So.....I'm thinking of changing the rings.

PRM068 wrote: Thanks Patton.

I have a lot to learn about bikes.

In any case, i just put in 4 brand new plugs.....bike is running good again, but I've no doubt the problems will arise again and the plugs will need to be replaced. Never mind. I think I'll just keep riding it.

I am going to trace where that "spliced" red wire is going and why it's there. It terminates at some relay under the seat which doesn't look standard (or is it?). The red wire from the relay is the one which goes to the right side coil.

Sounds like the infamous coil mod which is a band aid to avoid fixing the real problem on a bike's wiring.

PRM068 wrote:
Can I just ask....what do you think of those compression readings ?

If 100 psi reading is accurate, that's very bad.

I did check it a couple of times and the same reading came up, but I plan on doing it again shortly.

As mentioned I put in a new set of plugs - running good. Did about 60 miles today and it wasn't too long before the engine feels funny again.....almost like there's a miss, and I feel like it may even be pinging a little (??? knocking...???).

When I returned from my ride I left it running and pulled the plug caps off to see how it effected the engine....and there is strong spark from each cap to the plug.

Pulling No. 1 - engine shakes
Pulling No. 2 - hardly any change to engine....very minor
Pulling No. 3 - does effect engine...more than 2, less than one.
Pulling No. 4 - engine shakes.

Pulled the plugs out to see the condition - see the pictures below. No.1 is perfect......No. 2 (the problem cylinder) looks oily and moist, very black.....No.3, a little dirty, but almost as good as No.1.......No. 4 - perfect, like No.1.

What stuns me is that the bike - whilst obviously "losing" a cylinder - runs very stromg. It's just that you can feel something isn't right.

Peter

PLUG NO.1





PLUG NO.2



PLUG No.3



PLUG NO.4

Well, after everything (and mostly due to my inexperiencce with bikes i guess), it would seem that the problem I have is most likely due to valve adjustment.

Talking to my mechanic yesterday and today......compression in engine is good, so I decided to eliminate a possible fuel problem. Seems the oliy plugs are in fact wet fuel plugs and so, I decided to pull the carbs offf for a look at No.2.

There wasn't too much wrong, in fact if there was a blocked jet or anything I cleaned the whole lot out and disassembled it all, cleaning it, and put it all back.

Same problem....bike runs decent, but could run better. Still lots of power but - if you pull the plugs off all the cylinders the engine will shake EXCEPT with No.2....the motor just purrs along and doesn't change at all.

It was like the cylinder wasn't firing at all. So we disconnected the No.2 Plug, and took it to 3500 revs.....when the plug is replaced /removed there is a bit of a change. Came to the conclusion I probably have a valve out of whack allowing too much fuel through.

So that's my next play. Never done valve adjustment before, so God only knows how this will go with the damned shims etc.

The funny thing is......this bike runs really strong, and it would appear to be doing so on only 3 cylinders. I can't wait to get it running right.

Peter

Did you try swapping the coils to see if the problem stays or moves?

Try the pdf service manual in my signature, it is the correct one for your bike.

Yep....just switched them over now - no change.

This process of elimination thing is really dragging on. Quietly confident it's the valves. Having never done it before I'm hoping I can "wing it". Been reading the manual and seems straight forward enough. Just waiting on some gaskets i ordered from Z1.

Peter

One bad plug will cause both cylinders on that coil to suffer. It does look as though you replaced them recently, but when you swapped coils did you replace that one fouled plug?
It could be an issue with that carb. Check your fuel level with a clear piece of tubing attached to the drain and held up along the carb body. Drain open and petcock on Prime. It is explained in the manual. Also make sure the Choke is closing completely, etc.

You likely have a vacuum operated fuel valve/petcock. Remove the vacuum line and plug it. Replace the #2 spark plug and with the fuel selector on PRIME ride it and see if that fixes the problem. The diaphragms in the fuel valve can rot, allowing fuel to travel down the vacuum line into the #2 cylinder which causes it to flood out. Another possibility (depending on the type of carbs you have) is a rotted diaphragm in the accelerator pump on the bottom of #2 float bowl, with a similar scenario to what I described above. Took me a solid year to discover that on my 650. These are simple things that get overlooked and can cause the symptoms you have described.

Hey guys,

well.....I've gone from jubilation to sorrow in one short ride.

I went outside and disconnected the hose going to No.2. Plugged the valve and fired her up. She sounded fantastic and felt great through the throttle. i thought "Surely that can't be all it was?". I even pulled off No.2 plug and it actually made the engine vibrate - HAPPY DAYS.

So, I took it for a ride - very smooth, and accellerated great. Came home.....thought I'll pull the plug and see if it still effects the engine. Nothing happened. It was the same as before. Then I realised.
Earlier today I installed a new spark plug - the one that fouled earlier but still a new plug and I simply gave it a good clean with carby cleaner. That's what it must have been. Sorry guys.

No doubt it'll start fouling again soon.

Peter

Did you check your Fuel Level in your carbs yet? Might be to high, causing the fouling. Float Valve Issue, Or leaking float? Do you get any fuel out of the overflow tubes?
Something could be blocking the Air Jet Circuit, Air Filter coming apart or some other object. These jets are for Air, and are located in the Intake of the carb, two- one one each side in the bore of the small tube looking casting.

Just woke up, and walked outside to find a little piece of plastic tubing and one of those little bleeder valves from a "one man brake bleeder Kit"

Just quickly, I stuck the tube on the drain of the carbies (1 and 2)

No 2 does look a fraction overfull. I'm going for a ride today, but I think I'll sit down and do a measured test later today. I really hope this is nothing more than a float problem - that is what this test indicates.....right ?

Peter

Hey guys....well....what a fun week i've had.

Decided to take the bike for a ride a few days ago - regardless of No.2 not working properly.

So, I'm flying along and the bike is running a little worse than I'm used to - like I had an exhaust leak or something. Then, all of a sudden ....."BANG"..... I nearly had a heart attack. The engine ran like a dog and I couldn't pull over quick enough.

Engine still running (badly), I can see that No.3 plug has blown clean out of the head - stripped all the thread and hanging by the high temnsion lead. I stupidly picked it up.....you can guess what happened. I didn't want to, but i shut the motor down. i was in the middle of nowhere with the No.3 plug blown out of the engine....what to do ?

I grabbed a piece of old timber by the side of the road and stuck it between the plug and the fuel tank, hopeing it'd be enough to keep it in the engien to get home - it did. I rode for 20 minutes with No.3 plug being held in place by a bit of wood.

Fast forward......I now have a new helicoil in No.3. Bike starts better and idels better - I reckon there's always been a bit of a leak because the thread in No.3 was so poor. BUT.....I also still have No.2 playing up....not working basically. I took the engine cover off and checked valve clearances - all looks good and within the specs (0.05 - 0.15).

Whilst it was off I also cleaned that air valve thing which was pretty gunked up, and tried cleaning the passages and reeds. My No.2 still doesn't want to work. If i put a brand new plug in it seems to work better for a while, but eventually fouls up. I have swapped the coils and leads, and pulled the carbies apart twice - I know I'm missing something. I reckon this is an easy fix, but being a backyard hack I'm missing something simple. Motor still has heaps of power (effectively a 750 with one cylinder down).

Peter