61mm to 65mm Over-bore cost estimate

[gp_st3]

Hi, would be interested to hear from the forum what is considered a 'fair' price for a 61mm (standard) to 65mm (836) over-bore in the London/SE area?
thanks.

[Trigger]

Hi, would be interested to hear from the forum what is considered a 'fair' price for a 61mm (standard) to 65mm (836) over-bore in the London/SE area?
thanks.

That is quite a few runs with a boring bar, £200 to £260. And the liners will be prone to cracking 

[philward]

Pity your not 'oop North'  - I paid 50 squid for both my 836 from standard bore's - from a company in St Helens. He's a biker and been doing it for years.

[gp_st3]

Thanks for the quick replies and guidance.
Trigger, you mention 'prone to cracking', is that something you've experienced as I've searched the SOHC forums and not some across any references so would like to quantify the risk if possible?

[Trigger]

Thanks for the quick replies and guidance.
Trigger, you mention 'prone to cracking', is that something you've experienced as I've searched the SOHC forums and not some across any references so would like to quantify the risk if possible?

I have had 27 years experience with motorcycle engineering   
The more you bore the thinner the liner gets and is then prone to cracking. That is why top company's who sell big bore kits supply new oversize liners with the piston kits. Any oversize liner will not fit the crank case so, these have to be machined out.

[gp_st3]

Understood - on balance I'm going to accept the risk and should the worst happen then either find a replacement block or perhaps new liner(s) if feasible.
I will be using flat-top pistons (only small increase in compression) and the standard K4 cam so hopefully all will be well...