Can Am Bombardier 250.

[Cato]

Well that's most of the bits in primer, I just need to decide between Nato Green and Light Stone then get the colour on. Once that's done the bearings etc should be here and I can get it rolling again.

 

[Robotstar5]

It's a shame Seager bearings has gone from the estate, you could have almost walked round the corner to get them.

 

[Cato]

It's a shame Seager bearings has gone from the estate, you could have almost walked round the corner to get them.

Yeah, walking/driving to get most things round here now is a thing of the past. That was the main reason I ended up getting a lathe, the small engineering firms that you could walk in near lunchtime and get a spacer turned for a drink are long gone.

Still, no benefit in moaning about what I can't do. If you can read a bearing number, or use a set of verniers then you can order pretty much any bearing you want online. Even the radial and axial rollers for the head stock are available. A big plus was discovering that riveted brake shoes are available, so no more de-bonding of linings.

I'm keen to get it as a painted roller ASAP because everything after that is a fettle/fiddle/potter job and the other bits I need are just a question of waiting for a nicer one than I have to come up. The tank for example, or the front and rear mudguards, the old ones are usable for now but not great.

 

[stuvy]

@Cato

But with yellow number boards

 

[Cato]

Well that's enough bits in colour to be able to start rebuilding once it's cured.

 

[Cato]

Off to Wheelhouse tyres in the morning to get a pair of Heidenau K67 fitted, I'll have road tubes as that's where it'll see most action. Once they're on I can start building it up and should have it as a roller toot suite.

 

[redlig]

I'm afraid I cannot understand painting the whole wheel as a unit. Surely if an adjustment is required to the spokes ,for any reason, the the paint will be disturbed and cause possible corrosion under the painted surface.

 

[Farside]

Really enjoyed mine, but it had the world's most arsse-pinching seat on it for going more than 30 miles.
Fiddled with the mixture to stop it four-stroking so much and promptly holed a piston on the M1.
Got another piston from the seller in Edgware Rd and it went like stink after that.
Good times.

 

[Cato]

I'm afraid I cannot understand painting the whole wheel as a unit. Surely if an adjustment is required to the spokes ,for any reason, the the paint will be disturbed and cause possible corrosion under the painted surface.

Originally it's part of the 'hiding from the bad men' thing for the military. In this case it's because they were originally painted and had to be stripped, so they'd look rough as if they weren't painted again. Any paint chipped when working on any part of it is given a new coat with a brush when in service, and it'll get the same treatment from me.

It's worth bearing in mind that these military bikes are over 40 years old (plenty of B40 BSA's about in the same condition), and as you can see from the pictures after sand blasting there aren't any corrosion issues. It's a pretty good indication to me that it works pretty well when you consider what military vehicles go through. Given that everything's in good serviceable condition lacing on new rims using new spokes to make it look pretty would just be a waste of money.

 

[Cato]

Real progress being made now. I took the top end off of the engine to see what's what there, and it all looks decently serviceable. So the side cases, barrel and head can go off for blasting and get painted when they come back. That meant I can fit the bottom end back into the frame, so the swing arm pivot can go in.

I also had the tyres fitted this morning, which meant I could then fit bearings, build up the brakes and get the back end in.

 

[redlig]

Sorry to appear a trifle picky but that top end isn't what I would call 'decently serviceable' but we all have our own levels of usability. To me I'm afraid I couldn't rebuild an engine in anything other than in an as new condition as possible . @Cato
View attachment 395653

But with yellow number boards

 

[Cato]

Each to their own, but wear well within tolerance, and no damage = serviceable to me.

 

[redlig]

Each to their own, but wear well within tolerance, and no damage = serviceable to me.

As you say each to their own.

 

[Farside]

Real progress being made now. I took the top end off of the engine to see what's what there, and it all looks decently serviceable. So the side cases, barrel and head can go off for blasting and get painted when they come back. That meant I can fit the bottom end back into the frame, so the swing arm pivot can go in.
View attachment 396235

The two-ring piston was the one I was issued with, to replace the three-ring OEM one.

 

[Cato]

The two-ring piston was the one I was issued with, to replace the three-ring OEM one.

They're an odd design, stepped compression ring and a slightly reduced crown diameter to clear the step.

 

[Cato]

As you say each to their own.

Probably worth mentioning, but I didn't mean that I was just going to close it back up as is. I was referring to being happy that it didn't need an over size piston and boring to suit.

Once the barrel and head have been stripped of paint the bore will get a light hone, new rings (if available) then the piston and combustion chamber cleaned. Then it'll go back together with fresh oil.

 

[OJCar]

They're an odd design, stepped compression ring and a slightly reduced crown diameter to clear the step.

Called a Dykes Piston Ring.

Were very popular when I used to rebuild TZ, YZ & IT engines about 40 years ago.

 

[Cato]

Called a Dykes Piston Ring.

Were very popular when I used to rebuild TZ, YZ & IT engines about 40 years ago.

Not a name I'd heard of. I suppose 30 - 40 years ago was the peak of interest and development in two stroke stuff.

 

[Robotstar5]

Probably worth mentioning, but I didn't mean that I was just going to close it back up as is. I was referring to being happy that it didn't need an over size piston and boring to suit.

Once the barrel and head have been stripped of paint the bore will get a light hone, new rings (if available) then the piston and combustion chamber cleaned. Then it'll go back together with fresh oil.

No, no, it needs a ported big-bore kit, tuned expansion pipe and a bigger carb

 

[OJCar]

Not a name I'd heard of. I suppose 30 - 40 years ago was the peak of interest and development in two stroke stuff.

Part of the idea was they provide better ring to cylinder wall sealing as the combustion pressure pushes the ring tighter to the cylinder wall.
Also better at not picking up in ports.
They sometimes get used in boosted performance four stroke engines.