Author Topic: After a rebuild how long until rings seat?  (Read 6739 times)

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Offline ncstatecamp

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After a rebuild how long until rings seat?
« on: May 28, 2014, 03:16:33 PM »
I have a 750k2 that I did a rebuild on earlier this year (more then 500 miles less 1000) and im only getting 90 across the board. I kept stock piston size, new rings, lapped valves, new valve seals (*edit not guides), new gaskets all around, new plugs, honed cylinders. Everything was in spec (except rings) when I started, I rebuilt due to puck under valve train leaking and low compress/hard start. I was told on here my compression would build a bit as the rings seated but 90's what I started with and it hasnt changed....

My break in has been least amount of idle possible, least amount of staying in the same rpm range (varying as much as possible), the first 20 miles were pretty much me riding the engine up to 5k and slowing back down. Changed the oil at 100 miles, and again 500-600. First time had the typical flakes of break in, second time oil wasnt even that dark feel like I could have held off. Starts are hardish (but old bike). Burning a bit of oil (rings not seated?).

Timing is spot on, best ive ever seen it.

Thoughts?
« Last Edit: May 29, 2014, 01:25:32 AM by ncstatecamp »

Offline MRieck

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Re: After a rebuild how long until rings seat?
« Reply #1 on: May 28, 2014, 03:22:55 PM »
I'd do a leakdown test to see where you are losing pressure. After installing new guides you really should do a valve job as the valve centers differently to the valve seat. The leakdown will tell if air is moving past the valves, the rings or both.
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Offline ncstatecamp

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Re: After a rebuild how long until rings seat?
« Reply #2 on: May 28, 2014, 04:23:20 PM »

I'd do a leakdown test to see where you are losing pressure. After installing new guides you really should do a valve job as the valve centers differently to the valve seat. The leakdown will tell if air is moving past the valves, the rings or both.

Not to sound like an idiot but what do you mean exactly by valve job? Cutting the seats, or lapping or? And I meant seals not guide.

AJK

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Re: After a rebuild how long until rings seat?
« Reply #3 on: May 28, 2014, 10:51:48 PM »
Just some thoughts.

A lot of it should have settled by now. Most of the wearing in would have already happened, but its a continual process that will take more riding. The type of oil you run it in with should be a mineral oil without friction modifiers, otherwise it won't run in properly.

Is your compression gauge one for a car (with a long or fat hose) that won't read correct for a bike? It could be that your compression readings are actaully ok, but your gauge is not reading accurate for the bike, so bear that in mind. There are threads on the forum about this.

The flake in the oil, then no flake on the 2nd change is normal and expected, but you shouldn't be consuming much oil. You only mentioned a 'bit' so if its truly just a bit, then everything is normal & the lack of oil consumption will continue to improve as things continue to wear in.

I've done the same as you, now up to 3000kms. I have no oil consumption at all. I just run 20W50 mineral, but i broke it in on 10W40 & even then it didn't use much.
 I'd say give it another 1000kms and re-evaluate what its drinking oil wise. If possible, get a mate to ride behind you and see if he can see much smoke coming out of your pipes when you ride (coast) normally. There shouldn't be much, and after another 1000kms, shouldn't be anything at all.

Does the bike feel good on compression when you kick it over by foot? When giving the bike some acceleration, does it feel like it has a good bite when you give it some? A rebuilt motor that has just worn in should feel like it wants to go if everything is reasonably tuned.

Re the valve job, you have new guides, so that is good. Obviously you must have installed new valve stem seals as well, because if not, then that is also a source of oil consumption. The valves should be lapped in at a minimum with valve lapping paste, but if the valve face and seat are not reasonably married to each other due to new valves, then the valve job mrieck mentioned is to cut the valve seat at various angles to marry to the new valve. This is done first, then followed up with a valve lapping job.

I'd say keep riding it & it might continue to improve (& just check your compression gauge for bike suitability). You may have nothing to worry about.

PS: Its good that you didn't let it idle much.

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Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
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http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline ncstatecamp

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Re: After a rebuild how long until rings seat?
« Reply #5 on: May 29, 2014, 01:24:49 AM »
Just some thoughts.

A lot of it should have settled by now. Most of the wearing in would have already happened, but its a continual process that will take more riding. The type of oil you run it in with should be a mineral oil without friction modifiers, otherwise it won't run in properly.

Is your compression gauge one for a car (with a long or fat hose) that won't read correct for a bike? It could be that your compression readings are actaully ok, but your gauge is not reading accurate for the bike, so bear that in mind. There are threads on the forum about this.

