Leak Down Test (Don't Laugh!!)

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splatt said:
A waste of time trying to measure those, the pistons will have collapsed, wouldn't be surprised if the liners have distorted off the barrel in the middle.
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Well if the pistons have "collapsed" and you are measuring 0.004" to 0.005" clearance (with a paper thin feeler gauge - done all the time), what does that say?

Never heard of a liner distorting off the barrel, after all the liner is a hoop in compressive stress (press fit). Not saying it cannot happen, just trying to understand how.

I think comnoz's concern with the liner is if someone is trying to bore out an apparently already thin liner 0.020".

Trying to clean up the liner with a hone was worth a look based on click's assessment of the grooves and getting replacement pistons of the same diameter as long as the bore clearances (after honing) were good. No commitment on purchasing pistons until attempting to clean up the bores and measuring. In light of comnoz's offer, I would go with comnoz's offer and move on.
 
Dang it we strive so hard to have at least one nice special thing nothing distracts our pleasure while contemplating or riding it into the now w/o a care. In deep south only strongest medicine can comfortably numb ya to carry on, triple distilled corn cane sugar 190 proof Kickapoo Joy Juice. Numbs all nerves it touches so fast its smoothest there is, except if some charred oak chips from silvery century old oak barn wood dropped in... before deciding what to do with ya's expensive used up parts.

There are sad truths in the spoof movie Vampire Motorcycle yet so is Tunnel of Love. Will ya have to bargain more expenses with wife too?
 
hobot said:
Dang it we strive so hard to have at least one nice special thing nothing distracts our pleasure while contemplating or riding it into the now w/o a care. In deep south only strongest medicine can comfortably numb ya to carry on, triple distilled corn cane sugar 190 proof Kickapoo Joy Juice. Numbs all nerves it touches so fast its smoothest there is, except if some charred oak chips from silvery century old oak barn wood dropped in... before deciding what to do with ya's expensive used up parts.

There are sad truths in the spoof movie Vampire Motorcycle yet so is Tunnel of Love. Will ya have to bargain more expenses with wife too?
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We call that Poitín in Ireland;) can get up to the same proof level:rolleyes: you could run a Norton on it!!

Wife has been consulted & blessing given, I managed to get a good one who is also interested in motorbikes:)
 
I am with jim on this. 880 is as big i would go on a stock cylinder. the 920 has to many issues. the conversion removes to much materiel from the cylinder as you have seen, the cyl bore will not stay round, the bore is to close to the through bolts for a good seal, not fond of having to use a copper gasket, the pistons are to heavy. IMHO bite the bullet and go back to 850 or as jim stated to 880. yes you will need rods and a re-balance but you will have a better and more reliable engine.
 
OK, this is it, decision made . . . . . . . .

Barrels will be heading stateside to Jim C.

While the barrels are away I'll go over the oil system, just to be sure.

I also need to trace the electrical problem I had just before I was going to take the bike for a long spin, always something to do!!
 
I was a younger man back when this thread started. I had hopes and dreams of someday owning my very own 920.
Now I'm older and wiser I'll leave the parts in the box, let my kids or grandkids try to figure it out what they areo_O


880 sounds good tho. Actually only 26ccs less than the 80.5 mm. What would that be about 1 hp if all was well and the 80.5 stayed round ?
A nice round 880 will probably outperform a deformed 80.5 mm and hopefully keep doing it for a long time.
Glen
 
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Ah crap, click, ya resolved the decision quandary, relieving all our entertained pensiveness, but wasting an extra dose of wine in my case. One time I thought I'd keep track of all failures, my fault or not, in a day, to take a gulp of wine per let down, to quickly find out can't stand that either. Hope now is if head and gaskets can adapt to the new cylinder w/o more hassle. I'm flashing on ya being careful of throttle leaning over to align in your lane w/o spinning rear out from under before nailing it out of there : )
 
hobot said:
Ah crap, click, ya resolved the decision quandary, relieving all our entertained pensiveness, but wasting an extra dose of wine in my case. One time I thought I'd keep track of all failures, my fault or not, in a day, to take a gulp of wine per let down, to quickly find out can't stand that either. Hope now is if head and gaskets can adapt to the new cylinder w/o more hassle. I'm flashing on ya being careful of throttle leaning over to align in your lane w/o spinning rear out from under before nailing it out of there : )
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Don't worry, there will be a part2. I'm sure I'll be back on looking for lots of info. about running in a motor and, wait for it . . . . . . . . .WHAT'S THE BEST OIL TO USE!!!!
 
