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Old 08-30-2014, 05:06 PM   #1
silverhead OP
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Luke blue '75 R90/6 project log

I'm just going to start a running thread showing what I'm going to do to the R90/6 I got last weekend. Today I pulled both cylinders and we've got work to do on both sides. Stay tuned for back story, description of my own personal capabilities, and hopefully photos and videos as I proceed.

For now, a place holder photo for what the bike looked like when it arrived.

(Yes, I have posted photos of the bike in other threads already)
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Old 08-30-2014, 05:23 PM   #2
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Old 08-30-2014, 05:28 PM   #3
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:)

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Old 08-30-2014, 06:47 PM   #4
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ok



:))

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Old 08-30-2014, 07:28 PM   #5
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Initial impressions

The first thing that had to go was the Pacifico fairing. I'm sure these things are awesome to a specific segment of the population, but much like my no-minivan policy, I'm stubbornly adhering to my no-jammer policy.

That left me with this:



The OEM headlight bucket is intact and has a rubber cover over top of it. I'm searching for all the missing headlight parts if any of you are holding. (reflector, gasket, lens, clips, and trim ring.)

Then I figured I would replace the Conti K112 on the back because it looked older than me. I went with a Dunlop K70 since they just look like they have more traction than the Conti. The previous owner installed a new Conti RB2 on the front (rain groove finder!) So it'll be there a while unless it totally sucks and I get another K70 for up there.



(you can see some of my other bikes sitting in the garage.. currently a couple of 70s Vespas, a 93 Yamaha TW200, and my 00 Kawasaki W650)

I'm only posting this photo for the sake of sticking to a timeline. I doubt anyone will get excited looking at a K70 in 4.00x18.





The Dunlop is now made in Malaysia and kinda sucks. It took four oz of lead to balance it out even with the yellow dot at the valve stem.


Here's a walk-around video of the bike to show my initial assessment of it. It runs (badly) and there's something up with the right cylinder for sure. Compression in the left cylinder is crap, compression in the right cylinder is zero.

https://www.youtube.com/watch?v=4dPH_haDuxs
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Old 08-30-2014, 07:37 PM   #6
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You'll probably find the k70s have a love of rain grooves too, but otherwise a great tire. I'm running them front and read and quite like them.
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Old 08-30-2014, 08:11 PM   #7
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I'm pretty used to it riding scooters and my W650. Both like to get very 'vague' any time I end up on that crap.
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Old 08-30-2014, 08:49 PM   #8
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Today I uncovered a world of crap

The morning started out nicely enough. I drained and changed out all of the oils. 20w50 in the engine, SAE 90 in the transmission, driveshaft housing, and final drive.



I presume I can use copper washers? Nowhere in town (three auto parts stores, the farm store, and Lowes) had crush washers.




The mail man showed up with my exhaust nut wrench, so you know what happened next... I went buck wild and took the top end off of the bike, which took me most of the day to mark, tag, and bag every part. I also cleaned every part by hand since I don't own a parts washer.

Here's a video showing me using the wrench. There wasn't any anti-seize on the exhaust side of the head. So I guess I got lucky that the nuts came off relatively easily? Maybe 120 ft lbs to remove them.

https://www.youtube.com/watch?v=4Z1CMGP3B74


And once this all goes back together




Cover me.. I'm going in. I'd already been in here to check valve lash, but this time we're going for broke.




I labeled everything with a paint pen including individual nuts. I hate putting stuff back in new places.




Oh, you filthy whore.. Upon removing the right head this was waiting for me on the under side. The intake valve was not seated.





Why is that, you might ask? Well, at some point in the past the piston and intake valve got into a fight.




I'm not sure what the OEM valve guides look like. It seems like my exhaust guides are worn because the tip comes to a sharp point (both right and left cylinders.)




The cylinder and piston skirts look pretty good given 58k miles. There's no lip formed at the top of the cylinder. The right cylinder had these weird marks which I'm guessing is where water sat during storage. I hope it can be honed clean because I really don't want to buy new pistons and rings at the moment given the fact both heads need to be rebuilt.




Here's the right piston. Looks fine other than the fact the intake valve hit it.




This is what it looks like after you get yourself filthy in order to clean your engine in preparation for new goodies. Pushrod hanging in mid air thanks to zip ties.




OK, that's all the photos I took of the right side. On to the left side, which I photographed even less even though it ended up being just as bad as the right.

Whadda we got under the head? Oh, just a broken exhaust valve and the chunk fused into the edge of the piston. There's a small mark in the head from the valve chunk, but the cylinder wall has no scoring from it. I'm not sure if I need a new piston or not. I'll post a close up photo in the next post.




This is what the piston/cylinders look like after years of use and no cleaning.




Side two hanging loose. I stuffed a bunch of paper towels into the voids of the cylinder hole as well as the tappet holes on both sides. I'm not -that- dumb.




This valve spring compressor is a pile of crap, but it did work *barely* to let me get the keepers out with a magnet wand.




Self explanatory photo of the left side exhaust valve upon removal




I skipped taking photos of a bunch of useful information you'd need if you were hoping this was a tutorial. I labeled every nut and part with a paint pen and kept things isolated in different baggies. I cleaned every part with carb cleaner and a brush. Now my top end is hanging out in the basement on my work bench.

Tagged and bagged.



Left crap



Right crap

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Old 08-30-2014, 09:23 PM   #9
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So is my left piston a lost cause or is it useable? I dug the chunk of exhaust valve out of it and there's not a huge hole, but I'm not in the business of assessing damage like this.







The total area of damage isn't that large, but does this create hot spots on the piston that I need to be concerned about? I have no doubt that it'd still seal up and compress stuff.

