Engine/Gearbox Teardown & Rebuild

[iDemonix]

Hi all!

Long story short, parents moving, had to sell the classic mini as it was in their garage and be a nightmare to move it down here, so I can now fit a big bench and all my tools in my garage. Once I get a new bench, I plan on an engine rebuild, my first one!

I was riding along, fairly spirited ride, popped it in to 2nd or 3rd (can't remember which) and it broke. So I rode it for a month as a 5 speed, just skipping the gear that did nothing (just spun like it was in neutral). I popped a new engine in the bike and the old engine is now sat doing nothing.

What I'm looking for is a few answers to:

1. What special tools will I need?
2. What is it worth doing whilst the engine is in pieces? I'm not looking for big mods, just a nice rebuild for peace of mind.
3. Not looking to do any work like lapping valves as can't be bothered to re-shim.
4. Anything else you think is relevant!

Never done any bike engine work before, apart from changing the clutch and valve clearances. Looking forward to learning a lot and I'm happy to plod along with this over a long time as it's hopefully going to be my winter project.

Cheers,
Dan

[28hodge]

If you are just swapping the knackered gearbox for a working one i *think* you can do this from the bottom of the engine rather than having to take the heads off.

If your not wanting to lap the valves and replace the valve stem seals then there is little point taking the heads off and costing yourself £76 for head gaskets.

If it were me tho I'd have the heads off lap the valves and clean everything up.

[iDemonix]

What's the advantage of lapping the valves? It requires a re-shim which is a lot of messing about and expensive to source them, also I wouldn't feel comfortable doing it myself so there would be costs there too!

[28hodge]

sorry to answer your question

1 if you just change the box from the bottom of the engine, you should only need basic tools and a torque wrench

2 other than changing the box i dont think there is much you can do from the bottom of the engine in terms of maintenance, you could clean out the sump so there is no sticky sludgey oil hanging around if its been stood snce you swapped engines this might be a good idea.

3 If you changed your mind about the valves etc, then the following would be useful
Valve spring compressor
Micrometer/vernier calipers
Dremel to clean the combustion chamber and inlets and exhaust ports
Feeler gauges
Magnet on a car aeiral telescope thing
Suction cup to stick to the valve to lap it in
Grinding paste
Moly Grease

[Neosophist]

Hi all!

Long story short, parents moving, had to sell the classic mini as it was in their garage and be a nightmare to move it down here, so I can now fit a big bench and all my tools in my garage. Once I get a new bench, I plan on an engine rebuild, my first one!

I was riding along, fairly spirited ride, popped it in to 2nd or 3rd (can't remember which) and it broke. So I rode it for a month as a 5 speed, just skipping the gear that did nothing (just spun like it was in neutral). I popped a new engine in the bike and the old engine is now sat doing nothing.

What I'm looking for is a few answers to:

1. What special tools will I need?
2. What is it worth doing whilst the engine is in pieces? I'm not looking for big mods, just a nice rebuild for peace of mind.
3. Not looking to do any work like lapping valves as can't be bothered to re-shim.
4. Anything else you think is relevant!

Never done any bike engine work before, apart from changing the clutch and valve clearances. Looking forward to learning a lot and I'm happy to plod along with this over a long time as it's hopefully going to be my winter project.

Cheers,
Dan

Valve lapping is cheap and if your valves arnt sealing perfetly its the easiest and most important thing to do to ensure high compression and most power.

I always do the valves when the heads are off as its troublesome to take them off again later for the sake of not doing it.

Barring a flywheel puller and clutch nut socket I dont think you need any specific special tools from Honda.

A good toolkit should have everything you need to do work.

Depends how detailed you wont to get into it though. Its not cheap to rebuild a VFR engine, even more expensive to do it properly

Depends on whats up with you transmission and if you have the replacement parts. But while its apart id look at

1. lapping in the valves
2. check everything against the service manual specs for wear, youll need plastigauge for bearing shells and probably some dial gauges.
3. if everythings in tolerance perhaps a new set of rings?

Usually worth doing right as the cost of just tearing it down and putting it back toegher is quite a bit due to the gasket prices, if you skimp and save too much then you will be throwing the money on gaskets away if you need to get it open again anytime soon.

My advice would be since you dont have a rush for a motor as you replaced it, get it apart, get the service manual and check everything and get an idea of how worn the engine is and go from there. Can always break and sell it for parts if its not worth putting together again

[28hodge]

it'll help with compression as the seats are no doubt carbon'e up, meaning that the valve wont form an air tight seal so you will lose some performance from the engine.

Also with the heads off you can clean up all the water ways as these too will have some corrosion on them and will contribute to hot running.

Lapping the valves will result in re shimming the engine but you will be very unlucky if you need all 16 shims, some of the shims you have will be useable in the valves after they have been reshimmed.