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Old 07-11-2012, 09:43 PM   #16
noman
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freebie from 1976 r75/6

discovered a failed needle bearing on my left cyl/intake earlier this season. got a perfect used complete set-up (rocker/bearings/shaft but no mounting blocks) from bud p at a damn good price. so i have a spare rocker that needs needle bearings removed, and a shaft too. both in nice shape.

max bmw parts fiche says same part nmber for your/my bike. if interested, pm your address and i'll send pics and/or ship the assy out. gratis, of course.
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Old 07-11-2012, 11:33 PM   #17
Pica Hudsonia OP
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Quote:
Originally Posted by noman View Post
discovered a failed needle bearing on my left cyl/intake earlier this season. got a perfect used complete set-up (rocker/bearings/shaft but no mounting blocks) from bud p at a damn good price. so i have a spare rocker that needs needle bearings removed, and a shaft too. both in nice shape.

max bmw parts fiche says same part nmber for your/my bike. if interested, pm your address and i'll send pics and/or ship the assy out. gratis, of course.
That's very generous of you, sir. A PM is on its way, but I will insist on at least paying for the shipping.
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Old 07-12-2012, 03:56 AM   #18
patanga
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Quote:
Originally Posted by Pica Hudsonia View Post
When I opened the right cover, I found a little pile of scrap metal inside. Back when I was working on helicopters (German ones, no less!), if we found a gearbox with debris like this in it, we said it was "making metal."

Any ideas on what might have caused this failure, or advice on how I should proceed?
Hi Pica Hudsonia. If you've done hands on chopper work then you can fix an airhead. As already mentioned, the head won't need to come off. Looking at your photos though, there's a little more than just the bearings damaged. Replace all of the unserviceable bits and during assembly check all of the rocker end float shim clearances against specs to minimise lateral movement. I've only ever seen these bearings fail through too much lateral movement, or the rocker pivot shaft oil galleries being installed 180 deg out and restricting oil flow. Be sure to drop the sump and clean/check for metal as well as check/flush any scrap that might be on its way down the down the push rod tubes as well.

Here is a link to a thread I posted about a week ago re this very topic. Good luck.
http://www.advrider.com/forums/showthread.php?t=805601

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patanga screwed with this post 07-12-2012 at 04:17 AM
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Old 07-12-2012, 04:13 AM   #19
100RT
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Pull the push rods and run a pencil magnet down the tubes carefully.
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Old 07-22-2012, 10:56 PM   #20
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A Follow Up...

Well, I think I have my bearings sorted out, mostly. I ordered new parts from Max BMW, and John Martin there was very helpful. (I started out with A&S BMW, and I still have some other parts coming from them, but they didn't have my rocker parts in stock.) At first, it appeared that Max had everything I needed, but Mark called me back to say the computer was wrong about their inventory on the rocker arm assembly. Apparently, not one of those is available is the U.S., and it would have to be ordered from Germany, taking about 10 days to get here...

I decided to go with Plan B, which is to press new bearings into my rocker. The bearings were in stock. (Plan A was to get a complete assembly, ready to install in the bike, for quite a bit more money but much less work.) While waiting for my parts, I assembled a bearing remover/installer tool, as described by Disston, out of threaded rod, sockets, washers, and nuts. As shown in pics above, there was some damage to the bore of the rocker that caused me some worry--I thought it would harm the new bearing as it's pushed into place. As it turned out, the old bearing cage smoothed out the burrs on its way past, and I then felt comfortable reusing the rocker. Of course, I used a piece of fine sandpaper to smooth things out a bit further.

A generous inmate sent me a spare rocker with one bad bearing and one intact, in case I could use any of it--a very kind act. Unfortunately, it was a rocker for the wrong side. I needed a Number 2, and it was a Number 1. Still, I used it to practice with my newly fabricated tool, and I discovered something interesting. Disston said he believes that if one bearing comes apart, the others will probably soon follow. I was a bit dubious of that notion, but now I'm more of a believer. Once removed, the supposedly good bearing cage in this rocker showed some tiny cracks. They were not obvious, but noticeable through careful inspection. I think there was an impending failure here:



Anyway, I eventually got my new bearings, and they were not difficult to install. Put everything back together with a new shaft, and switched places with the upper and lower shaft supports, so there's a smooth, undamaged surface for the rocker to ride against:



Here's a view of the damaged support in its new position. Sorry about the coloration here; the red of my fuel tank and side cover is reflecting off the oily metal parts:



I carefully shimmed the rocker to make it fit as closely as possible without having any interference between the supports. It's not perfect, because I don't have a very good selection of shims. More are on the way, and as soon as I can, I will look at re-shimming all four rockers. I'm also going to replace all of the remaining needle bearings.

