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Getting slingers cleaned.. ugly piston..
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malmac
- Posts: 796
- Joined: Sun Jun 29, 2014 2:10 am
- Location: Toowoomba, Australia.
- Has thanked: 1 time
so many things to check
How long is a piece of string?
Once the crank is out for a slinger clean/replace there are so many things that can be checked.
Camshaft and cam follower pitting
Oil pumpgears
Bearings and seals?
Clutch plate wear
Pistons etc.
I guess the obvious questions re your piston are.
1. What is the bore like on that left side?
2. What is the piston to barrel clearance?
3. End gap on the rings
Also try and confirm why the piston had a problem. This extract from Duane Ausherman might be relevant.
https://w6rec.com/duane/bmw/piston/index.htm
"I picked out a set that seized in the first 250 miles, after boring, and looked new. I never knew why that had happened. I had the set examined by my machine shop. These guys only did work on exotic and expensive engines for repair shops in San Francisco. I was the only bike repair shop that was a customer. The owner looked at the pistons for only a couple of seconds and began removing the rings. He put a micrometer on it and immediately showed me the problem. The diameter just above the oil ring was only a few thousandths of an inch smaller than the piston skirt. It was supposed to be about .009" smaller. He pointed out that the seizure showed between the two rings, it had started there and spread to below the oil ring and widened out to the whole skirt at the bottom. His evaluation was that the Nural pistons were made incorrectly and couldn't work. Just another example of the advantage of using the expert.
This was rather shocking to me. He suggested that we just turn off about .004"-.005" and use them as before. Since I didn't have a lathe he suggested that we just remove the rings and use a file to take off a bit of metal. There would be no penalty for taking off twice as much as needed. The ring land only keeps the rings apart and the diameter was only important if it was too large and caused a seizure.
We bored many more sets and never had a single piston seize up after the modification. If I owned a R60/2 with good original Nural pistons, I would modify them to be sure."
At least from the look of the piston crown, the bike is not running too lean. That is one question answered.
The last point I would make is what are your expectations for this machine?
Maybe if the cause of the seizure has been resolved then a little tidy up might be acceptable for you.
I guess you just dont want it to suddenly cause a much bigger problem.
All the best.
Mal
Once the crank is out for a slinger clean/replace there are so many things that can be checked.
Camshaft and cam follower pitting
Oil pumpgears
Bearings and seals?
Clutch plate wear
Pistons etc.
I guess the obvious questions re your piston are.
1. What is the bore like on that left side?
2. What is the piston to barrel clearance?
3. End gap on the rings
Also try and confirm why the piston had a problem. This extract from Duane Ausherman might be relevant.
https://w6rec.com/duane/bmw/piston/index.htm
"I picked out a set that seized in the first 250 miles, after boring, and looked new. I never knew why that had happened. I had the set examined by my machine shop. These guys only did work on exotic and expensive engines for repair shops in San Francisco. I was the only bike repair shop that was a customer. The owner looked at the pistons for only a couple of seconds and began removing the rings. He put a micrometer on it and immediately showed me the problem. The diameter just above the oil ring was only a few thousandths of an inch smaller than the piston skirt. It was supposed to be about .009" smaller. He pointed out that the seizure showed between the two rings, it had started there and spread to below the oil ring and widened out to the whole skirt at the bottom. His evaluation was that the Nural pistons were made incorrectly and couldn't work. Just another example of the advantage of using the expert.
This was rather shocking to me. He suggested that we just turn off about .004"-.005" and use them as before. Since I didn't have a lathe he suggested that we just remove the rings and use a file to take off a bit of metal. There would be no penalty for taking off twice as much as needed. The ring land only keeps the rings apart and the diameter was only important if it was too large and caused a seizure.
We bored many more sets and never had a single piston seize up after the modification. If I owned a R60/2 with good original Nural pistons, I would modify them to be sure."
At least from the look of the piston crown, the bike is not running too lean. That is one question answered.
The last point I would make is what are your expectations for this machine?
Maybe if the cause of the seizure has been resolved then a little tidy up might be acceptable for you.
I guess you just dont want it to suddenly cause a much bigger problem.
All the best.
Mal
mal - R69s
Toowoomba- Australia
Toowoomba- Australia
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skyler.robbins
- Posts: 227
- Joined: Sat Sep 22, 2018 4:14 pm
Thanks for that input
Thanks for that input Mal...
