Technical questions for the list 're seized Bonneville

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Technical questions for the list 're seized Bonneville

Post by Nambo » Sun Dec 06, 2015 12:03 pm

Not BSA I'm afraid but respect the forums expertise.
I 're built a friend's 5 speed 650 Bonneville which she eventually seized the pistons on.
Now my theory is that she was so hesitant to use the bike's power that the piston rings didn't get chance to bed in before hardening, along with the fact that all the riding tended to be long journey s of constant low speed riding in top gear, it was under such conditions that the seizure occurred. I consider endless miles of riding at low revs with a bike laden with camping gear saw hot gases blowing past the rings to heat the piston and blow/burn away the oil. The burnt smell of the oil prior to this would indicate such.

She has wanted to put the fault on me however and took the engine to Rockerbox to be rebuilt.
They have told her that the fault lies in the fitting of a tighter C3 bearing which parts stockists now sell rather than the C2 originally fitted and that the bearing has gotten so hot, that it burnt away the oil from the bores.

My question is can anybody envisage such a possibility oft a bearing to get so hot it burns the oil from the bores and yet doesn't burn oil on the actual bearing itself which wasn't discoloured in any way.
Surely the bearing would have ran dry and seized long before the piston, it would have spun in the cases in which it wasn't a particularly tight fit in the first place necessitating the use off Loctite which still held.
The fact that the cases were a loose fit in the first place I would have considered more of a reason to fit the Triumph recommended later C3 bearing anyway?
When I had fitted the crank it spun completely freely, My friend has been told that it would have gone tight when hot, but if this was the case, how is it that the bike would still tickover even better than when cold?

Opinions greatly welcomed.

PETE

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Re: Technical questions for the list 're seized Bonneville

Post by petef » Sun Dec 06, 2015 2:10 pm

Hi Pete,

I deal with bearings on a daily basis at work & to say a bearing is getting so hot it is burning the oil on the bores without showing any signs of overheating is laughable. The clown who told your friend that story is trying to rubbish your reputation to get the work themselves IMO.
A bearing that could generate that sort of heat to do that & not discolour would have to be ceramic or some other exotic type (which it wasn't).

I think your theory is very close to the mark. It is well known that lower load (Lower gear) & higher revs is better for a new engine than high load & low revs.
Best remove the bearing, go round to the person with the "hot bearing" theory & insert it! :mrgreen:

Cheers,

Pete

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Re: Technical questions for the list 're seized Bonneville

Post by kommando » Sun Dec 06, 2015 2:16 pm

Never heard such claptrap, I am with you, rings never bed in, oil in the combustion chamber causing pre-detonation and then the piston heating up. Look at the seizure marks on the piston and if it is the classic 4 corner seizure it will show at 4 points 2 each side of the pin openings.

PS C3 is looser than C2

Suffix Internal clearance
C1 Smaller than C2
C2 Smaller than Normal
CN Normal, only used together with an additional
letter that identifies a reduced or displaced
clearance range.
C3 Greater than Normal

So even more tripe

But I would never fit a main bearing with loctitie into alloy cases, it does not work and reduces the internal clearance with its extra thickness (which means it probably made the C3 a C2), if the housing is too large you plate the OD of the bearing or bore and re-sleeve the housing.

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Re: Technical questions for the list 're seized Bonneville

Post by Mark Cook » Sun Dec 06, 2015 2:38 pm

Yes the bearing theory is bovine related.

Though I expect the blame can be placed on the quality of the rebore, seems to be a lost art these days.
Before pointed a finger at anyone I'd get someone with a bore gauge working to 0.001mm to check it's size and shape.
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Re: Technical questions for the list 're seized Bonneville

Post by midgie » Sun Dec 06, 2015 3:47 pm

to me it points to pistons, bore and lubrication, without knowing what pistons you used or what the piston to bore clearances were or indeed looking at it nothing can be gained here. but I would ignore the bearing red herring!

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Re: Technical questions for the list 're seized Bonneville

Post by Jeff K » Sun Dec 06, 2015 9:26 pm

Sounds like total bull! Common sense tells you that if the bearings were getting that hot, then they would also show signs of overheating! Low RPM and loading up an new engine will cause overheating. Did they run a compression check? Even a simple test of placing a piston in a bore and running a feeler gauge around it to check for out of round/high spots on the piston. It is getting very hard to find a machine shop that knows what they are doing when it comes to boring old bike cylinders anymore. I have gotten them back just at the outside wear limit and also too tight. I always print out the factory specs or the ones that came with the pistons and hand it to them.
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Re: Technical questions for the list 're seized Bonneville

Post by Banzaibob » Sun Dec 06, 2015 10:07 pm

Agreed, the hot bearing/seizure theory sounds like muffler bearings/blinker fluid theory. I would like to hear more details on the actual seizure though.

