CB550k1 US Import - UK registration

[Bryanj]

You do not put plastigauge between shell and rod, or cap, only on one shell and torque the cap.
The clearances are in the Honda manual, both max and normal but can't get at mine at the moment. There is also a table cross referring pin size and code to rod code, ideally you fit the specified new shell and check clearance with plastigauge altering shells if needed, that gets costly

[juitz]

You do not put plastigauge between shell and rod, or cap, only on one shell and torque the cap.
The clearances are in the Honda manual, both max and normal but can't get at mine at the moment. There is also a table cross referring pin size and code to rod code, ideally you fit the specified new shell and check clearance with plastigauge altering shells if needed, that gets costly

Thanks Brian. Think I need to sit and get my around the two different tables in the manuals.

[McCabe-Thiele (Ted)]

We've all been throught the learning dip - just to confuse you they use different designations between mains & big ends on the axis lettering/numbering on the tables iirc.

[Bryanj]

Yup, you have to remember that the Honda manuals were written for the dealers so assume you are a mechanic to start with, plus of course the technical translation can be a bit iffy

[Oddjob]

Thanks Mick.

Looking at the manual on how to select bearing shells for Conrods, I've got:
2D, 2D, 2D, 3D
All shaft pin diameter are 34.99

I've plastigauged rod one between the cap and bearing and between bearing and pin. Both measured 0.038mm clearance.

I'm not sure where to go from here though as the manual has bearing selection based on the rod stampings and pin diametera. Can't find where in the manual the clearances come in to select the correct shell?

If I go by the manual, I need 6 brown and 2 greens.

Not sure where you've got that info from for bearing selection, there is no letter D in the bearing selection chart. Your crank markings look very clear, I can clearly see 1A on the rotor end crank webbing, the number 1 is for the crankshaft main journal, the letter A is for the conrod journal, so whatever number is printed on that conrod is what you need to check selection. The letter on the conrod is it's weight code, all the rods should have the same code so the crank is balanced.

Take a pic showing the crank markings and if possible the conrods showing the numbers printed on them, just to confirm the colour selection. Your shells look ok for re-use TBH, I'd just clean everything meticulously and refit them with some graphogen.

[McCabe-Thiele (Ted)]

Oh dear Ken one of my 500 Conrods  (No4) is 3 all the others are 2.

Will this be an issue - presumably I could weight them individually then if 3 is heavier have it lightened ?

[Oddjob]

It's the letter not the number that's the weight code Ted.

[McCabe-Thiele (Ted)]

It's the letter not the number that's the weight code Ted.

Heart attack averted then.

[Oddjob]

The easiest way to remember to what letter and code to use is this.

The ones on the crankcase are letters, always remember that. Those are the ones stamped into the back of the bottom case usually, like BBABC. Honda would not do a letter and letter combination as there's far too much chance to get it wrong, so if the crankcase is letters then you need numbers off the crank to select the main bearings. If you remember that then it's simple to work out that the only thing left on the crank printing/stamping is the letter, so those must refer to the conrod journal. Again, must be letter/number combination so if crank is letter then rod must be number, that leaves the letter as the weight code.

If you can always remember that then working out what is what becomes so much easier. 

[juitz]

Thanks Mick.

Looking at the manual on how to select bearing shells for Conrods, I've got:
2D, 2D, 2D, 3D
All shaft pin diameter are 34.99

I've plastigauged rod one between the cap and bearing and between bearing and pin. Both measured 0.038mm clearance.

I'm not sure where to go from here though as the manual has bearing selection based on the rod stampings and pin diametera. Can't find where in the manual the clearances come in to select the correct shell?

If I go by the manual, I need 6 brown and 2 greens.

Not sure where you've got that info from for bearing selection, there is no letter D in the bearing selection chart. Your crank markings look very clear, I can clearly see 1A on the rotor end crank webbing, the number 1 is for the crankshaft main journal, the letter A is for the conrod journal, so whatever number is printed on that conrod is what you need to check selection. The letter on the conrod is it's weight code, all the rods should have the same code so the crank is balanced.

Take a pic showing the crank markings and if possible the conrods showing the numbers printed on them, just to confirm the colour selection. Your shells look ok for re-use TBH, I'd just clean everything meticulously and refit them with some graphogen.

Apologies, I think I'm confusing things here.

The Conrods had markings on one side of "2" for pistons 1-3 and "3"on piston4. They were all marked "D" on the other side - which are the weight codes. I just typed all the info in the last post.
The crank is marked 1A at all locations.

I took some pictures of all the bearing shells for visual "assessment". I have to replace at least one conrod shell though as I scrapped it trying to roemove it.

The conrod markings are gone or just barely visible. My fault for trying to clean these up in the ultrasoniccleaner


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[Bryanj]

To be honest, from the pics you posted they look contaminated by dirty oil infrquently changed, will br expensive but i would change them all. What do the mains look like?

[juitz]

To be honest, from the pics you posted they look contaminated by dirty oil infrquently changed, will br expensive but i would change them all. What do the mains look like?

Mains for example, these have scuffing .

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[Sesman]

Interesting exchange this one. My cases were stamped CCCCC. The crank webs were marked A1 and the rods D2.

All journals were in perfect unmarked condition. From this I deducted: Mains C1; big ends A2. All rods being weight ‘D’. The engine was untouched, as far as my forensic skills can tell, and the mileage being confirmed as 17k miles.

Some queries: how unusual is it have such repeatability in the cases, mains and big ends ID? Did Honda get better at manufacturing tolerances or just more relaxed about machining and weight tolerances? Motor is a 1977 F2.

[Oddjob]

In that case you'd be correct with 6 greens and 2 browns for the rods. The crank as I'm sure you've worked out are all yellows. Hard to find these days.

I have some if you need them, got more than 10 IIRC.

[Oddjob]

Interesting exchange this one. My cases were stamped CCCCC. The crank webs were marked A1 and the rods D2.

All journals were in perfect unmarked condition. From this I deducted: Mains C1; big ends A2. All rods being weight ‘D’. The engine was untouched, as far as my forensic skills can tell, and the mileage being confirmed as 17k miles.

Some queries: how unusual is it have such repeatability in the cases, mains and big ends ID? Did Honda get better at manufacturing tolerances or just more relaxed about machining and weight tolerances? Motor is a 1977 F2.

Luck of the draw TBH Phil, nice when it happens but it's rare TBH to see it..

Spot on with your deductions.