[Bilgemaster]

I just had a recurrence of something weird I had experienced only briefly a few weeks ago. While riding along happily at about 50 mph the engine started to lope and lose power and then the motor quit. When I pulled over to investigate, the kickstart would kick through without any compression...then a bit...then little or none. Eventually I got it started and limped on home, taking it very easy.

My working hypothesis is that the decompression valve may be sticking or clogged with some carbon or something. Perhaps it is just overdue for some adjustment?

Once home, I spent a few minutes running the engine with a bit of throttle and engaging the decompression lever on and off, hoping to blow out its valve and seat a bit, and sure enough, there's good compression again when I try the kickstart. Does my hunch that it's the decompression assembly getting a little cloggy or perhaps loose on its valve seat sound likely? My bike does run a little rich, though not alarmingly so. But some carbon buildup cannot be ruled out.

I haven't yet pulled the decompression assembly for a looksee and cleaning, but as far as I can tell the tappet pushrods are adjusted tip-top, spinning but with no noticeable upward-downward play. If it were a burned or broken intake or exhaust valve, I doubt good compression would have returned, right?

Any advice or tales of similar experiences and their resolutions would be most welcome...

Original


Bilgey's Extra Crispy

[cyrusb]

What would cause the comp release to open by itself while running? Once the mill is running I can't see how any debris could get under the decomp valve (it's closed). But getting crap under the exhaust valve is possible. Is your upper end still stock (Indian?)

[Bilgemaster]

What would cause the comp release to open by itself while running? Once the mill is running I can't see how any debris could get under the decomp valve (it's closed). But getting crap under the exhaust valve is possible. Is your upper end still stock (Indian?)

I haven't looked at the decomp assembly yet, but I'm wondering if it's been actually closing the whole way all along. The fact that I was able to run the engine with the decomp valve open today with just a little extra throttle gives me hope of an easy fix. I'm not exactly eager to pull the head. Another thing that comes to mind is that just awhile back, a month or so ago, it was taking a bit longer than normal to stop the engine with the decompressor, which is what I usually do. It would just keep churning along for half a minute or so with no extra throttle, though lately this hasn't been the case. I'm sort of wondering if the idle's just been set all along to compensate for a leaky decomp.

[ace.cafe]

Maybe the head needs a decoke?

[cyrusb]

Maybe the head needs a decoke?

That sounds about right ! After reading Bilgmasters second post, with the mill still running with the decomp valve open, it must be that. So I guess it's still stock Indian? With lots of miles?

[Bilgemaster]

That sounds about right ! After reading Bilgmasters second post, with the mill still running with the decomp valve open, it must be that. So I guess it's still stock Indian? With lots of miles?

I've no idea what number owner I am, but guessing the guts are still stock, with just shy of 14,000 miles on her, about 10,000 of which are mine.

I guess I'll be hauling out the Harbor Freight Inspection Camera boroscope kit for an intimate looksee into The Great Within. I'm REALLY hoping I don't need to pull the damned head off, but I guess it is the right time of year for it, if it comes down to it. Good riding days will be few and far between until the daffodils bloom again.

[axman88]

Carbon flake on the exhaust valve seat?

I was experiencing a an issue with what I thought might be carbon on the valve seat some months ago.  Mileage on the engine was less than 5000 but the decomp. cam on my 2012 UCE had gone problematic and noisy, then failed outright in the active position.  After I fixed that, I noticed a high frequency "frying" sound in the exhaust note that I hadn't previously.  Before taking off the head, I tried the Seafoam ingestion treatment and it did seem to improve things quite a bit, so that might be worth a shot.

I put about 4 ounces of Seafoam into a trigger pump oil can, removed the air cleaner and intake hose, and started squirting the juice into the throttle body with my left hand while keeping the engine running with my right hand on the throttle.  As I neared the end of the squirt can full, I increased the dosage until it choked the engine, then let it sit for a half hour before starting and running the engine.  It really seemed to help and I no longer feel any need to take the head off.

[fernf5]

On page 86 of the Snidal manual he mentions removing the exhaust pipe and looking at the deposits on the exhaust valve to get an idea of the extent of the problem.
Don't know yet how this will turn out on my "new" RE bike but when I fill up with gas I put a cap full of MMO in. On the old boxer sidevalve I have it's recommended to remove the head every few thousand miles to decoke it. I've used the MMO pretty faithfully and when I removed the head the last couple of times I found no built up carbon deposits at all.