After everything was back together and the valves carefully adjusted, the engine makes more ticking/tapping sounds than I'd like. Hopefully, a more exacting shim job will cure this. The important thing is that it runs, and pretty smoothly at that.

I rode it to work and back yesterday, happy to be on two wheels again. Tonight I went for a casual ride around town, maybe 10 or 15 miles, and new problems have arisen. It seems the gremlins knew that I corrected the bad bearing, so they've thrown another issue at me.

When I pulled to a stop to watch the sunset, the engine began running quite rough and almost died a few times. I shut it off and took a peek to see what's going on. Gas is dripping out of the left carb almost in a steady stream. It's coming from the overflow, so I suspect there's a bad float needle or seat. I got it home and shut the petcock before all that expensive fuel could return to the ground from whence it came, but it was dark and starting to rain, so I haven't looked into the carb yet. Wish I had a garage. I work on the bike under a shade tree in my backyard. Hopefully, I will find a piece of grit or something, and when I remove it the needle will seal again. I'll order new parts to make a permanent repair, but while waiting for them, I hope to get by through a simple cleaning/fiddling with it. A few days ago I pulled the carb bowls to drain them so I could crank the engine to pre-lube everything after an oil change. I of course looked closely in the bowls, and there were in fact a few spots of grime settled there--not a lot, but enough to make me suspect something could be trapped under that needle. There are no in-line fuel filters, so that's something I'll be adding. I recall that the previous owner told me to be sure to shut off the petcocks when I park the bike, otherwise a carb might leak. He was right about that--tonight it was leaking even with the engine running, so the needle lets gas through even faster than it can be atomized and burned.

I keep telling the missus it's a good thing I like tinkering with machines so much. If I had one of those ultra-reliable Hondas, I don't know what I'd do with all my free time... probably just ride. I'm starting to think that when you buy an airhead beemer, you don't just get a vehicle to take you from here to there, you get a new hobby.
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Old 07-23-2012, 04:02 AM   #21
Bill Harris
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Looking good. Slight axial play in the rockers is OK for a while, just get the really obvious end-play out (that's subjective, no?).

Carb being drippy thru the overflow just happens sometimes. Probably a bit of trash under the needle valve. Quick cure is to shut off the petcock, remove the float bowl and turn the petcock on to flush the trash from the needle valve.

Best filter setup is using the in-tank filter socks at the petcock and sintered-bronze in-line filters in the fuel lines. Primary and secondary filtration.

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Old 07-23-2012, 05:57 AM   #22
darklight79
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I have ordered from A&S often ... west coast equiv of Maxx without the M&Mss shipping is less but have to pay cal sales tax .. prices the same both competent outfits stu
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Old 07-23-2012, 06:47 AM   #23
disston
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The inline filters shown by Bill are very popular. I'll have to put mine on some day. I think I've had them for 10 years.

Several issues with the fuel system. The original red tank liner flakes off. Por 15 the favorite fix when you get around to it. Other wise rinse the gas tank once a year.

The fuel hose deteriorates. Seems to be Gasohol related. I replace the fuel line hose once a year. Some may do it every other year. I still do it once a year. There are some better hose materials available but I'm still using the braided type that doesn't last forever because it is the right size.

The Styrofoam floats get heavy. They are not Gasohol resistant. I change mine currently about ever two years. Some do more or less changing.

Bing makes a system that is Gasohol resistant. They claim it works. Some riders have had good results but some other riders have had problems with it. It is expensive. I think currently over $200 for two carbs.

The hard tip needles do wear out. The needle seat also wears and the seat is only available from Bing. Seems a lot of Bing carbs lately have been needing the needle seats replaced. Mine too.

One of the problems with the Gasohol resistant float system is that it eliminates the over flow tube. So if a petcock leaks or is left on and one of the floats is hung up or the needle doesn't seat then a very bad situation can happen with a cylinder hydro locked.

The petcocks can leak. They can seep gasoline. The petcocks themselves need to be checked sometimes.

There's more a lot more but I'll stop for now. This is really only an introduction to the fuel system.

You probaly just have a piece of debris under the needle tip. Clean needle seat a all's well again.
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Old 07-23-2012, 06:55 AM   #24
Wirespokes
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It's not always the float needle

Sometimes the fuel line to the carb will deteriorate at the inlet spigot, and fool you into thinking it's the carb over-flowing.

