coils and wires?

[26667]

I've been reading thru the archives and here's what I think I know:

The rough running from idle thru the rpm range (at least up to 5K), back-firing, and fouled plugs (Black wet) is most likely the result of a poor spark and can probably be accounted for by the fact that the spark plug wires and coils are all 30 years old.

If I'm reading stuff that's correct, the best replacement for the coils is oem, (rather than something like the Bosch Blue) but NGK spark plug wires might be an improvement. Or at least a suitable alternative.

I'm gonna try cleaning the connection where the wires connect to the coils Monday, just to see what happens. Then go shopping for new wires Tuesday when shops are open again. I'll be pleasantly surprised if anyone has coils just sitting on the shelf, but spark plug wires might be available.

Whaddaya thimk?

 

[JFDUCLOS]

I'd replace the plug wires before I did anything else. The coils are probably ok.

 

[35303]

The grounded spark plug caps are prone to internal arcing. I also suggest replacing caps and wires first.

 

[FRANKT]

Replace or rebuild the ignition system components one at a time. If your plug wires are old, definitely replace. Your bike originally came with a one piece plug wire including the spark plug connector. No problem replacing with separate plug wire and, for example, and NGK spark plug connector. FWIW, I still have my original stock coils on my '73 R75/5. Another potential problem area would be your carbs. If you don't know the last time they were rebuilt, it is probably time. At the very least, check your float bowl level. The stock fiberglass floats will absorb alchohol in our modern fuel causing them to sink resulting in a rich mixture. Alchohol proof float kits are available from Bing.

 

[sumran]

I replaced my plug wires with NGK and had good results. I have had good feedback from people I trust on the wires. Most suggested coils were likely fine if there was no visable damage. Check all connections at the coil for corrosion.

 

[26667]

What to look for

As always, thanx, you guys. There's a Kawa shop a few blocks from my house and a Honda shop a bit further down the road. Each much much closer than the BMW shop. I thought Tuesday morning at ten when they open I could call or stop by and look for NGK cables.

Since I don't expect their parts guy to be familiar w my scoot, what in particular am I looking for? My bike has an aftermarket electronic ingnition, not points etc.

I looked at Snowbum and he says, I believe, (I'll go back and double check) I want the ones marked "5000?" ohms? (later)I just went back and looked at S'bum and he's saying 500o ohm "caps" Is the cap simply the end of the wire that attaches to the spark plug? Or am i missing something else?

Meantime I'm gonna have another cup of coffee and then take a look and see what I see.

 

[rpeckham136133]

Doubting electrical side of this puzzle

I have been reading through your thread here, and am doubting that your problem is electrical..... The wet fouling of one plug is more likely caused by either carburetion, or an extreme case of valve mis-setting.... You can do a quick check of compression on the offending cylinder, compare it to the reading on the good side, which should tell you about valves. Then go back to the carbs.... the choke mechanism can be disconnected, check the float level, the needle height setting: something is off in that left carb (assuming valve clearance is acceptable)

Assume that engine timing is correct? Backfiring can be caused by seriously wrong ignition timing as well.

Keep us posted!

Bob Peckham
Vero Beach FL

 

[26667]

Oh fer cryin' aye hey!

Thanx, Bob. I believe you're right. I found the float levels were both high (+6-8mm) and uneven from R to L. So I started moving the "tang" on the floats described above and made them incredibly worse. Then better, then worse yet again, and finally pretty darned good. Then buttoned up the garage for the night.

I got ready to head down to Seymour's this morning to install new floats....and it wouldn't start. Not so much as a click from the starter.

I was stunned. I tried to imagine what had happened overnight and first thought I'd perhaps left the ingn tuned to pkg lights and run down the battery. So I put it on the charger and the light was solid green. I was so PO'd I didn't even look at the volmeter to 2ble check. But if the battery's ok, I'm about stumped. I'll take the tank off tomorrow morning and see if maybe I somehow pulled a wire loose while hooking up my tankbag.

I once had a starter relay go in just this fashion though. No warning. Just no go.

My wife thinks this "would make a good second bike." Me? I'm trying to find the humour.

 

[20774]

Do you habitually use the kill switch? Be sure that didn't get knocked into the wrong position.

My wife thinks this "would make a good second bike."

Does that sound like a "free pass" to buy another bike? I'm not familiar with wife-speak, so I can't be sure...

 

[sumran]

Starter relay is a common problem on these bikes. I just went through that. And since mine had that problem, it must be what is wrong with yours.

They are prone to corrosion on the connections of the starter relay. It is a cube relay under the tank. It will pull out easily if the connections are good. You may have to gently pry it out if the connections are corroded.

Check for brake fluid leaks while you are there. If brake fluid leaks or is spilled in that area it tends to run down to the relay and attract moisture.