850 not started in years- I need advise

This weekend I purchased 2 -850 commandos from the same guy for $1500. They are both early 1975s without electric start or rear disc. I think I got a pretty good deal considering they have been in a humid shed for years. It almost made me cry to see how two very nice bikes were left for dead?? The assembled one has not been started in years and the disassembled one has not either. They have a lot of chrome oxidation from a humid environment but very restorable. The assembled bike has 2500 original miles on it and the pistons move freely. It was running when it was put up at least 17 years ago but had a bad ignition switch that you had to jiggle. This is why it was garaged before the first owner died and his wife gave it to the fellow I purchased it from. He never rode it. I would like to start it but I need to know if I should pull the top end first and check it out??? What I propose to do is make sure the gas tank is clean with new lines. Clean both amals and put new kits in them. I will also drain all oil and refil with new with a filter replacement. It will neeed a new battery and cleaned points. I don't think it has a boyer. Is this cool to do or do I need to take down the top end or entire engine?? I don't have a lot of bucks right now but I will wait and save some money to avoid screwing something up. The other commando has 11,000. miles on it. The engine is on the frame but all else is removed. He was going to make a chopper out of it. Luckily he did not chop the frame and all can be put back to original. The plugs are out of the engine and I will have to pull the cyls off to make sure all is well inside or do a top end later. I did shoot a lot of wd-40 inside it stop any further damage until I can get time to tear it down. They are now both safe and sound in my shop. Please advise on the first mentioned Norton if I should attempt to start it and run it like it is or do a complete teardown. This bike is all original with no mods. The second bike is also all there but disassembled. He also has a 750 Atlas . I believe it is a 1964. He wants $500 for it. Is that a good price. It is a complete basket case but restorable. It is missing the rear wheel and original tank.==Thanks-- :roll:

There's a little man with horns sitting on one shoulder saying "change the fluids and start her up". On the other is a nice little guy saying "oh no! take her to bits you might hurt her"

If you take the risk and start it up it might tell you what's wrong if anything at all.

While in our teens a mate and I bought an old plunger ES2 combination that had been left in a tin shed for years. We pulled the plug free'd the motor and checked it had a spark, put some petrol in the tank, topped up the oil and it went after a few kicks. We had to cut the side car off the frame and we swapped it for a voltage regulator and a couple of tyres.
We thrashed that old bike for over a year and it never let us down, not ever, it was as if it had a soul.
My mate bought my half and traded it in for a T110 that kept seizing up. I bought a Honda (there I've confessed) that I would drop once a month.
I reckon it cursed us both.

Buy the darn Atlas too you lucky ******

The big idem to do for this before you start, clean the oil tank. There will be lots of grinding dust in the bottom of the tank. It's better to remove the tank for this so you can check the bottom mount and modify it. Then on the center stand drop it into 4th gear and with a friend to help turn the rear wheel in gear till new oil returns to the tank fully priming the oil system.
It wouldn't be bad to check the valve movement with a scale just to see that the cam lobes are still there.Then you lash the valves after a little run with cheap oil that gets dumped out fast.
While your cleaning the Amals...New needles and needle jets and drill out the pilot jets with a .016 drill.

I wouldn't tear down the engine. Besides doing the things you've already mentioned, remove the sparking plugs, remove valve covers, rotate engine over ensuring rockers operate correctly. Maybe listen to bottom end and gearbox with a mechanic stethoscope to check for any nasty noises. Will need some elso to kick it over while you listen.

You will probably also have to remove the mechanical advance mechanism behind the points plate to free it up.

Put some marvel mystery oil or similar in the cylinders to loosen up rings. turn engine over lots of times to get oil circulating.

After removing the mechanical advance, you'll need to static time the machine, but before doing that, use a degree wheel to check the timing marks on the timing plate riveted to the primary chain cover. These are notoriously wrong by as much as 12 degrees. :shock:

By all means, thoroughly clean gas tank, petcocks and carbs, making sure you clear all the tiny orifices. I would also verify that the carbs have all the factory specified components in tham, and check float levels. Check for good spark on both cylinders while plugs are out.

After you've done all this carefully, fire it up. It'll smoke for a bit, but will clear out unless the rings are frozen. Check for oil circulating back into oil tank.

I did all this recently to a 73 Guzzi that appears to have sat since 78. Runs good now.

Mark

I think you have got a bargain. I have to disagree with most of the other posts, I would take it apart to make sure everything is OK, maybe not completely but enough to satisfy myself that things are good, you got chains and bearings in there that have been static for 17 years, everything could be A-OK but do you want to chance it. I wouldn't. I would rip the blokes hand off for the Atlas by the way, $500, its a gift.

Cheers John

I'd go for the check, change all fluids and give it a go. Unless its throws a rod (very unlikely) you will know whats wrong but also whats right. These late 850's are very robust and also wear very little.

$500 for an Atlas with a few missing parts? I've seen featherbed frames go for $1000 on ebay. JUST the FRAME :!:

850 -not stated

I have to say -- being a cautious type,take the motor down,after standing idle for many years the main bearings will probably have suffered some damage -- the weight of the crank etc. on one small point of contact in the bearings will cause flat spots. The isolastics are probably shot also,you may get some heavy rumbling from the unsupported engine,unless you have a "tuned" ear you may ascribe the rumblings to main bearing noise. For the time it takes to strip a motor and verify it's health, it will be worth the effort.
Good luck. James
Snag the Atlas also,may as well have the complete stable!

Please note that cleaning the oil tank should give you a good idea about start or not. From what I have seen I would be more worried about the lay shaft bearing in the back of the transmission if the oil tank didn't have to many solids in it.