Otherwise, it's probably just some debris between the seat and float needle.
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Old 07-23-2012, 08:47 AM   #25
Pica Hudsonia OP
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Quote:
Originally Posted by Bill Harris View Post

Carb being drippy thru the overflow just happens sometimes. Probably a bit of trash under the needle valve. Quick cure is to shut off the petcock, remove the float bowl and turn the petcock on to flush the trash from the needle valve.
Thanks, that's a good tip! Since my time is limited this week, I'll let it try to flush itself clean with the float bowl off. Makes sense, because that needle never moves very far when the bowl is on. You have potentially saved me lots of time, and I'm looking forward to trying this when I get off work this afternoon.
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Old 07-26-2012, 09:23 PM   #26
Pica Hudsonia OP
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Float needle un-gunked

I had some family obligations, so I couldn't mess with the bike for a few days. Tonight I got the chance to work on it, and I'm happy to report that the overflowing carb now seems to be sorted out. All I had to do was remove the bowl and let a little fuel flow through, flushing out whatever was stopping that needle from seating. That was the easy part...

I thought I'd better add some in-line filters to keep crud from spoiling my fun in the future, and then I thought while I'm at it I'll just replace the fuel lines too. No telling how long the old ones have been on, with ethanol laced fuel deteriorating them from the inside. In fact, it's possible that's what caused the needle to stick open in the first place, if you get my meaning.

So replacing fuel lines is an easy little project, right? They're right out in the open, and about as technical as the simpler parts of a 1937 Farmall tractor. With new fuel hose and filters in hand, I started what was expected to be a 20 minute project.

When I got to the crossover line, something in my head told me I should somehow link the new hose to the old one and pull it through. I didn't listen, and pulled the old one out. I spent the next hour tearing into the airbox to get at those two forward bolts that hold it to the transmission, so I could slide it back a wee bit and make room to feed the new crossover hose into its position. Whose idea was all that nonsense zig-zagging around in the airbox? I now really want to remove my pulse air system, because that stuff can't possibly give enough benefit to justify its existence, considering how much it's in the way when I'm working on other stuff.

Anyway, it's all back together now, and it runs good. Tomorrow my daughter and I will load up our camping gear and head for the hills! Please help me keep this on the down-low, because I'm afraid if the gremlins find out the bike is running right, they'll mess up something else.
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We have a date with Destiny, and it looks like she's ordered the lobster. - The Shoveler from "Mystery Men"
A noble spirit embiggens the smallest man. - Jebediah Springfield
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Old 07-26-2012, 11:17 PM   #27
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I do not recommend those inline filters like in the photo above. I have seen them let way more junk by than was in the filter so many times it isn't funny. They just simply do not work.
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Old 07-27-2012, 07:36 AM   #28
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Originally Posted by supershaft View Post
I do not recommend those inline filters like in the photo above. I have seen them let way more junk by than was in the filter so many times it isn't funny. They just simply do not work.
The sintered metal ones don't really do much besides filter out sticks and gravel. If you're going to use fuel filters get the pleated paper ones. They work really well.

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Old 07-27-2012, 08:26 AM   #29
Pica Hudsonia OP
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Thanks, guys, for the tips on fuel filters. I went to NAPA looking for their part number 70-2323, because that's what Snowbum recommends on his site. It was not in stock, but they had a very similar one. Eight bucks apiece seemed a bit high, but I'll consider it money well spent if they keep the carbs working right. I plan on replacing the hoses every two years and flushing the tank every year.

For what it's worth, Snowbum says the type of filter shown in Bill Harris's picture above is also acceptable. I think the main thing is to have a filter, and the style used is not critical.

I used to put these on my air cooled VWs, and someone gave me an important tip on that. Everyone had a tendency to locate the filter downstream from the fuel pump, so the gas would be filtered right before it went into the carb. The trouble was, if the filter got clogged, the backpressure could theoretically pop the fuel hose right off, causing gas to spray all over the place, most notably on the nearby distributor--yikes! After I heard about that, I always put the filter between the tank and the pump, where it worked under suction, not pressure.
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Then, who would live at home idly (or think himself any worth to live) only to eat, drink, and sleep, and so to die? - John Smith
We have a date with Destiny, and it looks like she's ordered the lobster. - The Shoveler from "Mystery Men"
A noble spirit embiggens the smallest man. - Jebediah Springfield

Pica Hudsonia screwed with this post 07-27-2012 at 08:44 AM
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Old 07-27-2012, 09:27 AM   #30
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Piffle. The sintered bronze filters work as intended:

Quote:
Best filter setup is using the in-tank filter socks at the petcock and sintered-bronze in-line filters in the fuel lines. Primary and secondary filtration.
"RTFM"

:)
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