Running in after rebore

iansoady
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Running in after rebore

Postby iansoady » Thu May 18, 2017 10:46 am

My Arrow's piston bosses were so worn the gudgeon pins were rattling like a bag of spanners so I've had to go for a +.020" rebore with Suzuki pistons. A shame as the bores were fine.

I know that ordinary mineral oil is recommended for running in four strokes - would the same be true for a two stroke (this is my first since a couple of MZs on the 1970s). I don't want to spend the rest of my life running it in, but neither do I want to lay down an Atlantic Convoy style smokescreen for the next couple of years.
Ian
1962 Ariel Arrow
1992 Honda CB400 Super Four ("modern" bike)

nevhunter
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Re: Running in after rebore

Postby nevhunter » Fri May 19, 2017 1:01 am

Iron bores run in fine as long as the ring gaps and piston clearances are correct for the situation. Since the cylinders are not the same as the Suzuki the proper clearance may be different to what was used with the Suzy. Just use a good aircooled two stroke oil (mineral) and be ready for a nip up if you give it a squirt too soon. It takes a long time to wear off metal if the original fits are wrong. Nev

iansoady
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Re: Running in after rebore

Postby iansoady » Fri May 19, 2017 11:46 am

I understand that the Suzuki pistons are lower coefficient of expansion than the originals and the people doing the bore (Nametab) are very experienced with Ariel (and other) two strokes.

I'm not aware of any difference between air-cooled 2 stroke oil and liquid-cooled?
Ian
1962 Ariel Arrow
1992 Honda CB400 Super Four ("modern" bike)

nevhunter
Holder of a Golden Anorak
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Re: Running in after rebore

Postby nevhunter » Sat May 20, 2017 12:54 am

There's a difference. The ring land area temperature is the criterion. Air cooled run hotter and some liquid cooled oils are TC W 3 outboard spec which has no application for road bikes. I would go for a high performance mineral type of TS oil if you can find it. You shouldn't need the full synthetic racing type of oil. Sometimes it doesn't have the corrosion resistance others have. Re expansion rates I agree about the pistons. The ORIGINAL pistons made in Japan often have low expansion rates and can be run with close fits. Some forged aftermarket ones cannot and the iron barrels don't get the heat out as well as alloy or liquid cooled nikasil lined type that expand with the piston to some extent and need less clearance. Nev

bob.keevil
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Re: Running in after rebore

Postby bob.keevil » Wed May 24, 2017 10:48 pm

Hi Ian
I ran both of my arrow rebuilds on mineral @ two litres of fuel to one cap of oil(32/1)after the first couple of tank fulls at a extra 1/2 cap to ten liters
of fuel taking it a bit steady for about 700 miles, seems to work for me.
Cheers Bob K

iansoady
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Re: Running in after rebore

Postby iansoady » Thu May 25, 2017 10:48 am

Thanks Bob.
Ian
1962 Ariel Arrow
1992 Honda CB400 Super Four ("modern" bike)


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