Topic: Connecting rod clearance selection

[_mark]

Hi.
my engine is a late K1 (108...)
I have some doubt regarding the clearance selection about the crankpin/connecting rod.
Crankshaft has "3333" and for crankshaft is fine.
The connecting rod are showing on their faces more numbers, compared to what explained on the manual.
On one side there is a letter + number (F1 or F2) , on the other side there is 3/27 or 3/29.

Combinations for the 4 connecting rods are:
3/27 ; F 2
3/27 ; F 1
3/29 ; F 1
3/27 ; F 1

Anyone can tell me which number has to be taken account  ? Thanks and Regards.

[david 750f]

The letters are the rod weights that Honda uses. Match the number (1,1,1,4) to the crank journal ones (3,3,3,3). It looks as if you will need 3 yellows and one green. I've never seen those date codes before, maybe someone else can answer that question.

[_mark]

well. Thanks for the moment. By the way I was trying to figure out how much could be the error to put the wrong bearings and to see if is possible to see, through the bore size of the connecting rod, the original diameter of the connecting rod bore.
This last option needs a metrology lab and you need to measure the microns !
Even the bearings of the different sizes they differ of 4 microns (less than 2/10000") ! 
I have a caliper certified for 2/100 uncertainty, with sensitivity 1/100 and I don't see any difference between old bearing, green brand new and yellow brand new.
Is there really the need to code different sizes of bearings ??
It seems that such precision is a little bit excessive.

[bryanj]

All it takes is accurate measuring equipement in the factory, which is why you cant just mic the journals, air gauges were used at source.
Hondas idea, according to the reps i talked to, was to build an engine with clearances as if it had done about 5000 so all the owner needed to do was "bed in" the surfaces

[Bodi]

I think 4 microns is about 0.00015, less than 2 10,000ths.

[david 750f]

You would need a micrometer and bore gauge accurate to .0001” or a metric one accurate to .001mm. This can get expensive, that is why most people just use plastigage.

[_mark]

I think 4 microns is about 0.00015, less than 2 10,000ths.

yes