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Cylinder hone

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NOC Advice was to hone my cylinders +20 leaving 5 thou clearance.i just bought them second hand and had to buy new pistons to take to the engineers,i gave my instructions,but when i picked up the cylinders its honed to 7 thou.clearance.They should have left them alone if they where 5 thou already.So can i use them at 7 thou or have i got to buy new pistons + 30 and have a rebore + 30 Engineer smiled and sead im only charging a tener.?

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This honing howler will work ok but it has taken a large chunk of the bore life away. A 7 thou clearance is more suited to a big single engine. The Norton Maintenance Manual says that the recommended piston running clearance is around 4 to 41/2 thou. and that when reaches 9 to 10 thou a rebore is needed. Your engine is halfway towards this upper limit already.

With new rings set at about 12 thou gaps the engine should run ok and if anything will be easier to turn over and start. The downside is the pistons will rattle a bit when cold. You will probably need a rebore after another 20,000 miles. Are you likely to cover that sort of mileage?

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Previously phil_hannam wrote:

This honing howler will work ok but it has taken a large chunk of the bore life away. A 7 thou clearance is more suited to a big single engine. The Norton Maintenance Manual says that the recommended piston running clearance is around 4 to 41/2 thou. and that when reaches 9 to 10 thou a rebore is needed. Your engine is halfway towards this upper limit already.

With new rings set at about 12 thou gaps the engine should run ok and if anything will be easier to turn over and start. The downside is the pistons will rattle a bit when cold. You will probably need a rebore after another 20,000 miles. Are you likely to cover that sort of mileage?

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Thanks Phil i have a small collection of bkes so it is unlikely i will ride her much,i will go with what i have for now.You can tell i was a teen of the mid 70s Triumph T160 Kwaker 9 Commando mk 1 fastback every day bike is my v rod,but im getting on now.Thanks againe..

 


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