71 norton top end break in now?

concours · Sep 23, 2012

Re: Gathering top end tips!!! 71 norton....

"
Boring to suit the ring gap sounds like a back-to-front way of doing things - you'd want to have in writing the piston manufacturers recommended clearances to make this work.
So KNOW that that clearance would work..."

Standard procedure, bore and hone to size with the piston in the machinists hand, using known good clearances. Some aftermarket pistons I have used do come with clearance data, usually because in the two-stroke world, the aftermarket forged pistons have a different expansion value than the OEM cast, therefore different (than the OEM service data) clearance.
Modern manufacturing process is so repeatable, that piston rings can be produced to give spot on end gaps, PROVIDED the bore is spot on.

Rohan · Sep 23, 2012

Re: Gathering top end tips!!! 71 norton....

concours said:
Tolerances... the LARGEST piston allowable by the sizes published and the SMALLEST bore yields .0033 clearance and the SMALLEST piston in the LARGEST bore calculates out to .0047 clearance. THAT is the range allowed. See? All the 'rithmatic has already been done. No guesswork.

But for what pistons ?
AE Hepolite pistons at those sizes haven't been available since about 1980 ?

Other pistons will have different clearance requirements.
Forged pistons will need a lot more clearance.
Wire-wound type pistons (for singles) run a lot quieter - at quite small clearances.
Those liitle Honda pistons (with high silicon content?) required ZERO clearance.

You won't get big fat feeler gauges into curved spaces when you are chasing tenths of a thou...

Rohan · Sep 23, 2012

Re: Gathering top end tips!!! 71 norton....

concours said:
Standard procedure, bore and hone to size with the piston in the machinists hand, using known good clearances.

Absolutely - bore and hone with pistons in hand to suit.
But read what was said - boring to suit ring end gaps alone is ass-about stuff.... ?

Now, if the piston clearance specs agreed with what was required for the ring end gaps, then all is hunky dory. But you'd want that in writing from the piston manufacturer.

concours · Sep 23, 2012

Re: Gathering top end tips!!! 71 norton....

Rohan said:
concours said:

Tolerances... the LARGEST piston allowable by the sizes published and the SMALLEST bore yields .0033 clearance and the SMALLEST piston in the LARGEST bore calculates out to .0047 clearance. THAT is the range allowed. See? All the 'rithmatic has already been done. No guesswork.

Click to expand...

But for what pistons ?
AE Hepolite pistons at those sizes haven't been available since about 1980 ?

Other pistons will have different clearance requirements.
Forged pistons will need a lot more clearance.
Wire-wound type pistons (for singles) run a lot quieter - at quite small clearances.
Those liitle Honda pistons (with high silicon content?) required ZERO clearance.

You won't get big fat feeler gauges into curved spaces when you are chasing tenths of a thou...

School me Ro, what is a wire wound piston? Never heard that term before. The zero clearance thing, well, I'm not even touching that :lol:

Rohan · Sep 23, 2012

Re: Gathering top end tips!!! 71 norton....

British bikes for quite some years used wire-wound pistons - there was wire wound into the alloy in the vicinity of the piston rings and upper skirt. Didn't see this explained seriously, no idea how they did it, but it was to limit expansion/deformation. My old Matchless single 1950s had one - renowned for their quiet running motors. Impossible to obtain these days - unless someone has a stash of NOS ones. ? Think they are Hepolites ??

Didn't know about Honda pistons until I held one long enough it wouldn't go into the bore.
Serious metallurgy applied there.

Didn't I see that F1 / MotoGP pistons have something like 27 coatings applied to them these days. Thats gone beyond serious metallurgy....

MFB · Sep 24, 2012

Re: Gathering top end tips!!! 71 norton....

I bought a stock base gasket for the jugs and a copper gasket for the head. i have some copper spray for the head gasket. I might use the base dry or add something on it.[/quote]

My dad worked on aircraft engines during WW2 - Spitfires etc - and he told me to always use grease on gaskets. I rarely use gasket sealant, IMO if sealant is needed then something is wrong with the mating surfaces. And it's so much harder to clean off when later dismantling. With grease, you can often re-assemble with the same gasket.
Oh and I forgot to mention before, after fitting the head, don't forget to squirt plenty of oil down the pushrod tubes to pre-lube the cam followers and cams.

Cheers
Martin

concours · Sep 24, 2012

Re: Gathering top end tips!!! 71 norton....

