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Old 12-12-2009, 05:32 PM   #1
One Less Harley OP
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New rings,valves,guides and rod bearings for R80G/S

A little history on the 1984 R80 G/S- It shows 100,420 miles, but this isn't correct as the speedo was broken when I got the bike. I believe the mileage is close. Oil use is high, but it only smokes when starting, and that isn't every time, but at times there is a cloud of blue smoke belching out the exhaust. Quite embarrassing for a BMW, even for an old bike. Also compression is 124 and 120 psi, which is the very low end. So it's winter time and off season for ridding, what a better way to spend the cold day in the garage.
I didn't bother pulling the cylinders off and checking things out 1st, to see what parts I need, but new Swiss intervalves, high temp elco guides, piston rings, std rod bearings, rod bolts (any time these are removed, they must be replaces w/ new ones), wrist pins (found out after ordering that one shouldn't replace only the wrist pins as according to the Clymer Manual the pistons and pins are A MATCHED SET), also new cir clips for wrist pins, valve springs and keepers and small end bushings for the rods. All those parts came to $440 USD.


Today I spent a little less than two hours pulling the heads. So I removed the front cover so I could turn the engine over to get the bike to TDC. Removed the exhaust pipes from the collector forward. Then pulled off the carbs.






Then I removed the 4 nuts on the valve train and two other nuts in the center of the head one each top and bottom. The head and cylinder came off easily. I made sure to support the piston as it came free of the cylinder.





Opps no picture of the piston and rod still connected to the crank.

I used a longer torx bit to loosen up the rod. I slackened off the two bolts and then tapped the head of each torx bolt with a hammer to free the rod cap from the rod.



The cylinders walls looked very good, no ring grove visible, actually I cold see cross hatching on the cylinder walls. A few very light scratches up the sides of the cylinder walls. The pistons had very light scratches and carbon deposits on the top. I removed the rings and used a piston to insert one ring into the cylinder to check the end gap........I didn't need a feeler gauge to se the gaps was to large, probably 1mm. Rings fit very well in the groves of each piston.
The heads each had carbon deposits, not excessive. valves didn't look like they were receding,but I'll have to check w/ the machinist on this. Same for guide wear.
Main bearings looked very good, but some normal wear was present.

So now I'll have to take the heads, cylinders, rods and pistons to the machine shop. There I'll have the pistons and rods balanced. New valves and guides installed and the cylinders lightly honed.
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One Less Harley screwed with this post 12-29-2011 at 09:02 PM
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Old 12-12-2009, 05:47 PM   #2
crazydrummerdude
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So, just a torx bit, then?

Hmm..
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Old 12-12-2009, 06:01 PM   #3
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That and the exhaust nut wrench.
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Old 12-12-2009, 06:26 PM   #4
bgoodsoil
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any maintenance history on the engine? Has any work been done on it before?
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Old 12-12-2009, 06:45 PM   #5
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I can see no sign that the engine has ever been cracked open (I did the pushrod seals last year) same w/ the tranny (until recently..bearings kuput), final drive never opened until I replace the ring gear bearing (chasing a potential cause of the wobbles)

The previous owner who didn 't have it very long said the guy he got it from was a stickler for changing the oil every 3,000 miles. I think he used synthetic. I won't go that route w/ synthetics, but i will do the oil changes quite often. When I bought the bike I droped the oil pan just to check for signs of slunge, also just to see if there was anybuild up. All I can say is this motor is CLEAN inside, seems very well taken care of. Yeah I've dropped some bucks on it (fork seals, clutch,starter rebuild (did myself),enduralast,bigger front brake, the reason being is that I want to make sure there aren't any issues on this bike, especially given it's intended use of back road...or should I say trail use.


I don't want to have to keep an eye one the oil usage that close when on the TAT next year (I hope, didn't happen this year).
The bike's plugs looked perfect in spite of low compression
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Old 12-12-2009, 07:12 PM   #6
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I'd love to tag along for Tennessee section. Got any idea when you're going?

I try to keep my oil changes as cheap as possible. Castrol GTX and $9 filters from Parts Unlimited. I got a gallon jug of Valvoline Max-Life this time though. It's a semi-synthetic that's pretty cheap and comes in 20W-50. We'll see how many leaks it causes.
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Old 12-13-2009, 08:55 AM   #7
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I'll probably do the TAT in May, after things start to dry out a bit. Not doing the complete thing,but about 10 days.

When removing the cylinder I was concerned about getting the cylinders mixed up, but after looking at the two I noticed that part of the cylinder which goes into the block is cut away. This goes to the back of the motor.

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Old 12-14-2009, 07:39 AM   #8
loveall13
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Where did you get your parts and who is going to do your machine work? I am fixing to do the topend gaskets and rings on my r75/7.
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Old 12-14-2009, 07:11 PM   #9
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Ahhh, you are close to me. One more airhead in the area. We are few and far between here.



I got the parts from MOTOBins in the UK, definitely worth ordering from. I actually get the parts quicker from them than the stateside dealers. I'm having Scott at Promachine do the work. Hone cylinders, install guides, grind seats, seat valves, ballance rods and pistons, and clean the parts. He said it would be about $200 in labor. He's done engine work for me before, TR6 Car, Triumph T100C, and an Elsinore MT250 two stroke. If you have to bore the cylinders I'm sure it'd cost you more. He charged me $75 to bore the MT250 60 over.

Scott was the machanist at Scotty's, untill he bought out the shop for the machine shop.
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One More DRZ does the TAT (Ride Report)


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Old 12-23-2009, 05:36 PM   #10
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I just got the cylinder heads, cylinders, and the pistons back. The rods were weighed and balanced. The pistons and rod weights were about equal, only one rod cap needed to have some metal removed and that wasn't very much.







