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Discussion in 'Airheads' started by civhatch90, Jan 15, 2012.
Wow that site is an airhead encyclopedia! Although I must admit it can be overwhelming at times.
So I had some time today to start looking at the bike. Did not have much time but I did notice a few things:
1. I ran it around the block and the clutch seems to slip at higher RPMs. I will try to figure out how to adjust it and see if that improves the grip. One thing I noticed is that the cluch will start to grab only when I have almost completely let go of the lever. First 3/4's of lever travel do not do anything.
2. The gas tank appears to be leaking. I looked at the inside and there does not seem to be any significant surface rust which could lead to pinholes. I did notice there was some duct tape on the underside which I'm not sure what the purpose of it is. Next time I will bring some sand paper to clear the area where the tape sat and see if I can spot any holes or any other place from where the gas could be leaking. There seems to be some rubbing with other components but I would think it nearly impossible that the rubbing could have worn through the tank.
These are not cracks, it is where the paint was worn out and now the metal is exposed.
3. Crack on the subframe, I do not think this is a big deal, I just have to get someone to lay a bead on it. Will require a bit of paint but not much else. Crack is where red line is on pic below.
So now my initial priorities have changed. Next things at the top of my list are now: fixing the gas leak and checking out the clutch.
Some other random pics from the day let me know if you see anything that may look weird or different/broken:
deal of the day fer sure man!
i love my airhead. my old BritBike buds all say the airhead beemers are too agricultural. i dispute this notion.
there is definitely a certain something about them. i think they seem....
they have their own feel, and a solid following. boatloads of available knowledge and parts. you got a nice bike there.
no reason in this world why you couldn't ride that anywhere you want.
Sounds like the clutch cable at the throw-out arm and clutch lever are simply out of adjustment. I don't have the specs handy for a /6, but I'm sure someone here can advise. Sounds as if the cable is too tight, as the last few MM of lever travel should be slack when properly adjusted. If the cable is too tight, it won't allow the clutch to fully engage, thus the slippage at high RPM.
Judging by the picts and descriptions you have provided, the PO seems to have neglected some of the dutiful TLC that you can now provide, and I would bet you can properly adjust the cable via the lever and throw-out to get rid of this behaviour.
Yeah unfortunately the history of the bike is rather unclear. The guy I bought it from had supposedly traded it for a guitar of some sort and he never rode it, had it parked for 2 years until he decided to get rid of it.
These are great news! I really hope I don't have to replace the clutch disc and all it needs is some adjustment. I will play around with this thing for a bit and see if I can get it to release earlier and grip better.
I was kinda disappointed this afternoon after finding out about the clutch + tank but I guess those are the risks we all take when buying older bikes. Just not something I had considered earlier.
Thanks! There surely seems to be something special about them and let me tell you those cylinder heads stick out way too far! It will take some time getting used to them. I sure hope I can ride this thing a lot and enjoy it.
Thanks a ton I appreciate all your help.
You guys have made this ownership experience very rewarding thus far! Its a good feeling to know that there are supportive people out there who are willing to spend the time explaining & helping others.
I'd be careful with poking and sanding on that tank. You will only make the leak worse. Good used gas tanks are getting dearer all the time. Could you try to clean and dry the tank so you would be able to see where it's leaking? There's a good chance the leak is from around the petcocks. There is a gasket between the petcock and the tank. The old red fiber gasket is probably what you have. The petcock can be carefully tightened a little to sometimes stop a leak there. But only lightly. I forget the sizes but I do have wrenches on board that fit the large double threaded nut and the petcock itself. If you use pliers you might scratch the soft metal. The petcocks have square portions that an open end wrench will fit. The really tricky part is that the petcock is left hand threaded and the tank is right hand threaded. You have to hold the petcock while turning the attachment nut. Since the tank is right hand threaded turn so the nut is tightening the normal direction on the tank. I hope that is clear. And don't over tighten.
The gas lines leak after not enough mileage. But we are stuck with them. Some use SAE sized lines but they cause other problems. The correct gas lines are 7mm and available at your dealer or from an old VW shop. You need three feet.
There is a new gasket for between the petcocks and tank. It has a new larger screen that fits in the tank as the primary, 1st, debris filter. Next time you are at the dealer, and you probably need new gas line, also get the new design petcock filters/washers. Also get some inline gas filters. They are not a BMW part but most dealers have them behind the counter. They trap a finer sort of debris that the in tank screens will miss.
The petcocks can also be rebuilt but they are a royal pain to get back together. Most get new petcocks instead of messing with rebuilding them. If they do leak, that is, this only comes up about once every 25 years.
I probably left something out. Tell us how far you get.
Oh yes. The clutch cable needs adjusting.
Well after a few weeks I finally had a chance to work on the bike and make a little bit of progress.
