Main and rod brg grades

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Commando77
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Main and rod brg grades

Post by Commando77 »

Well just waiting on an iveco stud to pull the flywheel so I can release the tensioner from the bottom case. What are the chances this B in blue under the selector mech refers to both sets of brgs or just the mains? See pic. Still debating whether to pull the rod caps.
All looks nice downstairs but I'm itching to find out what the mainshaft brg feels like without gears. It all looks original but the grommet sealing the pickup tube was not installed properly... Honda? It was not in the pump hole fully but doesn't look distorted now its returned to its shape. Tiny bit of scoring on the pump faces but that rubbed out on a plate with some 1200 paper.
tony.mon
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Re: Main and rod brg grades

Post by tony.mon »

No picture so can't help with the markings.
Now you're that far then pull the big ends apart, too.
You'll need new bolts, they are not reusable but they aren't expensive.
It's not falling off, it's an upgrade opportunity.
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Commando77
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Re: Main and rod brg grades

Post by Commando77 »

Thanks Tony. It was yr comment a while back suggesting splitting cases without removing heads or chains. Looks like pics are beyond me, it's a big capital B in blue on lower inside edge of case under mainshaft. Tks anyway.... I'll do the brgs. Cheers.
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Re: Main and rod brg grades

Post by tony.mon »

Ah, that mark has been mentioned before, it is thought it's a production mark or quality check mark.
The smaller bearing code marks are on the inner web and will only be seen when you lift the crank out.
You will also be able to see the main bearing codes.
Lifting the shells reveals the backing colours so you can check which marking refers to big ends or mains using the code chart in Haynes.
It's not falling off, it's an upgrade opportunity.
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Commando77
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Re: Main and rod brg grades

Post by Commando77 »

Cheers for that.
On a separate thing I noticed the sump was bare aluminum. I've seen pics of bikes where it matches the engine colour so I'm assuming mine was replaced at some point.... Would I be right? It would explain the badly fitted pickup strainer🙄
tony.mon
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Re: Main and rod brg grades

Post by tony.mon »

I haven't noticed painted ones, only alloy finished with a bit of lacquer on.
I guess if someone had pulled the whole engine out and sprayed it then you'd have the same colour all over.
It's not falling off, it's an upgrade opportunity.
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Commando77
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Re: Main and rod brg grades

Post by Commando77 »

Ok that makes sense, can't say I've looked that close at others. For now wheel silver and lacquer will do. It was scabby. Appreciate your help.
I've a couple more questions, on the gearbox found a duff main shaft brg as expected so the effort to strip was worth it....was beginning to wonder :? What do you reckon on a sloppy needle race in 1st gear? It's pretty loose on the layshaft but then I'm not sure what's normal. I don't see any specs in the manual. I know it takes a hammering and mine is a bit whiny. (34k). Mating gears look good so I'm thinking this play and the worn brg right next to it could be contributors. I've measured 0.2mm clearance between brg rollers and gear bore. It certainly looks and feels that much. I think the gear turns with shaft when in 1st but with that much play it won't be concentric with its shaft.....or am I overthinking this :D no point in shelling out on a needle race if it's not needed.
On the oil seals I see they locate in lips machined in the cases. I'll assemble like this but i assume they can be conventionally installed with a mallet and sockets etc?
Main brgs are yellow and brown and don't look worn. Still I'll pull the rod caps which are under more stress.
Thanks for any added input.
Cases came apart nicely after I'd removed a hidden bolt near the clutch. One of the camchain slippers got pushed down but one cylinder had to be under valve spring load. I'll recheck the timing when I get the bottom end sorted.
Chhers :beer:
tony.mon
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Re: Main and rod brg grades

Post by tony.mon »

For the amount of work it takes to get to that bearing, I'd replace while you're there.
It's not falling off, it's an upgrade opportunity.
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Chris58
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Re: Main and rod brg grades

Post by Chris58 »

Commando77 wrote: Thu Nov 15, 2018 10:34 pm Ok that makes sense, can't say I've looked that close at others. For now wheel silver and lacquer will do. It was scabby. Appreciate your help.
I've a couple more questions, on the gearbox found a duff main shaft brg as expected so the effort to strip was worth it....was beginning to wonder :? What do you reckon on a sloppy needle race in 1st gear? It's pretty loose on the layshaft but then I'm not sure what's normal. I don't see any specs in the manual. I know it takes a hammering and mine is a bit whiny. (34k). Mating gears look good so I'm thinking this play and the worn brg right next to it could be contributors. I've measured 0.2mm clearance between brg rollers and gear bore. It certainly looks and feels that much. I think the gear turns with shaft when in 1st but with that much play it won't be concentric with its shaft.....or am I overthinking this :D no point in shelling out on a needle race if it's not needed.
On the oil seals I see they locate in lips machined in the cases. I'll assemble like this but i assume they can be conventionally installed with a mallet and sockets etc?
Main brgs are yellow and brown and don't look worn. Still I'll pull the rod caps which are under more stress.
Thanks for any added input.
Cases came apart nicely after I'd removed a hidden bolt near the clutch. One of the camchain slippers got pushed down but one cylinder had to be under valve spring load. I'll recheck the timing when I get the bottom end sorted.
Chhers :beer:

