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CT-175 Engine Rebuild Check Point Please
- landyr67g
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CT-175 Engine Rebuild Check Point Please was created by landyr67g
Thanks for any comments.
Joe M
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- Tinkicker
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Replied by Tinkicker on topic CT-175 Engine Rebuild Check Point Please
2. Again, how stiff is a new crank. Where to start? Subjective again. As a guide, if you spin it and the rod is above the case and not catching it, I would expect it to rotate at least twice after giving a good hand spin.
3. In 12 years as a motorcycle tech, I never once used any sort of puller to pull the crank into the gen side case. I heated the case till when spitting on the case makes the spit go into a little "ball" (around 120C) and not just sit flat boiling away. I then just dropped the crank straight in under its own weight. Pulling it in at room temperature can cause galling, mishapen bearing locations, bruised bearing tracks and even cracked cases if you get it badly wrong.
I trust you lubricated the bearing location and the outside of the bearing before you started pulling?
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- RT325
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Replied by RT325 on topic CT-175 Engine Rebuild Check Point Please
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- MarkT
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Replied by MarkT on topic CT-175 Engine Rebuild Check Point Please
As RT325 said, does the new LH main bearing have C3 internal clearance?
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- landyr67g
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Replied by landyr67g on topic CT-175 Engine Rebuild Check Point Please
Regarding current fit, crank will not continue rotating after I flick the RH spline side between thumb and fingers (while keeping the rod free). Only other factor is that I greased the bearing in moly (didn't force "pack" it, just rubbed on one side working it in) and I have a LH double seal. Don't know if those are enough to conspire against but I can imagine how it won't spin like a top - as the loose bearing did lightly oiled out of the bag. The bearing is standard "partzilla" made in Japan...and only noted its basic sizing on its face. This morning I tried drenching the bearing through the crank and down the case lube hole with mineral spirits (paint thinner). Loosened up a bit but still not spinning free on its own. Myabe I'm worrying too much but at this point don't know if I should continue forward hoping its just the grease, or pull out the crank, measure the shaft, and compare to others. When I did both the failed and frozen stalls the journal and bearing ID were lubed.
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- Pete-RT1
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Replied by Pete-RT1 on topic CT-175 Engine Rebuild Check Point Please
It should be marked on the bearing.
As RT325 explained this relates to internal clearance of the bearing ie. the play between the rings of the bearing, not the fit onto the shaft or into the crank case.
If you have a problem, which isn’t clear, it could be that the diameter of the crank at the bearing journal hasn’t been machined to the correct diameter.
Can you get a micrometer on the shaft to measure it.
I was lucky on my CT3, the seal area was rusted and pitted but the bearing area was ok so PJME in the UK machined the seal area only and I replaced the seal with a smaller one to suit.
Sorry, that’s not helpful to you right now.
Yamaha CT1-C
Yamaha AT1-C
1978 Yamaha DT175MX
2020 Honda CB500X
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- landyr67g
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Replied by landyr67g on topic CT-175 Engine Rebuild Check Point Please
Regarding the resized bearing and oil seal journal, does anyone have an actual or published measurement for that diameter? Curious what I got! And regarding the cranks stiffness, still wonding if from damage or from the double seal...or both.
Joe M
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- Ht1kid
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Replied by Ht1kid on topic CT-175 Engine Rebuild Check Point Please
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- RT325
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Replied by RT325 on topic CT-175 Engine Rebuild Check Point Please
Anyway--i just google & came up with this link. Too much for me to take in but are talking about a 6205 as it happens. Got halfway down the page & fell asleep haha.
www.darbarcompany.com/darbarcompanyblog/bearingfitclearance
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- landyr67g
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Replied by landyr67g on topic CT-175 Engine Rebuild Check Point Please
Although I haven't got the bearing off the stub yet, I measured the exposed journal just adjacent to the bearing and I get approx 24.99 - 25.00 using my digital calipers and pressing together the jaws them selves. So guessing at this point the entire journal dia is correct. So maybe the bearing slightly undersized (can't read and measure it yet) or are people comparing assembly fit using "used" cranks while this one is resized to "new"? Don't know, but definitely going to swap the bearing and maybe the seal. So its pn is "DC 25 40 8" with a "2" 180 degree away. This is a double lip/spring seal. Maybe overkill for LH case?
Regards,
Joe M
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