I’m returning to riding after an approximately 15 year hiatus, and now retired. Picked up my new bike, an 84 R100RT in the Bay Area on Friday, and had a nice ride to our Son and family in the Santa Cruz Mtns. Leaving for out home in the Sierra Foothills Sunday morning, while going over Pacheco Pass at about 75-80 mph, I looked down and noticed the speedo pegged to the max. Once off the highway, and back to around 50mph., it stabilized and was about correct in my estimation, for the rest of the 1 1/2 hours to home.
I have the Factory Shop Manual on its’ way to me now, but want to have a look-see. I am guessing either the cable needs lubricated, or a gear is stripped. School me, please. And thank you in advance.
Steve
► If the cable was at fault, you'd be getting zero from the instrument head (broken cable), or squalling noises from the sheath (lack of lubrication). You can check and service both conditions by unscrewing the outer cable from the bottom of the head, pulling the inner drive cable out from the top, dropping about 5 drops of synthetic motor oil into the top of the cable housing and then re-inserting the inner cable. (Silicone based lubricants work well here too due to their resistance to water and temperature changes.)
► The only repairs the owner can make inside the instrument pack is to install a Katdash LED circuit board lighting ( https://katdash.com/ ), or epoxying the cast gear that slips on the spindle and makes the odometer fail to register. That's it.
► Everything else inside either instrument is akin to "watch repair" and therefore requires specialty lubrication and repair. (My other hobby is watch and clock repair, and even I send my instruments out.) I would not expect your instruments need anything other than cleaning and renewed lubrication with a modern instrument oil. (Remember, 1984 pre-dates most of the now-common silicone and synthetic lubricants, and so you can wager money that the OEM lubricants have merely oxidized and solidified during the past 42 years.) Your Airmail has speedo repair shops listed, or do a Search here for recommendations.
NOTE: This same oxidation of the OEM lubricants is also present in other locations around the bike and was most proabably NOT treated before the bike's sale to you. You'd do well to investigate and correct these while the bike is in storage during this coming winter's down time. This preventive maintenance will ultimately save you a lot of money. In order of importance they are...
• Change the engine oil before riding again (unless you know the bike was regularly ridden last year), using an oil like Valvoline VR1 20W50.
• Change the gearbox, drive shaft & final drive oil before riding again (unless you know the bike was regularly ridden last year), using an oil like Valvoline 85W140 synthetic gear oil.
• Change the fork oil. This will improve steering.
• Repack the 2 bearings in the starter motor with modern synthetic wheel bearing grease. This will improve starting.
• Repack the upper and lower steering post bearings with modern synthetic grease. This will improve steering.
• Inject modern synthetic grease into the L & R swing arm bearings.
• Repack the wheel bearings with modern synthetic wheel bearing grease. This will improve steering.
• Replace ALL the DOT4 brake fluid. This will improve stopping.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
@wobbly Appreciate the good advice. I do know that the engine oil was changed the week before I bought it, so, less than 2 weeks ago. Gearbox, driveshaft, and final drive oil within the last year.
I’m waiting on shop manuals to arrive, before I start to tackle the other items you mentioned.
I will try lubricating the cable, preparing myself for the fact that the speedo head may need some professional attention.
Thanks for the response.
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