The flake in the oil, then no flake on the 2nd change is normal and expected, but you shouldn't be consuming much oil. You only mentioned a 'bit' so if its truly just a bit, then everything is normal & the lack of oil consumption will continue to improve as things continue to wear in.

I've done the same as you, now up to 3000kms. I have no oil consumption at all. I just run 20W50 mineral, but i broke it in on 10W40 & even then it didn't use much.
 I'd say give it another 1000kms and re-evaluate what its drinking oil wise. If possible, get a mate to ride behind you and see if he can see much smoke coming out of your pipes when you ride (coast) normally. There shouldn't be much, and after another 1000kms, shouldn't be anything at all.

Does the bike feel good on compression when you kick it over by foot? When giving the bike some acceleration, does it feel like it has a good bite when you give it some? A rebuilt motor that has just worn in should feel like it wants to go if everything is reasonably tuned.

Re the valve job, you have new guides, so that is good. Obviously you must have installed new valve stem seals as well, because if not, then that is also a source of oil consumption. The valves should be lapped in at a minimum with valve lapping paste, but if the valve face and seat are not reasonably married to each other due to new valves, then the valve job mrieck mentioned is to cut the valve seat at various angles to marry to the new valve. This is done first, then followed up with a valve lapping job.

I'd say keep riding it & it might continue to improve (& just check your compression gauge for bike suitability). You may have nothing to worry about.

PS: Its good that you didn't let it idle much.

The compression gauge is I believe for a car but when I tested another engine (cb750) ive gotten a 150 (what these bikes got from factory) reading on a cylinder so I know it tests just fine for my bike. Plus its the only damn thing I could find with an adapter. Ive seen the thread youre talking about, but psi is psi, atleast in my mind.

Im running Valvoline motorcycle oil 10-40 at the moment, when/why would a move to 20-50w be necessary?

Kicking over it does feel ok on compression, but cold it never starts on the first hit of the starter, i gotta play around with throttle/choke/kicking over to clear out fumes etc til it decides it wants to catch... Warm she starts up like a champ.

I mistyped in my first, not new guides, just new seals (ill be editing that now), the guides were fine, no wobble what so ever, I cleaned and lapped the old valves and used those. I did not cut a new seat.

AJK

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Re: After a rebuild how long until rings seat?
« Reply #6 on: May 29, 2014, 02:16:05 AM »
Just some thoughts.

A lot of it should have settled by now. Most of the wearing in would have already happened, but its a continual process that will take more riding. The type of oil you run it in with should be a mineral oil without friction modifiers, otherwise it won't run in properly.

Is your compression gauge one for a car (with a long or fat hose) that won't read correct for a bike? It could be that your compression readings are actaully ok, but your gauge is not reading accurate for the bike, so bear that in mind. There are threads on the forum about this.

The flake in the oil, then no flake on the 2nd change is normal and expected, but you shouldn't be consuming much oil. You only mentioned a 'bit' so if its truly just a bit, then everything is normal & the lack of oil consumption will continue to improve as things continue to wear in.

I've done the same as you, now up to 3000kms. I have no oil consumption at all. I just run 20W50 mineral, but i broke it in on 10W40 & even then it didn't use much.
 I'd say give it another 1000kms and re-evaluate what its drinking oil wise. If possible, get a mate to ride behind you and see if he can see much smoke coming out of your pipes when you ride (coast) normally. There shouldn't be much, and after another 1000kms, shouldn't be anything at all.

Does the bike feel good on compression when you kick it over by foot? When giving the bike some acceleration, does it feel like it has a good bite when you give it some? A rebuilt motor that has just worn in should feel like it wants to go if everything is reasonably tuned.

Re the valve job, you have new guides, so that is good. Obviously you must have installed new valve stem seals as well, because if not, then that is also a source of oil consumption. The valves should be lapped in at a minimum with valve lapping paste, but if the valve face and seat are not reasonably married to each other due to new valves, then the valve job mrieck mentioned is to cut the valve seat at various angles to marry to the new valve. This is done first, then followed up with a valve lapping job.

I'd say keep riding it & it might continue to improve (& just check your compression gauge for bike suitability). You may have nothing to worry about.

PS: Its good that you didn't let it idle much.

The compression gauge is I believe for a car but when I tested another engine (cb750) ive gotten a 150 (what these bikes got from factory) reading on a cylinder so I know it tests just fine for my bike. Plus its the only damn thing I could find with an adapter. Ive seen the thread youre talking about, but psi is psi, atleast in my mind.

Im running Valvoline motorcycle oil 10-40 at the moment, when/why would a move to 20-50w be necessary?

