One cylinder still missing at start up.

[dougfollett]

I posted on this subject a while back where my bike would fire on only one cylinder on cold start ups for about fifteen seconds. I got some good suggestions but finally decided that at my level of skill that I didn't need to be chasing around trying to fix things I wasn't even sure were a problem. I took the bike in to the local BMW dealer in Tacoma, WA where they are supposed to have one of the best Airhead mechanics in the NW. When I picked the bike up two weeks later they said that the problem had to do with the starter relay and that they had replaced it. They also suggested that my problem had to do with the fact that I had recently installed a non BMW coil from http://www.motoelekt.com/index.html (problem preceded this upgrade). $375 later I was very confident that they had solved my problem. This morning it was a bit chilly and I decided to take the bike to work for the first time since I got it back. To my supprise it had the same wonky start up issue that it had prior to taking it in for repair. Now I'm confused as to how to proceed. I'm afraid to take it back to the shop as I am already over budget on what I can spend for repairs. I know if I take it back to the shop they will say that the part they replaced needed replacing any way and my bill will go up from there. Any ideas on how to proceed on this one? My tendency is to just ignore the problem and accept it as just one of those quirky Airhead thing that you have to live with. 1989 R100RT.

[mrich12000]

So here the deal

Is there cmpretion?
is there spark
is there fuel ?
why in heaven did they say it was a starter realay


take it back scream at the service manager FIX IT!!improper dianosis is a real problem . Have a seanior tech look at it make sure he does the 3 things as I shown in my rant,:stick :stick

Michael .:stick My two cents at todays rate 96.45 can not bad now I think That Gillette trip might be worth it as the dollar may be worth more in 08:clap :buds

[dougfollett]

I apologize, starter relay was my word. I couldn't remember if that was it exactly. I need to check the bill. I just know that when I picked it up they had replaced something to do with the starter. I'm going home for lunch so I'll get the bill and re post with the correct part that was replaced. What ever it was it cost $160. The bike has always run perfectly once it was warmed up.

Hoo

[20774]

So, during the 15 or so seconds, if you were to pull on the throttle cable down where it enters the knurled nut at the top of the carb, does the cylinder pick up and run OK? Seems to me, if you did that you could tell if the problem was electrical or fuel related. If pulling the throttle cable makes everything better, then you need to look at rebuilding the carbs following by a good synch.

Are you sure the enricheners are working OK? Are the enrichener cables properly connected at the back of the carb? Could be the one cylinder is not working because it's running too lean due to a malfunction with the enrichener. Once the bike warms a bike or things move around, it gets the gas it needs to run.

Remove the air tubes leading to the carbs and start the bike. Can you reach in with your fingers and easily move the slides up and will they fall back to rest on their own? What do the back side of the slides do during this 15 second period when running on one cylinder? Do they move up and down together or is one stuck?

I'd try to rule out fuel related issues before I moved on to electrical...

And did they give you back your old starter relay (if that's what it was)? Since it was obviously good, it would be nice to carry a spare on the bike...

[donbmw]

I still think that you have a carb problem on that cylinder. I bought 75 R90/6 in 85 at the time it seem to run fine. When the weather started to turn cooler I had and problem with it starting like you are having. After it warmed up it would run fine. I removed the carbs and found that the jet in the fuel bowl that goes to the enrichment valve was stopped up. Unstopped the jets and went through the carbs have not had this problem again unless I let the bike sit to long with the fuel in the bowls between rides.

Don

[dougfollett]

Ok I have the paper work here in front of me. It was the ignition control unit When I took it in I told them it was probably something to do with the carb and more than likely the enrichener because of the tips I had gotten when I last posted here. I mean isn't the reason you take it to the shop is so that you don't have to figure it out yourself? I'm very interested and capable of working on my own bike but I have some time constraints right now and need to get it fixed before I leave on my trip. Looks like I might have to go as is. I don't think it will be a problem but I just hate to head out knowing there is something that needs attention. I'm going to try pulling on the enrichener cable and see what that does. The carbs were gone through a year ago by the Seattle BMW dealer.

The comment section on my bill states:

"Startup on one cylinder caused by old style ingnition control unit. Replaced control unit. Also found power wire for Hall Trigger pinched under fairing mount. Also found pin in connector for ignition control unit that had become disconnected from the multiplug. Still was making connection but would have come loose soon. Reinstalled connector in multiplug."

[beemerguru]

The ignition control unit will cause intermittent cut outs at speed...not at startup...and it certainly won't get better when the engine warms up.

So completely bogus diagnosis there.

And if you have a Dyna coil from Motorad Electric..they're pretty much bullet proof so that diagnosis was just a SWAG

If it's anything electrical..it MIGHT be a spark plug wire about ready to die - replace with NGK with the correct ohm.

95% probability that it's in the carb. sticky slide because of gunk or just needs a rebuild. Also check the cables for proper adjustment.

The fact that this condition last maybe 15 seconds and only when cold pretty much points to something around the carb.

