new R90S owner

["James Marciano"]

Hey All -

I've been riding BMWs exclusively since 1987 and am excited to finally join
the ranks of R90S owners. It's a 1975 DO. Any "must have" modifications?
It's bone stock, as of now.

Also, what gas do you use? I was going to buy VP Vintage Lead
<https://vpracingfuels.com/product/vp-vi ... ded/?c=217> unless someone
thinks there is a superior fuel?

FYI, I live in Bucks County PA, and enjoyed meeting Hans on two of his
trips (this is one of the bikes he signed).

best,

James

["Harold"]

James,
I run mine on 100LL aviation fuel. Here in San Diego it is only about 40
cents a gallon more than our crappy 91 octane 10% ethanol gas, doesn’t
degrade with time, and the bike runs noticeably better. The low lead in the
AV gas isn’t a problem for the bike, me, or the environment. After all, all
of our gasoline powered aircraft are burning it and lots more than I use.
Did I mention that the bike loves it? My gas generator and outboard use it
also and carbs stay perfectly clean and start easily.
My bike, my money, my choice.
Harold

["Robert Fleischer dba Fleischer's Service"]

I won't get into the legalities….or….morals/whatever.
But, in spiking an Airhead's gasoline with aviation gasoline, for the protective effect on valves and valve seats of the TEL in the av-gas, one only needs one or two CUPS worth, per tankful of auto fuel unleaded.
Note that the Reed Vapor Pressure specification for Av-gas is very different than for auto fuel, and use of very high concentrations of av-gas (perhaps, guessing, at over 50%...?) will likely make cold weather starting of your Airhead much more difficult.
BTW…AvGas can be stored for years, without serious deterioration.

Lots more details in my valves article.

Snowbum (AKA Robert Fleischer)
<https://bmwmotorcycletech.info/> https://bmwmotorcycletech.info
<https://bmwmotorcycletech.info/search.htm> https://bmwmotorcycletech.info/search.htm
<https://bmwmotorcycletech.info/sale.htm> https://bmwmotorcycletech.info/sale.htm
<https://vintagebmw.org/> https://VintageBMW.org
<https://lists.micapeak.com/archives/airheads/login.php> https://lists.micapeak.com/archives/airheads/login.php
<https://fleischerelectronicsservice.com/> https://FleischerElectronicsService.com
Learn from the mistakes of others, because you cannot
live long enough to make them all yourself!
A large number of good tests, inspections, measurements and both good
and bad experiences, are more valuable than most opinions.
ABC 1843; MOA Life 17058; AMA Charter Life 73254; etc.
‹(•¿•)›
♥

["Scott Blaylock"]

Congratulations James and welcome to the R90S club.

>From the "must have" modifications, it really depends on what you plan to do with it. If it's a Starbucks runner then probably not much more than some Speed Shine to be sure it looks it's best while you sip a cappuccino and answer questions about it. If you plan to tour with it, then first off you should pickup some luggage. If you plan on cooler weather riding and want bike powered heated gear, you may want to upgrade the charging system. Personally I'm not a fan of the lead acid batteries with the little filler plugs and the overflow tubes. AGM or another sealed battery is a good option. Again personally, I'm a big fan of the MotoBatt MBTX30UHD. It's an AGM and fits the /6 bikes with 400CCA. I put these in all my customer /6s when a battery replacement is called for. On the ignition front, you may want to move to an electronic ignition. The EME Digital Ignition is nice as it bolts to the end of the crankshaft, which means you have very accurate timing for both sides and the bike just seems to run smoother. It's also nice as you have the stock ignition as a backup. If the Digital Ignition fails you just put the advancing unit back on the camshaft and reconnect the trigger wire to the coil. Another nice upgrade is the Easy-Clutch. It makes driving around town significantly easier on the hand due to the reduction in force needed to depress the clutch.

I'm sure other people will chime in on what they think is a good upgrade for the bike.

Again, congratulations,
Scott.

["Josh Withers"]

Oshmo makes a stainless top clamp that looks stock, but much more rigid.  Slightly thicker than stock.  I recommend one.
+1 on an electronic ignition.  EME seems to have the most modern one out there.  I've had good luck with Dyna ignitions too.
+1 on Stainless brake lines
I'm a fan of Avon Roadrider tires
Maybe some cool Oshmo swingarm caps...
Progressive front springs and Ikon/Koni rears shocks are a common set up.
Do your proper maintenance and you are good to go!

-Josh Withers