I'm getting more updates as tho motor comes apart.
Unfortunately none of it is good news.
"Robert - Considering the mileage none of the following findings are too surprising. The scratches on the piston were something of a surprise. But the motor got very hot on some occasion, or it was put together too tight. I’ll be able to tell once i hone the barrel.
What I’ve found :
The front rod is loose, but just barely. Note I have not yet flushed out the bearing cage so we may have more play after that.
But the rear main bearing journal is undersized and the bearing has been spinning on its seat. As you can see in the photo the bearing fell off the back of the crank when I pulled the crank forward. This is supposed to be an interference fit.
One lifter is chattered and should be replaced. Maybe another as well, but it is stuck in the bore. I’ll get it out tomorrow.
Both slingers are chock full and as you can see some debris has begun migrating down the front rod pin, contaminating the bearing. Same for the rear, but it is not so much.
Bottom line is we do need to swap out the crank, and replace at least one piston and one lifter.Hope this isn’t too hard on your budget. I’ll pull the pan and clean up the case tomorrow. And get all the carriers loaded with new bearings, and send a few more photos." KB
I'm getting more updates as tho motor comes apart.
Unfortunately none of it is good news.
"Robert - Considering the mileage none of the following findings are too surprising. The scratches on the piston were something of a surprise. But the motor got very hot on some occasion, or it was put together too tight. I’ll be able to tell once i hone the barrel.
What I’ve found :
The front rod is loose, but just barely. Note I have not yet flushed out the bearing cage so we may have more play after that.
But the rear main bearing journal is undersized and the bearing has been spinning on its seat. As you can see in the photo the bearing fell off the back of the crank when I pulled the crank forward. This is supposed to be an interference fit.
One lifter is chattered and should be replaced. Maybe another as well, but it is stuck in the bore. I’ll get it out tomorrow.
Both slingers are chock full and as you can see some debris has begun migrating down the front rod pin, contaminating the bearing. Same for the rear, but it is not so much.
Bottom line is we do need to swap out the crank, and replace at least one piston and one lifter.Hope this isn’t too hard on your budget. I’ll pull the pan and clean up the case tomorrow. And get all the carriers loaded with new bearings, and send a few more photos." KB
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skyler.robbins
- Posts: 227
- Joined: Sat Sep 22, 2018 4:14 pm
Getting slingers cleaned.. ugly piston..
Hey Gang...
I'm getting my slingers cleaned on my 1969 R60/2..
The mechanic sent me some photos of what he has found so far.
The left piston looks like shit.. right looks good.
I've had the bike for 2 years and do all the maintenance and keep track of everything. I've put around 3000 miles on it and has ran perfect. My compression is consistently at 120psi on each cylinder, never any weird noises. I had the heads rebuilt by Paul Sturges last year.
So...
What's your thoughts on the left piston looking like this? Previous seize not cleaned up?
I've posted this on the Facebook forum as well..
https://ibb.co/w7g1q4S
I'm getting my slingers cleaned on my 1969 R60/2..
The mechanic sent me some photos of what he has found so far.
The left piston looks like shit.. right looks good.
I've had the bike for 2 years and do all the maintenance and keep track of everything. I've put around 3000 miles on it and has ran perfect. My compression is consistently at 120psi on each cylinder, never any weird noises. I had the heads rebuilt by Paul Sturges last year.
So...
What's your thoughts on the left piston looking like this? Previous seize not cleaned up?
I've posted this on the Facebook forum as well..
https://ibb.co/w7g1q4S
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skyler.robbins
- Posts: 227
- Joined: Sat Sep 22, 2018 4:14 pm
Update...
Another update...
"Made a little progress today in preparing stuff for re-assembly. All the components are cleaned up and bearings loaded. The last lifter came out easily once I could push it from the back, and is in good shape. Both cylinders are standard size, so there is plenty of room for a rebore if necessary. I ran a ball hone thru the left cylinder ( see photos ) and it cleaned up somewhat after only a light honing. I won’t go any further until I have a replacement piston and can match sizes.At this time I’d suggest getting another standard piston and hone the cylinder to size. I’ll measure the bore tomorrow and that’ll tell me if that is feasible - it could be that the left side is just a little small and the fit was too tight. If so then we open it up and fit a new piston. Easier and less expensive than two new pistons and boring both cylinders. There is every indication that this is the first time this engine has had a slinger service. So at 55K miles I’m not surprised at what I’ve found."
