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Post by minnesota750 on Dec 21, 2014 23:42:41 GMT -5
I'm going through the engine on a 73, and need crank and rod bearings. The casing numbers are all 5s and the journal numbers are 2,2,3,2. Based on the formula in the manual that makes the numbers needed 3,3,2,3 - but how does that translate into part numbers for the plane bearing? Any help would be greatly appreciated. (posted in troubleshooting as well)
Thanks.
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Post by Claude on Dec 22, 2014 21:12:03 GMT -5
«if you go to a parts site like partspitstop.com you will find bearing numbers for the con rod and main bearings.
The number 1 bearing as per your service manual chart will be the first item listed ending in 00
The number 2 bearing as per your service manual chart will be the second item listed ending in 10 and so on
«If your magic numbers are 2 and 3 your bearing part numbers will end in 10 and 20»
I hope that helps, I am presently in the middle of rebuilding two engines so «i have done the research.
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Post by minnesota750 on Dec 23, 2014 1:02:53 GMT -5
Hello and than you very much for the insight. I really appreciate it. I'd be interested in chatting about how your rebuilds are going and what you've run into. I've done quite a bit of research on the updates and needed part numbers as well if I could be of any help to you.
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bigskyforever
Junior Member
I reside in Edmonton Alberta Canada. I am presently rebuilding a couple of TX`s.
Posts: 87 
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Post by bigskyforever on Dec 23, 2014 12:27:17 GMT -5
Thanks for you comments. I have had some issues with one engine with wet sumping. «oil filling the engine»
I found the shuttle valve stuck open, which had already caused the base gasket to start leaking. So I am doing a complete tear down on this one as well. The biggest challenge I can see on these engines is the original ignition not being very consistent. I will be installing some type of electronic ignition. I have not decided which system yet. Valve train is also an issue as the tappets have poor contact and a light drive chain makes for more adjustments. One engine has the balancer mods and the other doesn't. I have a donor engine (74) with the balancer but I require the shaft inside bushing specifications. I was wondering if you have the second shaft removed if you could measure the two bushings. «of course that is if you have the changeup»
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Post by minnesota750 on Dec 23, 2014 15:58:11 GMT -5
BSF - re: measurements - what part number are you asking about? I have the update in my 73 and everything broken down right now. Be happy to mic it for you.
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bigskyforever
Junior Member
I reside in Edmonton Alberta Canada. I am presently rebuilding a couple of TX`s.
Posts: 87
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Post by bigskyforever on Dec 23, 2014 23:28:46 GMT -5
items requiring dimensions.
ref. 5 part number 90387-20236-00 threaded collar thickness and o.d of collar
ref. 14 90837-16235-00 i.d. & o.d.
ref. 15 90837-16234-00 i.d. & o.d
I thank you for your help.
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Post by minnesota750 on Jan 8, 2015 17:16:36 GMT -5
Okay, I'm still confused about this. I've gotten some mixed info. I have pictures attached of the case engraving, the crank engraving and the numbers on the caps for the con rods. Re Claude: Can you help me confirm what I need for bearings? Thanks. Russell |
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Post by minnesota750 on Jan 8, 2015 17:17:34 GMT -5
Here are the remaining images. Attachments:
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Post by argo1974 on Jan 10, 2015 19:07:58 GMT -5
Since all three crankcase main bearing slots are #5s and all main crank journals are #2s, you need all #3 bearing shells for the mains. I can't see the number for R.H. big end while L.H. big end shows #3. That newer type conrod shows F5, which means #5. The other one looks to be #5 as well. So you will need #2 with either conrod used on L.H.
BTW, I strongly recommend to remove the plugs and clean crank oil passages.
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Post by minnesota750 on Jan 11, 2015 10:06:57 GMT -5
Argo - thanks for the confirmation, I really appreciate it. I've seen your examples you posted on the expansions you've done. - this site and another site.
I've been toying with the idea of enlarging the oil passages in certain places in the case, but I'm not sure how that would affect the overall engine performance. I know there is a service update to the banjo bolts to enlarge between 1.5-1.7 for the oil lines (I believe).
What's your opinion on enlarging oil passages in the lower half of the case?
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Post by argo1974 on Jan 11, 2015 23:55:08 GMT -5
I have done it on my NOS set of early cases. You can find here and the couple of mm. I also chamfered few areas with Dremel tool. Then, check the plugs not protruding into oil passages. While doing that, I used late style cases as example. You will clearly see the differences what Yamaha did back then.
At first, remove oil relief valve and get it checked for release pressure. Most of them should be near 60 psi, but very early ones open at much lower pressure. On 60 psi example, you can add another stock shim or 1-1.1mm washer to raise the pressure into 80-ties. Then, go with 1.7mm banjo.
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