Installing completed engine assembly into the frame, Will this work?

I will be picking up my engine components from my machinist later this week. I plan to assemble the power unit on the bench using an engine stand and then set it into the frame. I have left the front end of the bike intact on the frame and have it standing on my lift table. I spent some time earlier today researching how to get a completed engine in the frame and seeing all the different methods employed,
i.e., lay frame over power unit etc, I can see the issue is clearing the cradle. Also getting the gear box into the cradle (or out) with the engine in place is difficult.
If I support the frame on the lower loops to allow for engine clearance below the frame loops and the cradle to swing freely, (not the big single block you see pictured), and place the partially assembled gear box into the cradle,I think with the front ISO on the engine, I should be able to set the engine in the frame and bolt up the front ISO, then present the cradle by swinging it into place, tipping the engine as needed.
I simply ask, "why wouldn't this method work?". Will the cradle clear or is that the flaw in my plan? Looking at my other 850 Commando, it appears it would. Thanks for your replies!

Jonez69 said:

I will be picking up my engine components from my machinist later this week. I plan to assemble the power unit on the bench using an engine stand and then set it into the frame. I have left the front end of the bike intact on the frame and have it standing on my lift table. I spent some time earlier today researching how to get a completed engine in the frame and seeing all the different methods employed,
i.e., lay frame over power unit etc, I can see the issue is clearing the cradle. Also getting the gear box into the cradle (or out) with the engine in place is difficult.
If I support the frame on the lower loops to allow for engine clearance below the frame loops and the cradle to swing freely, (not the big single block you see pictured), and place the partially assembled gear box into the cradle,I think with the front ISO on the engine, I should be able to set the engine in the frame and bolt up the front ISO, then present the cradle by swinging it into place, tipping the engine as needed.
I simply ask, "why wouldn't this method work?". Will the cradle clear or is that the flaw in my plan? Looking at my other 850 Commando, it appears it would. Thanks for your replies!
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I never fit the head to the engine unit for a bench rebuild .. My last rebuild I had to pull the head to get it to fit , with the weight . .ask for help ... Big plus to using wood .

Jonez69 said:

I will be picking up my engine components from my machinist later this week. I plan to assemble the power unit on the bench using an engine stand and then set it into the frame. I have left the front end of the bike intact on the frame and have it standing on my lift table. I spent some time earlier today researching how to get a completed engine in the frame and seeing all the different methods employed,
i.e., lay frame over power unit etc, I can see the issue is clearing the cradle. Also getting the gear box into the cradle (or out) with the engine in place is difficult.
If I support the frame on the lower loops to allow for engine clearance below the frame loops and the cradle to swing freely, (not the big single block you see pictured), and place the partially assembled gear box into the cradle,I think with the front ISO on the engine, I should be able to set the engine in the frame and bolt up the front ISO, then present the cradle by swinging it into place, tipping the engine as needed.
I simply ask, "why wouldn't this method work?". Will the cradle clear or is that the flaw in my plan? Looking at my other 850 Commando, it appears it would. Thanks for your replies!
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If you can pickup a complete engine, curl it, and have someone help align the cradle and front mount, it can be done.

I build the power unit, lay it on the timing side on a piece of foam, and lower the bare frame over it. Put in the rear ISO bolt and then wiggle the front ISO into place. Then stand the frame up. I'm still strong enough to do that by myself and it's actually easier with no one helping.

Once the cases were back together, I have always built the engine in the frame as I work alone. The head is a bit of a fiddle but not that bad. Just make sure the pushrods are pushed as far up in the head as possible. Use rubber bands to hold the rockers into the pushrods once you drop them into the lifters.

marshg246 said:

If you can pickup a complete engine, curl it, and have someone help align the cradle and front mount, it can be done.

I build the power unit, lay it on the timing side on a piece of foam, and lower the bare frame over it. Put in the rear ISO bolt and then wiggle the front ISO into place. Then stand the frame up. I'm still strong enough to do that by myself and it's actually easier with no one helping.

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Yes you can do it yourself ... but at 67 I always ask for help . Many help . I live in a good neighbourhood .

Torontonian said:

Yes you can do it yourself ... but at 67 I always ask for help . Many help . I live in a good neighbourhood .

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At 67, a Norton engine wasn't too heavy for me. At 75, with one arm mostly unusable (destroyed shoulder) and the other shoulder somewhat damaged - I cannot pickup a Norton engine. I also cannot install Norton barrels in the frame unless I use my engine hoist. I can still remove/install a Norton head in the frame by myself (just). I still build Triumph engines in the frame from the crankcase up - they are easy.

It's shocking to me how far down I've fallen in 8 years! I can get help, but often just find a way to use my engine hoist to be my helper.

When I was in my 60s, I picked-up an H1 Kawasaki motor. I think I held it for too long. I went inside my house, sat in an armchair and had a stroke. With most British road bikes - the top end of the motor can be assembled while the bottom end is in the frame. Holding a dead weight for too long can be dangerous. Whenever I do anything, I always think ahead and take my time.

When I installed an engine in a 1980's Suzuki GSX1100 (very heavy) I laid the engine on it's side, lowered the frame over it and put the bolts in.
Then I stood it upright and assembled the rest of the bike

acotrel said:

When I was in my 60s, I picked-up an H1 Kawasaki motor. I think I held it for too long. I went inside my house, sat in an armchair and had a stroke. With most British road bikes - the top end of the motor can be assembled while the bottom end is in the frame. Holding a dead weight for too long can be dangerous. Whenever I do anything, I always think ahead and take my time.

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Al, you KNOW you can't trust a 2-stroke. It'll either chuck you down the straightaway, or, in your case, find another way to hurt you.