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Re: Technical questions for the list 're seized Bonneville

Post by Richard Beard » Sun Dec 06, 2015 10:23 pm

Sounds like typical poor breaking in technique to me.
As soon as you start the engine after a rebuild you have to make it work to get the pressure behind the rings so that they wear to the bore and the bore wears to the rings. Not constant 30mph but acceleration in the gears and then off with the throttle and then repeat etc etc.
All the talk about the main bearings is b*****ks.
Although +1 with Kommando about not using Loctite between the main bearing outer and the crankcase.
Long journeys at low speed in top gear---this girl needs a Hardly Daveson.
That is my two centsworth anyway.

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Re: Technical questions for the list 're seized Bonneville

Post by minetymenace » Sun Dec 06, 2015 10:58 pm

Hot bearings can be a real issue. Hot apian jewlery suspended from the lobes are inclined to sting your temples. This can be fatal. :ban

Almost as fatal as posting T-brand twin problems on a BSA unit Singles forum.

Post moved to Off Topic. <910

I'm not as clever as some here but to run in an engine at high load, low revs over a long distance is asking for trouble.
There is no evidence to support the notion that life is serious.
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Re: Technical questions for the list 're seized Bonneville

Post by hwan » Mon Dec 07, 2015 10:53 am

Wow impressive BS from Rockerbox.

As previously stated C3 has an INCREASED clearance, so less 'tight' - as in all bearings they can be incorrectly fitted, in which case the effect is not bore seizure, more often a locked bearing spinning in the cases.

Suspect incorrect rebore - i've had the problems where the rebore shop seems to think all pistons are low expansion japanese/Chinese/Taiwan jobbies and do not give enough clearance for older manufacture/forged/etc pistons.
Couple that with wrong ignition timing and .............

Another one is the oil used - almost certainly something intended for a watercooled car engine - these older iron cylinder, air-cooled engines do not like modern thin synthetic oils.
Particularly when everything is running tight and the oil film is trying to break down!

Many will argue the opposite over the above comment on oil (i run synthetic in the B25, but that's a slack as a yak's .....), but thats my experience, particularly on triumph twins - i used ROTELLA 30 or 40 mineral oil (recommend by a shell technician) for racing and never suffered a lub related engine problem - unlike when i ran Mobil 1 !!!!!!

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Re: Technical questions for the list 're seized Bonneville

Post by Nambo » Mon Dec 07, 2015 9:44 pm

Thanks for all the replies guys.
Regarding the C2 C3 thing, I wrote them around the wrong way in my post, the earlier Triumphs had which ever one is looser, a Triumph Service Bulletin came out saying to only use the later tighter one which is the one I used and the one Triumph parts stockists supply.

Other evidence I would say is the fact that the outer part of the bearing was still held firmly in place by the Loctite, if I bearing was running too tight wouldn't the loctite break and the bearing spin, bearing in mind the bearing hadn't been a particularly tight fit in the first place.

When I built the engine I probably measured the pistons in the bores, I certainly remember measuring the ring gaps which were fine.

All through running in, both myself and her partner kept on saying she has got to rev it more, but she would say that shes not going to blow it up, even when I told her another friend used to cruise up to the North of England every weekend to see his kids, a couple of hundred miles that he would cruise at the ton all the way, this on a four speed 650 Bonneville.
She hardly ever used the bike except to go to rallies on which involved her sitting at 60 for mile after mile of motorway riding.

As the owner of this bike is the partner of a friend I have known since school, I didn't charge a penny to do the work, the couple of times I rode it it was a sweet running and smooth motor, not a single oil leak, would have been a great bike.
I would then have rebuilt again for her for free, but she doesn't like to admit she has done anything wrong and so has been searching for ways to blame me, and used Rockerbox to rebuild it instead, apparently these days this costs a fortune so the bike has been off the road for a couple of years whilst she saved the money, she could only afford the bottom end but now she has the money for the top end, Rockerbox seem rather hesitant to finish the job, my guess is that like me, they are worried she will ride it in exactly the same way, have the same problem, and don't want the danger of warranty.

