A couple of thoughts come to mind:
1.) What kind of condition is the battery in?
2.) When's the last time the bike had a valve check and adjustment?
3.) What kind of condition are the spark plugs in?
4.) How do the plug wires look?
5.) What kind of condition are the intake boots in?

Just a few thoughts.

 

Thanks for the quick response.

1.) What kind of condition is the battery in?

- Brand new in April this year.

2.) When's the last time the bike had a valve check and adjustment?

- Late August 2012 they were checked/adjusted at 34,000 KM. Currently sitting at 51,000 KM.

3.) What kind of condition are the spark plugs in?

- Both black on top. Front plug is black and dry. Rear plug is black and slightly oily.

A couple of thoughts come to mind:
4.) How do the plug wires look?

- Will check when I get home tonight.

A couple of thoughts come to mind:
5.) What kind of condition are the intake boots in?

- Will check when I get home tonight.

 

Also worth noting, I took the air box off and it was damp on the bottom. Not sure if oil or gas as I was not paying attention. Will double check that tonight.

 

When you describe the oil around one of the plugs, it sounds like the spark plug hole gasket in that cylinder needs to be replaced - hence the oil around the threads and electrode of the spark plug wire.

Have you seen oil in the airbox by any chance?

 

Airbox was damp, yes. Did not look to close though, will double check tonight.

 

There was oil in the airbox.

I noticed the carb was not very secure, boot was not very tight.
Took the carb off completely to take it apart and clean it.
Winter plan was to reject the carb, may as well start now.

Picture of spark plugs attached.

Plug boots and wires look good. Not cracked, split or loose. No oil or other materials on them. Clean and dry.

 

Looks like the bike's been running rich, or possibly low quality fuel. Not a lot to do there except get fuel from a different gas station.

As for one cylinder completely shutting down, the only suspicion I have now is that the coil isn't delivering spark to the cylinder. Either that, or the plug wire is corroded internally, or possibly broken.

The loose intake boot would make the bike run lean more than anything. Potentially could keep the bike from running right, but it would have to be sucking in a LOT of air on that one cylinder to shut it down.

At this point, though, it sounds electrical. If the coil is OEM, that could be the culprit. If the plug wires are OEM, then they could be brittle and possibly have broken internally. A multimeter would answer the question pretty quickly - take one lead, touch one end of the plug wire and touch the other one to the opposite end. If there's an excessive amount of resistance, then that would be what's going on.

As for checking the coil, this link gives a pretty decent rundown: How to Test a Motorcycle Ignition Coil | DoItYourself.com

 

The loose intake was more of a "hey, look at that" type of thing.

Carb has been cleaned. Was not horrible, but not sparkly either. The slide and needle were pretty black though.

Went to get new plugs and all 3 of the shops I went to had none. 1 does not carry them at all, the other two carry a few but were sold out. Trying a fourth shop tonight. Once I get new plugs I will start testing the electrical.

NOT a fan of anything electrical, so hoping for the best and simplest solution.

 

On an 800, fuel taps are very prone to leaking. When that happens, the fuel tends to flood the carb when sitting and upon start, it fouls the rear plug.
Rebuilding the fuel tap is a hit and miss operation with most getting replaced with new for a permanent repair.

 

I have had the tank off many times with nothing more than a drop of gas spilled. Yesterday, I smelled gas. I have the tank sitting on an old tire at the back of the garage. I lift it up and see the ground is wet. 10 minutes later, I get an email alert about a reply to this thread. Reply was about a fuel leak.

Freaky!

Will order a new petcock before I put it all back together. Crossing my fingers that a clean carb, secure boots, new plugs and non-leaking tap will cure the issue and get it running right.

 

How much of a leak is too much of a leak?

 

No love.

Carb reassembled and reinstalled. Clean and tight.

New spark plugs installed.

Tank back on.

Full choke and start it up. Runs normal for a minute then backfires. I reduce the choke, it pops and dies.

I pull choke and start it again and it is back to sounding terrible. Really rough.

Checked the pipes and both are hot, so both cylendars are firing

Here is a video if that helps.
https://www.dropbox.com/s/wvj09ixjmk6lb5i/VID_20151103_200857.mp4?dl=0
Thoughts?

 

1. Did you replace the fuel tap?
2. Check the valves. 800's are very fussy about valve adjustment with ugly results if not checked regularly.

 

1. No. Very small drip from tap. It will be replaced, but will take a few weeks to get the part (not available locally).

2) Never checked valves before. I have the manual, will look into it and see if I can do it. They were checked/adjusted at the the 30,000km or so point. Current just over 50,000 km.

