How not to B33!

[Dan_B33]

Hello Neil,
I will tell you when it comes back to me.

I think it will be irrelevant to give any measurements from before.

Dan

[Dan_B33]

Hello,
Piston company called me today.
They of course take no blame.
However the have removed high spots and honed the cylinder.

When I have it back will make measurements to get you opinion.
Will start searching for possibility to fit some good quality piston to what I have in cylinder.

Looks like tis season will be on W650 rather than BSA.

Who knows?

[Dan_B33]

By the way they say the fit for cylinder piston is 0.1mm which is standard for air cooled engines.

Will se to the measurements

[iansoady]

That's about .004" which I would say is on the tight side for a B33.

[neil1964]

There are solid vs slipper types of skirt requiring different tolerances.

It will be interesting to know which type you have in your iron barrel.

I would be inclined to accept a touch of piston slap when cold vs nipping up.

[iansoady]

I would be inclined to accept a touch of piston slap when cold vs nipping up.

Always my attitude too. Plus it means, with the limited mileage I do these days, that I don't have to spend months running in. As long as it's not smoking too much / fouling plugs I'm happy.

[Ian C]

That's about .004" which I would say is on the tight side for a B33.

I agree.. BSA Service Sheet 701 states 0.0045 to 0.0065" for the B33 plus 0.010" for ring gaps.

[Dan_B33]

Good read as always.
I will give a call to them tomorrow to check if it is already on portage.

When you say we start 0.0045" what would be your recommendation? 0.005"?

Dan

[Ian C]

As others have stated Dan, you're better to have some piston slap when cold than to have the clearance too tight, so it is up to you what to use.

[Derek996]

If BSA state  .0045" to .0065" then I would go for .005"

[Dan_B33]

Thanks Derek for straight reply.
Problem in here (Poland) is whoever I'm asking they sate 0.1mm (0.004") like mantra for all aur cooled engines.

I Wii go for 0.005" if possible.

Yesterday printed petrol tank inside wit special paint.

Started with installation as well

[Derek996]

Thanks Derek for straight reply.
Problem in here (Poland) is whoever I'm asking they sate 0.1mm (0.004") like mantra for all aur cooled engines.

I Wii go for 0.005" if possible.

Yesterday printed petrol tank inside wit special paint.

Started with installation as well

0.005" = 0.127 mm. Surely they can bore to give a 0.125 mm clearance which is was near as make no difference or a clearance of 0.15 mm is .006". Either of these should be ok.

[iansoady]

I always struggled with metric / imperial conversions till I realised that 1mm = .040" (or near enough, at least for my purposes).

[Dan_B33]

I think I will go for 0.006".
This shall do.
0.005 might be still too tight.

Won't take risk. I would like to start riding it without problems from piston side.

Dan

[Dan_B33]

Hello,
The company finally made their homework and expressed their apology.

Unfortunately I had to send the set to them again.

Reference to the BSA manual wit a page number was of a great use.

Now waiting they will to it properly and send it back.

Many thanks for your help !


Dan