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Re: new pistons quality [Re: reverb] #570680
11/06/14 2:30 pm
11/06/14 2:30 pm
Joined: Jun 2007
Posts: 5,558
Maui Hawaii
HawaiianTiger Online content

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HawaiianTiger  Online Content

BritBike Forum member
Joined: Jun 2007
Posts: 5,558
Maui Hawaii
Rider profiling. It just isn't the police doing it...

Well, I've rebuilt many engines using local machine shops and never questioned what hone they used. I discovered Castrol 20-50w, the oil of choice for decades wasn't what it claimed about 15 years ago and switched. But not because it was loosing valuable additives....it was because I lost confidence in multi-viscosity oils.

Never had a seizure on any bike I ever rode that was a result of rings that didn't seat. I did have one on a bike that had a weak charging system and a Boyer. Once the Boyer was tossed, no more problems even with the weak charging system. I've done a lot bikes up with JCC pistons and whatever rings Keith or JRC sent with them with .0035 clearance.

One of the bikes I rebuilt, broke in, and sold off had a seizure, though. The new owner installed new carbs and didn't loc-tite the manifold bolts(pre unit) and they loosened causing an air leak.

I can't tell you how many times I've tried to drill into the heads of Triumph owners that they shouldn't be afraid of revving these things. On the contrary' they should be afraid of lugging them. And you're right. I have to admonish the younger riders not to thrash the things while they're new.

But it's always the vibration that tempers the throttle hand. If it's vibrating, it feels as though you are damaging things. (nerves in your hands included. My hands fall asleep in an instant anymore because of old British Bikes) I tell them if they turn the throttle and nothing happens, that is very bad indeed.

So I've always spent good money trying to smooth out these motors. It's one of the best things you can do to keep them running, I think. A smooth, free revving motor is a natural to ride in the manner that is most appropriate to the design.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
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Re: new pistons quality [Re: HawaiianTiger] #570733
11/06/14 7:40 pm
11/06/14 7:40 pm
Joined: Aug 2011
Posts: 416
OZ
O
Old Cafe Racer Offline
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Old Cafe Racer  Offline
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O
Joined: Aug 2011
Posts: 416
OZ
The instructions with new JCC (Hepolite) pistons sitting on my bench specify 0.004" piston to bore clearance.
I take that as a bare minimum and had the cylinders bored and honed to 0.0045" with a 180 grit hone.
The last time I used 0.0035" on an engine I had a partial seizure.

davy

Re: new pistons quality [Re: reverb] #570745
11/06/14 9:10 pm
11/06/14 9:10 pm
Joined: Mar 2005
Posts: 10,026
Boston, Massachusetts
J
John Healy Online content

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John Healy  Online Content

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J
Joined: Mar 2005
Posts: 10,026
Boston, Massachusetts
If I can make the assumption that the engine we are talking about is the one in the link on your signature the factory clearance for these pistons would be .003 to .0045". It has been my experience that JCC pistons work well with the same clearance as the factory originals. I would have no hesitation using .003" if I had full control over the boring/honing, assembly and break-in. So .0045" would be the most I would use.

As a rule of thumb I like to profile the customer. If he is an experienced British bike rider, regardless of age I fit toward the lower recommended clearance. If the rider is inexperienced, regardless of age, I go for the higher recommended clearance. Along with experience I kind of look for how much spirit the rider has in him - if he is a young rider who you have to remind to take it easy I tend to fit tighter. If the rider acts like he has passed by maturity by some years I tend to give him a bit more clearance.


Re: new pistons quality [Re: reverb] #570750
11/06/14 9:29 pm
11/06/14 9:29 pm
Joined: Jun 2007
Posts: 5,558
Maui Hawaii
HawaiianTiger Online content

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HawaiianTiger  Online Content

BritBike Forum member
Joined: Jun 2007
Posts: 5,558
Maui Hawaii
For joe blow, you don't know and don't trust, .045 is insurance for yourself. I've seen too many guys who as soon as they get out of earshot, give it a good blast. That's after the lecture and " you break it and it's your fault" caveat. Doesn't matter. They're gonna give it the stick and blame you if it breaks.

I don't feel warm fuzzies for those folks.....

For myself and those who I trust, it's .0035 just because I like a quiet motor. But I have the restraint necessary and I check things over and over until I'm sure they're right.

I like the JCC pistons. They've never let me down and since the weight and size is always so consistent, the pistons are interchangeable left to right.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: new pistons quality [Re: reverb] #570752
11/06/14 9:37 pm
11/06/14 9:37 pm
Joined: Dec 2012
Posts: 28
Saratoga Springs, NY
U
UGOTBIT Offline
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UGOTBIT  Offline
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U
Joined: Dec 2012
Posts: 28
Saratoga Springs, NY
John,

Because we are on the subject, what would you consider "proper" break in?

There is good info in this thread!


1967 TR6 = 650 ways to waste money
Re: new pistons quality [Re: reverb] #570970
11/08/14 8:54 am
11/08/14 8:54 am
Joined: Jan 2014
Posts: 1,640
South cone
R
reverb Offline OP
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reverb  Offline OP
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R
Joined: Jan 2014
Posts: 1,640
South cone
...hello Bill, so if you do not use Castrol 20/50 which one do you recommend? Im asking cause there in Hawaii there s no cold like here...so the use of proper oil for that weather is a must.

By the way, I do not rev my motorcycle too much due to I had 2 near death experiences with 2 broken conrods so I changed the sprocket and bear from that.

Re: new pistons quality [Re: reverb] #571025
11/08/14 2:43 pm
11/08/14 2:43 pm
Joined: Jun 2007
Posts: 5,558
Maui Hawaii
HawaiianTiger Online content

BritBike Forum member
HawaiianTiger  Online Content

BritBike Forum member
Joined: Jun 2007
Posts: 5,558
Maui Hawaii
Reverb,
You could start with an oil designed for use in a motorcycle. Motorcycle shops sell it. Barring that, you can use an oil for racing that has high levels of zinc which is much friendlier to our old bikes.

If you run low compression, you can get away with running your bike hard at lower rpms. The problems arise from detonation which happens with a combination of higher compression and poor quality fuel.

There are other ways to avoid detonation, too, but these require some tuning expertise or preparation while assembling the motor.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
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