The Airheads Beemer Club is a non-profit club reclaiming the 'Legendary Motorcycles of Germany'

Topic-icon New member. Engine and carbs sitting on workbench, pics attached, now what??

  • imtheant
  • imtheant's Avatar Topic Author
  • Offline
  • Forum Newbie
  • Forum Newbie
More
2 months 16 hours ago #4607 by imtheant
Hello all, new member here and happy to have found the group. I have done a few frame off restorations on old Jeep CJ7s but this is my first motorcycle project and I'm loving it already. Here is where I am currently:

I bought a 1992 R100RT, 24K miles, started up and ran pretty well last week before I stripped it down to the bare frame. I have the engine out and it is on my workbench ready to be worked on. My questions are as follows:

-I am not interested in a complete engine overhaul if I can avoid it, especially with the warmer weather on the way. Love to hear your expert opinions on what are a few "must have" items to inspect/change while its on the bench without going too deep?

-Is there an extensive mini-overhaul/service type of kit that would include the necessary gaskets/seals to tackle the job?

-I am planning on replacing the clutch - any thoughts/brands there I should consider before doing so?

-My tool collection over the years has grown pretty extensive, however are there any necessary that should have on hand for the engine work?

- One of the carbs was leaking fuel pretty bad. I would love to find a place to send out both carbs to be rejetted and rebuilt, any recommendations?

I live on the Eastern Shore of Delaware, hope to connect with a few local members for advice and again, glad to be a member of the group! -Mike

Please Log in to join the conversation.

More
2 months 9 hours ago - 2 months 9 hours ago #4608 by Wobbly
Welcome to the ABC !

Sorry to disappoint, but nothing needs to be done to your Airhead engine or clutch except put it back in the frame and ride it ! Heck, it's just barely broken in !! If additional mileage turns up any oil leaks, then all that can be done easier with the engine in the frame.

► You should replace several items in the carbs due to ethanol in the fuel....
• All the gas line (use the US made 1/4" ID marked SAE J30)
• Both floats
• Both float valves
• Both rubber intake tubes
• Replace the small jet (which I think is a #45) in both carbs
• Blow out the starting jets in the bottom of the float bowls
• And lastly check the diaphragms for any holes or rips (if any, replace both)

► Strobe time the engine at high RPM using the "F" mark on the flywheel

► Buy a shop manual and learn how to dynamically adjust the carbs at idle and adjust the throttle cables at 1500 RPM

► The trouble point on your bike is not the engine, clutch or gearbox, but instead the single-sided final drive. The big bearing is highly stressed and wears quickly if the oil is not kept changed and topped-up. ANY play in the rear wheel is a sign the final drive is near death.

► The other trouble point, to a much lesser degree, is the single shock. Your OEM shock is probably dead. The bike isn't going to handle worth a toot until it's replaced and they cost big bucks. So you probably DO NOT want to spend money on needless engine parts, and instead start saving your hundred dollar bills for a new rear shock.

Hope this helps. :)

Don't hide 'em, Ride 'em !!
#15150
Last edit: 2 months 9 hours ago by Wobbly.

Please Log in to join the conversation.

More
2 months 4 hours ago #4609 by 8166
Do yourself a favor and review the tech articles you'll find under the AirLore section of this website. Then swing over to www.gunsmoke.com/motorcycling/r100rt/index.html where you'll find a review of the maintenance and upgrades I made on a '95 RT I purchased a few years ago.

Your clutch will probably last 100,000 miles unless the rear main seal has been leaking and it is contaminated with oil. Since you already have the clutch out, pull the flywheel and replace the RMS, along with the o-ring under the oil pump cover and the other o-ring around the RMS distance ring. Don't forget to block the crank to the rear or you'll find yourself in some deep dodo. If none of that makes sense, read up on it until it does.

The biggest improvement you can make to that RT are a pair of modern tires. I had good luck with Avon RoadRiders, but like the Michelin Pilot Activs I have on it now to put the same thing back on when they wear out.

Next, find a matched set of fork springs and rear shock. I've been very happy with the Wilburs on my bike; it totally transformed the handling.

Change out all the fluids and filters so you have a known baseline to work from. Purchase and use new crush washers for the drain and fill plugs.

As Wobbly mentioned, replace any rubber line or gasket on the bike; they'll be hard and cracked. Look at the intake tubes on the carbs, fuel lines, etc. I like Continental brand cloth braid covered 6mm fuel line made in Germany. Pull the air filter box and replace the fuel line that runs on top of the transmission, as it is likely hard and starting to wear through.

If someone hasn't already done it, remove the pulse air system and fuel solenoids. The pulse air makes the heads run hot, and the solenoids significantly delay the flow of fuel when you switch over to reserve.

Check the exhaust system for leaks. BMW uses aluminum shims between the parts, and they mash themselves into uselessly thing foil over time.

Replace the plastic hinges on the saddlebags, and buy an extra set to carry with you when you're touring.

Unless you're an ironbutt, start shopping around for an aftermarket seat. I love my Russell DayLong, but it's not for everybody and the Corbin that came on the bike was down right painful.