So, how much was the cost for machine work? It was $200 for bead blasting the cylinders, pistons, cylinder heads. Plus balancing the pistons and rods, then new valves, springs and guides were installed.




So now all that needed to be done was to install the goodies!!!!

Bellow is the left rod w/ new rod bolts on the left with the torx bit and the old rods to the right of the rod. The STP oil treatment is what I used for assembly lube on the bearings and wrist pins.



I made note as to the placement of the rods as to left and right, but also which way the rod fit on the bearing shell. As the rod can be installed with the marks on the bearing shell caps either up or down. The side of the caps had markings which looked like "G3". No problems in getting the pistons mixed up as there is an arrow on the top which points forward.




I shouldn't need to mention this, but line up the tang on the bearing shell to tang on the rod and cap.




Apply assembly lube to bearing shells (in my case STP oil treatment), then put the cap on the crank journal. I had some help to keep the cap on the journal. As I offered up the rod the cap, help used a wood stir stick to keep the rod cap in place while I screwed the rod bolts in place. The bolts were snugged up and the checked the rod to make sure is moved freely. Then the bolts were snugged up evenly then torqued.




Then the ring gaps were checked to make sure they were in spec.




Rings where then installed on piston (gaps at 120 degrees to each other), make sure to have the words "top" facing up....duh. Rings and piston were oiled and inserted partially into cylinder,leaving the wrist pin accessible. This way is easier than trying to install piston into cylinder while the piston is on the rod. Notice the light coating of silicone on the cylinder flange, also a very thin coat on the small o-rings which go on the top cylinder studs.

I've installed these w/o sealer and had the cylinders seap oil. Also the pushrod tube seals (raised lines down) coated lightly w/ hylomyer.




The cylinder and piston are then offered up to the rod. The rod is guided in place until the wrist pin is pushed through the small end of the rod. Push wrist pin all the way through then install circlip the correct way w/ the beveled edges towards the piston. Make sure circlip is fully seated.



Install head gasket make sure that the push rod tube holes are not obstucted buy the gasket. If so it is on upside down.



Install the head and two nuts which hold the head on, don't torque them down completely yet. Until the push-rod seals are partially seated in the block you won't be able to get the nuts to the valve train on. So less valve train,snug up bolts in an alternating pattern to partially seat the push rod seals. Remove the nuts then go ahead and install pushrods, making sure they are seated in tappets. Offer up the valve train make sure the push rods are seated in the valve adjusters of the valve train. Then snugg up the valve train nuts eaqually increasing the torque to the specified torque.

This is the end of my pictures.... Once head is torqued down, go ahead and adjust valves, oh surely I don't need to explain that, or connecting the carbs, and exhaust.

Once buttoned up, turn engine over w/ starter until oil light goes off. Then set choke and start motor. Since it was cold I spun the engine till the oil light came on. I knew it wouldn't start till the choke was used. Listen for any unusual noises, of course if you hear any then you've screwed up something. Also look for leaks. Take bike out and proceed to break in by your own method.
I didn't attempt to tune the carbs for the 1st 20 mile, but will need to readjust the carbs.
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2004 BMW R1150RS
1984 BMW R80G/S
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2003 Suzuki DRZ 400S (TAT Prep)
One More DRZ does the TAT (Ride Report)


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Old 12-23-2009, 05:48 PM   #11
BrianK
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Maybe I didn't read carefully enough but I thought your ring gaps were too large to begin with? How did you deal with that?

Nice writeup, BTW.
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Old 12-23-2009, 06:10 PM   #12
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Notice in my 1st post...new rings!!!! The old ones were shot, I didn't measure them but they looked like the end gap was about 1mm.
The new ones were within spec.

With 100,000 miles there was no way I'd be using them.

The machinist honed out the cylinders which I don't believe was mentioned.

Guides were worn, especially the exhaust, the valves had noticeable wear at the seat, plus seats were refaced.


BTW- this was a hell of a lot easier than doing the job on the T100C I had restored. A LOT EASIER. Brit bikes sure a pretty bikes until you work on them, after working on both I've come to realize the BMW airhead is absolutely gorgeous!!!!! Things just go together so much easier on the BMW, plus youcan ride them anywhere and not worry about all the leaks and other issues.
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Old 12-24-2009, 08:20 AM   #13
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I've always heard that pushrod tube seals aren't to be siliconed or gasket sealed. Just oil them so they'll wiggle around and are free to move. I've used silicone grease on the pushrod tube where the seal resides and on the face that mates to the block.

It's not obvious just looking at the engine - but while it's running the head and cylinder dances around on the block, especially under hard acceleration. It's important to let that big chunk of rubber expand and contract to fill the void.

I hope the machinist knew the proper procedure for honing nikasil - I believe a light touching up with a ball hone is the most they should get. I'm not sure what would happen if any other method was used, but it's a no no.
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Old 12-24-2009, 08:31 AM   #14
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Thanks wire spokes, No I didn't use silicone on the pushrod tubes, just a bit of hylomyer which never drys it just stays sticky, and yes he did use a ball hone and oil. Good of you to comment on that.

I've tried before installing the base gasket and two small o-rings dry but they leaked, hence the very light coat of silicone. I was very careful on the upper o-rings not to get any in the oil holes. When inserting those I gave them a slight twist to coat the o-ring.



Here's a shot of the one of the beat up exhaust valves, you can see the ridge around the edge, 100,000 miles of pounding.



and one of the intakes.......




Then the bearing shells,

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2004 BMW R1150RS
1984 BMW R80G/S
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2003 Suzuki DRZ 400S (TAT Prep)
One More DRZ does the TAT (Ride Report)


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Old 12-24-2009, 11:37 AM   #15
Wirespokes
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Good! But those bearing shells look like they could have gone another 100K. That's a good sign.
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