Andy Higham said:

When I installed an engine in a 1980's Suzuki GSX1100 (very heavy) I laid the engine on it's side, lowered the frame over it and put the bolts in.
Then I stood it upright and assembled the rest of the bike

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When I rebuilt my XS1100, I set the engine in the frame, sitting upright on the mainstand. I was 24yo.

Thanks again for the replies. So the basic question has been answered, the cradle will swing into place from behind. The weight and manhandling the power unit into place is the stumbling block of my proposed method. Pulling the head in the frame when I tore down this machine was my first go with a Norton, That was a nightmare, but I got it done.
Next I pulled the cylinder off the cases while in the frame which was straight forward. Removing the cases with the gear box in place took some figuring, but not bad. I am just looking for any possible way to completely assemble the power unit on the bench because the head installation in the frame will be a real challenge for a first timer.
I turn 66 years old next month and am in very good physical condition. No back, or joint issues, blessed. I'll let you all know how I finally get the engine and frame together
once it happens.

Jonez69 said:

...I am just looking for any possible way to completely assemble the power unit on the bench...

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Find an old mattress (typically a 5 minute job if you live near a low-rent neighborhood).
Lay it on the ground, lay the engine down (a la Greg), then gently lower the frame (with cradle & trans already in place) over the engine.
Easier with a helper, even a little kid, just for balance.

Make sure you installed the swingarm plugs first! hee hee

I'm no stranger to the lay the bike on its side drill. Rebuilt a basket case 69' Bonneville 6 years ago (my first major rebuild) and had to lay it down to install the
crank case breather tube after forgetting it earlier in the project! I brought the foam along to my new smaller shop when we moved last year.

Jonez69 said:

I'm no stranger to the lay the bike on its side drill. Rebuilt a basket case 69' Bonneville 6 years ago (my first major rebuild) and had to lay it down to install the
crank case breather tube after forgetting it earlier in the project! I brought the foam along to my new smaller shop when we moved last year.
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HA HA HA HA !!!!!

I did that ONCE! Never again. I have my own "order-of-assembly" that I stick to - one for Triumph, one for BSA, and one for Norton.

Jonez69 said:

Thanks again for the replies. So the basic question has been answered, the cradle will swing into place from behind. The weight and manhandling the power unit into place is the stumbling block of my proposed method. Pulling the head in the frame when I tore down this machine was my first go with a Norton, That was a nightmare, but I got it done.
Next I pulled the cylinder off the cases while in the frame which was straight forward. Removing the cases with the gear box in place took some figuring, but not bad. I am just looking for any possible way to completely assemble the power unit on the bench because the head installation in the frame will be a real challenge for a first timer.
I turn 66 years old next month and am in very good physical condition. No back, or joint issues, blessed. I'll let you all know how I finally get the engine and frame together
once it happens.

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You are overthinking the difficulty of reinstalling the head while the engine is in the frame. It’s a little fiddly aligning the push rods into the rocker arms but not overly so. I did it alone my first time with no prior experience of Nortons or motorcycles in general. A second set of hands makes it easy.
More important is making sure that the bores in the barrels for the front head bolts haven’t broken through into the push rod tunnels (poor factory machining work). Epoxy at the breakthrough combined with thread sealant will solve that.

I've just disassembled my first Commando and found removing the cylinder head far easier than my N15. I expect reinstalling the head after the engine is in the frame will also be far easier as the Commando provides much more room to move head and pushrods AND I don't have to remove the exhaust rocker shafts to make room for pushrods!

lazyeye6 said:

You are overthinking the difficulty of reinstalling the head while the engine is in the frame. It’s a little fiddly aligning the push rods into the rocker arms but not overly so. I did it alone my first time with no prior experience of Nortons or motorcycles in general. A second set of hands makes it easy.

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I came up with an easy method:

-Tear two strips of old t-shirt about 6" long
-Lay head on the bench upside-down and insert pushrods onto rockers
-Shove one wadded up strip of t-shirt into each tunnel, snugly, with a 2" "tail" sticking out
-Invert head, tip into place GENTLY, so as not to disturb the snug fitted pushrods
(saying a prayer for pushrods to be properly sat on cam follower tips is optional at this stage)
-Pull out the strips of T-shirt and proceed per shop manual.

These days, I use the rubber band method I learned here to install the head. I continue to use the cuss a lot method to remove the head!

Big difference working with dry verses oily pushrods!

When I build the engine in the frame I put the pistons in the barrel on the bench. Barrel upside down on the bench. Install the inner circlips on the pistons. Ring clamps on the pistons assembled with rings. Insert pistons leaving pin boss exposed. With the crankcase mounted in the frame lower the barrel/pistons over the rod ends. Rods need to be a tdc. A piece of wood helps to hold the barrel. Heat the pistons a bit and freeze the pins. Slide the pins in and install the outer circlips. Be sure that you stuff the crankcase with rags first in case a circlip escapes. Lower barrel. You may need to raise it a bit to provide clearance for nuts.

htown16 said:

When I build the engine in the frame I put the pistons in the barrel on the bench. Barrel upside down on the bench. Install the inner circlips on the pistons. Ring clamps on the pistons assembled with rings. Insert pistons leaving pin boss exposed. With the crankcase mounted in the frame lower the barrel/pistons over the rod ends. Rods need to be a tdc. A piece of wood helps to hold the barrel. Heat the pistons a bit and freeze the pins. Slide the pins in and install the outer circlips. Be sure that you stuff the crankcase with rags first in case a circlip escapes. Lower barrel. You may need to raise it a bit to provide clearance for nuts.

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This one on the bench, same in frame, hanging from my engine hoist:



Whole process starting at Nov 8, 2025 here: https://gregmarsh.com/MC/Norton/Combat5.aspx