Abajo se anota un intercambio sobre una reparación de mi anterior moto, BMW K1100LT 1993.
Otro hilo de un proceso de reparación y apoyo obtenido, pero para una Honda ST1300 2003 en la correspondiente lista de correo de mecánica es el siguiente:
Anoto estos datos porque creo que es importante reconocer como se puede con ayuda de la correspondiente lista de correo y un cuidadoso intercambio resolver cualquier problema de mecánica uno mismo tardándose menos y a menor costo y con la confianza de que luego en el camino tendrá uno la confianza de saber buscarle y resolver problemas mecánicos con mayor facilidad.
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Esta es copia de un correo enviado a la lista de correo de mecánicos y aficionados a talachear sus propias motos - BMW-Tech:
This is a work in progress report for repairs to "The Couch". An LT is truly a comfortable big motorcycle! My friends and previous owner nicknamed mine "The Couch". Some call it "The Living Room". I decided to write this up before further dismantling because I’m still unsure about the problem, writing it up makes it clearer and I’m hoping for some further pointers from you all:
Work done:
1. I removed the lower left hand side of the fairing and the crash/roll bars.
2. Cleaned thoroughly the area around and bellow the intake tubes, butterfly assembly and injectors with spray carburetor cleaner.
3. Arranged and moved stuff far away. Placed a fire extinguisher and a connected and pressurized water hose handy.
4. Sprayed the area this time with engine starter spray. (I discovered this wonderful stuff in England with my first motorbike, old and plagued with troubles. Even so it would start up even in the coldest winter morning with a short spay into the air intake.)
5. Started the engine: Very smooth. No hiccups. No misfires.
6. When it started to lose its smooth running I added more engine starter spray and it evened out again.
7. On close inspection the spray liquid around the intake hoses "seemed" to indicate air leaks, but this was unclear. It could simply be the slight movement of the whole butterfly assembly with the engine running.
8. After a while I let it run and dry up. The smoothness started to become more irregular again, but still no misfires.
9. After more time I finally got a misfire. This time I could see the air clearly hiss out of the base of the injector on the number two cylinder. In fact, the first time it spit some of the remaining starter spray liquid at me. I think I got some in my eye. Bother. Lots of water. Should have used some old glasses or goggles. Nothing serious though. (Don’t use nice new plastic eyeglasses for such work because they can get irretrievably damaged with solvents. Better glass.)
10. Listening carefully it is clear there is a knock inside the engine, simultaneous with the misfire and the air hissing out of the base of the number two piston injector entrance point. (Well, it seems simultaneous to me.)
11. Using a flat tip plain screw driver placed squarely against each injector and with the handle end in my ear I listened for the clicking at each injector. Boy is it loud and clear. However, I could not tell a missing click at the injector when the number two cylinder misfired. The whole process is rather fast, so I’m not sure I’m able to discern the missing click. It may just be missing and I can’t hear it.
12. After first writing up these notes and progress report, I sealed with black silicon the base of the number two cylinder injector entrance point in preparation for a further test before taking out the injectors and maybe the butterfly assembly.
13. Having plugged that spot, number 2 cylinders still misfired and the air now came out the hose at the base of the butterfly assembly at number 2.
Hypothesis I’d love to have second opinions for:
a) First, I can see that with the engine starter spray everything smoothed out, so it seems I’m enriching the mixture.
b) This would seem to indicate clearly that there are one or more entry points around there for this explosive liquid to enter and enrich the mixture.
c) The clearest spot seems to be the base of the number two cylinder injector, where the air hisses out when misfiring. Maybe it’s the only spot. On first writing up these notes I thought "Maybe I should plug it with some silicon or something temporarily, before dismantling everything, in order to test the engine running and possibly rule that out?"
d) But, would this mean the only problem is an inadequate seal at the entrance point for that injector? What do you think the symptoms indicate?
e) Otherwise the rubber intake tubes bellow and maybe also above butterfly assembly would have to be repaired or checked, which is the next step I think. Changing them all would be prohibitively expensive, since each of the eight costs US$75 here.
f) More important: Would the symptoms indicate something further? Maybe if the leak or leaks were there anyway the problem would not be like this and I would actually have to be looking for an intermittent failure in that injector or in the spark for that cylinder or somewhere else.
g) When I sprayed with engine starter everything smoothed out and this would tend to indicate that all leaks have to be found and plugged and that would be the end. But when I plugged one leak at the base of injector 2 the air came out elsewhere, so is it a matter of air leaks or of a very strong other motive that produces them?
