Author Topic: Think my #4 ring is JUST FINE and it Looks to be and Electrical Problem. (Read 3590 times)

UnCrash · « **on:** June 01, 2009, 06:19:51 PM »

I worked a bunch on my K6 this weekend.

Mounted my freshly drilled rotor, new brake pads, bled brakes, adjusted rear drum, re-made my new custom clutch cable as it didn't fit (but was too long fortunately).

Took it for its first real ride today at lunch and got the brakes bedded in and could get a little squeal from the front tire on hard braking. Life was good.

45 minutes later I'm approaching work and stop at a red light. Upon acceleration I notice that uncomfortable sound and lack of power that come with a loss of a cylinder. I lost 2 and 4 last year while riding due to an ignition failure so I know that sound. I turned into work and thought better of parking it and drove the 10 minutes home.

Blue smoke at my first intersection. The bike (76 CB750K) was definitely shy of power but had plenty enough to get me home. I thought I heard tiny metal bits a couple times but the mind can play tricks on you when you're paranoid.

When I pulled into the garage I touched the headers. All were hot except #4 which was warm. I pulled the #4 spark plug and it was oil fouled. I cleaned it off and put it back in. Bike fired right up and sounded ok for about 2 seconds then started sounding anemic. All other plugs were dry and slightly brown when pulled. #4 has great spark when the plug is in the cable and laying against the engine.

I have a bad and sinking feeling that my #4 needs new rings.

I've done a little searching and have determined that a leak down test is optimal, but a wet/dry compression test would let me know a lot.

I think I can borrow a compression tool from the auto parts store to get a sense of things, but my gut tells me this motor is coming out before I'm riding again.

WHALEMAN · « **Reply #1 on:** June 01, 2009, 08:02:40 PM »

I always thought ring wear was a slow process not an immediate light switch type of failure. I would look for an ignition problem specifically a burnt or shorted out plug wire, a internally corroded resister inside the plug connector, or a bad plug. Try switching 1 and 4 plug and wire. The tiny metal bits could be the sound of a shorting plug wire as the sound is audible. Dan

andy750 · « **Reply #2 on:** June 01, 2009, 08:56:39 PM »

Ben,

It could also be a worn/leaky valve oil seal. Same thing happened to me in the time frame you describe. Only problem was, I was in Germany, 1000 miles from home. However the bike made it home on 3-cylinders albeit a little more slowly

. In case, you might eventually get oil coming out of your exhaust. Either way only thing you can do is pull engine and replace.

good luck!
Andy

new2novas · « **Reply #3 on:** June 01, 2009, 09:00:54 PM »

i agree with andy, sounds like a valve seal and or guide sucking oil down in....a bad ring wouldn't really pull oil in there like that, rather, with a bad ring you would have a bunch of crankcase pressure....

WHALEMAN · « **Reply #4 on:** June 01, 2009, 09:09:59 PM »

I do not think a clean plug can oil foul in 2 seconds. Can it? Dan

new2novas · « **Reply #5 on:** June 01, 2009, 09:16:21 PM »

i was curious as well but he really didn't mention if he pulled the plug again, just that it started to run like crap again.

UnCrash · « **Reply #6 on:** June 02, 2009, 03:20:14 AM »

The second time I pulled my plug it wasn't completely oil fouled but was a little oily and smelled of gas. But you're right, I pulled it because of how the bike was running. It seemed relatively normal for the first couple seconds but then started sounding a lethargic at 3K rpm.

Another symptom I had when riding after the problem was evident was backfiring. Strong backfires on gear change and a bit of exhaust popping when pulling away from a light.

I was riding higher in the RPM range than I usually do, and having lots of fun accelerating up to the red line on my ride. I peaked at 8K or 8.5K but was careful not to go higher. I don't usually push the motor this much....

Anyway, later when I pulled the plug the second time, I cleaned it and put it in the plug wire and laid it against the engine and it has a strong blue/white spark. These plugs have about 1,000 miles on them.