worntorn said:
I was a younger man back when this thread started. I had hopes and dreams of someday owning my very own 920.
Now I'm older and wiser I'll leave the parts in the box, let my kids or grandkids try to figure it out what they areo_O


880 sounds good tho. Actually only 26ccs less than the 80.5 mm. What would that be about 1 hp if all was well and the 80.5 stayed round ?
A nice round 880 will probably outperform a deformed 80.5 mm and hopefully keep doing it for a long time.
Glen
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If ya want to go bigger just stick with the 79mm bore and add a 92mm stroker crank for 924cc.
You will end up with a larger gain than just increasing the bore to 920cc.
 
I'm confused on why a sane mature owner, their living and family depends on would want a more touchy powerful fault prone insanely dangerous handling Commando in public. Any-all factory Commandos can do 13 sec 1/4 miles, if ya run em like Norton designed them too. If not comfy with risky tire abusing sounds over exhaust or wind blast, think about next millennial generation, milk toast owner facing renewal issues w/o the likes of comnoz to save ya bacon. If not having to feather off throttle to avoid hesitation of catching rubber/rear spin on shifts, then waste of resources to jump over Norton parts number fence. If thinking will live forever like me then go for the max and die terrorized happy. I only use moonshine for facing wild Indians, snake bites and deaths of family, best friends or Ms Peel and Norton ralleys. Tell your wife she's a keeper above motorcycles and likely get laid to distract 'briefly' for real desire.
 
hobot said:
I'm confused on why a sane mature owner, their living and family depends on would want a more touchy powerful fault prone insanely dangerous handling Commando in public. Any-all factory Commandos can do 13 sec 1/4 miles, if ya run em like Norton designed them too. If not comfy with risky tire abusing sounds over exhaust or wind blast, think about next millennial generation, milk toast owner facing renewal issues w/o the likes of comnoz to save ya bacon. If not having to feather off throttle to avoid hesitation of catching rubber/rear spin on shifts, then waste of resources to jump over Norton parts number fence. If thinking will live forever like me then go for the max and die terrorized happy. I only use moonshine for facing wild Indians, snake bites and deaths of family, best friends or Ms Peel and Norton ralleys. Tell your wife she's a keeper above motorcycles and likely get laid to distract 'briefly' for real desire.
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The answer to why ........ why not

The next generation can figure out how to solve their own problems + they can get older & wiser reading threads like this on accessnorton
 
worntorn said:
Sane people don't ride old Brit bikes.
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My wife has a great saying ‘that person is so normal they frighten me’ anybody who conforms so tightly to the textbook definition of normal is to be avoided!!

All bikers I’ve come across are all slightly mad, since we are all nuts about bikes that’s our ‘normal’
 
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click said:
Don't worry, there will be a part2. I'm sure I'll be back on looking for lots of info. about running in a motor and, wait for it . . . . . . . . .WHAT'S THE BEST OIL TO USE!!!!
Click to expand...
Oh you’d never catch any of us in an oil debate...!

After all, there are only 3 choices:
1. Cheapest, nastiest, non brand mineral.
2. Expensivist, sexiest, best brand synthetic.
3. Something in between.
 
Fast Eddie said:
Oh you’d never catch any of us in an oil debate...!

After all, there are only 3 choices:
1. Cheapest, nastiest, non brand mineral.
2. Expensivist, sexiest, best brand synthetic.
3. Something in between.
Click to expand...

But FWIW, I won’t use anything other than Redline, 20/60, fully sysnthetic, dedicated motorclye oil in my old bikes.
 
Nice try, FE, but we're all too old and wise to fall for that old "reel the suckers in with the oil hijack" ploy! :)

Re this entire thread...I've been working on engines since I was 15 and this exercise really emphasizes to me how much I'm going to enjoy it when sufficient battery capability finally allows electric motors to kick these absurd methods of generating rotating motion into history's dustbin!
 
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