R75/6 restoration advice

[spokanetom]

I recently bought a 1976 R75/6 that hasn't run for probably 35-40 years. Been in a barn/garage and needs a lot of work. This is my first airhead. I've restomoded an 82 Honda XL250R, but I had the engine work done. I want to do it myself this time around.

I've been reading different threads here and elsewhere that say the first thing to do is get the engine running. Even if you're going to tear the bike down to the frame, you'll know you have a good engine. That seems logical. Do you guys feel that's a good start for me?

The engine turns, so it's not seized and all the parts are there. Just really dirty. This is a to-do list I've come up with on my own:

• Rebuild the carbs
• New battery
• New plugs (it already has new plug wires)
• New exhaust (or just let it be loud to start with)
• Clean up and test the starter (it's really filthy)
• Clean up the air intake area, new air filter
• Drain the oil, change oil filter
• New points and condenser
• Completely clean and re-seal the fuel tank (new petcocks?)
• New fuel lines

Anything missing or advice you can offer?

Here's a picture of the bike at the moment. Just started to examine it to see how things are.

 

[swall]

Don't attempt to remove the exhaust header nuts. Cut them off.

 

[Seaweed]

Right side header nut seems to be off already, but good advice.

 

[20774]

How many miles on the engine? I suppose miracles can happen, but an engine sitting this long likely needs to be torn down. At least take the top end off, maybe pull the conrods and inspect the main bearing shells. You could send the heads out to have new seats/valves installed.

 

[GTRider]

If the bike has actually been sitting for that long with oil in the crankcase, I’d drop the pan and clean out whatever has settled out of the oil, then reinstall with a new gasket. Beyond that, I think the OP has a workable plan to first get the bike running again, then assess what, if any, further repairs need to be done. Part of any barn find assessment is in knowing the story behind why the bike was parked in the first place—accident, mechanical breakdown, loss of interest, etc. OP may have that info but we don’t.

Best,
DeVern

 

[stevenrankin]

Your list is pretty good as it goes so far. It looks like the bike was not exposed too much to wet conditions so, maybe you will get lucky and once you get it spinning over, check the compression. Better yet and of course more time consuming would be to take off the heads and do a thorough inspection of bore, ring gap, and valve condition.
It doesn't look like you will need header pipes, just mufflers. Before you cut off the exhaust nuts, try tapping the big special wrench with a soft hammer a bit. Most times a gentle tap will fee them up. IF at that point, they don't thread off properly, they can always be cut off.
High mileage may need a timing chain.
Unless the engine was starved for oil, there is a good chance you will NOT have to do anything with main bearings or cam bearings.
Of course the main input shaft of the transmission should be inspected along with the clutch system. New tires and inspection of the final drive dog and spline.

LOL, not an organized list, sorry. A lot of what you do will depend on mileage and what you want to do. Good luck, and have fun, St.

 

[melville]

Yes, hear it roar first. You might be $50 or $5000 into the motor with something like this. My usual thing:

1. Drop the pan and clean it. Remove the oil pickup, clean it, and put it back on with Loctite. Fresh oil--I use Brad Penn straight 30 weight break-in oil as I think it gives the rings a chance to get unstuck.
2. Rebuild the carbs.
3. Check valve adjustment. Start with checking the torque on the head fasteners. 25 ft-lbs is plenty. My RS, as it turned out, had been parked in 1985 in mid-valve adjustment where the mechanic had relaxed the head fasteners as some of them do.
4. Carbs back on, new fuel hoses, fresh battery, and see what you've got!

If it fires up (and it probably will) look for obvious signs and sounds of distress. Spin it to 3000 and see what kind of voltage is getting to the battery.

You'll just be so jazzed about the bike once it makes some noise.

I've had varying levels of luck as regards the bores and rings. One R75 had to get bored 1st OS. The R100/7 had functional but weak rings and got a hone 'n' rings when the heads had to come off for other reasons. Otherwise, I'd probably have left it. The R100RS will probably keep its OG rings.

 

[spokanetom]

Thanks a ton for the replies!

The exhaust nuts are already loose. The previous owner did that. Current mileage is 48k. That doesn't seem too much for a timing chain, right?

Short backstory. I'm the third owner. Original owner put 48k on it and then stored it in 1984 (last tab year) for about 30 years. But it was a runner when stored. Second owner bought it for a project bike but didn't get to it.

Adding to my list:

* remove oil pan and clean it and the oil pickup, then reinstall with new gaskets
* check valve clearances

 

[69ZEFF65]

Where's the Tank? Where's the carbs? My usual and annoying attempt at humor falls flat but they are obviously not there. Do a basic rebuild on the carbs, check for spark, drop the oil pan & change oil and filter, get the starter working, ensure fire does not occur in the wrong places with battery voltage and use a remote gas tank set up. If it fires up with no bad noises and shifts through gears on the center stand without bad noises its up to you how much you want to spend of a rider or a restoration. The fenders and frame look to be very well preserved, if the gas tank is just as nice I would suggest keeping it as original as possible and enjoying the ride.

Turdzilla had a few additional challenges that I had to deal with before it was ready for an initial fire up, after a few tweaks the old "Baby Boxer" runs like a fine Swiss watch only quieter. This '71 R 50/5 sat in damp storage for 30 years and then on a trash pile until a fellow Airhead Vintage enthusiast dragged it home, he was kind enough to let me have a crack at it. I have to say I never even looked at the points or timing, I just change the plugs and caps chasing a cough on acceleration.

 

[spokanetom]

Tank and one carb is off. The PO took one carb off and cleaned it, but didn't reassemble it. Other carb is in place. The paint is good enough on the tank and fenders (and matching Luftmeister topcase) that I'm going to keep it as-is. Once the engine is in a runnable known state, I'll pull it and do rest-o-mod on it. It'll be nearly stock, but I'll probably upgrade the front brake and ignition. There's a bunch of clean up work ahead of me before it's a rider. But that was what I was looking for: a bike with all the potential for riding later after I've clean it, replaced parts that need replacing, etc. I like the tinkering aspect of this project. And retiring this spring will give me a lot more time to do it.

 

[stevenrankin]

You know I will stress taking the heads off and inspecting things. Why? Because at this point most everything removed to remove the heads is off or loose. Really it doesn't take that much more time to do it.

At 48K miles, (if the odometer is accurate), most likely you won't need any major work at all but, why put everything together in time for spring only to find out you have shot rings or a bad valve? Oh I suppose you could ride it for next summer and do any repairs the next winter, but you could save yourself that issue by a bit more work now. Another day now in the winter to fix things beats a day of riding season. Just saying, I see a lot of bikes come into my friend's shop "to get running". Most every time, there is some wrong with them other than what is obvious to the eye. St.

 

[omega man]

FWIW- I try to get old stuff running to give me a clue where to start….. and if I need to go deeper right from the start.
OM

 

[stevenrankin]

On a bike that is 100% together, I can understand some of the views on running it then seeing if it needs anything. In this case, why put a bunch of stuff together, carbs air box and who knows what else only to perhaps find out it will all have to come apart again because of bad valves or rings? Again, it is not like taking the heads off at this point is a week long job, a half day will tell you a lot at this point. St.

 

[AntonLargiader]

Does the engine spin freely?

 

[spokanetom]

Does the engine spin freely?

Yes. I pulled the plugs, put it in 2nd and rotated the rear wheel and the engine moved just fine.