Topic: crankshaft bearing selection (no letters stamped and no colors)

[mazingerzeca]

Hello all.
I'm rebuilding a cb 750 F2 engine, and I arrived to the crankshaft.
I have the tables for selecting the crankshaft bearings crossing the letters stamped on the crankcase and the letters stamped on the crankshaft. They would give me a color to order the replacement bearings. Well, I did not find any code stamped on the crankshaft where it was supposed to be. Is this possible or maybe that is an aftermarket crankshaft? I tried also to order the replacement bearings according to the color codes painted on the old bearings, but there were no color paint on them. Maybe they are also aftermarket bearings? I don't know the story of the bike, I own it since 2003.
Are the bearings the same for all F2 models or that tables are made because the bearings vary from engine to engine, even being all of them F2 engines? If I order a set of F2 bearings, will they fit or is it really necessary that color codes and that letters stamped that my crankshaft doesn't have?
Thank you.

[scunny]

not all crankshafts are stamped,I have 2 that aren't. the upper case should have 5 letters stamped on it to give you that end of the equation. failing that the only way I know is to get a couple of new bearings(say green) and then use plastigauge with them on each journal to find which bearings will be best.
hopefully someone who can explain this better will chime in.

[mazingerzeca]

not all crankshafts are stamped,I have 2 that aren't.

Do these crankshaft come from a 750 F2 model? Are they aftermarket? Thank you

[Jerry Rxman Griffin aka MuthaF'er]

Not that I've seen many cranks but I have yet to see one stamped. The ones I've seen have been hand scribbled on in a Japanese accented (if that makes sense) lettering. Looks like they could've taken a screw driver and marked it. You will probably need to take it out into the sunlight and move it around until you see what could be mistaken for light scratches near #2 or #3. The crank I recently pulled and sent to Big Jay at APE for balancing was marked: J-)L-AAAAA  P)L-4444. Real difficult to make out until you've done the first one. Keep in mind what range of letters you're looking for because you'll need to use your imagination a little to determine what the Japanese tech was attempting to write in English letters. 

[dakeddie]

Yup.. my crankshaft looked like the letters with written on with white pencil crayon.  Verrry difficult to read... also one letter I couldn't tell whether it was an A or a B cause of the chicken scratch.

Look really carefully on the flywheel where the manual says the letters are "stamped".

[rhinoracer]

Mine's scribed in one of the counterbalancers too, you can barely read it. However you have to buy the bearings separately for each main, you can't buy them as a set unless all measure the same.

If you want the same size you can mic the original bearings which will not give you the right size since used bearings have wear.

You can also mic both the cases and the crank and use the tables to determine size.

You can use plastigage but this will only tell you if your actual bearings are within tolerance but not which color you should buy.

[Big Jay]

Measure the journals and see what number they are.

Jay

[bryanj]

To the best of my knowledge there is noone making aftermarket cranks or shells, Modified cranks yes---but they are Honda cranks to start with.
The markings, as said, are VERY difficult to see but they are there

[MRieck]

Measure the journals and see what number they are.

Jay

You should measure them even if you can read the marks.

[Big Jay]

Absolutely.  These cranks are 30 years old. The journals aren't necessarly the size of the code after all those miles.

Jay

[bryanj]

After many years of looking i find that there are two types of Honda crank:-

(1) Those with no measurable wear from when manufactured

(2) Those that are only suitable for use as ballast or offensive weapons

Never yet found one somewhere in the middle!

[mazingerzeca]

Hello all.
I've checked the crankshaft but I did not find anything readable where the codes for replacing bearings should be.
But I've found something that can add some information to identify the crankshaft bearings. From alternator side, I've seen the following letters stamped on the crankshaft bearings:

- D7G STD
- D7G STD
- D7G STD
- D7H (the color seems to be green)
- D7H (the color seems to be green)

That's all the information I've got from the bearings. Given that the two bearings with a green color have the same code stamped, maybe the other codes mean another color? Do that codes mean anything related to bearing size?

Thank you

[scondon]

Given that the two bearings with a green color have the same code stamped, maybe the other codes mean another color? Do that codes mean anything related to bearing size?

   Honda gets their bearings from several different manufacturers. The codes marked on your bearings might mean something to the manufacturer, but I don't think that they can be referenced by Honda. If you stand the bearings on the side you might be able to see a small color mark. Much like a green or yellow or brown pen mark.

   I've taken out two F2 cranks and neither one had markings on it. Even if you knew what color bearings were installed when new you really can't skip the step of measuring(plastiguage) with new bearings to see what you need for replacement, as others have stated above.

   If it were me, I would order two pairs of Yellow bearings for measuring purposes. Insert the new bearings in 2 of the 5 journals and put old bearings in the remaining three and plastigauge the new Yellow bearings. Then switch the Yellow bearings to different journals and repeat. This means you will have to torque down your crankcases three times to measure all five journals. Bwaller turned me on to this method and it was a real time/money saver.

    I ended up putting 4 black and 1 Yellow for my crank.