First and update on the gas tank. I'm happy to say it is in good shape and the tank nor the petcocks were the source of the leak. More on that below.
I have started looking for oil leaks and noticed the following:
1. There appears to be a slow leak from the front of the engine
2. There appears to be a slow leak from the rocker arms/gasket where the cylinder head meets the block
3. There appears to be a slow leak from the back somewhere and maybe the oil pan.
All of the leaks above I'm not too worried about for now since I know the bike will run fine and its not leaking quarts and quarts of oil. just a bit which up to a point I'm sure is normal on a 75k almost 40 year old motorcycle.
Now on to my new discoveries:
I have been noticing that when I engage the starter motor it seems to spin but not engage the flywheel. I considered that a serious problem and decided to pull the starter off. Well it seems as if the starter is grinding down the flywheel slowly but surely. I have done some reading on this and it appears that I need to lubricate the bendix and that may solve the problem. Can somebody confirm this? Also, I assume this would be a good time to change the brushes on the starter motor are these the ones I would need?
I would be following this write up to freshen up the starter:
What the starter looks like:
Next big item on the list is a leaky master cylinder which is where the leak (that I initially thought was the gas tank) is coming from. I believe there are several options here:
1. Rebuild kit
2. New master cylinder
3. Do the handlebar master cylinder mod
Which one would be most cost effective? I want to keep this as low budget as possible.
Last question, can I change the fork seals without having to worry about the fork alignment?
Put the clutch splines on the backlist to get to after many other more important duties. Start with the pure safety issues. Tires, Wheels/bearings, steering head bearings, forks, swing arm bearings, rear wheel bearings. Problems here can put you into the ditch or curb.
Then brakes, flush and bleed the fluid, adjust, test.
Don't be ripping sweepers with it until you get to that safety level.
Then verify tuning and balance.
Don't just start replacing anything. Just do the maintenance inspection, verify what you got and make the adjustments.
Then have on next winter's list the tranny pull and clutch spline inspection. Do the 6k inspection first, then the 12k items to follow up. Keep notes as you go or you won't have a history to use or pass on.
Thanks, the splines will definitely have to wait- solving the master cylinder issue became a priority as well as the fork seals, starter motor, and clutch adjustment.
The easiest way I've found to adjust the clutch is to get a piece of coat hanger, cut to exactly 201mm. This is the space between the transmission housing front casting area where the cable fits through (rear surface of the transmission housing there), to the forward edge of the lever rear hook area. You can adjust the cable at both ends. When you are done you should have just a little free play at the lever. Hope that helps...
The splines go completely dry a lot quicker than that and the clutch will work perfectly if ridden regularly until you need a new clutch or seal. No matter how much lube you put on them as evidenced in a recent thread. At least half of the airheads that I know of get that treatment with no more ill effects than the other half that gets regularly lubed splines. Maybe it would hurt less feelings if the "don't lube them unless they need it crowd" put it in words like dt did in this thread which is put it on the backburner till all the more important stuff gets addressed first. I can wholeheartedly agree with that advise since I always have more important maintenance to take care with bikes that get ridden regularly. If civh90's clutch is like a lot of them that I have caught slipping with no free play in the lever, he is going to have to go in there to replace clutch parts soon enough anyway. It doesn't do them any good. Good luck civh90!
Back at it...
Since my last post, I have rebuilt the starter and started tearing down the front end.
I realized both fork tubes were bent and one was even cracked! The cracked one is stuck to the lower triple/steering stem (if that's what its called). I hope once I can pull the tube out the triple+stem will not be bent- I really would not want to replace these. Do these ever get bent?
How the bike sits:
"Can't wait to ride it. I want to see what you old folks love so much about them..."
I remember being young Now I can look back at all the Airheads I had and why I had them.
Was it because they were COOL? NAH!
Was it because they handled and stopped so well right from the dealers showroom? NAH!
Was it because chicks dig them? NAH!
It was something deeper, rooted to my passion of riding, knowing that someday when I am old, some young guy will post on a website "Can't wait to ride it. I want to see what you old folks love so much about them..."
Welcome to the passion kid
Looking at this picture I see two things.
1. The clutch arm may be too close to parallel to the gearbox. It's usually at a bit of an angle. Hard to tell, but sure worth checking and may solve the clutch adjustment issue.
2. You're about to lose the float bowl. The clip needs to be on further. You should feel a click when it seats correctly. The wire seats at both sides of the bowl.
Have a good read here...http://forum.boxerworks.com/viewtopic.php?f=1&t=5461
Airbear has done the brake conversion to his single disc 90/6 and he is very happy with the result. It may even be cheaper and better than using BMW second hand bits and pieces.
Sad news on the front end but very awesome that you found it that way!
Check out the prices at Forks by Frank: http://www.frankmain.qpg.com/