Kicking over it does feel ok on compression, but cold it never starts on the first hit of the starter, i gotta play around with throttle/choke/kicking over to clear out fumes etc til it decides it wants to catch... Warm she starts up like a champ.

I mistyped in my first, not new guides, just new seals (ill be editing that now), the guides were fine, no wobble what so ever, I cleaned and lapped the old valves and used those. I did not cut a new seat.

Sounds like everythings in order and you just need to get a few more miles on it. I'd retest in another 1000 miles or so & keep an eye on oil levels, etc. You are using your gauge at wide open throttle i'm assuming?
 If your guides were fine and you lapped the valves back in, then that should be ok. Plenty of oil threads to pick from, so its personal preference. Hondaman says the top end of these engines is particularly hard on the oil and chops it up fairly quickly. I've found that on 20W50, the shifts are nicer and oil pressure is maintained better when hot (i can see it on my gauge). In winter i'll probably run 10w40 again. Stick with a low detergent high zinc oil as flybox mentioned in one of his posts.

Offline cougar

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Re: After a rebuild how long until rings seat?
« Reply #7 on: May 29, 2014, 06:18:01 AM »
BIG +1 on PeWe's link !! Some may not agree, but I can see Mototune's line of thinking and will use his process on the next motor I build !!! Sounds logical to me.   ...cougar...
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Offline grcamna2

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Re: After a rebuild how long until rings seat?
« Reply #8 on: May 29, 2014, 06:46:50 AM »
Start 'running it out' more,ride it harder and faster now
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Offline ncstatecamp

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Re: After a rebuild how long until rings seat?
« Reply #9 on: May 29, 2014, 08:27:14 AM »
Using gauge at wide open throttle? No.... Just screwing it in and turning the engine over no spark until the pressure stops climbing.

Offline 750K

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Re: After a rebuild how long until rings seat?
« Reply #10 on: May 29, 2014, 09:13:43 AM »
Do it with the choke off and the throttle wide open, motor warmed up when you do the compression test.
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Re: After a rebuild how long until rings seat?
« Reply #11 on: May 29, 2014, 09:52:06 AM »
BIG +1 on PeWe's link !! Some may not agree, but I can see Mototune's line of thinking and will use his process on the next motor I build !!! Sounds logical to me.   ...cougar...

I found the link in a Swedish guy's thesis where he had compared 2 ways of breaking-in. The old style driving really easy for 1000km (620mi) and the harder style from the very beginning. The pistons looked much better after the harder break-in.
I remember my break-ins for my 2 sets of 836 pistons. It was difficult to not twist the throttle back in the days.

This year with the 3:rd setup I twist really good from the beginning.
One thing though, I ran the engine a lot when tuning the carbs finding proper jets. A  bad Ultimate coil with bad contact of 2-3 wires tricked the carb tuning with too much idle. I revved 1500-2500, 2500-5000rpms when warm but probably not enough, pistons just moving up-down.
I'll hone the cylinders again next time when I have a reason. This break-in will hopefully be better than before anyway.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline lrutt

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Re: After a rebuild how long until rings seat?
« Reply #12 on: May 29, 2014, 10:05:59 AM »
I'd recommend giving it a good thrashing. Really rev that sucker. Ride it like you stole it. That should help. I know on a Trumpet I freshened up that sucker smoked like a steam engine at first. Taking it easy did not good for the first 100 miles so I spent 1 tank of gas and flogged that old gal. She cleaned right up and has not smoked or used a drop of oil since. The rings just needed to be forced into bedding. You can be too easy on a break in.

Also, the oil, is it syn? You never want to break in a new motor with Syn, the lighter the better so your 10 / 40 is good.
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Offline Airborne 82nd

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Re: After a rebuild how long until rings seat?
« Reply #13 on: May 29, 2014, 10:06:54 AM »
I'm with MRieck if you really want to know beg,buy,borrow or make a leak down tester then you will know where the air is going simple quick and no more guessing. You might be able to borrow one from Advance or AutoZone But for your purpose a home made one will be just fine.

http://forums.evolutionm.net/evo-how-tos-installations/481133-how-make-your-own-faa-spec-leakdown-tester.html

Offline grcamna2

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Re: After a rebuild how long until rings seat?
« Reply #14 on: May 29, 2014, 10:08:39 AM »
I'd recommend giving it a good thrashing. Really rev that sucker. Ride it like you stole it. That should help. I know on a Trumpet I freshened up that sucker smoked like a steam engine at first. Taking it easy did not good for the first 100 miles so I spent 1 tank of gas and flogged that old gal. She cleaned right up and has not smoked or used a drop of oil since. The rings just needed to be forced into bedding. You can be too easy on a break in.

