Rebore costs

[llessur]

I have just had a quote fore boring my 400 barrels to 54.5mm for a big bore conversion. They said £40 per cylinder.
I just wanted to check this was reasonable as I have not done this before. What do you think?

[kevski]

Nothing wrong with that.

[Zunspec]

It is in the ball park.  Steve at Pistonbroke in Bristol charges approx £30/barrel so may be a bit cheaper.  The handy thing is if you make an appointment he will do the job while you wait. He's been doing it for 40+ years so he knows what he doing.

Cheers  Geoff

[Trigger]

£40 is cheap, seeing it is multiple cuts and a few times they have to re-set the boring bar.

[llessur]

Thanks everyone. I took them in this morning. My only concern is that there is not going to be a great deal of wall thickness left at the bottom of each sleeve and the loss of any usable chamfer may mean a faff with the rings. Just an idea but is it possible to sick two pistons in the barrel first then just fit the gudgeon pins rather than attempting all four piston whilst lowering the cylinders ?

[mike the bike]

Doesn't sound feasible.   Everything's going to move out of alignment while you're trying to something fiddly.  I make ring compressers from drinks cans, held in place with cable ties.

[Chris400F]

I tend to agree with Mike. It may be a faff with the rings, but I think it would be a bigger faff with the gudgeon pin circlips when the pistons are in the bores

[Rozabikes Tim]

Doesn't sound feasible.   Everything's going to move out of alignment while you're trying to something fiddly.  I make ring compressers from drinks cans, held in place with cable ties.

What about the yogurt pots and double sided sticky tape Val?

[mike the bike]

If you're happy with the Blue Peter method, go for it.

[llessur]

Thank you for the responses. I will avoid the copydex, coathangers and sticky backed paper ( nice to know we are of a similar generation ) but I do like the Coke can idea. I will give it a try.

[Tomb]

Doing drag racing means we do this job several times a year on two engines, I have polished the chamfers and polished a small radius between the bore and chamfer. Using engine oil and fitting the block over 2 + 3 pistons first the block almost falls on, then rotate the crank slightly to lift 1 + 4 pistons and drop the block onto them, the rings slide in easily. Best done with two people, one each side of the engine.

[kevski]

Doing drag racing means we do this job several times a year on two engines, I have polished the chamfers and polished a small radius between the bore and chamfer. Using engine oil and fitting the block over 2 + 3 pistons first the block almost falls on, then rotate the crank slightly to lift 1 + 4 pistons and drop the block onto them, the rings slide in easily. Best done with two people, one each side of the engine.

Just the ticket, i have never used coke cans, plastic bottles, bits of drain pipe, or even ring clamps, and have never broken a a single ring, you just take care and do as tomb says .

[Underdog1]

Thanks everyone. I took them in this morning. My only concern is that there is not going to be a great deal of wall thickness left at the bottom of each sleeve and the loss of any usable chamfer may mean a faff with the rings. Just an idea but is it possible to sick two pistons in the barrel first then just fit the gudgeon pins rather than attempting all four piston whilst lowering the cylinders ?

That bloke on hackaweek did something sort of similar by fitting pistons and conrods in that barrels and then fitting them to the upper crank case, looks an awkward way to do it

https://youtu.be/y-CsqUiatKk

Are you not able to add a small amount of new chamfer to the bottom of the sleeves?