Other work previously recommended and which I will undertake next week (because I have agreed to help a cousin out with his bike this weekend:
i. Check the cleanliness and good connections at the ignition amplifier (No. 17 in the ignition system parts diagram).
ii. Remove the fuel rail and injectors, swap one and reconnect to see if the fault follows the swapped injector originally on cylinder 2 to the new cylinder it’s placed at.
iii. For the first time, check out the valve clearances. (If there is need for a shim change the Haynes manual gives a rather grim and complicated perspective without the special BMW tools. But if that’s the case, I’ll have to first read up on the adequate documents on the list web site first.)
[Doing mechanical repairs is fun. It may be clear I read "Zen and the Art of Motorcycle Maintenance" some years ago and took it rather literally. My line of work and research is self-help groups and mutual aid, so this list and doing your own repairs is very much in line with that. But when you’re way up in the sierra of far away places in the depths of little travelled Mexico, it’s a good thing to be able to repair whatever goes wrong yourself. I bet you all agree on that.]
Thanks again to everyone on the list for previous and future help and pointers.
Rolando
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Esta es copia de un correo a la lista BMW-Tech de mecánicos de motos BMW:
Here’s the report back for repairs done after receiving much appreciated and valuable advice and info for my bike’s ailments from the BMW-Tech list:
- Removed gas tank and fuel tubes.
- Changed gas filter with the similar one I use (for a Nissan Tsuru).
- Removed left side panels, injector cables, fixing belts and throttle position switch cable.
- Disengaged and rotated rubber tubes going to butterfly assembly from air filter.
- Disconnected throttle and choke cables.
- Discovered that in order to adjust the idle speed screw for the accelerator cable I don’t need an L shaped screw driver, but rather to simply adjust it with the engine off and the handgrip fully twisted open. (Such a simple thing I could not figure out. Not very smart.)
- Removed fuel rail complete with injectors.
- Disengaged butterfly assembly complete, cleaned it and did not move anything.
- Replaced damaged and leaky tubes under the butterfly assembly with similar diameter and size pieces cut from a fuel tube for some car’s gas tank to filler cap. (I just took one as an example and found an adequate piece of tubing at an auto rubber parts shop.) Cost: US$4.00 against a fortune for the original ones. Used standard metal belts to replace crimp ones. Excellent results: Perfectly air tight now.
- Cleaned the whole area, with care not to do anything to the butterfly assembly.
- Took the injectors to a lab to clean and replaced the rubber seals with standard ones, literally twenty times less expensive than the original ones at the dealer.
- Reassembled everything carefully.
- Never removed the air filter housing.
- Took the bike to check with an exhaust analyzer for a US$2.50 tip and managed now easily to set the CO2 adjustment screw so that the number the guy said indicates fuel not being burned went from 8% to 3%. I think that’s the CO measurement on the analyzer screen. Anyway, the awful gas smell, black carbon and excess fuel use is all gone now. Still, I don’t know if I should strive for less than 3% though.
- All work was done spending one or two hours each morning from next to last Monday to a Friday. Five days of very easily distributed work. Only scratched my hand once.
The only thing I haven’t been able to get right is that throttle position switch. The instructions on the web page document say I should hear a click when the throttle is fully closed and I hear no such click. When I decelerate hard the engine sometimes dyes on me, which is bad. Anyway, will keep trying.
The end result is incredible. The engine is smooth as a sewing machine.
The change for the better is fantastic. Many thanks for advice and help here.
Anyone here in Mexico? Care for a ride from the City to Veracruz and the north of Puebla sierra? (This is preparatory for Easter week around Chiapas.)
Take care. Ride safe.
Dr. Rolando Montaño Fraire
www.rolandomontano.info
www.ayudamutua.org
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