Also, the oil, is it syn? You never want to break in a new motor with Syn, the lighter the better so your 10 / 40 is good.

+1  :)
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Offline ncstatecamp

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After a rebuild how long until rings seat?
« Reply #15 on: May 29, 2014, 10:34:20 AM »
Do it with the choke off and the throttle wide open, motor warmed up when you do the compression test.

Choke has been off, motor was warm. Not makin any sense in my head as to throttle open would make a difference but next time I'll give it a try.

A leak down test is just putting in conpressed air when cylinder is at TDC to see where it's leaking right? (exhaust,air box or oil tank right)

The oil is non-synthetic. Just 10-40w motorcycle oil from advanced auto.

I'll ride it like I stole it then and see of that helps.
« Last Edit: May 29, 2014, 10:36:09 AM by ncstatecamp »

Offline lucky

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Re: After a rebuild how long until rings seat?
« Reply #16 on: May 29, 2014, 11:14:36 AM »
Throttle MUST be wide open during compression test.
Battery must be fully up.

Offline grcamna2

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Re: After a rebuild how long until rings seat?
« Reply #17 on: May 29, 2014, 01:28:51 PM »
When you do each cylinder's compression test hold the twist grip Wide Open(Full Throttle)so you'll have the least air restriction through the carbs. and airbox.
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Offline 750K

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Re: After a rebuild how long until rings seat?
« Reply #18 on: May 29, 2014, 02:03:22 PM »
When you do each cylinder's compression test hold the twist grip Wide Open(Full Throttle)so you'll have the least air restriction through the carbs. and airbox.

+1
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Re: After a rebuild how long until rings seat?
« Reply #19 on: May 29, 2014, 05:12:16 PM »
Do it with the choke off and the throttle wide open, motor warmed up when you do the compression test.

Choke has been off, motor was warm. Not makin any sense in my head as to throttle open would make a difference but next time I'll give it a try.

A leak down test is just putting in conpressed air when cylinder is at TDC to see where it's leaking right? (exhaust,air box or oil tank right)

The oil is non-synthetic. Just 10-40w motorcycle oil from advanced auto.

I'll ride it like I stole it then and see of that helps.

If you close your mouth and pinch your nose, then try and take a big breath, your not going to get much air. The motor is the same. You must do the compression test with the throttle wide open. Pewe's link is an old one and I also agree with it, but the run in needs to be progressive. You are past that point now so give it some herbs.

Offline bjbuchanan

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Re: After a rebuild how long until rings seat?
« Reply #20 on: May 29, 2014, 06:44:56 PM »
Ride that thing like its some crappy 80cc dirtbike, it needs to be run hard. It would have blown up already if it was gonna from assembly errors, you need to get it run in good now
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Offline ncstatecamp

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Re: After a rebuild how long until rings seat?
« Reply #21 on: May 29, 2014, 11:14:31 PM »
Bat outta hell status it is then

Offline grcamna2

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Re: After a rebuild how long until rings seat?
« Reply #22 on: May 30, 2014, 06:05:01 AM »
I think a lot of freeway on-ramps will help  ;D  keep an eye in the mirror for the local Constabulary  :o
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
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Offline dave500

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Re: After a rebuild how long until rings seat?
« Reply #23 on: May 30, 2014, 06:24:11 AM »
Ride that thing like its some crappy 80cc dirtbike, it needs to be run hard. It would have blown up already if it was gonna from assembly errors, you need to get it run in good now

+1 except don't peak rpm it yet or downshift heavy,you didn't install any rings upside down?they look square but the top have a slight taper,the chrome one?any manufacturing marks on rings go upwards,i still gotta rematch tim on this drag race,i wasn't ready!kr250 two stroke versus new rebore 550,hes geared down six teeth on the rear since then,it fair flys!two bloody fifty!
kr drag
« Last Edit: May 30, 2014, 06:31:47 AM by dave500 »

Offline grcamna2

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Re: After a rebuild how long until rings seat?
« Reply #24 on: May 30, 2014, 06:35:07 AM »
Dave,
Have you scheduled the re-match yet ?  8)
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
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Do your BEST...nobody can take that away from you.

Offline ncstatecamp

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Re: After a rebuild how long until rings seat?
« Reply #25 on: May 30, 2014, 09:46:47 AM »
The rings were all installed correctly. I quadruple checked that.

Offline bjatwood

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Re: After a rebuild how long until rings seat?
« Reply #26 on: May 30, 2014, 10:43:48 AM »
I did the rings wrong once.....Then bought a nice big Magnifiying glass to see the darn lettering....I had the scraper ring going up instead of down. Was pissed but I did it myself, lesson learned..  :-[
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Offline iron_worker

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Re: After a rebuild how long until rings seat?
« Reply #27 on: May 30, 2014, 10:50:42 AM »
Some rings (Ie the ones I got from Cycle X) are square cut and don't have an up and down. You just put the chrome one in the top groove and you're good to go.

