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#570674 - 11/06/14 1:45 pm Re: new pistons quality [Re: reverb]  
Joined: Mar 2005
Posts: 9,964
John Healy Online content
John Healy  Online Content



Joined: Mar 2005
Posts: 9,964
Boston, Massachusetts
HB With dealing with these bikes as a mechanic, dealer, and distributor I am looking through the funnel from the spout end rather than the top. You get a much wider view of things. Through some quirk in this business I ended up with nearly all of the dealer distribution of Hepolite pistons in the USA just at the time when we started to have wholesale problems with piston seizures and oil control problems - the early 1990s. With out getting into a long post it was when two things were happening - oil was changing more in a few years than it had in the previous 50, and modern automobile cylinder preparation was starting to find its way into our world.

Oil started to contain more and more friction modifiers to help auto manufactures meet fuel economy standards and the 150 grit cylinder honing standard used for our thousandths world was supplanted with cylinder preparation designed for engines designed, manufactured and prepared in a tenths world.

Because we were having so many reports of problems with all of the pistons and ring brands we carried (we would have 5 or more brands available for each application) started to keep track of the age of the rider and his explanation of what happened when when a problem was reported. It typically went like this: The oil was typically Castrol 20/50 available at that time, the cylinder was prepared by the local automotive machine shop, the engine had around 50 miles on it since the new rings and piston installed, the rider was 50 or older, he was in high gear doing 50 mph, he was going up a slight grade and had just turned the throttle open some to keep up the speed. The problem was distributed equally no matter which brand of piston or ring was used. Rarely was a seizure reported when the rider was in the 18 to 35 range.


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#570678 - 11/06/14 2:05 pm Re: new pistons quality [Re: John Healy]  
Joined: Oct 2012
Posts: 3,098
Hillbilly bike Online content
BritBike Forum member
Hillbilly bike  Online Content
BritBike Forum member

Joined: Oct 2012
Posts: 3,098
Running from demons in WNY
JH,tell me about that 50 MPH high gear seizure... A 69 Bonnie I rebuilt with about 50 miles in it around 1997 and pulling a slight grade at 55 mph and rolled on the throttle to pass a car and the bike just got slow.....I was in my early 50's at the time.. grin It was .080 and I suspect the clearance was too tight.I replaced the barrels with .040 set at .0055.
But it didn't use oil grin
As a dealer you had to see all sorts of stuff unknown to the rest of us.


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
#570680 - 11/06/14 2:30 pm Re: new pistons quality [Re: reverb]  
Joined: Jun 2007
Posts: 5,450
HawaiianTiger Online content
BritBike Forum member
HawaiianTiger  Online Content

BritBike Forum member

Joined: Jun 2007
Posts: 5,450
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.
#570733 - 11/06/14 7:40 pm Re: new pistons quality [Re: HawaiianTiger]  
Joined: Aug 2011
Posts: 416
Old Cafe Racer Offline
BritBike Forum member
Old Cafe Racer  Offline
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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

#570745 - 11/06/14 9:10 pm Re: new pistons quality [Re: reverb]  
Joined: Mar 2005
Posts: 9,964
John Healy Online content
John Healy  Online Content



Joined: Mar 2005
Posts: 9,964
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.


#570750 - 11/06/14 9:29 pm Re: new pistons quality [Re: reverb]  
Joined: Jun 2007
Posts: 5,450
HawaiianTiger Online content
BritBike Forum member
HawaiianTiger  Online Content

BritBike Forum member

Joined: Jun 2007
Posts: 5,450
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.
#570752 - 11/06/14 9:37 pm Re: new pistons quality [Re: reverb]  
Joined: Dec 2012
Posts: 28
UGOTBIT Offline
BritBike Forum member
UGOTBIT  Offline
BritBike Forum member

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
#570970 - 11/08/14 8:54 am Re: new pistons quality [Re: reverb]  
Joined: Jan 2014
Posts: 1,581
reverb Online content
BritBike Forum member
reverb  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 1,581
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.

#571025 - 11/08/14 2:43 pm Re: new pistons quality [Re: reverb]  
Joined: Jun 2007
Posts: 5,450
HawaiianTiger Online content
BritBike Forum member
HawaiianTiger  Online Content

BritBike Forum member

Joined: Jun 2007
Posts: 5,450
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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