Andy's suggestion does seem more plausible than the ring (I don't know a ton about motors). I do believe that a leak down test will help to determine this as well right?

I know I can fire the bike up and drive it to the bike shop for the test.

WHALEMAN · « **Reply #7 on:** June 02, 2009, 03:56:48 AM »

Did you swap #1 and #4 plug and wire? I mean just pull out the 2 plugs and just put #1 wire on #4 and #4 on #1. These fire at the same time and it will not hurt anything. Dan

UnCrash · « **Reply #8 on:** June 02, 2009, 04:37:40 AM »

Quote

Did you swap #1 and #4 plug and wire? I mean just pull out the 2 plugs and just put #1 wire on #4 and #4 on #1. These fire at the same time and it will not hurt anything. Dan

Hi Dan,

I agree it's important to be methodical. I haven't done that particular test and will do so tonight.

Thanks.

kghost · « **Reply #9 on:** June 02, 2009, 04:41:00 AM »

With a wet gassy plug and the popping you described.....

You may be running too rich on #4.

I think before I'd pull the engine I'd check a few things......

Float level being the first.

Idle screw settings

Make sure the sync didn't wander off.....

new2novas · « **Reply #10 on:** June 02, 2009, 05:59:07 AM »

i was going to say the same thing, are you sure its oil and not fuel....smell it, or try and light it on fire....there is a big difference in the route you should be taking depending, especially the sync, just do a quick test with a drill bit

UnCrash · « **Reply #11 on:** June 02, 2009, 09:56:33 AM »

Ok, maybe I'm being a fatalist

Thank you guys for your logical test progression advice.

Symptoms / evidence experienced --> sudden change in behavior from running great to running poorly. Poor acceleration. Bluuuuuuuggg sound in the exhaust. Blue smoke at a couple of my stops. Strong backfire when changing gears. Bike was still capable of 60 mph, just needed to ease into it. Plug #4 seemed oil fouled when first pulled. I cleaned it, put it back in and the bike sounded normal at fire-up but within a few seconds started to gain the bogged down sound especially as I raised the RPMs. I shut the bike off with 30 seconds, and pulled the plug again. It did smell like gas. #4 pipe was very warm, but I could hold my hand on it, while all other pipes were too hot to to more than just quickly touch.

So in the garage tonight I'll:

1. Swap plug wires between 1 and 4
2. Pull the carbs and have a look see. (carbs were bench synched 2K miles ago and vacuum synched last week)

kghost · « **Reply #12 on:** June 03, 2009, 02:07:37 PM »

Quote from: UnCrash on June 02, 2009, 09:56:33 AM

Ok, maybe I'm being a fatalist

Thank you guys for your logical test progression advice.

Symptoms / evidence experienced --> sudden change in behavior from running great to running poorly. Poor acceleration. Bluuuuuuuggg sound in the exhaust. Blue smoke at a couple of my stops. Strong backfire when changing gears. Bike was still capable of 60 mph, just needed to ease into it. Plug #4 seemed oil fouled when first pulled. I cleaned it, put it back in and the bike sounded normal at fire-up but within a few seconds started to gain the bogged down sound especially as I raised the RPMs. I shut the bike off with 30 seconds, and pulled the plug again. It did smell like gas. #4 pipe was very warm, but I could hold my hand on it, while all other pipes were too hot to to more than just quickly touch.

So in the garage tonight I'll:

1. Swap plug wires between 1 and 4
2. Pull the carbs and have a look see. (carbs were bench synched 2K miles ago and vacuum synched last week)

I think theres hope......oil smoke is usually whitish grey in color.

Fuel tends to be the bluish black your describing.....

I think you have a sick #4 carb

UnCrash · « **Reply #13 on:** June 03, 2009, 08:01:23 PM »

Ok I'm an overly pessimistic idiot I guess.

