Breaking in a rebuild

If all goes well this weekend I'm hoping to fire up my 850 MKII after a couple months of fettling. I'm getting anxious about the initial runin procedure, I don't want to hurt anything.

I'm replacing main bearings, camshaft, and big end shells. All lubed up with assembly lube. The head has had a total rebuild also. Pistons and rings have 2000 miles on them (done last year), so that part is OK.

My concern is breaking in the new cam. Norvil says run the engine at 2500 rpm for 30 minutes.. that'll be one HOT motor. I also have to set the Boyer timing at 5000 rpm. All this while wondering if the oil is circulating and my crankshaft is gonna hold together.

Anybody have a checklist of things to do before firing up for the first time? I just need to build a little confidence and know I've done everything that I can do.

Thanks

He actually says 10 minutes, not 30. I agree, running a new engine for 30 minutes with no airflow does not sound like a good idea.

I basically followed his advice for running in both of my engines. At the end of that first short run I did a quick test ride around the block, which he says you're not supposed to do. I couldn't resist though, and it didn't seem to hurt anything.

I didn't want to run my new 850 motor up to 5000 either, so I waited a couple hundred miles. When I finally strobed it, the timing was 5 degrees retarded. That's not good either. Six of one, half a dozen of another - what can you do? Actually with a Pazon you only have to rev it to 4000, which isn't quite as bad.

Don't lug it, don't let it get too hot, and make sure you do those head retorquings...

Debby

I haven't started up a new cam so can't comment on the 30 minute run time there. It does seems like a hell of a long time to run an aircooled motor while stationary. If that really is what is required, you might get yourself a large fan and keep as much air moving over the engine as you can. I think the 2500 rpm minimum is to ensure a good oil supply to the cam. My experience with startups is that it will take about 30 seconds to a minute to start to see oil coming back into the oil tank. It takes a while to fill up the oil filter on a Commando. You can speed this up by priming the oil pump and some people will squirt oil into the end of the crankshaft until they see it exiting the main sump drain and some will squirt oil into the rockers. This probably isn't necessary if you have used assembly lube on your big end bearings and main bearings. I think the assembly lube will cover you until your oil gets circulating. Keep a close eye on the return pipe into the oil tank. If you aren't getting oil by a minute or so, shut 'er down and figure out what is wrong. I wouldn't worry about strobing the Boyer until you have everything running and your cam bedded in. My experience with Boyers is that they will run fine with static timing and you probably don't want to run at 5000 rpm right away anyways. If your head was rebuilt you will also want to go through a few heating and cooling cycles while retorquing the head. I am doing that on my Commando now after a top-end rebuild. I drove my bike about 20 minutes yesterday and today will retorque the head and set valve clearances today. Some people advocate several cycles of heating and cooling and checking the head bolts to make sure your head gasket doesn't blow. Good luck!!

Don't do list.
Don't let it idle below 1000 RPM do not let it idle too much at all, ride it.
Don't let it run without a fan on the motor for more than 5 minutes.
Don't top off the oil all the way before it's fully warm. Half way up the stick is fine.
Don't baby it too much put some load on the motor as soon as you dare.
Don't over tighten things thinking that this is the last time it will be apart.
Do list.
Do strobe the timing real soon, a quick rev to 5000 or till the mark quits moving under the light will not hurt the motor.
Do check the oil tank for a strong return gush and check the over all pressure.
Do re-tighten the fork pinch bolts and all the fasteners after the first ride.
Do re-torque the head after the first heat cycle and after the first 50 miles 150 miles and so on depending what you find.
Do re- lash the valves on every re-torque.
Do prepare yourself mentally to take things back apart if there are noises or adjustments that change.
Do keep a sharp eye out for primary and main chain adjustment moving . Head steady, Transmission bolts and all.
Do make sure your brakes work well, don't laugh too hard, many people forget the basics.
In your rush to put the fuel tank on don't foul your wire and cable routing.


I fitted up a Tri-spark to a friends Commando the other day removing a Boyer. Now he is an old hand at starting it but couldn't get it to pop at all. So I gave it a try and first kick it ran. He looked at me with that OK smart ass look. Had to explain to him that tweaking the throttle was no longer needed nor was a full kick. The bike will now start with a quarter turn just a push through really, prime the Amals and go. Always use your clutch lever to be sure the clutch is free before clunking into gear.

With the Boyer if you time it to 28 degrees BTDC at 3000 it will usually be right on 31 at 5000 rpm. Close enough anyway.