MFB said:
I bought a stock base gasket for the jugs and a copper gasket for the head. i have some copper spray for the head gasket. I might use the base dry or add something on it.

My dad worked on aircraft engines during WW2 - Spitfires etc - and he told me to always use grease on gaskets. I rarely use gasket sealant, IMO if sealant is needed then something is wrong with the mating surfaces. And it's so much harder to clean off when later dismantling. With grease, you can often re-assemble with the same gasket.
Oh and I forgot to mention before, after fitting the head, don't forget to squirt plenty of oil down the pushrod tubes to pre-lube the cam followers and cams.

Cheers
Martin[/quote]
A GREAT old time trick. Try Loctite 518 as gasket dressing.. peels off like a sticky note, seals like crazy. Best of both worlds!

iceteanolemon · Sep 24, 2012

Re: Gathering top end tips!!! 71 norton....

Well I got the head on last night. The installation went smooth, I did have a fun time bringing home the pushrods though. I got one side then the other side would jump out.

In order to get the pushrods to stay up in the head I took a rubber band and wrapped it around the first pair of rods then around the studs to the other pair of rods. This worked well to keep them up while rotating the head onto the cyl. Once this was done I then had some issues with keeping the rods to seat properly, that was the tricky part for me.

Now on the bottom gasket I used a very light film of black stuff. I dont think its a big deal. If I had the loctite stuff I woulda used it, I just wanted something on there for good measure.

On the head gasket I did that copper spray and did the floss trick too just for fun. As for torque settings I follwed the manual on this but had to practice a few times to get the "feel" before doing the few nuts that the torque wrench wouldnt reach.

Still have to fit the exhaust and stuff. I got to the carbs and then wanted to relax before the next session....

drones76 · Sep 24, 2012

Re: Gathering top end tips!!! 71 norton....

iceteanolemon said:
Well I got the head on last night. The installation went smooth, I did have a fun time bringing home the pushrods though. I got one side then the other side would jump out.

In order to get the pushrods to stay up in the head I took a rubber band and wrapped it around the first pair of rods then around the studs to the other pair of rods. This worked well to keep them up while rotating the head onto the cyl. Once this was done I then had some issues with keeping the rods to seat properly, that was the tricky part for me.

Now on the bottom gasket I used a very light film of black stuff. I dont think its a big deal. If I had the loctite stuff I woulda used it, I just wanted something on there for good measure.

On the head gasket I did that copper spray and did the floss trick too just for fun. As for torque settings I follwed the manual on this but had to practice a few times to get the "feel" before doing the few nuts that the torque wrench wouldnt reach.

Still have to fit the exhaust and stuff. I got to the carbs and then wanted to relax before the next session....

I was in the same boat this weekend. Got the head on Saturday evening. I used the one hand to hold it and the other to guide the pushrods method. My shoulders hurt today. Easier with two people. Nobody available.

I forgot about how the springload of the valves keep the head raised a bit. I knew all of the pushrods were where they belonged but there seemed to be too much gap where the head meets the base....until I read it in one of the aftermarket manuals.

Slowly snugged the #1 bolt and she went home. I used a non copper head gasget dry. So far so good. Only a few miles on it.

And the first time around with the torque wrench, I am sitting there just hoping that thing goes 'click'. Sometimes it seems like it is past the point it should be. I can only properly torque 7 of the 10 fasteners. The one dead center in the back requires a manifold wrench and I cannot get the torque wrench on the two that go up into the front of the head.

New exhaust went on. It was a bit of a bitch getting the mounting studs out of the original mufflers.

Good Luck.

DogT · Sep 24, 2012

Re: Gathering top end tips!!! 71 norton....

As I remember, the rods would not seat in the rockers until you had a bit of tension on the side that kept the head pushed up. I just kept tightening the bolts by the plug holes until everything fit, with turning the engine over to make sure all the rods were still seating in the rockers. When the head was real close to the cylinder, things started coming together and that's when you need to make sure the rods are seated and finish tightening up the rest of the bolts.

Dave
69S

MFB · Sep 25, 2012

Re: Gathering top end tips!!! 71 norton....

concours said:
A GREAT old time trick. Try Loctite 518 as gasket dressing.. peels off like a sticky note, seals like crazy. Best of both worlds!

NOW you tell me! I've got Loctite 518, I used it on the crankcases. Bugger!

