OP - sorry to step on your thread...
* To inspect a diaphragm you'll need to pull the slide out, then go around the rubber part stretching every segment to look for splits, tears and cracks, no matter how tiny. Diaphragm cracking is common on older bikes because the original diaphragm material (like that of the floats and float needles) was not rated for Ethanol fuel. It doesn't matter that all the internal parts "look new", if they are pre-Ethanol then they must be replaced.
Remember: Your 1989 bike pre-dates the fuel change. So anyone working on an older vehicle has to have a "sense of history". There's a certain historical context that must be kept in mind when looking at these issues which demands more than a cursory glance. Each piece must get looked at under a microscope.
Are there other parts in the carbs that would need to be swapped out for ethanol compatibility? I have a '75 R60/6 that I wasn't really prepared to rebuild the carbs on, but it came from Canada, and the PO suggested swapping fuel lines for ethanol (which I have done) but didn't mention carb rebuild...
Richard, I'm quite familiar with the carbs as I have owned airheads for many years. This one of 3 I currently own. The floats are ethanol resistant and nearly new. The diaphragm I checked was pulled and examined under a bright light. the idle adjustment is precise as it should be on a well functioning carburetor. The plug caps are NGK, one piece with the wires and in new condition. The Pulse Air Injection has been completely removed by a PO, apparently even changing the air box housing and heads to eliminate the connection points for the pipe. The spark plugs that I took out looked just a little rich but not bad. Really appreciate your help!
Are there other parts in the carbs that would need to be swapped out for ethanol compatibility? I have a '75 R60/6 that I wasn't really prepared to rebuild the carbs on, but it came from Canada, and the PO suggested swapping fuel lines for ethanol (which I have done) but didn't mention carb rebuild...
I've read at one time Bing offered an "Ethanol kit", but I've never actually seen one.
To me the main parts are float, float needle, and diaphragm (not present on the R60), but mainly the fuel hose. The older hose (from ANY source) will crack and break off from the interior. Then, very small black chunks will fall/float down and block the float valve.
If you use American made fuel hose from an online supplier or your LAPS, then the hose should be marked "SAE J30".
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Richard, I'm quite familiar with the carbs as I have owned airheads for many years. This one of 3 I currently own. The floats are ethanol resistant and nearly new. The diaphragm I checked was pulled and examined under a bright light. the idle adjustment is precise as it should be on a well functioning carburetor. The plug caps are NGK, one piece with the wires and in new condition.
This is the issue with technical help via written forum. The devil is most often in the details, which are rarely photographed or discussed. I'm a "detail guy" as you might have guessed. In the absence of detail, all I can do is stress greater and greater detail. Speaking of details, I see no mention of the odometer reading.
I really don't think your issue is fuel-related... but something like 85 to 90% sure it's electrical. I'm sure
The Pulse Air Injection has been completely removed by a PO, apparently even changing the air box housing and heads to eliminate the connection points for the pipe.
Then the obvious answer is that no one would ever go through that expense. You obviously have (something like) a European model that some serviceman brought back with him. The US military will ship anything for a serviceman. My son brought back a car, a full dining room suit, and several foot lockers full of wine and beer ! Shipping a motorcycle is definitely not a problem.
I'd think a European model bike, being emission system free, might be easier to deal with, but you can never tell what requirements the EU might have added that we Americans are simply not looking for.
The spark plugs that I took out looked just a little rich but not bad. Really appreciate your help!
Speaking of missing details... "You'd be able to see this result on the plugs if you looked at the plug colors exactly at the RPM of the issue." I see no mention of riding for 5 miles at a constant throttle on flat ground, then hitting the kill switch and pulling in the clutch lever as you coast to the side of the road for a plug reading at that RPM.
I think we are at an impasse. The last 2 solutions I can offer are basically backtracking. I'd go back and...
1) Add the "new bean can" pigtail based on the historical evidence and extreme age of the bike.
2) Coat all the electrical connectors, relays and terminals with an anti-oxidation compound, such as NO-OX-ID.
All the best, my friend.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Hello Rick. Really curious if you have made any progress in sorting out your RT? Would like to know what you found.
Richard W, David, Thanks to the help I got here, yes it is sorted! First of all, when I replied concerning the Pulse Air system, I was frustrated after dealing with it for several hours and replying without looking closely. (I haven't had one with Pulse air on it since my long departed R80ST) It HAS been deleted but appears to be very well done. The plugs on the air box are almost invisible and the ones on the heads are well recessed and hard to see. Thanks! Now, the answer I was looking for was found here in your replies: Things are not always as the seem! The carbs were spotless, apparently new floats, float needles and seats. The diaphragms had no visible imperfections and the slide needles showed no VISIBLE wear. (I believe Richard W said it was hard to detect). So, after reading that and admitting my own assumptions about the carburetors could be wrong, I switched them out with my "88RT non runner. Started right up, did a test ride, accelerates and runs smoothly at all speeds! Did a 100 mile ride today and the engine performed flawlessly, (although I'll be pulling the transmission to lube splines and possibly replace the clutch (I already have one on the shelf) as there was a problem with intermittent clutch slippage but the bike rides, handles, shifts and stops like new.
Can't thank you guys enough for your help! I bought my first airhead new in 1976, with the nearest dealer almost 100 miles away, so I learned to work on them myself. Not as astute as I once was and perhaps too sure of my assumptions. Thanks again!
A humbling experience - I chased a subtle carb issue on my ‘78 quite literally for a couple years. Sometimes i could feel it, most times not. It felt like one side would run lean when cruising at steady throttle. Just a funny little slight hesitation. Of course, i had rebuilt the carbs. I would work on it intermittently, then put up with it. I double, triple checked everything. Replaced everything. Played with various needle jets and needle settings. It was crazy. Then one day i was reading some carb material on Snowbum’s site, and it sparked a new thought. I dug back in. And i found the problem. There was a sharp edge at the top of the steel center post on one of my carb pistons. See picture. With a little lateral force, that piston would catch or “snag” in the bore in the carb top. It was slight, but it was there. I dressed the top of the post so it would slide smoothly and EUREKA!, my troubles were gone.
so, my theory is, when i had the carbs apart they were on a bench at a school i worked at in maintenance. I believe that someone, probably a student in shop class, knocked or dropped that piston on the floor. Of course, they put it back and said nothing. Years later, i finally found it.
Richard W, David, Thanks to the help I got here, yes it is sorted!
That's great news ! Ride safely, my friend.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Glad you have your RT going again! Hope you find the issue with old carburetors.
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