Russ

hi maylar,if you know someone with a rolling road dyno you could do what you want to do on that without the engine even firing up,or you could rig up a set of starting rollers long enough to fit under your cars driven wheels and extending out so you have enough room to get the bikes rear wheel on it,you will need a mate to give you a hand with this though,i believe triumph did this (but not with a car)in the factory on newly built bikes before they went out on a road test

What you should do is prove oil flow is the pull the plugs, place in 4th gear and wheel it around the block. Everything will prime and you can then crack one of the oil line banjos to the head to prove oil flow when it weeps.

good grief :roll: :roll: :roll: if you do use this method get mum or the kids to push then you can go round twice

GavinJuice said:

What you should do is prove oil flow is the pull the plugs, place in 4th gear and wheel it around the block. Everything will prime and you can then crack one of the oil line banjos to the head to prove oil flow when it weeps.

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I also use this method as outlined by Gavin, it is quicker than kicking it over 100 times and I think gets the oil flowing better due to continuous rotation of the engine. It depends on how big a block you live on whether Gavin's description might seem like a training regimen for 'iron man' triathalons or not!

dave M said:

I also use this method as outlined by Gavin, it is quicker than kicking it over 100 times and I think gets the oil flowing better due to continuous rotation of the engine. It depends on how big a block you live on whether Gavin's description might seem like a training regimen for 'iron man' triathalons or not!

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FInd a road racing buddy and borrow his starting rollers.

norbsa48503 said:

Do prepare yourself mentally to take things back apart if there are noises or adjustments that change.

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That's the hardest part. I really want to ride it, as the weather has turned nice. But I ignored some "ticking" noises last year and am paying the price for that now. Maybe I'll ride without my full face Arai for a while so I can hear the motor better.

Thanks for the tips, guys. I'll post a blog of this project when she's on the road again.

Dave

GavinJuice said:

What you should do is prove oil flow is the pull the plugs, place in 4th gear and wheel it around the block. Everything will prime and you can then crack one of the oil line banjos to the head to prove oil flow when it weeps.

Click to expand...

This brings up a question I've been wondering about. I've heard it said that kicking the engine over 100+ times, or pushing it around the block, is not a good idea as turning the cam over against full spring pressure, but without oil flow, can gall the lobes and quickly ruin that brand new cam. It's been said that you can destroy a new cam before the engine is even fired for the first time.

What sayeth the experts about that? I don't quite know what to think about that. I've always just primed the crank with an oil gun as described in the factory service manual, and relied on assembly lube to do the job until the engine has oil pressure. I do use cam assembly lube on the cam lobes.

Debby

debby said:

This brings up a question I've been wondering about. I've heard it said that kicking the engine over 100+ times, or pushing it around the block, is not a good idea as turning the cam over against full spring pressure, but without oil flow, can gall the lobes and quickly ruin that brand new cam. It's been said that you can destroy a new cam before the engine is even fired for the first time.

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Yes, there is an argument against turning the engine over slowly, as many parts are lubricated by "splash", then those parts won't be getting sufficient lubrication until the crankshaft is spinning fast enough to start throwing oil, so turning the engine over by the kickstarter, or pushing the bike whilst in gear with the plugs out until oil is seen to return to the oil tank, according to some, should be avoided-especially if no assembly lube has been used?

I would prime the crank, remove the exhaust valve inspection covers and add some oil to the cylinder head so that the tappets and cam lobes get an initial dose of lubrication, and then start the engine, preferably with an oil pressure test gauge fitted (if it's a bike with no O/P warning lamp?). If the crank has been primed correctly then oil pressure should register on the gauge (or the O/P warning lamp should go out?) within a couple of seconds of starting up.

Ditto on the cam breakin. 2500 noisy rpm for 30 mins with lots of oil poured down the tunnels and also cam lube on the lobes. Problem is if it doesn't start right away all that gets wiped off very quickly. If you want to fill up the crank so you have good oil pressure at start up (and you must) fill the tank and turn the engine over a few times with the barrels and head off (or at least the head off). Yes I realise that's too late if it's all assembled but just something I do. Alternatively, let the engine sump for a week at BDC. That'll fill the crank. Debbie's oil gun prime as per manual is the best way of course.
And when you run the engine at 2500 rpm be sure to have a good fan blowing on the pipes, head and barrels. I didn't and the pipes glowed red and I wrecked the chrome. Now It looks like mine runs very hot but just the result of cam breakin....impresses some people though!!

I don't agree with Norbsa.
I would set up your Boyer static, and not rev to 5000 yet
If you wanna strobe, do it at less revs to start with, untill the motor beds in. Here are the figures supplied by Boyer to me when I went through the same issue.

Dear Sir, Strobing at the crankshaft, the ignition will be 7 Degrees short of maximum advance at 3000 rpm.

At 4000 rpm the ignition will be 2 degrees from the maximum advance timing.

So you can subtract the 7 or 2 degrees off the 31btdc depending on what revs you choose.

Varying the revs always helps during a breaking in period, just keep em low to start. Don't run for ages without airflow, a hot motor is not good. Just go for some steady runs on roads where you can avioid holding for ages at constant revs.

Stuart.