"Made a little progress today in preparing stuff for re-assembly. All the components are cleaned up and bearings loaded. The last lifter came out easily once I could push it from the back, and is in good shape. Both cylinders are standard size, so there is plenty of room for a rebore if necessary. I ran a ball hone thru the left cylinder ( see photos ) and it cleaned up somewhat after only a light honing. I won’t go any further until I have a replacement piston and can match sizes.At this time I’d suggest getting another standard piston and hone the cylinder to size. I’ll measure the bore tomorrow and that’ll tell me if that is feasible - it could be that the left side is just a little small and the fit was too tight. If so then we open it up and fit a new piston. Easier and less expensive than two new pistons and boring both cylinders. There is every indication that this is the first time this engine has had a slinger service. So at 55K miles I’m not surprised at what I’ve found."
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malmac
- Posts: 796
- Joined: Sun Jun 29, 2014 2:10 am
- Location: Toowoomba, Australia.
- Has thanked: 1 time
What about the crank
The piston issue is to some extent, not the big issue. Well not at the moment. Given the bike was running OK then the piston was obviously doing the job, even if back down the track it had a hard time.
Not that I am in favour of putting it back. New piston sounds like a much better idea.
However what is happening about the crank. That seems to me to be the major issue.
I don't know how long they will last once the big ends get beyound a certain point. But the consequences of a catestrophic failure of a big end bearing can get really ugly.
My crank has much the same problems as yours, one loose big end and rear main bearing journal worn beyound spec.
I have tried on a previous engine using 680 loctite but it didnt work.
The crank I have on the current bike was obviously loose and they used locktite and it did not work.
So I wouldn't recommend using that approach.
I have splashed the cash and purchased a new reproduction crank from Ulis which will go into my motor.
Mal
Not that I am in favour of putting it back. New piston sounds like a much better idea.
However what is happening about the crank. That seems to me to be the major issue.
I don't know how long they will last once the big ends get beyound a certain point. But the consequences of a catestrophic failure of a big end bearing can get really ugly.
My crank has much the same problems as yours, one loose big end and rear main bearing journal worn beyound spec.
I have tried on a previous engine using 680 loctite but it didnt work.
The crank I have on the current bike was obviously loose and they used locktite and it did not work.
So I wouldn't recommend using that approach.
I have splashed the cash and purchased a new reproduction crank from Ulis which will go into my motor.
Mal
mal - R69s
Toowoomba- Australia
Toowoomba- Australia
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skyler.robbins
- Posts: 227
- Joined: Sat Sep 22, 2018 4:14 pm
Crank...
I believe my crank is being replaced with a rebuilt crank he has on the shelf...
I should know more here soon on any updates.
I suppose the good news out of this will be that I shouldn't have to go that deep into the motor ever again.
Rob
I should know more here soon on any updates.
I suppose the good news out of this will be that I shouldn't have to go that deep into the motor ever again.
Rob
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malmac
- Posts: 796
- Joined: Sun Jun 29, 2014 2:10 am
- Location: Toowoomba, Australia.
- Has thanked: 1 time
Well a properly rebuilt crank will be needed
Rob
That sounds good.
Cheers
mal
That sounds good.
Cheers
mal
mal - R69s
Toowoomba- Australia
Toowoomba- Australia
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skyler.robbins
- Posts: 227
- Joined: Sat Sep 22, 2018 4:14 pm
Update..
Update on the bike from Kevin...
"I was able to hone out the tight cylinder for a good fit and install a NOS nural piston just as was in originally. So you still have matched pistons, and are still at the standard bore. I hate to ‘throw away bore’ if it isn’t necessary."
Also good news is that my clutch looks like it was replaced at some time and is in great shape.
No really super exciting photos to share, but here's some of the assembly..
He's doing the test run soon.
"I was able to hone out the tight cylinder for a good fit and install a NOS nural piston just as was in originally. So you still have matched pistons, and are still at the standard bore. I hate to ‘throw away bore’ if it isn’t necessary."
Also good news is that my clutch looks like it was replaced at some time and is in great shape.
No really super exciting photos to share, but here's some of the assembly..
He's doing the test run soon.
Hey Skyler, notice the bike
Hey Skyler, notice the bike in the background has Oregon, special interest plates. Are you and the mechanic in Oregon? Just asking because I’m in Bend and don’t know anyone for heavy motor work in Central Oregon.
Central Oregon