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Old 08-30-2014, 10:29 PM   #10
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I wouldn't sweat the dings in the left piston or the left head. They'll carbon up in a few miles and be unnoticable. Since the left cylinder wasn't scratched or scored by the chunk o'valve, that eliminates one major concern. Of course the margin on that exhaust valve is paper-thin, and I doubt that the chip will buff out.

What does the other exhaust valve look like? The valve seats in that one picture look OK, considering.

Unless something really bad turns up at the machine shop, you'll come out OK-- valve job, one new intake and (probably) two exhaust valves, maybe exhaust valve guides, new valve springs, hone the cylinders and a new set of rings.

Remove the lifters (tappets) and see how the contact face looks-- there should be no galling. Especially look at the right intake tappet (the one where the valve kiss'd the piston. Roll that pushrod in a flat surface, see if it's bent.

One concern (being a worrywart) could be the bottom end. Drop the pan, see what is collected in there. Remove the oil filter, cut it apart and unroll it-- "read the filter". This is a good time to check the rod bearings. You'll need a 10mm tri-square wrench (a NAPA/KD tool) for the rod bolts, and new rod bolts (not reusable).

How many miles on the clock? High mileage (like over 50K) may compel you to think timing chain replacement in the near future.

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Old 08-31-2014, 06:23 AM   #11
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Quote:
I presume I can use copper washers? Nowhere in town (three auto parts stores, the farm store, and Lowes) had crush washers.
Even though we call them "crush washers", they haven't been true crush washers for decades. They changed over to copper washers, then, when the cost of copper skyrocketed, over to aluminum washers. The idea is to have something soft and conformable. Though you are not supposed to reuse them, copper can be annealed by heating, which may be a plus to them. AFAIK, the only true crush washers left are the big ones on the bottom of the /5, /6 fork legs.

Quote:
This valve spring compressor is a pile of crap, but it did work *barely* to let me get the keepers out with a magnet wand.
I had one of those at one time. Can be really hazardous if it doesn't have a good and square grip on the spring.

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Old 08-31-2014, 08:51 AM   #12
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All good advice! Thanks. I looked at the right intake tappet and it looks ok. All four of them released the push rod with a kind of oil-based pop, releasing their hold on them. All four of the pushrods are straight. I rolled them on glass and they all look good with no runout.

The bike has 58k miles on it, but the bottom end seemed fine. At the moment I'm going to hold off looking at the rod bearings because I don't want to source new bolts. I do own the 12 point sockets needed to remove those bolts though. End play on the rods was seemingly good. No back and forth movement on either rod and I wasn't hearing any signs of knocking when running the bike.

I measured all of the valves with calipers. The width variance along the stems aren't horrible. The only real valve that looks to me like it could be retained is maybe the left intake valve.












The left exhaust valve is obviously ruined, pitted, broken, etc...





The right intake valve is bent. Looks fine, like the other one otherwise.

The right exhaust valve is pitted along the seat face, so I think it'd have to be replaced as well, right?




Finally, the valve guides may be OK on the intake sides. But I'm guessing I'll have to replace at least three of them (both exhaust and the right intake.) They all measured out to about 7.91mm at the top side, but the exhaust sides both look like they were wearing thin. The left exhaust valve guide was starting to lose material at the tip.




I'm looking forward to any advice because I'm not a machinist and I'm always learning as I go. Should any basic machine shop be able to do this for me, or do I need a specialized place to do head work for the airhead? I have two local machine shops as well as a place called Midwest Cylinderhead. But I think MC mostly handles car/truck/tractor stuff.

Would be be wise to have hardened valve seats installed now or anything like that? The valve seats all look like they could be reworked to get a good seal.
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Old 08-31-2014, 09:18 AM   #13
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Originally Posted by silverhead View Post
Should any basic machine shop be able to do this for me, or do I need a specialized place to do head work for the airhead?
best to use a shop that refurbishes these heads regularly. They'll replace your valve guides right the first time.
New valves and valve springs... your valves have reached the end of their service life and the springs aren't expensive, best to replace them now.

If there wasn't nearly so much wear then you could do some of this yourself, such as lapping-in the valve seats... but those valves are ready to be re-purposed as paperweights or something.

Beyond the obvious damage, aged and abused valves occasionally come apart in service, making a lot of noise.

I'm liking your pics. Great representation and they're not blocked by my employer.
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Old 08-31-2014, 09:22 AM   #14
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Do you guys have a recommendation on a shop to send these out to? As in CURRENTLY. I've found old threads, but it seems like the good old dudes come and go for this sort of thing. Is there currently a short list of 'THE GUYS' to send these to? And fast service is a plus. I'm anxious to ride this.



I forgot to mention that last night my neighbor GAVE me this.




He's a good guy!


And I used this book to read about removing/installing valve guides and have decided that YES, I need to send them to someone who knows what they are doing. I don't really trust my local guys to do this right. They might be able to though. I will probably check in early in the week to see if they are familiar with the process. Any time the instructions are to bake oily motorcycle parts in the oven I already know my wife's answer.

silverhead screwed with this post 08-31-2014 at 09:29 AM
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Old 08-31-2014, 09:37 AM   #15
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Randy Long does excellent head work, very popular... as is Ted Porter's Beemershop.

You might give these folks a call as well: http://www.abcbmw.com/service-list.htm

I was looking for shops in or near Iowa and they're the closest I could find... not that location matters so much, what with shipping... but I don't know what resources you have so just providing more options.

I found Forever Endeavor Motorcycles listed in the vendors section here: http://vintagebmw.org/v7/resource_links
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