Doesn't happen when you restart the bike after a short ride does it? Just starts right up with no problems?

[dougfollett]

It only happens on a cold start up. After sitting all night it wants to cough a bit on one cylinder until the other one catches. About fifteen seconds into the start up it smooths out and runs just as sweet as can be. I tried pulling on the choke cables where they enter the carburetor but didn't notice any changes. It is a bit elusive because by the time I start fiddling with it, it has gone away. I replaced the spark plug wires with NGKs from Motorad Electric at the same time I did the coil. What gripes me is that they did $375 worth of repairs and the bike still runs the same way it always has which is perfect except for the wonky start. I'm afraid that if I go back in and complain that they will tell me that the bike needed what ever it was they already did and that anything else will be extra. I can't afford another $400 - $500 shop bill right now.

[Motor31]

Sounds like it might be a slightly gunked up carb. What does the plug on that side look like? Is it black and carboned up way more than the other side, oily, wet or nice tan color. Just because the carbs were done a year ago doesn't mean something hasn't backe dout or gotten either a gas leak (rich) or air leak (lean). Have you checked the fuel filters from the tank for grunge?

If the carb does check out try swapping the spark plugs to the other cylinder. If the missing moves then it's the plug. Also have you checked the plug wires for problems?

[tghsmith]

check the four screws that hold the choke lever body to the carb body, they can be loose and give you hard starting . if the they werent tighten well when the carb was rebuilt they will loosen up, its much easier to suck air than fuel! make sure the gaskets haven't deformed also

[dougfollett]

I just got home and tried starting the R100RT again. I keep thinking it's going to work because I can't believe that they would send me home with a bike that still has the same problem that it came in the shop with. I keep thinking that maybe I'm wrong and it's my imagination but no, it's still missing on one cylinder. I pulled the plugs and one is quite a bit darker than the other. That irks the hell out of me. You would think it was a simple thing to check, especially when I told them that I suspected the problem was somewhere in the carbureator. I'm really pissed now because I have to work out transportation to and from the shop 40 miles away and I'll probably get charged more money. Some how I think they are going to stick me with the cost of the work and parts even though it didn't change the way the bike operated one bit. The bike has always run fine once it is warmed up. If anyone has any ideas on how I should approach the service department about this I am open for suggestions. Not being well versed in BMW shop talk I'm at a bit of a disadvantage here. I know that they are going to try and tell me that I needed the ignition control unit but did I really? Was an upgrade necessary? Apparently not as it still has the same problem. What should I expect from them in terms of remedying the situation? Remove the ignition control unit and fix the carburator? I can't afford another $400 repair bill. Thanks for the support. Mostly I just need to vent.

[tghsmith]

quik advice and questions.
1. are you starting on the side or center stand
2. look at the end of the choke shafts, they have a punch mark towards one side, this should be nearer to the bump on the cast choke body, they can be put in 180 degrees out off position, no choke for start up, choke on when running( black plug )

[Bill Burke]

Three suggestions:
1. Join the Airheads club: http://www.airheads.org/
2. Hook up with some local airheads, Olympia is a big town; and
3. If you know nothing about multimeters, call the nearest independent bike shop and say this:

"Hi. I don't have a multimeter and I wonder if you'd put a meter on my spark plug caps"

If they say yes, take the bike to them, turn the ignition off and ask them to set their meter on the ohms scale to measure resistance. Pull the spark plug caps off of each plug. Have the boys insert the meter probes into the end of each spark plug cap. One probe in each cap. Got a good steady reading on the meter? What does the number read? Have 'em do it a second time. Same number, or close? Good. Write that number down. Pay attention to the meter. Some might read: 22,000 ohms. Most will read something like 22.05K. The K stands for "thousand."
Report that number back here for further comments.

[Pierce]

Weak coil. My R65 did this forever. After I sold it the owner took the trouble to fix this issue, and as I suspected, it was a weak coil. All is well now I'm told.

[RUNAWAY]

My R65 does this also, only when cold and resting on the side stand. When it's on the center stand, the problem never appears.

Not exactly a solution, but it works for me.

[dougfollett]

Weak coil. My R65 did this forever. After I sold it the owner took the trouble to fix this issue, and as I suspected, it was a weak coil. All is well now I'm told.

I replaced the coil last month in an attempt to correct the problem but it continued to do it. I took it in to the BMW dealer and the Airhead mechanic put a new IGN control unit on it as well. Right now I don't know if I am coming or going because for the last two days it has started fine. I guess I'll forget about it for now but for the first two days after I got it back from the shop it was trying to start on only one cylinder and now it's fine. I wonder if the slight rise in temperature around here made the difference? I'm heading over the mountains to Washington Tech day. Should be a good education for me. The gear/tire noise is still driving me nuts. I want some other Airhead owners to listen to it and tell me what they think. That is if I make it over there. Some times I think the bike is going to self destruct it's so noisy.