Author Topic: watermark in honed bores  (Read 758 times)

Online mikeb

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watermark in honed bores
« on: 28.11. 2015 03:25 »
Hello
one benefit of progressing one of the world slowest rebuilds is that previously invisible problems emerge where a hasty rebuild may just not get to find them...

the barrels on my 61  super rocket are already on +060" but just serviceable with a hone which i had done 6 weeks ago. Today an experienced engineer helping me (and I need it) noticed the dark lines down the bores as per the photo (where the arrows point). They weren't there immediately after the hone and the bores were oiled after honing. He assumes they are rust in the bore from sitting idle for years with old stationary rings (it was off the road for many years). I can feel a slight ridge of one. The fear is they'll wear new rings quite fast and the ring landing on the piston, causing new trouble. and click a lot while doing so.

Has anyone seen this sort of thing? any view on what to do?

thanks

Mike
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Online KiwiGF

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Re: watermark in honed bores
« Reply #1 on: 28.11. 2015 04:00 »
My 2 cents worth given its on 060 over is chance it ....but it comes down to how big the ridge is.....

Could you hone it out some more and still leave some bore life left?

I had rust pitting and got it honed until they were almost gone and this left me with 006 clearance on new Pistons....this was OK as the piston brand was jp, from aussie, and I was advised to go a bit loose with those Pistons anyway.

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Offline duTch

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Re: watermark in honed bores
« Reply #2 on: 28.11. 2015 08:48 »

 ..and my one cent worth; what KiwiGF says especially regarding ridge, others might know better....when I did mine which had sat for 10+ years, I used a 80mm flapper-wheel to hone it (can't remember the grit#),- with trepidation... but seemed to work ok especially with instructions to clean the bore with white rag and warm soapy water until clean
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
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Online mikeb

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Re: watermark in honed bores
« Reply #3 on: 28.11. 2015 09:18 »
KiwiGF - I'm in Auckland - where it rains all the time and everything rusts.
there's not much more to hone out before its all too lose and I guess no way of knowing how deep the rust vein is. I'll see it i can polish it out.

I wonder if anyone has had these problems leading to failure?
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Online Triton Thrasher

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Re: watermark in honed bores
« Reply #4 on: 28.11. 2015 11:07 »
If what you're is feeling a protrusion of rust, scrape or etch it off.  Don't make the new rings scrape it off.

If it's a palpable or measurable groove, how can rings ever seal there? It will trap oil, which will be pushed up into the combustion chamber and burnt.

How can the rings keep (or ever get) their bedded-in edge while being forced over that furrow hundreds of times a second, for hundreds of hours?

Will it break rings? I don't know.

You don't have much to lose by honing the entire bore until the groove cannot be felt, then measuring. I don't know what the absolute maximum piston clearance on an A10, but I don't see why you wouldn't get off with 7 or 8 thou.

An oversize parallel bore is better than a tight bore with a loose bit.

Online chaterlea25

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Re: watermark in honed bores
« Reply #5 on: 28.11. 2015 21:23 »
Hi All,
It would be worth getting an accurate measurement of the bore as it is before trying to hone any damaged area
The danger being  it could wind up a bellied bore  *eek*

Just today I saw that Draganfly are advertising  + 0.080 pistons so presumably some manufacturer has made a batch ???

Cheers
John

1961 Super Rocket
1963 RGS (ongoing)

Online mikeb

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Re: watermark in honed bores
« Reply #6 on: 28.11. 2015 22:21 »
the bores have been carefully measured and are pretty straight but near their limit for new +060 pistons.
what surprised me is the marks appeared over 6 weeks and were not apparent after the hone. maybe this happens more than I assume just that most of us put them back together before rust creeps out again.
further honing might solve one problem by making another

the only +080 pistons around are JPs (I called draganfly a while back) and there's a few threads about the perils of those.
i do have some other barrels with 3 broken fins, strangely a tiny bit under +060, but maybe worth a revisit.
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Online chaterlea25

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Re: watermark in honed bores
« Reply #7 on: 28.11. 2015 22:25 »
Hi Mike,
Yes I have heard of the perils of using JP's  *sad2*

John
1961 Super Rocket
1963 RGS (ongoing)

Online RichardL

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Re: watermark in honed bores
« Reply #8 on: 29.11. 2015 19:02 »

...what surprised me is the marks appeared over 6 weeks and were not apparent after the honing.

It's hard to imagine that those rusted areas were not there after the honing. Maybe they were hidden, first by the honing residue, then by the protective oil. It looks to me that one of the rust rings developed after sitting for some time (maybe years), then, someone wanted to check to see if the engine was frozen-up. It wasn't, and the next rust ring formed at the new piston location after more sitting (maybe years). Just speculating, of course.

It seems that if you can feel them and they are within ring travel you might as well hone until they are gone and test the resultant clearance. As TT said, you might get away with .007 or .008. After my recent experience at being just over .006, with 1000 miles on her since then, .007 would be very tempting. As for .008, I bow completely to anyone who can testify.


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Online cyclobutch

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Re: watermark in honed bores
« Reply #9 on: 30.11. 2015 05:21 »
Some good points here - kind of a rock and a hard place. If the marks genuinely weren't there after the hone but appeared subsequent then does that suggest this is all occurring pretty much at a molecular level? And 9 times out of 10 you'd be in a hurry to button up and would not have seen them.

I'm not sure I wouldn't go with them as is. But then I don't know what I'm talking about.
(I always feel like the slightly 'challenged' cousin on this forum).
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Online mikeb

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Re: watermark in honed bores
« Reply #10 on: 30.11. 2015 05:51 »
hey cyclobutch I know that  'challenged' cousin feeling too. but that's what's so great about this forum.

i think its more accurate to say the marks were not apparent after the hone - the vein of rust must have been there, just polished out a bit / scoured over. question is how deep is it. I've had a look at the other barrels I have (also +060 with broken fins) and there's similar ridges in those too. so the options are stick them in as-is (risk wear, not bedding-in, breakage), keep honing these out (risking too lose, smoking, rattling) or rebore with some JP +080.
at this point its looking like JPs.

thanks for the thoughtful comments everyone
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Offline BSA_54A10

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Re: watermark in honed bores
« Reply #11 on: 16.12. 2015 08:55 »
Hi Mike,
Yes I have heard of the perils of using JP's  *sad2*

John

No problems with using JP;s, I use them all the time.
My Roller has 4 of them in there machined to match the wet liners ( they are all different from new ).
What you can not di is use the junk rings they put on them as they will never bed in.
I have sent so many sets back that now they ship my pistons bare.
Then do tend to be heavy because they use 1 casting for all sizes so they get heavier the larger the oversize.
Bike Beesa
Trevor

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Re: watermark in honed bores
« Reply #12 on: 16.12. 2015 15:11 »
Hi Trevor,
Some time ago JP made a batch of pistons to suit The Blackburne 350ohv engine as fitted to my Chater Lea project. these were commissioned by Martyn Adams who has since moved to Australia
Martyn experienced seizures on the engine fitted to his Rex Acme, 
He fitted a liner to my cylinder to bring it back to std, The clearance needed to avoid seizures is 7-8 thou
which is almost twice the figure for the A10 on the same bore size  *????* *????* *????*
I dont have the bike together yet so fingers firmly crossed  :-\
I wonder how the JP rings would work on a total loss lube setup?? I will look and see if I can get something the same size ??

Cheers
John
1961 Super Rocket
1963 RGS (ongoing)