Leak Down Test (Don't Laugh!!)

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Fast Eddie said:
You will probably end up pulling the barrels. But I for one would try a prolonged period of thrashing the arse off it first!
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I go along 100% with the "thrashing the arse off it first". Then if you manage to break something else - you can fix everything with just one tear down. This is how racers save wrenching time.
 
If still ridable and weather allows and don't know how long might be down - Notice how seasoned racers/builders and maniacs converge on same practicality.
I'd put some Bon Ami that never scatched anything (or order it from ignorant TotalSeal rings) in bores and some in a sock to bounce/dust in front of carbs blipping till fully warmed, then a water spray bottle to de carbon coke some, then run it like ya stole in w/o the mufflers on to both eliminate that element and feel/hear the difference in sound and response w/o 12 lb restriction mass. On glee full return, the fasteners will never be easier to break free, to start another round of quality fettering tasks.
 
Bernhard said:
Re; “I was having an oil burning issue which seemed to be a valve seal. I did the rope trick & replaced the valve seal with the head in situ & it seemed to solve the problem but only for a short while. I did the rope trick procedure again but dropped a collet down the pushrod tunnel!! After 4 days of fishing around I had no choice but to take the head off. While it was off I thought what the heck I'll get the head freshened up. Jim was up to his tonsils so I sent it to a well known cylinder head shop in the UK. I had a few issues with the head after I got it back, it looked like they had installed the rocker arm shafts cold as they were very loose in the head. I ran the bike for a bit like this but always felt the bike deserved a better job done on the head.”

Here’s someone I wouldn’t trust with my c/head! For all you know they might have fitted the rocker shafts in the wrong way round resulting in excess oil in the rocker box?
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As part of my testing when I got smoke from the exhaust I checked the rocker shaft orientation, you can do this with a bit of wire locating the hole, 2 of the shafts were orientated incorrectly! + 2 of the were very loose when previously they were fine. The chap concerned has mixed reviews but I was impatient & I didn't want to wait for Jim C., should have waited!!!
 
Torontonian said:
Yes, rocker shafts might be loose in the head from a bad cold install. They should be tight in place. I'd take off the rocker covers and with a large screwdriver see if they rotate or move too easily/with slop to confirm that. Easily done. One or two could have rotated on the right side so start there.
Also you mentioned replacing a valve seal . Was it on the right side? It could have popped off again due to a poorly cut ridge for it's placement over the intake guide.
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Sorry guys you are getting confused, this was a different head NOT the head I got from Jim C. his work is spot on, no problems with shafts etc.
Just want to clear this up!
 
jseng1 said:
I go along 100% with the "thrashing the arse off it first". Then if you manage to break something else - you can fix everything with just one tear down. This is how racers save wrenching time.
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Would you know anybody who sells parts for these Nortons :) (only joking)

I'm leaning towards this on the basis of what have I got to loose apart from being embarrassed by leaving a major smoke trail everywhere I go!!!

I've already given the engine a good blast up to 90mph when I first put the head on so I think giving it a longer trash is a calculated risk rather than being reckless.
 
hobot said:
If still ridable and weather allows and don't know how long might be down - Notice how seasoned racers/builders and maniacs converge on same practicality.
I'd put some Bon Ami that never scatched anything (or order it from ignorant TotalSeal rings) in bores and some in a sock to bounce/dust in front of carbs blipping till fully warmed, then a water spray bottle to de carbon coke some, then run it like ya stole in w/o the mufflers on to both eliminate that element and feel/hear the difference in sound and response w/o 12 lb restriction mass. On glee full return, the fasteners will never be easier to break free, to start another round of quality fettering tasks.
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I like your style hotbot :)

I can only imagine how loud the bike would be without the silencers/mufflers!! I don't live in the country, just an average housing estate for Ireland. I plan on living here for a while yet & don't want to fall out with my neighbours!!!

I'm aware of the water spray trick inducing a blast of steam which could/might loosen up carbon build up, not sure about the Bon Ami!
 
OK, minor but I think significant update!!

I blocked off the oil line to the head & ran the bike for 4 1/2 minutes lightly blipping the throttle, at approx. 3 1/2 mins smoke started to exit the silencer/muffler. I was being cautious with the throttle & didn't rev the bike very high just light 'blipping'.

I know this could be oil burning from the silencer/muffler but it could also point to the issue being lower down in the barrels??

I'm waiting for things to cool down & I'll check the plug for oil. If I see oil it would again point to the issue being lower down in the barrels.

More anon!
 
O.K. it's not in the head itself. This leaves a bad head gasket seal or piston/ring issues. Time to pull the head to investigate. Labour.
 
Torontonian said:
O.K. it's not in the head itself. This leaves a bad head gasket seal or piston/ring issues. Time to pull the head to investigate. Labour.
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Or option 2, give the bike a good run
Torontonian said:
O.K. it's not in the head itself. This leaves a bad head gasket seal or piston/ring issues. Time to pull the head to investigate. Labour.
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OK just checked the spark plug, oil on surface of plug so that seems to be a clear indication oil is getting past the ring(s) or CH gasket leak into combustion chamber.

Before I take the head off I'm going to give the bike a good run, I'll try & clock up 100miles, just need to free up some time to go for a spin!!!
 
Aw ya know ya iching to experience open headers extra loud spunk on cam. If lowish rpm low ish throttle speed its more deep pleasant huff than conversation stopping HogVtwins though about matches em snapping throttle hard. Water only hydrolyzes carbon to soft grey dust that blows away, or wipes off. Bon Am is not abrasive in ordinary sense but breaks oxide layer to leave smoother polished. TSrings knows dry rings with Bon Am like polish is way to go. As better than normal tests so far its still a head scratcher as gasket internal leaks usually weep outward some too. Good hillbilly tune up engine check might reveal this, before wrench/straining anyway.

