re-furb the fuel tank '88 R100RT ?

A few months ago I bought an '88 R100RT with 85K miles on it from a gentleman in UT. We spoke on the phone a few times, he sent me pics and some service history, and I took him at his word that the bike was in pretty good shape. The price was $3K which I thought was fair.

Long story short, I'm in CA, I didn't want to fly to UT, confirm the condition of the bike, and try to ride it back to CA in December, so I had it shipped.

Oooops.

When the bike got here, I'm glad I didn't try to ride it back from UT. The tires were seven years old, the push rod tubes were leaking, the cylinder head stubs were loose, the turn signal switch was intermittent. The carb bodies were so filthy, I had to use a plastic paint scraper to get the first few layers of hardened UT dirt off them, hit them with S100, Foamy Engine Bright, Simple Green, and then ran a few cycles in the Ultrasonic Tank.

Since the carb bodies were so dirty, I thought I'd better rebuild the carbs, and check the petcocks and the interior of the fuel tank too.

The petcocks were okay, but I got a couple of tablespoons of tank liner when I drained the tank. Does that seem normal for 85K miles? Or should I re-furb the tank while I do the pushrod tube seals?

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Not normal

Having a gas tank liner dissolve in 85K is NOT normal for a bike that is ridden, but for one in storage it is normal.

Improper storage of a bike with gas in the tank and moisture getting into the tank while being stored is the probable cause of your liner going away. I bet the bike was run hard for the 85K miles and parked several years ago with gas in the tank. Your comment about the shape of tires is a good clue.

Beside the mess of dealing with the carbs and gas tank I would advise draining all the fluids in the final drive, drive shaft and transmission and make very sure moisture or water didn't get into them. I have seen a few bikes after long term storage with damage done to gears and bearings in the transmission due to water in the gear oil.

The forks should be drained and flushed as well, there is less chance of a problem here but it is a good thing to do, Gunk in the forks and low oil don't help the ride or handling.

Sorry you got burned by the previous owner flu, and I hope it doesn't cost you a ton of money to get things straightened out. Once the bike is sorted, it will be a nice ride. Cheers, St.

Starting in ‘88 there were quite a few upgrades to the BMW airhead series. I personally like the monolever series. Get it up to speed, ride and enjoy.

If it were me, I'd take a look at the inside of the tank with a flashlight. See any rust? If not, I'd probably leave the liner be and use it as is, especially of you are riding it regularly and keeping fresh fuel in it.

Assuming you are dealing with the baseline maintenance items Steve notes, I agree with Barry- ride it and enjoy.

Nice Airhead

Agree with others here, once you get the bugs out, you are gonna have a very nice Airhead to ride.

When you said loose head bolts, I hope you do not mean stripped head bolts. I hear the later Airheads were prone to the case threads stripping. Consequently, BMW dropped torque specs a few ft pounds, and no longer recommends retorqing other than when the heads are removed. I've noticed seepage on both heads of my 1995 R10RT, and plan to retorque them when I adjust the valves, in another 2500 miles or so. But not looking forward to it, given what I've heard about the case threads stripping.

I've rode mine over 7000 miles since purchase last October, and love it. It's also much warmer in winter than my 2008 GoldWing. On it, I had to use electric socks or Hot Hands brand foot and toe warmers. But on the Airhead everything stays warm from the knees down, though I've only ridden down to upper 20s this year, and usually ride in the 30s-40s. When the weather turns hot again, I may get back on the Gold wing, but it's mostly been sitting, in favor of the Airhead. Get yours sorted out and get out on the road ASAP, life's too short!

Stuff

The stuff on the cloth is what is left of your tank liner. No doubt about it it is not a good thing for you. I would as suggested look inside the tank with a good light to determine how bad the liner is destroyed as well as a look to see if there is any rust formed. You may get lucky and refurbish the inside of the tank with one of the products available these days. Worst case is there is bad rust as well and the tank is NG.

I once bought a 79 RT for a parts bike and it had a very nice gas tank bra protecting the gas tank. Removal of the bra showed a very shiny outer finish. Problem was, the owner had improperly stored the bike with gas in it and the inside of the tank was like yours, the liner was gone along with rust and the start of pinholes from the inside. That tank went to to the metal scrap yard.

A comment on the loose head bolts, if the previous owner had the heads off and chose not to install new head gaskets, down the road, you might have a problem. Your bike has the nikasail coated bores so unless there was a drastic amount of moisture in the engine, there should be no problem with the pistons and cylinder bores. Bike with the cast iron cylinders are not happy with improper storage and they are know to develop rust in the cylinders.

I know, I keep adding thing to the list to inspect, sorry I am just trying to save you problems down the road. Perhaps you could touch base with the previous owner and determine what he has done to the engine? St.

"I bet the bike was run hard for the 85K miles and parked several years ago with gas in the tank. "

Thanks to everyone for the feedback. I believe that Steve nailed it; the PO told me that he has terminal cancer and he hasn't been riding. He didn't say how many years the bike has been sitting, but it was registered for 2020. The service records he sent me said "Steering Head Bearings, Transmission, Rear End, driveshaft oil, Throttle cables, Clutch Cable" in June of 2020 so he probably did that to prep it for sale. I'll take a good look in the tank and drain the fluids as suggested.

Now that I look at his records again, the previous entries before 2020 were minor maintenance items in 2018, before that in 2015, and before that in 2014 with only about 6K miles accumulated during that time. So he wasn't riding much.

I'm not going to blame the guy, he probably remembers the bike in it's prime and genuinely thought it was in good shape.

And I meant the threaded stubs on the cylinder heads where the carb rubbers attach were loose, not that the head bolts themselves were loose.

Thanks again to all.

Thanks for the update

Thanks for the clarification regarding the posts. With more information I can be less critical of the previous owner. So I will retract my ridden hard statement. I just was not stored properly.

With alcohol blended gas if that was what was in the tank, and there is no way to tell, moisture is the killer. St.