Low compression high leak down test

[herdygerdy]

I agree with EMS on this one. The two ends of the bearing shell appear to have been crushed together so they closed up slightly, hence the gap on the LH side in the image.

Maybe the installer dropped it and then accidentally stood on it and thought, "Nah, she'll be right!".

As EMS say, circumferentially, it looks right for the rod and if you imagine it 'opened back up' again (which you wouldn't do), it looks like the ends of the bearing would most likely sit correctly on the mating halves of the con rod.

Methinks maybe replace just the two bearing halves for that rod and you would be good to go?

Keep us posted.

[EMS]

I agree with EMS on this one.
.

[Jeff Bennetts]

It's the only plausible explanation, it's mind boggling that someone would take the effort to tear the motor down to the crank and then reassemble it with the bearing shell bent like that.

I hope the OP gets back to us with the backstory on this motor.

[rsuarez]

Thanks to all for the responses. I agree that the circumference is right. If I roll it over the big end from side to side it matches the edges. Just changing it should fix it.

Now, to add more look at this.



These are the bolts that join the cases at the fifth cylinder. The same. They have been pressed to widen them or order to make them bite the upper case striped threads. Even one of them is slightly bigger than M8. Not sure right now if it's metric or standard. What happend first or if they related I don't know. I still think this engine has not been opened before but I could be wrong.

Best

[rsuarez]

Forgot to ask the important thing. I need to re-build 3 of thr threads. Do you recommend using helicoil for these bolts?
Thanks.

[daves79x]

Main bearing case bolts often have stripped threads in the upper case. The reason is that some of those castings are very porous and have big gaps. If one of those gaps are where the threads are, they have very little holding power. I've fixed quite a few of them with Helicoils. 2 inserts thread in quite well. You'll need 2 replacement cap bolts also, by the looks of things. My idea is your bearing issue is separate from this.

Dave

[rsuarez]

Thanks Dave. You've been very helpful. Hopefully I am done with the surprises.

One last question, what do you recommend for the cylinder base gasket, Hondabond or Copper Sealant?

Thanks again.

[daves79x]

Base gasket goes on dry, as do they all.

Dave

[rsuarez]

Thanks

[rsuarez]

I will start assembly today. Finally!!

Two questions if you don't mind.

The manual calls for grease on the threads of crankcase bolts, was wondering if grease is the best option or someone else is using blue Locktite or anti seize. Any suggestions? For the washers also?

Second. How to know how much Hondabond should I apply to the cases? I understand its a light coat but is there an indication on how much it should be? As simple as this is, it is something you definitely don't want to do wrong.

Thanks for all your help.

[daves79x]

Yes, I grease all the crankcap case bolt threads and sealing washers. Honda specs moly grease, but any will do I suppose, as it's for gaining an even torque on those bolts - not for sealing anything.

The case sealant goes on in a pretty thin layer, evenly on the bottom case half everywhere it seals and just on the top half where the shop manual shows. Just enough so the thin sealing surfaces are covered. I've done a bunch and never had one leak, so I don't think it's a critical thing, just if you use too much, it'll squeeze out and be noticeable. Won't hurt to squeeze inside as it won't dissolve in oil, just might be a bit unsightly on the outside. You can trim off any excess, however, that might show. Also trim flush the excess where the crank end caps seal and the clutch cover seals. Get everything super-clean and work pretty quickly - the stuff sets up in a few minutes. Get everything ready, including the transmission in first gear and the shift forks positioned properly. You can guide the forks into their grooves through the sump, but get them centered first by hanging the already-prepped with sealant lower case half. The shift drum also needs to be in the first gear position so the forks line up. Once you drop the lower case onto the upper case, do not try to lift it again or you'll pull the O-rings off their seats and possibly dislodge them.

Take your time prepping and make sure you are completely ready to apply sealant before you actually do.

Dave

[rsuarez]

Thanks Dave. I am amazed by the time and detail you take to help us get through these projects.

Best.

Ramon.