I rebuilt my engine last year replacing all of the bearings. the loose roller on first is normal... I replaced it with a new one and it was the exact same.
I believe on my bike, it makes a slight rattle noise in neutral. but once you put it in first, the gear is locked onto the shaft and the bearing isnt spinning

I replaced the large bearing on shaft with a press/mallet and socket with no problems.
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Commando77
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Re: Main and rod brg grades

Post by Commando77 »

Thanks for that. Did wonder if the play was normal, much like the same gear on Norton's. Have ordered the brgs anyway and the main shaft ones.
Utterly confused by the shell bearings, grades and markings on brgs that don't match anything listed....except the colour is of course. I'm going with identical replacements, tempted as I am to get some plastigage and measure. I think I'll just confuse me even more. The rods have different shell sizes and miking shows a tenth (0001") taper. That's Japanese quality I guess! Of course the mains are also different grades side to side. Tis fun.
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Chris58
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Re: Main and rod brg grades

Post by Chris58 »

Commando77 wrote: Fri Nov 16, 2018 8:31 pm Thanks for that. Did wonder if the play was normal, much like the same gear on Norton's. Have ordered the brgs anyway and the main shaft ones.
Utterly confused by the shell bearings, grades and markings on brgs that don't match anything listed....except the colour is of course. I'm going with identical replacements, tempted as I am to get some plastigage and measure. I think I'll just confuse me even more. The rods have different shell sizes and miking shows a tenth (0001") taper. That's Japanese quality I guess! Of course the mains are also different grades side to side. Tis fun.
Good idea to replace shells as well. The service manual is very helpful when it comes to the markings, theres a pdf on the site here somewhere.
I replaced the shells on everything as well.. When I first plasitigauged, they were all on the loose end of the spectum, but still within spec.

you may want to mic everything before ordering in case you could tighten up the clearence a bit
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Commando77
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Re: Main and rod brg grades

Post by Commando77 »

I have the honda manual downloaded... I just didn't get to grips with the ID marks immediately. It took a while for them to sink in. I'm used to 10 and 20 thou undersizes not 5 different std grades over only 6 tenths and different front to back. What happens on a crank regrind... Are shells available? Plastigage on its way so will check all journals. The rods are on black and blue so that's min journal dia already. Still I have no oil press issues so should be good for another 34k and will outlast me😏.
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Commando77
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Re: Main and rod brg grades

Post by Commando77 »

Well all journals plastigaged and rods seem OK and within limits at an avg 0.0016" but the mains are over the nominal limit at 0.002" although within service limit. I don't have any oil pressure issues I know about but without a gauge who knows? I have yellow and brown shells so can reduce clearance but how far do I go? Can I rely on miking the existing shells to guage wear? It would be nice to have a selection of shells but not got that luxury.. Any suggestions gratefully taken on board.
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Chris58
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Re: Main and rod brg grades

Post by Chris58 »

Commando77 wrote: Thu Nov 22, 2018 8:04 pm Well all journals plastigaged and rods seem OK and within limits at an avg 0.0016" but the mains are over the nominal limit at 0.002" although within service limit. I don't have any oil pressure issues I know about but without a gauge who knows? I have yellow and brown shells so can reduce clearance but how far do I go? Can I rely on miking the existing shells to guage wear? It would be nice to have a selection of shells but not got that luxury.. Any suggestions gratefully taken on board.
At 0.002 clearence on the mains you should be fine with no considerable loss of oil pressure.

Rule of thumb for engine building is 0.001 clearance for every inch of crank journal diameter.

Im not sure the diameter of the crank journals, but if you measure that, and do the math you'll know the Ideal clearance.

if you look at the shell thickenesses in the manual you can do the math to make the proper selection.

Just keep in mind that each shell size is .0001 different which would equal a total of .0002 of clearence
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Commando77
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Re: Main and rod brg grades

Post by Commando77 »

Thanks for that. I'm overthinking it as I usually do! I've ordered what was fitted as the journals look good and difficult to get an accurate thickness on the shells. Managed to slide out the top case mains by loosening the mccts and lifting the crank. Works a treat and they go back OK.
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