I must spend more to more forward on my 2 Cdo's, so cooling jets over winter slack time.
 
click said:
OK just checked the spark plug, oil on surface of plug so that seems to be a clear indication oil is getting past the ring(s) or CH gasket leak into combustion chamber.

Before I take the head off I'm going to give the bike a good run, I'll try & clock up 100miles, just need to free up some time to go for a spin!!!
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If it were to be coming through the head gasket, wouldn't that have been disproved by your earlier leak-down testing? As for the rings, even though they hold good compression, they make piss-poor oil scrapers. My money is on a jacked-up oil ring.

Nathan
 
Nater_Potater said:
If it were to be coming through the head gasket, wouldn't that have been disproved by your earlier leak-down testing? As for the rings, even though they hold good compression, they make piss-poor oil scrapers. My money is on a jacked-up oil ring.

Nathan
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I agree about the leak-down test, I think I should have heard some hissing/leaking sounds if the seal between the pushrod tunnel & the RH cylinder chamber was leaking, also pressure would drop.

I'm leaning more towards the oil ring as the problem but I'm willing to run the bike, get it plenty hot & under load & see if anything changes!
 
hobot said:
Aw ya know ya iching to experience open headers extra loud spunk on cam. If lowish rpm low ish throttle speed its more deep pleasant huff than conversation stopping HogVtwins though about matches em snapping throttle hard. Water only hydrolyzes carbon to soft grey dust that blows away, or wipes off. Bon Am is not abrasive in ordinary sense but breaks oxide layer to leave smoother polished. TSrings knows dry rings with Bon Am like polish is way to go. As better than normal tests so far its still a head scratcher as gasket internal leaks usually weep outward some too. Good hillbilly tune up engine check might reveal this, before wrench/straining anyway.

I must spend more to more forward on my 2 Cdo's, so cooling jets over winter slack time.
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Hydrolyzes, great word, I'm just going out to hydrolize my Norton :)

Sure enough, if I give the bike a good blast, any weakness in the head sealing will show up!
 
click said:
OK just checked the spark plug, oil on surface of plug so that seems to be a clear indication oil is getting past the ring(s) or CH gasket leak into combustion chamber.

Before I take the head off I'm going to give the bike a good run, I'll try & clock up 100miles, just need to free up some time to go for a spin!!!
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Suggest a fresh set of plugs before you head out.

You really don't need the peak speed so much as a warm to hot engine and several good bursts to get heat into the pistons. This might (wing and a prayer) loosen up a hung ring....or totally blow a head gasket:) Make note of when you get the smoke (on throttle or off throttle).
 
Dances with Shrapnel said:
Suggest a fresh set of plugs before you head out.

You really don't need the peak speed so much as a warm to hot engine and several good bursts to get heat into the pistons. This might (wing and a prayer) loosen up a hung ring....or totally blow a head gasket:) Make note of when you get the smoke (on throttle or off throttle).
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Yep new plugs will go in. Don't plan on thrashing it, just use the bike well. I find it difficult to figure out how guys look at their exhausts while riding :)

I might strap a GoPro to the back of the bike & review the footage later, much safer option!

Might not get a chance to do this until Friday.
 
Yes, maybe a pillion rider mounted backwards - extra ballast is good. Also make sure you find a round trip test route that is up hill the whole way.;)
 
click said:
Yep new plugs will go in. Don't plan on thrashing it, just use the bike well. I find it difficult to figure out how guys look at their exhausts while riding :)

I might strap a GoPro to the back of the bike & review the footage later, much safer option!

Might not get a chance to do this until Friday.
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You might adjust one mirror so it focuses on the exhaust from that smoky side.
That way you'll know at a glance if it is smoking or not.

Glen
 
Dances with Shrapnel said:
Yes, maybe a pillion rider mounted backwards - extra ballast is good. Also make sure you find a round trip test route that is up hill the whole way.;)
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I'll explain to my wife I need extra ballest AND I need her to sit on the bike backwards, I'm sure she will understand :(

I could always go up to Down as Down is always up from were I live :rolleyes: (Irish joke)
 
worntorn said:
You might adjust one mirror so it focuses on the exhaust from that smoky side.
That way you'll know at a glance if it is smoking or not.

Glen
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of course, obvious & simple, thanks. I'll still fit the GoPro as I'd prefer to be watching what's in my future rather than what's in my past :)
 
I wonder if the 3-4 minute wait for smoke is somewhat of a red herring. Perhaps the elapsed time to start of smoking is simply related to combustion chamber temperature and nothing else. It is possible that upon initial start-up the combustion chamber is too cold to combust liquid oil in the chamber, hence no smoke. However, with further warm-up the combustion chamber comes to temp and the oil present begins combusting and smoking, rather than just being moved through the combustion chamber in uncombusted liquid form.

As far as thrashing the engine, I thought you indicated it had 12K mi on it, so any chance of altering the ring performance seems likely 12k mi in the past.

When you removed the head previously for inspection was carbon thick on top of the piston or was it mostly washed off the top of the piston. I ask because if the piston top was mostly/partly clean it suggests the oil is coming from below. If the piston top has a thick layer of carbon building up I’d suspect the leakage is from somewhere above (head or head gasket).

Interesting problem you/re working on and excellent job of communicating the background of the project and the observations as you progress.
 
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