Tonight I followed the game plan I outlined earlier I pulled the carbs and gave them a look see... They were off a little so I did a bench sync for good measure (Thank you FAQ) and put them back in. Same condition existed, #4 pipe stayed cold.

At the suggestion of Whaleman (Dan) I swapped #1 and #4 plug wires. Was promptly THRILLED to find that #1 stayed cold!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Full of piss and vinegar, I grabbed a spare set of coils off my shop shelf, screwed on the plug caps, connected the wiring, and fired the bike up.

She sounded good! All 4 pipes promptly warmed up and got too hot to the touch!!!!!!!!!!!!!!

HALLEFREEEEAKINGGGGGLUUUULIIIIIAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!

Thanks for the methodical reasoning Dan.

Much appreciated.

I get to ride to work tomorrow, and the next day.... until my next failure.......

kghost · « **Reply #14 on:** June 03, 2009, 08:03:47 PM »

Send Dan a six pack

gilesclement · « **Reply #15 on:** June 03, 2009, 08:05:16 PM »

I love success stories! Wish I could figure out my f***ing brakes now.

JBMorse · « **Reply #16 on:** June 04, 2009, 04:16:53 AM »

So when a coil fails, it can be only one side? I had a cylinder not firing and I ruled out coils because I thought I'd have two not running if the coil was bad. Still haven't fixed it. I tore down my carbs and rebuilt them, have to put them back on tonight after work and see if that was it!

UnCrash · « **Reply #17 on:** June 04, 2009, 04:42:16 AM »

Well I may have spoken too soon.

#4 didn't want to wake up this morning. It was fine after the coil swap. I fiddled with the spark plug cap, got on and it seemed fine all the way to work.

I need to do further work tonight, but this may boil down to a poor connection in the spark plug cap on #4. They were purchased new last year.

Tonight when I get home I'll snip back 1/4" of the wire and put it back on.

This would explain poor firing, and when I pulled the plug and laid it against the engine I may have achieved a good contact between the plug and the cap.

Dunno.

Sheesh.

At least I rode in to work.

Still more checking to do, but am thanking God it isn't a motor problem.

Otto · « **Reply #18 on:** June 04, 2009, 05:22:55 AM »

Ben,

I have a couple sets of coils off running bikes. Come and get what you need.. I'll be home tonight.

bc

UnCrash · « **Reply #19 on:** June 04, 2009, 08:03:05 AM »

Thanks Bob,

These coils are good. I've got a spare set of plug ends I'll try for #4.

It would be good to catch up sometime regardless. Maybe a beer or two is in order.

Cheers

Otto · « **Reply #20 on:** June 04, 2009, 08:09:13 AM »

I always have cold beer!

bc

ev0lution7 · « **Reply #21 on:** June 04, 2009, 09:37:46 AM »

i've had the exact same prob on my #4 it turned out to be a bad connection on my plug cap... so i trimmed 3/8in off and really wacked that thing back on the threads for the plug cap and it seemed to do the trick now the bike runs GREAT! and smooth just did a 900 mile trip to Winemucca, NV !!!

UnCrash · « **Reply #22 on:** June 04, 2009, 10:09:10 AM »

Quote

just did a 900 mile trip to Winemucca, NV !!!

Sweet!

WHALEMAN · « **Reply #23 on:** June 04, 2009, 04:28:11 PM »

Try new plug ends from Dennis Kirk.com. The plug ends have a resister inside them. If you smash one open you will see the resister looks like a solid fuse. The connections to this fuse like resister can corrode. They are cheap. Dan

UnCrash · « **Reply #24 on:** June 04, 2009, 06:03:18 PM »

Thanks Dan,

These plug ends are only 1 year old. The problem seems to be in the cable end. I cut 1/3" off the end of #4 and all is good now.

Thanks for the positive guidance!

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Author Topic: Think my #4 ring is JUST FINE and it Looks to be and Electrical Problem. (Read 3590 times)

WHALEMAN

WHALEMAN

WHALEMAN

gilesclement

ev0lution7

WHALEMAN