Author Topic: Running in/breaking in a new engine  (Read 1536 times)

Offline bill harrison

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Running in/breaking in a new engine
« on: 04.08. 2015 14:57 »
Hi,

I've 2 bikes with "new" engines and wondered if there's a thread somewhere on how best to run the bikes in.  One is a Rocket Gold Star so its a fairly highly tuned (for an A10) motor.  I'm using Millers Pistoneze 40 which is a straight 40's and this has been recommended for the life of the bike.  I was using a mineral 20-50 on my other A10 and B31 which I'm assured is OK as well.

Online Greybeard

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Re: Running in/breaking in a new engine
« Reply #1 on: 04.08. 2015 15:19 »
As no one else has yet posted a reply I'll give you my tuppence-worth. My advice is to not make the engine to work too hard; either by high revs in any gear or changing gear too early causing the engine to 'plod'. In the first few miles I'd recommend stopping every few miles to let the engine cool down a bit; apart from saving engine pick-ups this might save your exhaust down-pipes from getting blued. Other members will no doubt have other advice/opinions.

Online metalflake11

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Re: Running in/breaking in a new engine
« Reply #2 on: 04.08. 2015 15:40 »
Small throttle openings, and let the engine rev out through the gears. That will give you good oil pressure, and little engine load.
Oil change at 50, 500 and then 1,000 mile intervals after that.
Good luck with it!
England N.W
1960 A10
England

Online bsa-bill

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Re: Running in/breaking in a new engine
« Reply #3 on: 04.08. 2015 15:42 »
Think the above have it covered, worst thing you can do is let the engine slog
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline bill harrison

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Re: Running in/breaking in a new engine
« Reply #4 on: 04.08. 2015 15:52 »
Sounds good.  How many miles do you need to run in for?  I've done 400 so far on the RGS and its getting a little more free running I think.  I've changed the oil twice already as it began looking quite black quite quickly.

Offline Topdad

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Re: Running in/breaking in a new engine
« Reply #5 on: 04.08. 2015 15:56 »
Yes avoid load, if you feel the motor labouring change gear  and that's good advice about oil changes although one train of thought I've seen did voice the opinion that oil being so much better these days you could prolong the running process by changing to often , personally I changed my oil as mentioned , Bob
" rules are made for the guidance of wise men and the blind obediance of fools"
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Offline Topdad

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Re: Running in/breaking in a new engine
« Reply #6 on: 04.08. 2015 16:00 »
with 400 on the clock start to ease the throttle farther open for short spells and then slow off again, when  about 500miles then build up the pace just keeping the load down but opening the throttle further , take your time and you'll notice the difference.
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Offline bill harrison

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Re: Running in/breaking in a new engine
« Reply #7 on: 04.08. 2015 16:03 »
Thanks.  Sounds sensible.  Hopefully can get a few longer runs now before the weather turns.

Offline Topdad

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Re: Running in/breaking in a new engine
« Reply #8 on: 04.08. 2015 16:13 »
Fingers crossed ,it's bloody awful up here in merseyside at the mo, rain and wind , Bob
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Offline chaterlea25

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Re: Running in/breaking in a new engine
« Reply #9 on: 04.08. 2015 16:45 »
Hi All,
Just one more thing (or 2 ?)

Triple check ignition timing,
Make sure carbraution is near as possibl;e correct

Theres nothing that will wreck a new engine quicker than weak mixture or bad timing *warn* *warn* *warn*

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Offline Klaus

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Re: Running in/breaking in a new engine
« Reply #10 on: 04.08. 2015 17:14 »
Run in my raceengines is done in a 20 minutes *eek*
First run is starting and give the engine 3000 revs about 10 minutes, with a cooling fan.
Let the engine cool down, I do the second run next day.
Second run is the same procedur, after cooling changeimg oil and check valvle clearance.
I had never problems with this and I run the bike at the racetrack allways full throttle.

Cheers Klaus


If you think, everything is under control, you are not fast enought.

Online Triton Thrasher

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Re: Running in/breaking in a new engine
« Reply #11 on: 04.08. 2015 17:43 »
Or you might make it pull hard in bursts, to bed the rings into the bore.

Offline East_Coast_BSA

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Re: Running in/breaking in a new engine
« Reply #12 on: 04.08. 2015 19:34 »
The fellow who built my engine gave me a "Two-step" process to follow.  Start the bike with good sized Boxfan blowing air on the engine.  Let it run @ 2000 RPM for a few minutes and shut off for a few minutes.  Repeat five or six times until the engine has completely warmed up.  The following day pop off the rocker-box and re-torque the head while the bike is cold.  Repeat this everyday until all the bolts remain tight.  This took four days initially for the bolts to settle in.  I re-torqued them at 25, 125, 250 and 500 miles.  I'll check them again @ 1000 (since I still have two that get loose).  As far as break-in, I am a firm believer in a "Hard Break-in".  Don't let the motor run below 3000 RPM and don't be too shy with the throttle for the first 500 miles.  As you accumulate mileage, you can get more aggressive with the acceleration.  The object is to Seat the Rings.  The best time for the rings to seat is when the hone marks on the cylinder are at their sharpest, when the cylinder is new.  Cylinder Pressure is what forces the rings outward and causes the rings to seat.  Going easy is the worst thing you can do for a new motor.  Riding it easy (with low cylinder pressure) will allow for blow-by (which glazes the cylinders) and the rings won't seat.  If you look at pistons that were subject to easy break-in, you would see all the discoloration on the skirts.  Hard break-in pistons have clean skirts.  This works for four stoke motors as well as two stroke motors.  Race teams build motors and take them right to the track.  I only did the short heat cycle in the beginning for torquing the head, nothing else.  I don't know why people "Heat-cycle" new engines as a rule, because it serves no purpose that I can see.  If you keep riding that bike easy, that oil will be black for a long time.  Blow-by is what's turning that oil black and until the rings are seated, it will stay black.  Don't be afraid to wind it up and make it work.  As mentioned before lugging the engine isn't good either.   

Offline chaterlea25

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Re: Running in/breaking in a new engine
« Reply #13 on: 05.08. 2015 00:46 »
Hi,
Quote
The following day pop off the rocker-box and re-torque the head while the bike is cold.  Repeat this everyday until all the bolts remain tight.  This took four days initially for the bolts to settle in

With a solid copper gasket and the head bolt hole seats spot faced flat + 3mm thick head washers I have never needed to re torque the head bolts
I have checked them but no re tighteninfg was needed

I do not agree with running the engine unloaded as you suggest, quickest way to glaze a bore I know

John
1961 Super Rocket
1963 RGS (ongoing)

Offline East_Coast_BSA

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Re: Running in/breaking in a new engine
« Reply #14 on: 05.08. 2015 05:25 »
Looking at the big picture, a fast idle for a few minutes at a time isn't going to hurt anything, riding around at a light load will cause more glazing problems than that.  I had a new solid head gasket, new bolts and the seats were spot faced.  I've checked the head bolts four times in the last 900 miles and the two center bolts near the exhaust have always taken a little "Twist".  The rest have pretty much stayed tight.  The motor had over 30k miles before I had it rebuilt.  Maybe there is a fatigue issue with the aluminum head over time, I don't really know.  I didn't check it after the initial run-in torquing and I the gasket started to leak at 1800 miles.  There were three bolts that were very loose.  So off it came and I started over again.  The fellow that rebuilt the motor said that it's not uncommon to see loose bolts for a while.  This is my first British bike so I'll just keep an eye on everything.  There isn't much more I can do except periodic checking.