[Bilgemaster]

Thanks axman88! Lazy fatass that I am, I do like the idea of trying the aggressive SeaFoam chemical treatment and soak before undertaking major surgery. As it happens, last month I had the bike on a SeaFoam regimen just in the fuel--a couple of ounces per tankful until the bottle was done. I am now wondering if this may have dislodged just enough crud in the combustion chamber to foul up the decompression or other valves. I normally run just an ounce or so of Marvel Mystery Oil per tank in the ethanol-free fuel I use. Ironically, it seems, I use these additives to try to keep that combustion chamber tidy.

When it warms up a bit later, I'll likely be taking a closer look in there. In the meantime, I'm gonna go grab a can or two of SeaFoam and pick up my new $99 Craftsman tool kit special at the local Ace Hardware.

[fernf5]

Sorry, a case of preaching to the choir on the MMO. Fingers crossed for you....

[cyrusb]

With the amount of oil most stock Infields burn I'm not surprised about the coke problem. Odd that Japanese machines and any other modern bikes do not have this problem. Mine shows no smoke during a day ride, but at night with the lights of a car behind, the oil smoke can be seen.

[ace.cafe]

Most Bullets have worn valve guides, and even on the models with stem seals, the seals could be shot.

The valve gear on stock Bullets is poor, and rocker geometry is terrible.
Earlier Bullets didn't even have stem seals. Side thrust on the valves from poor rocker geometry wears out the valve guides fairly quickly.

On top of that, the factory piston rings are "lawn mower grade", and pass a lot of oil compared to modern designs.

[Bilgemaster]

I didn't have a lot of time to tinker today, but I did manage to pull the spark plug and plunge the business end of my Harbor Freight Inspection Camera down in there for a looksee. As you can see from the attached photos, the plug looks pretty reasonable, but then it's only a few weeks old. As for the top of the piston, I'd say it's about as coked up as Steven Tyler's nasal cavities in the hotel room after a '70s Aerosmith concert. One imagines the head and valves must be similarly grimy.

So, for the time being I got a spray can of SeaFoam with one of those clever tubes for injection into an intake manifold vacuum hose or port and one of the bottles too. I sprayed just a bit into the spark plug hole, buttoned it back down and kicked it over a few times. I did this twice, the second time with the decompression lever engaged in order to let it get all up in there. Now I'm gonna just let it marinate until nicer weather is said to return in a couple of days. I also dumped about 2/3 of the bottled SeaFoam into the fuel tank as a sort of shock treatment. Lots of folks do this as a quick Spring Shock Cure for the "ethanol snots," stale crap fuel having often mucked up the system over the winter. I imagine a little overdosing might also do my combustion chamber the power of good and perhaps help trim down at least a few of those black stalactites.

On Wednesday or Thursday I'll pull the decompressor assembly off to see what's going on there, clean it up, adjust as necessary, re-install it, and then fire her up. Once she's warm, instead of pulling the air filter assembly, I might just rig up some reasonably airtight hose from the spray can SeaFoam into the little Pulse Air Valve vacuum hose port on the underside of my intake manifold. Bit by bit I'll empty the can and then stall it with the stuff for a good hot soak for a bit. After a quick run I'll then see how she looks.

Plan B is that I might break out my little handheld steam cleaner for drapes and upholstery and such, jam its little nozzle into that PAV vacuum hose tube off the intake manifold, and just let it and the bike run together for a bit. Nothing gets a combustion chamber so squeaky clean as water injection.

Plan C is to probably repeat Plans A and B...maybe a couple of times.

Plan D is to be a man, and pull off the damned head already.

[ace.cafe]

See all those little pockmarks on the piston crown?
Every one of those is from a "ping"(detonation) event.

[ROVERMAN]

I see a de coke in your future Bilge! I had an exhaust pushrod come off during riding, might of over revved it a bit, which effectively dumped most of my compression. But it did make it to work and i fixed it in 20 minutes, loved my old Iron Barrel! Good luck.
Roverman.