IW

Offline dave500

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Re: After a rebuild how long until rings seat?
« Reply #28 on: May 30, 2014, 02:35:03 PM »
Dave,
Have you scheduled the re-match yet ?  8)

itll happen!

Offline ncstatecamp

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Re: After a rebuild how long until rings seat?
« Reply #29 on: May 31, 2014, 08:47:47 AM »
Luckily my eyesight up close is pretty damn good. The rink logo is up.

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Re: After a rebuild how long until rings seat?
« Reply #30 on: May 31, 2014, 10:40:24 AM »
BIG +1 on PeWe's link !! Some may not agree, but I can see Mototune's line of thinking and will use his process on the next motor I build !!! Sounds logical to me.   ...cougar...

When BMW introduced the S1000RR at the end of 2009, engines were blowing up at an alarming rate. By the beginning of the next year, the new bikes came with an rpm limiter installed which was removed at the first service (600 miles/1,000km). Amazing that the clueless engineers at BMW managed to build the superbike of the year with unrivaled performance, but are so clueless regarding the break-in procedure. Pure coincidence that the measure worked fine, right?. But, then again, the RR is not such a modern bike as the CB Four which probably helps to explain the different procedures. Wait a minute? Wasn't it the other way around? Oh well. What do the engineers at BMW know anyhow?

Offline Lostboy Steve

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Re: After a rebuild how long until rings seat?
« Reply #31 on: May 31, 2014, 11:28:16 AM »
Should I post that link again? The one about break-in procedures? Again, I don't know what to believe, but the link is a good one. Here:
[url]http://www.mototuneusa.com/break_in_secrets.htm/url]
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AJK

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Re: After a rebuild how long until rings seat?
« Reply #32 on: May 31, 2014, 06:35:02 PM »
Just some thoughts,

Load is more important than revs. When loaded, the combustion pressure gets forced behind the ring groove and forces the ring out which helps it mate the new ring surface to a freshly honed bore. You have a limited window in which to take advantage of this before you wear that ring in against the new bore/hone properly. Thats why its no good to let it sit there and idle on a fresh build, because all your doing is wasting the opportunity to make a good ring seal by wearing out the cross hatch you put in there in the first place for that very reason. You want to get those surfaces mating under load to get a good seal for a long time.
  On a new motor, everything is tight, so you need to keep the revs moderate to start with, but you have to give it load, so get climbing some hills. In doing so, you also need to keep temperature in mind because everything is going to run a lot hotter until its all run in due to increased friction, so after a short run, let it cool down again and repeat. After 20 to 50kms of riding, the piston has already gone up and down thousands of times, so you can imagine what its taken off the liners & ring surface in terms of shavings in such a short time on a fresh hone. You will see this as glitter (a lot of it) in your first oil change. Thats why its real important to change your oil and filter on the first change because the engine is spewing this stuff out. You will find this glitter in the oil, but also when you take your filter out, rip it apart and take a look at what you will find in the bottom of the v-grooves and also in the bottom of your filter housing cup. Get some between your fingers and give it a rub and you will quickly understand whats going on in your motor.
  As you start to put on more kms, continue to increase the revs. You will get more shavings, but they will be a lot less in quantity, even with more kms.
 As someone said, use cheap crappy mineral oil without friction modifiers for the first 1000 miles at least before going to something better. You want the surfaces to marry (with clean but crappy oil), then once thats done, put something decent in there. After a few several thousand kms, it would be good to pull the pan and clean the screen as well.
  Modern engines still are honed in the same manner, but these days they finish it off with a plateu hone which knocks off all the high peaks but allows good oil retention in the lows, making for a motor that requires less & quicker break in than a traditionally honed one. A few hard runs and its all done.

So the short of it is, think load first, then revs, and as it starts to free up after some kms, increase the revs and keep giving it more load at the same time.

The following pics (in this order) are:
(1) Filter ripped apart - have a look at the particles in the v-grooves
(2) same as (1) but reverse/clean side of the filter for comparison
(3) Cup housing.

All this happened in the first 20kms.


This is why I also like this idea
http://forums.sohc4.net/index.php?topic=103432.0
&
http://forums.sohc4.net/index.php?topic=137793.0


There are different schools of thought on the matter. These are just my thoughts & something thats worked well for me over the years.
« Last Edit: May 31, 2014, 06:48:51 PM by AJK »