Thanks

 

I would check the valves before doing anything else because if you have a tight one, you can play with everything else until the screws are worn out and get nowhere.
Also, if the fuel tap is dribbling when the bike sits, it will cause problems too. If bad enough, it can fill your crankcase with gas....not a good thing.

 

I will start on the valve check tomorrow evening. Running tight on time this week.

Fuel tap can be ordered on Friday, delivery in a week or two. I can get a rebuild kit in 3-4 days for 1/3 the price. Thinking it is worth the extra time/money just to buy a direct replacement.

Thanks

 

. Thinking it is worth the extra time/money just to buy a direct replacement.

Thanks

Your thinking is sound. The rebuild success rate is pitiful.

 

Another small item to check= if you have the usual resistor type spark cap and they are originals- do an ohms test on them after removing them. They should be about 5k ohms. I've seen these fail outright and cause poor running.

 

Plug boots are not original. We changed about 20,000 km ago. But, cannot hurt to check anyway.

Thanks

 

Took the tank off last night and start removing everything to do the valves.

1) Yep, tank leaks. Far more than I originally thought. Will order a new petcock when I determine what shims I need so I can order all at once.

2) Front spark plug still looks brand new. Rear plug was slightly wet and slightly black.

Bike was running for all of 4 minutes since installing new plugs, so I assume my issue is with the rear jug. Will go through both obviously, but I assume I will find an issue back there.

 

See second sentence, post #10.

Replacing fuel tap may fix your plug issue. Be sure before taking anything else apart.

Post back with results.

 

Will do, however it will be a week at least before the new tap arrives.

From what I have read about the valves though, I should check them since it has been 20,000km since last checked/adjusted.
But I will do the tap first and move on from there.

Winter has arrived, so no big rush to get it running today or anything.

 

Petcock arrived and has been replaced. Chnaged the oil/filter. Fresh premium gas. The new spark plugs. Cleaned the air filter.

Fire it up and it is okay while it warms up on choke. Sounds a little...off but not outrageously so.

Twist the throttle and it hesitates.

Turn off choke and it dies as soon as I twist throttle.

Start again on choke, go play with dog for 2 minutes, come back and turn off choke. Sounds rough on idle but does not die when giving throttle. Sounds very, very rough when giving throttle. Not right.

Engine has an odd sound too when idling. Not sure how to explain it, but kind of like TV Static if that makes sense.

Too a video of it, will add it when I can upload it.

 

Video is here, if it helps. Crappy video, not one of my good skills.https://www.dropbox.com/s/v2shx3ai79id90e/20151115_103127.mp4?dl=0

 

To recap:

1. The fuel tap has been replaced.
2. The valves have been checked.

Is the above correct?

 

1. Yes. Brand new OEM one was installed. No leaks at all now.
2. Valves have not yet been checked. Replaced tap first, as suggested.

Will be doing valves next.

 

Good on the fuel tap.

Post back when valves are done.

The basics have to be in place and sound to avoid any tail chasing.

 

As an add, after valves are done, check/clean plugs as required and then try running again.

 

Only had time for the front jug. If I understood correctly, 2 are okay and 2 need replacing.

 

It appears that you have a single ohc with rocker arms. I can't see from your pics, but generally the rocker arms have an adjustment above the valve. I don't think it has shim adjustments. SFAIR is right it will not run properly with those tight inlet valves. I would do the back one too.

 

800's use shims.

 

Sorry, should have clarified. That engine photo was not mine, googled it. Though it is the same engine, just out of the frame so easier to point out items.

I remeasured the front cylinder clearance (always good to recheck) and discovered I was wrong on all 4. No idea how, I checked six times. But rechecking all now, with no changes, it is different.
:/

Front cylinder:
Exhaust 1: 0.18mm (20 will go but very tight)
Exhaust 2: 0.18mm (20 will go, but very tight)
Inlet 1: 0.05mm
Inlet 2: 0.03mm (a little tight but smallest I have)

Rear cylinder:
Inlet 1: 0.09mm
Inlet 2: 0.10mm
Exhaust 1: 0.23mm
Exhaust 2; 0.23mm

Not at all what I was expecting to be honest. All 4 front need swapping out. 1 rear needs swapping.

Should I replace the .10mm on the rear while I am at it as preventative maintenance?

Also, after I removed the rear cover I noticed it was quite dirty along the seal. Almost a rusty colour. The front however is very clean and clear.

 

When adjusting valves, better to set to the loose side rather than tight.

EG. If spec calls for .012 and all you can get is .011 or .013, go for the .013

 

Thanks. Done for the night. Below 0 celcius in an unheated garage, working with itty bitty little oily metal disks teaches me many curse words.

Will order new shims soon. Will post back when all is back together.

Thanks.