[mattsz]

Ok, time to put more thought into my pinging problem.  2011 B5, just over 7000 miles.

I'm not mountain climbing here; I'm talking about a fairly gently grade which my bike can usually handle easily in 5th gear at 55mph on my commute home from work.

My latest ride of any distance found me trying to keep up my speed on long, gradual uphill grades such as described above.  5th gear can't handle it without pinging, so now I'm in 4th gear doing 55mph with the engine spinning just over 4000 rpms, and it begins pinging there, too.  It's a relatively cool day (60℉), but the engine is hot, because it's been pushing me along for the past hour in the 3000's rpm range.

The pinging was more common before my decomp was fixed, but it still happens occasionally, when the bike is hot.  Never happened below 5th gear, though, until just recently.

Can there be any explanation other than excessive carbon buildup?

[ace.cafe]

Heat is a big culprit for pinging.
But it could be carbon getting hot and acting like a glowing ember inside the chamber somewhere.
It could have something to do with the ignition timing. Maybe the crank position system might be a little off adjustment, giving too much advance?
Could be a little lean?

Might try the next colder heat range plug, and see if that helps anything.
Also might try the next higher octane grade of fuel.

[AussieDave]

Mattz , I recommend de-carbonising sooner rather than later. I found flakes of carbon in the filter chamber during my rebuild which may have been a contributing factor to the big end failure. I didn't find an actual blockage but the potential was definitely there. And carbon hotspots can cause early firing....

[Arizoni]

mattsz
It's time for you to stop buying the cheapest gasoline you can find.

Start buying the highest octane fuel that's available at your local pump.

IMO, with its 8.5:1 compression ratio, made for running on questionable octane Indian petrol, a 90+ octane fuel should never ping in your Royal Enfield.

[mattsz]

Heat is a big culprit for pinging.
But it could be carbon getting hot and acting like a glowing ember inside the chamber somewhere.
It could have something to do with the ignition timing. Maybe the crank position system might be a little off adjustment, giving too much advance?
Could be a little lean?

Might try the next colder heat range plug, and see if that helps anything.
Also might try the next higher octane grade of fuel.

It's definitely related to how warm the engine is.  Does that change your position on the possible timing issue?  I'll have to look into how to check the timing.

Not sure what to do about running lean - but the plug looks normal.

Could try a colder plug.

Mattz , I recommend de-carbonising sooner rather than later. I found flakes of carbon in the filter chamber during my rebuild which may have been a contributing factor to the big end failure. I didn't find an actual blockage but the potential was definitely there. And carbon hotspots can cause early firing....

Dave... filter chamber?  I don't know what that is.  Could you elaborate?

IMO, with its 8.5:1 compression ratio, made for running on questionable octane Indian petrol, a 90+ octane fuel should never ping in your Royal Enfield.

I hear what you're saying, but really, in my (and many others') opinion, giving the considerations you stated, our 87 octane fuel should never ping, either.  Of course, higher octane is worth a try, but if I'm the only one of all the 87 octane users out there complaining about pinging...


I believe that I went through my first 4000 miles with a malfunctioning decompressor, which was activating the exhaust valve for much longer and at much higher rpms than was intended - I've been led to believe that this condition could cause carbon issues, and other valve problems.

I'm about ready to put the bike to bed for the winter anyway - my long rides are done; it's just commutes to work now or short rides for a few more weeks... where the bike behaves - so I'm wondering about whether it would make sense to plan to lift the head this winter and have a look around.  As I recall, there's limited viewing through the exhaust outlet.  And of course, it's easy enough to test the compression - I don't have a baseline for my bike, but it might tell us something...

[ace.cafe]

Any of those things I listed could be a problem, if they exist in your engine.
If the timing is off for any reason, it can cause higher heat than normal. I don't know if it's that. These are things you can check, or have your dealer check.
If your decompressor was activated during riding rpms, that could definitely cause valve problems. A compression test would be a good idea, if your decomp is now removed.

[gremlin]

......it's easy enough to test the compression - I don't have a baseline for my bike, but it might tell us something...

I've been wondering about that ..... with the auto-decomp ..... how do we test compression on these machines ?

[ace.cafe]

I've been wondering about that ..... with the auto-decomp ..... how do we test compression on these machines ?

