Killer pinion bushes 25593-52

Production K Models

Re: Killer pinion bushes 25593-52

Postby hennesse » Fri May 07, 2021 12:40 pm

The close-but-no-cigar manufacturer would be the big-V people.

Eastern Motorcycle Parts makes these bushings, and an amazing amount of K, Sportster, Big Twin, and 45" Harley engine internals. Unfortunately, Eastern does not sell retail, so you'll need to find a cycle shop that has an account with them.
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Re: Killer pinion bushes 25593-52

Postby Monti » Fri May 07, 2021 1:24 pm

Jon
I highly appreciate your thought and comments. Oil pressure is not issue after changing the oil flow to the crank (as soon as the engine is slightly revved, the oil light goes off also when hot). Metering a repro pinion shaft is certainly a good idea (this also went through my head).
I am pleased that you found the big end bearings in good condition. I was not so lucky, and I think that my engine must have been done up by somebody who had no idea about KH engines or even engines in general. Based on the condition of the big end and the additional hole near the pinion shaft busing, the engine must have run with no oil to the crank at some point. This was just one of a lot of mistakes, e.g., the cylinder oiling jets were also blocked by cylinder sleeves, the right crank bearing race was not line with the one on the left, both threads of the drain plugs were completely pulled and as a result the case was cracked, there was 0.12 thick copper cylinder head gasket installed (to avoild that the valves hit the welded heads) etc.
So I spend a lot of time to get the engine back running, but I think it was worth the work and one more KH is on the road.
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Re: Killer pinion bushes 25593-52

Postby John R » Fri May 07, 2021 2:07 pm

Just to be beyond doubt - the original pinion shafts had continuous end feed, which brings me to a crazy thought! Are there repro pinion shafts out there with side feed, and the 'bad' repro bushes match them??

If so, there could be the baaaad situation of people not replacing as a pair.

Keep in mind there are early flywheels and shafts, and late. The -52 have all the shaft and pin fits as parallel interference, -54 went back to traditional taper fits.

BTW - the pinion bushing should not be considered a bearing - it's just a way of transferring oil to the rotating pinion shaft.
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Re: Killer pinion bushes 25593-52

Postby Monti » Fri May 07, 2021 2:40 pm

Maybe I was not clear - I meant the left Timken bearing and the right roller bearing in the two crankcase halves were not in line with each other (according to the belly No, the right half is a replacement part). The pinion shaft bushing in the timing gear cover was so badly worn that it was not worth checking.
For the changing the oil feeding to the crank, a side hole was drilled into the pinion shaft (correct position so that oil get to the big end just before TDC) and the one at the end was closed. As far as I know there are no repro shafts which have the side feeding - so nothing to worry if the pinion shaft bushing is altered.
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Re: Killer pinion bushes 25593-52

Postby sportsterpaul » Fri May 07, 2021 7:11 pm

I had a friend that worked at the GE electric motor plant in San Jose. He did a study on the big generator bearings, and indeed he found that some oil flow makes them run cooler, but too much flow raised the temperature of the bearing. We all assumed it was joule heating of the oil, but it might have been oil skating the bearings. I doubt this happens in a K-Model, but you never know.

Thanks so much for the tip about satin-blasting the chrome or just painting it over, that is what I will do. The engine kicks OK, so I am curious what it will look like when I open it up in a month or two. I will be making videos and talking pictures of the parts to help folks out.
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