe showcasing a rebuilt bike, he rides it like its supposed to be ridden, 3 or 4 thrashes like that, if it don't break, its good to go.  DonG

But, Moe isn't breaking in Nikasil cylinders...

My own preference (right or wrong, but works every time) is to ride it fairly normally on my 18 mile "secret test loop" through the Frederick County, Maryland countryside. Varying throttle and load. There is one long, steep grade and I ride up that a gear higher than normal with lots of throttle to "load" the rings and help them break in more quickly.

Regarding head nut retorquing: I assemble the engine except for the rockers, let it sit overnight. Next day, retorque the head nuts, install the rockers and set the valves. You'd be surprised how much the gaskets have already compressed. Start it and run approx. 20 mins. with a fan blowing on it, while I twiddle the carbs and adjust the timing if needed. Let it cool completely back to ambient temp. Retorque the nuts and set the valves. 5 complete heat/cool cycles - do it again. 500 miles - do it again.
Title: Re: 75 850t Cylinder
Post by: Gliderjohn on November 24, 2023, 08:49:12 PM
The original Wichita area Guzzi dealer did my T-3 with those jugs, etc. Anyway he recommended about 500 miles of varying the rpm and every so often take it to high rpm, just don't keep it there, just up and down. So city riding, hilly and curvy roads that entice you to not keep a steady throttle. Around 35,000+ miles since overhaul. Runs great and maybe uses a tablespoon of oil between changes.
Title: Re: 75 850t Cylinder
Post by: 850brian on November 29, 2023, 08:01:09 PM
Well went to ho start her up and it's only running on the right cylinder. I have spark on both plugs. Confusing.