1961 CB72 Project

jerry · Post by **jerry** » Sun Oct 11, 2015 10:46 am

Dear G Man Probably bad information giving on my part. July 1 post on my Timeline. Have sent it through to you as a share. All the best Jerry

G-Man · Post by **G-Man** » Sun Oct 11, 2015 11:48 am

Hi Jerry

Many thanks

G

Luzreawy · Post by **Luzreawy** » Tue Oct 13, 2015 2:20 am

A simple illustration of this see me.

rpr851r · Post by **rpr851r** » Fri Oct 16, 2015 12:52 pm

honda brian wrote:Hi G Man, regarding the side clearances at the big end. I seem to remember reading in a Honda manual that the allowable side clearance on the con rod was 0.006 thou to 0.019 thou.I set mine up to 0.006. I reckon it takes out a bit of that "rocking" motion that you speak of. Keep up the good work.
See you at Mallala, Jerry.
Brian.

Hello all,
Sorry to hijack the thread. I am putting a CB77 crank together and am in the process of setting the side clearance on the connecting rods and noticed a discrepancy. The manual I have gives a range of clearance from .0027" to .012" and not .006" to .019". Am I reading something wrong or is there a miss print? The image is out of the Honda 250-300 shop manual.

Thanks,
Rich

And oh yeah, Beautiful work G-Man.

G-Man · Post by **G-Man** » Fri Oct 16, 2015 4:55 pm

Rich

I have been travelling for a while so haven't looked at the specs in the manual recently. You have read the table correctly, but people do form their own opinions.

Personally, I am not convinced that bigger clearances increase oil flow through the bearing when the restriction appears to be on the inlet. I'm tempted to think that the bigger clearances reduce frictional heating as the crank twists under high loads.

Guy's like Jerry have considerably more experience than I do with these motors, so listening to what he has to say is always a sensible plan......

G

rpr851r wrote:
honda brian wrote:Hi G Man, regarding the side clearances at the big end. I seem to remember reading in a Honda manual that the allowable side clearance on the con rod was 0.006 thou to 0.019 thou.I set mine up to 0.006. I reckon it takes out a bit of that "rocking" motion that you speak of. Keep up the good work.
See you at Mallala, Jerry.
Brian.
Hello all,
Sorry to hijack the thread. I am putting a CB77 crank together and am in the process of setting the side clearance on the connecting rods and noticed a discrepancy. The manual I have gives a range of clearance from .0027" to .012" and not .006" to .019". Am I reading something wrong or is there a miss print? The image is out of the Honda 250-300 shop manual.

Thanks,
Rich

And oh yeah, Beautiful work G-Man.

jerry · Post by **jerry** » Fri Oct 16, 2015 6:13 pm

Dear rpr851r, Have done a few road cranks at .006" to .008" conrod side clearance. You wont have any problems. As Loudmouse sais use 30 or 40 monograde mineral oil depending on climate temperature and with specified oil change intervals and filter cleans you will help your engine live a long life. All the best Jerry Kooistra

rpr851r · Post by **rpr851r** » Sat Oct 17, 2015 6:24 am

Thanks Jerry and G-Man. Unfortunately I pressed up my crank yesterday and the clearance ended up a little tighter than I was aiming for at .about 004. I don't have a great way to control the final clearance but will try and bump the clearance to .008. The good news was the crank was much straighter than I expected right out of the press with .007 runout being the worst. I am letting it set for a few days before trying to bring it in.

Thanks again for the feedback.
Rich

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1961 CB72 Project