Check the steering head bearings for proper preload and Brinelling. If they feel at all notched, look up the SKS cross reference online and pick up a new pair at your friendly neighborhood bearing house because BMW tries to sell you the same thing for twice the price. Use the money you saved to purchase the Cycle Works tools for removing the outer and inner races.

The auto advance may be sticking, but you'll need to get some miles in during hot weather to see. If you're idle doesn't come back down when you come to a stop, but you can apply the front brake and use the clutch to load the engine to lower the RPM and they stay there, the auto advance needs replaced.

Those are the basics, so ride the bike and see if anything like pushrod tube seals or the swingarm boot are leaking. You should probably get a speedo cable boot and replace it because it'll be leaking water into the transmission when it rains or you wash the bike. Once you give that RT a little love and cleanup, it'll take you anywhere you want to go and keep you warm and dry in the process. Probably too warm in the summer; I park mine in May and don't get back on it until November, but this is California and it's warm enough to ride year 'round.

Also, keep an eye on the WhAIR And When Calendar in Airmail and the web site, and try to get to a Tech Day. You'll meet a bunch of real nice, friendly, and knowledgeable people that can get you pointed in the right direction.

Good luck and have fun!

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
Check out the Yankee Hill AirTech Weekend, April 20-21, 2019

Please Log in to join the conversation.

  • imtheant
  • imtheant's Avatar Topic Author
  • Offline
  • Forum Newbie
  • Forum Newbie
More
1 month 4 weeks ago #4610 by imtheant
Thank you both for the detailed responses and I am happy to hear the consensus of not needing to do major engine work, especially with the riding season upon us.

As I embark on a few of the work items you guys suggested, is there an engine seal/o-ring kit that I can pickup that will have the necessary items rather than trying to source each piece individually? I will need various boots/fittings, etc - all those LITTLE parts that you find out you will need as you start to reassemble the engine and bike that halt progress on a saturday afternoon!

Also along the same lines, I remember I bought a full stainless hardware kit when I did my frame off restoration of my my CJ7 which made reassembly with all new bolts and hardware a breeze. Does something like that exist for the airhead rebuilds?

Thanks again, what a great site!

Please Log in to join the conversation.

More
1 month 4 weeks ago #4611 by Wobbly
Mike -
That was one of the biggest shocks to my system after coming to BMW. Some dealers will prepare small kits, but BMW seems to sell everything by the piece part. Get used to looking at parts fiches, my friend. After 2 or 3 years you'll start to think like a German, and it will all become very clear. :lol:

One of the big differences between car and motorcycle work is that most all the bolts on a motorcycle are doing multiple jobs and are typically highly stressed. You'd do well to recognize that common stainless steel bolts are about 1/2 to 1/3 the strength of the OEM steel fastener. There are indeed strong stainless fasteners available, but you had better have some deep pockets like the DoD or NASA to afford them. The 3 or 4 fasteners that can be safely substituted are easily had at the hardware store.

All the best.

Don't hide 'em, Ride 'em !!
#15150

Please Log in to join the conversation.

More
1 month 4 weeks ago - 1 month 4 weeks ago #4612 by 8166
BMW does supply a few parts in kits. However, in my experience, the kits will not contain all the parts needed to do a particular job, or they will include parts that your motorcycle will not use. For example, the rebuild kit for your Bing carb will have lots of o-rings and gaskets, but does not include floats, float needles, needle jets and jet needles, nor the o-rings for the throttle shaft or the tiny screws that hold the butterfly in place. And the oil change kit will contain a paper gasket for the oil filter cover, which should almost never be used (see Oak's writings on the infamous $2000 o-ring for details).

If you're looking for parts, head on over to www.realoem.com . Drill down through the Motorcycle/Classic section to your model and year, and you'll find exploded parts diagrams for everything on the bike. Makes it real easy to put a list together for your dealer's parts guy, but don't be surprised if some of the realoem numbers are outdated and the part number he hands you is a superseded one. You should also be aware that in spite of previous promises by BMW AG, more and more parts for our airheads are becoming unavailable through the BMW dealer. Often this can be remedied by a google search using the part number. Sometimes this leads to German sources, some of which are very good, others not so much.

Typical yield strength of low carbon steel is 50,,000 psi, while 304 stainless steel tops out at 30,000 psi, a significant drop. However, many of the fasteners on our airheads are in non-critical areas, and I've had very good luck substituting 304 and especially 316 stainless steel for the BMW hardware. For example, the three socket head cap screws that hold the oil filter cover on the right side of the engine, screws for the fender stays and luggage racks, turn signal lenses, headlight shell, handlebar switches, that sort of thing. Stay away from stainless steel axles or anything you'd use a torque wrench to tighten. Also get in the habit of using anti-seize on stainless steel fasteners, especially stainless on stainless. This will prevent galling, probably the main reason stainless steel fasteners have a bad reputation in some circles.

Rocky Point Cycle used to sell kits for our bikes, but I don't know if they still do. I source most of mine from McMaster-Carr. For a recent /2 rebuild, I found a wide variety of stainless reproduction hardware at Bench Mark Works.

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
Check out the Yankee Hill AirTech Weekend, April 20-21, 2019
Last edit: 1 month 4 weeks ago by 8166.

Please Log in to join the conversation.

Moderators: Wobbly
Time to create page: 1.262 seconds