Cheers
Martin

iceteanolemon · Sep 25, 2012

Re: Gathering top end tips!!! 71 norton....

Got the rest of the stuff connected last night. Tank, exhaust, oil lines etc.

Placed some oil in the tank and rechecked everything..... Got the bike started first kick.

I didn't get around to doing much but letting it idle for about 40 seconds then reving it to 2k. I shut it off and kicked it on twice. Starts right away and sounds nice.

Thanks to everyone for your help, I appreciate all the people in the group for their patience and attention to details....

concours · Sep 25, 2012

Re: Gathering top end tips!!! 71 norton....

MFB said:
concours said:

A GREAT old time trick. Try Loctite 518 as gasket dressing.. peels off like a sticky note, seals like crazy. Best of both worlds!

Click to expand...

NOW you tell me! I've got Loctite 518, I used it on the crankcases. Bugger!

Cheers
Martin

lol, it makes the two stroke base gasket purgatory ( 8 studs dulling your scraper) a thing of the past. I stole the idea from the Rotax service manual. But, like Robin Hood, trying to share.

iceteanolemon · Sep 26, 2012

Re: Gathering top end tips!!! 71 norton....

OK now that I got the bike running its time for a break in.

Running 15w-40 rotella
warmed the bike up and ran around the block a few times. After this I retorqued the exhaust and head and rechecked valves.

starts immediately and seems fine.

Any suggestions on running it the first 500 miles? I see tons of conflicting advice everywhere on how to break it in. When warming it up I rode it about 2 miles and got it to 50mph stop and go and ran it through the gears. No big hills or rpms over 3000 yet....

Any tips?

comnoz · Sep 26, 2012

Re: Gathering top end tips!!! 71 norton....

iceteanolemon said:
What ring gaps are everyone running with the JCC rings and pistons? I just measured and one of the rings comes to 20 thou....

That is about normal. A little wider than ideal but I haven't seen any problems at that gap. Jim

worntorn · Sep 26, 2012

Re- having to guess at the torque setting for the spanner only tightened head bolts/nuts.
If you have a common spring scale for weighing fish, you can attach this to the end of the spanner to turn it into a "torque spanner"
You can also wire on a wooden or metal extension to the spanner so that it becomes a foot long (from bolt centre to attachment point of scale, then just pull twenty pounds on the scale for twenty foot pounds, thirty for thirty and so on.

The other method of calibration is to use your regular torque wrench to tighten a bolt to the torque value you want to achieve with the torque spanner. Note the position then back the bolt up a bit. Now you can use the torque spanner to bring the bolt back to the torqued position and note the poundage on the spring scale when that is reached. With this method of calibration the length of the spanner can be whatever you desire.
These mehtods might be a foot pound or two from perfection but are probably closer than most of us can get by guessing.

Glen

iceteanolemon · Sep 26, 2012

should I give the bike a healthy 30 miles ride or nurse it a little till its got 5 or 10 miles on it before going farther?

ashman · Sep 26, 2012

Just ride it, just take it easy but you shouldn't have any problems, after about 500 miles just retension it and check valve clearances, after my rebuild I just rechecked every thing after 500 miles, so far after 2 years and over 12,000 miles I have had no problems at all

Ashley

Rohan · Sep 26, 2012

Nursing it too much is supposed to be not good for it - everything needs to build up a healthy working clearance, and too gentle can inhibit this ?. Flogging it too hard too early is also not supposed to be good. Apparently the idea is to vary the revs as much as possible, not holding the same rpms for long times...

Its your engine, tell us how it goes in another 100,000 miles !!

pete.v · Sep 26, 2012

Re: Gathering top end tips!!! 71 norton....

I would drive it normal, what ever that is.
Some around the town, some highway. Do some visuals when you get home.
I think 500 mile is a good before you start pushing it too hard. I am not disciplined enough to wait any longer than that. I would not baby it.
You could change the oil at that time and run another 500 with the break in oil if you see fit.

iceteanolemon said:
OK now that I got the bike running its time for a break in.

Running 15w-40 rotella
warmed the bike up and ran around the block a few times. After this I retorqued the exhaust and head and rechecked valves.

starts immediately and seems fine.

Any suggestions on running it the first 500 miles? I see tons of conflicting advice everywhere on how to break it in. When warming it up I rode it about 2 miles and got it to 50mph stop and go and ran it through the gears. No big hills or rpms over 3000 yet....

Any tips?

71 norton top end break in now?

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