Measuring Cylinder Bore

[Ex3t3r]

Hi,
am undertaking replacement of both cylinder base gaskets soon,
but i need to measure the diameter of each bore accurately to see whether
they are within the service limit, as i do not own an internal micrometer
can the more experienced of you please suggest an alternative
method and procedure.

Thank you in advance for any help.

[Limey_Dave]

Your manual should give you the fitted ring gap.
Place a ring in the unworn portion at top of bore and square it up with a piston.
Measure ring gap with feelers which should be correct.
Push ring down about 1/2" to the worn part of bore where piston changes direction.
Measure gap and check if it is within limits.If the gap is over by much then it is unlikely to be corrected by new rings and you should go to your reborer of choice who will take exact measurement with dial bore gauge.

To measure actual bore size without equipment the best you can do is measure piston front to back at skirt with mic or vernier,place in bore and use feelers in gap between skirt and cylinder.

If there is any ridge at top of bore, and you don't rebore,it must be removed as if new base gasket is thiner or you have cylinder base skimed the top ring will hit it.

If bore seems ok then I would glaze bust it before fitting new rings.Use the flap wheel type, that you can get from engine reconditioners,in a slow drill with plenty of oil.

After glaze busting or rebore use white spirit and clean rag to clean bores till rag stays fairly clean.Alot of dirt can get left in the cross hatch marks (but then I'm a fussy old bugger)

Hope you're all tucked up,it is COLD out there this morning.

[Hawkeye]

As you know i have my barrells off at the moment. I took them along to my Indy who said reboring a Harley is very rare. They dont appear to wear that much, but there are exceptions of course.

Dont know what milage mine had on them but there was no lip at the top and they look in good condition, will be picking them up tomorrow. Will let you know

[Mr B]

You really do need the proper measuring equipment to get a true reading. I measure hydraulic cylinders for wear, and they are similar to what you are going to measure. With something as precision as your cylinders....near enough is not good enough.

I'd take them to a shop that does engine reconditioning...any type of engine, as long as they do machineing, and take your manual with you. Slip the bloke a few quid and ask him to measure them for you as per the manual specs with the proper bore guages.
They need to be measured at the top, then at 90 degrees, then at the bottom and again at 90 degrees. All cylinder bores are oval to a point when they've seen a few miles.

Brian.

[Ex3t3r]

Many thanks for all the replies, and i think due to the labour/time involved in removing the barrels i will indeed take them to an indy mech and have him take a look as Brian has suggested.

[45Brit]

without being rude, or meaning to at any rate, if you are asking questions like that you would be better off with a professional doing it.

This is another aspect of Girlyglides posts under 'fitting things', a workshop can do things a home mechanic can't

[Ex3t3r]

Originally Posted by 45Brit

without being rude, or meaning to at any rate, if you are asking questions like that you would be better off with a professional doing it.

This is another aspect of Girlyglides posts under 'fitting things', a workshop can do things a home mechanic can't

Also without seeming to be rude, if i had sufficient enough finances
i would gladly hand the whole maintenance work over to a 'professional'
but alas i do not.

Also this is a good learning curve for anyone who has never attempted to
undertake this type of work on his/hers H.D, as their are many experts here
who can provide a guiding hand, for which we are indebted to.

[Ukkid76]

Take your pistons and barrels to your local machine shop and ask them to measure and advise you on what to do next, if they are within the recommended tolerances than ask them to hone them out for you, then you can fit a new set of piston rings and base gaskets knowing all is well for a few more thousand miles!! There is no way you can do it in the garden shed especially without the correct tools.

Ukkid76

[Ex3t3r]

Originally Posted by Ukkid76

Take your pistons and barrels to your local machine shop and ask them to measure and advise you on what to do next, if they are within the recommended tolerances than ask them to hone them out for you, then you can fit a new set of piston rings and base gaskets knowing all is well for a few more thousand miles!! There is no way you can do it in the garden shed especially without the correct tools.

Ukkid76

Please read my replies before adding any further unnecessary comments!

"Many thanks for all the replies, and i think due to the labour/time involved in removing the barrels i will indeed take them to an indy mech and have him take a look as Brian has suggested."

[45Brit]

doing a job on the cheap is a pretty good way to end up with a big bill. UKkid76 is right.

but, there is a lot you can do which will save you a lot of money. All that dismantling and reassembly costs labour time, and it's only spanner work. Get the proper manual, a new gasket set , torque wrench and the right size sockets, and a ring compressor, and refitting the barrels isn't hard.

if you're telling me you can afford to buy a Harley and can't afford to maintain it, I can't help you with that. But, what I don't understand is, why you have got your barrels off anyway? I see you are replacing both cylinder base gaskets, why?