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Re: Technical questions for the list 're seized Bonneville

Post by beat » Mon Dec 07, 2015 10:49 pm

have you changed the brand of the oil by the rebuild ??
if so, - any infos from wichone to what now ??
beat <201

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Re: Technical questions for the list 're seized Bonneville

Post by Nambo » Tue Dec 08, 2015 9:34 pm

beat wrote:have you changed the brand of the oil by the rebuild ??
if so, - any infos from wichone to what now ??
beat <201
I don't know if she changed the oil, would have still been a 20/50 mineral oil for running in.
She hasn't got anything "now" as she is still waiting for Rockerbox to do the top end as she couldn't afford the whole rebuild at once.

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Re: Technical questions for the list 're seized Bonneville

Post by minetymenace » Wed Dec 09, 2015 12:30 am

Just noticed you said about Rokerbox:
They have told her that the fault lies
The truth is there somewhere.....
There is no evidence to support the notion that life is serious.
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Re: Technical questions for the list 're seized Bonneville

Post by BSA_WM20 » Wed Dec 09, 2015 6:39 am

Firstly I agree 100 with the others, bearing theory is total garbage.
Ask them if they are serious and if they say yes the tell them you will never go there again and post this lunacy on the 20 British bike frums you are on.

Secondly no comment about the seizure without any evidence.
We need to see photos of the bores, & the piston, all sides and more importantly the inside of the piston otherwise all you will get is each persons pet problem dumped at your feet.
We also need to know which brand of rings, which brand of pistons, what grit and type of hone was used, what the original piston to cylinder clearence was and as Mark noted how good was the rebore & who did it.
A lot of shops bore motorcycle barrels off the head and not off the crank flange and almost every time you end up with an offset or tapered bore
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Re: Technical questions for the list 're seized Bonneville

Post by Nambo » Wed Dec 09, 2015 8:28 pm

Barrels have been rebored again, I will see if she lets me take a picture of one of the old pistons, though she does get very defensive when challenged.

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Re: Technical questions for the list 're seized Bonneville

Post by Nambo » Sat Dec 12, 2015 11:27 am

Sorry guys, I requested pictures to show you and her reply was "I don't see the point in photographing them".
This translates as "I like the bearing theory so much as it absolves me from responsibility so I have decided this one is the truth and so whats the point in considering what actually caused the problem". This despite the fact she has found and read this thread and chosen to disregard all your comments.
I guess this demonstrates how the female mind works, what makes you feel good is more important than logic in arriving at the truth.

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Re: Technical questions for the list 're seized Bonneville

Post by minetymenace » Sat Dec 12, 2015 4:35 pm

Dorothy Parker wrote:You can lead a whore to culture but you can’t make her think.
There is no evidence to support the notion that life is serious.
Abyssinian Wire-Haired Tripehounds Gnash.

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Re: Technical questions for the list 're seized Bonneville

Post by Barry Creary » Sat Dec 12, 2015 5:21 pm

MM :laugh :laugh :laugh the female mind :roll: you wouldn't be one for a bet :werd

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Re: Technical questions for the list 're seized Bonneville

Post by Nambo » Sun Feb 21, 2016 2:55 pm

I have been informed by the owner of said Bonneville, that Rockerbox didnt claim the bearing got so hot that it burned the oil from the bores after-all, but that she "Misunderstood" them. I have suggested she apologise to Rockerbox.

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Re: Technical questions for the list 're seized Bonneville

Post by LONGSTROKE » Tue Mar 01, 2016 7:27 pm

I have just read through this post for the 1st time and as I read through it my thoughts were - ''Rockerbox are a reputable bike shop with a lot of experience with Triumph twins'', can't believe they would say that! <201 And then I got to your last post! - ''I thought so''!! :grin: If I were them and read this I think I would tell the young lady that her motor is in a box on the outside of the workshop door and she should come down and collect it, or words to that effect :oops:

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Re: Technical questions for the list 're seized Bonneville

Post by HPbyStan » Tue Mar 01, 2016 8:42 pm

You know I want get back to beating on the oil subject. imo, Mobil 1 was NOT a good product when it came out. It just didn't cost enough. being synthetic it can be whatever you want it to be or are smart enough to make it be. I believe Mobil did what they did to be able to sell it to the average customer price wise. Mobil 1 has gotten a lot better but it costs a lot more also.

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