Well he has his removed, so it's easy for him to do it normally.
I think with the auto decomp in place, it is not really possible to do a normal compression test. I think it would have to be taken out, at least temporarily for the test. At least, that's as far as I know about it.

[gremlin]

.......the engine is hot, because it's been pushing me along for the past hour in the 3000's rpm range..........Can there be any explanation other than excessive carbon buildup?

Setting aside the combustion chamber (temporarily) your TPS and MAP sensors would also be running significantly warmer than is usual.  These are the two inputs that have the most significant effect on the amount of fuel delivered.

I might try pulling over, shutting down, a quick wipe of those sensors with a cool rag, restarting, and then see if there is any difference in performance.

[singhg5]

I had done compression test on my G5 and values were about 140 PSI with electric start and about 110 PSI with kick start.

If I am not mistaken doesn't the compression gauge record highest compression and the needle stays at that place ? So even if compression is lost somewhat after reaching the max, the needle should not fall below the max. The gauge has a separate release valve that needs to be pressed to bring the needle to zero.

Obviously the kick start creates enough pressure to start the bike, it must spin engine faster than 700 rpm so that exhaust valve is closed and compression is built. There must be some numerical value of compression that can be determined.

I am not sure if my bike's decomp was removed when my 2009 model was recalled for transmission issues or it is not just working anymore or it works and readings are what they are with it.

May be someone who has a brand new bike with known working decomp do the compession test properly and determine the specs of bike 'as is', confirm compression values and resolve this dilemma.

http://www.youtube.com/watch?v=etHvHlPCQgU 

[AussieDave]

Mattz , I meant in the oil filter chamber ... I found a few flakes up against the back wall - trying to squeeze past the rubber o- ring I think .

[SteveThackery]

Obviously the kick start creates enough pressure to start the bike, it must spin engine faster than 700 rpm so that exhaust valve is closed and compression is built.

Actually, no.  The engine will start and run with the decompressor permanently engaged.  I did some experiments on mine, and it ran at super-low idle speeds with the decomp doing its "clack - clack - clack - " thing all the time.  In fact, both starting and running are no problem with the lower compression - they have to be because even the electric starter won't reach 700rpm (on mine it gets up to a little over three compressions - six revs - per second, which equates to 360-400rpm or thereabouts on the starter).

Remember that it doesn't hold the exhaust valve open permanently - rather it extends the exhaust opening time somewhat, thus reducing the compression, not losing it altogether.

[mattsz]

Thanks guys!

To be clear: my auto-decomp was not removed, and is not disabled - at least not intentionally!  In my musings, I was wondering aloud about whether it was now not working at all after the dealer repair, considering how much harder it is to move it through compression with the kick lever.  Also, it's dead quiet; the noise of the engine idle never changes now, even in the cold.

The engine will start and run with the decompressor permanently engaged.

I believe that's what mine was doing before the repair.  For more detail, read this post: http://www.enfieldmotorcycles.com/forum/index.php/topic,20143.msg221717.html#msg221717


I can do a compression test - it's easy, after all!  Singhg5 did one on video, and as I recall, Ducatti Scotty did it too, about the same time, and posted his results to compare with Singh's.  Could be useful.

Gremlin, thanks for the sensor suggestion.  I think it's too late in the season for me to effectively attempt such a test, but I'll keep it in mind for the spring.

AussieDave - thanks for the clarification about the filter chamber.

Ace - the dealer isn't the ideal option any more... 4 hours away, and now out of warranty.  For the last two problems I went in with, they couldn't see/hear/feel/detect one, and determined the other was normal ops.  I'll be researching how to check the timing... 

Looking ahead: If I do end up pulling the head, there's two valve cover gaskets and the head gasket... can they be re-used, or should they be renewed?

[AussieDave]

Hi Mattz. The valve/rocker cover  gaskets can be reused if they are in good condition , but the head gasket should be re placed . There will also be some carbon buildup in a ring around the top of the cylinder extending down the the height of the first piston ring at top dead centre . To clean this you may want to remove the barrel as well, so you may as well replace the piston rings and hone the cylinder while you are there .... And you'll need the gasket for the base of the cylinder . And new clips for the gudgeon pin . And while your there you may as well replace the valve stem seals......

[Ducati Scotty]

Remove the spark plug and get the engine to TDC.  Just take a small flashlight and look in the spark plug hole.  You'll see if it's caked with carbon or not.

Scott