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XS400 con rod stamping #'s

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Hi I am trying to order new con rod / crankshaft bearings for my 82 XS400 SJ (sohc) engine.

The bearings are orderd by cross referencing stamping numbers on the case ,crankshaft and connecting rod.I can find the stamping numbers on every thing but the connecting rod. Does anybody know if they are stamped on or printed on? It almost looks like there might be something printed on but I can't read it.

Thanks!

ps any body know where to get con rod bolts? :rolleyes:

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Hi I am trying to order new con rod / crankshaft bearings for my 82 XS400 SJ (sohc) engine.

The bearings are orderd by cross referencing stamping numbers on the case ,crankshaft and connecting rod.I can find the stamping numbers on every thing but the connecting rod. Does anybody know if they are stamped on or printed on? It almost looks like there might be something printed on but I can't read it.

Thanks!

ps any body know where to get con rod bolts? :rolleyes:

the numbers are on the crank web and case housing numbers as per haynes manual. nothing on the con rod for you to worry about!

those bolts are expensive and I had to send off to speed sport to get mine! I since got a set on ebay but I think that was a one off!!

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Thanks Drewpy

I also have the Haynes manual and the way that I read it is that for the Crank bearings you subtract the numbers on the case from the nunbers on the crank ( or the other way around). I have found those #'s ok and I have found the set of numbers on the crank that relate to the con rod. But I am sure that there is a number on the con rod itself so that you can do the same subtracting formula to get the correct bearings.

I have found that the con rod bolts are discontinued from Yamaha and they were expensive when available. The manual says they should be changed but if I can't find any is it OK to use the old ones?

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Thanks Drewpy

I also have the Haynes manual and the way that I read it is that for the Crank bearings you subtract the numbers on the case from the nunbers on the crank ( or the other way around). I have found those #'s ok and I have found the set of numbers on the crank that relate to the con rod. But I am sure that there is a number on the con rod itself so that you can do the same subtracting formula to get the correct bearings.

nope!

just checked me yam service manual and it says:

"use bearings of identical color for assembly (for both connecting rod and journal bearings)"

I have found that the con rod bolts are discontinued from Yamaha and they were expensive when available. The manual says they should be changed but if I can't find any is it OK to use the old ones?

did you try speed sport?

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Thanks for the info about speed and sport :D i'd never heard of them before. They are deffinitly going into my binder. Plus they are on my side of the pond.

I have a Haynes manual and one I downloaded (?) and they both talk about the stamping numbers but I if you have the genunine Yamaha manual it's hard to argue.

What does your manual say about the rod bolts?

Thanks again for your help. You seem like the go to guy for xs400's around here.

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Thanks for the info about speed and sport :D i'd never heard of them before. They are deffinitly going into my binder. Plus they are on my side of the pond.

I have a Haynes manual and one I downloaded (?) and they both talk about the stamping numbers but I if you have the genunine Yamaha manual it's hard to argue.

What does your manual say about the rod bolts?

Thanks again for your help. You seem like the go to guy for xs400's around here.

nothing about replacing them!

does say assemble with molybdenum disulfide to the threaded portions of bolts, nuts and nut seats

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Thank you again.

I was hoping you were going to say that. :D

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OK I finally got all of my plain bearings and thought I would share what I found out. Through all this I managed to get a partial photocopy from my local Yamaha dealer. I assume that this is from the factory service manual and this is where most of my information comes from. The photocopy, my Haynes manual and the manual I down loaded all show a chart for selecting the crankshaft and con rod bearings. As I stated earlier the #’s stamped on the engine case and crankshaft are easy to find but I could not find any number for the con rod big end bearing. I think the number might be printed on the arm when new but does not last to long inside the engine. Looking at the crankshaft bearings I could not find a color or a usable number on them so I did not have much confidence in finding markings on the con rod bearings. I hade no choice so I just took the big end bearings out. To my surprise there were obvious color marks on the edge of these bearings half way from the ends.

So with this info and part numbers from Yamahas online parts catalogue I went to my local dealer and ordered my parts. Now I should note here that I ordered parts for my second engine which came out of an 1982 XS400SJ. When the dealer looked on his computer based parts catalogue it only showed the dual overhead cam models. When I pointed out that he was looking at the wrong engine he had to go to the parts fiche to find my model. I was told the parts would be here in 4 days which surprised me. It ended up though that some of the parts were backorder to Japan, which is what I expected anyway. After several weeks all the parts were in except for one crankshaft bearing. After a couple more weeks I found out that the bearing had been discontinued. The dealer gave me the current part number and suggested that I try on the internet. I managed to find it from a dealer the next province over and it was even cheaper.

So when I picked up my parts I noticed that the colors for the crank bearings were off. The part numbers were right but the colors were wrong. I suspected that they were packaged incorrectly and asked the dealer to re check them. When he got back to me he told me that all of the stock in the warehouse was the same. He suggested that I plastiguage the bearings it I didn’t feel confident in them being right. I agreed but mentioned that it gave no tolerances in either of my manuals. He said he would look into it further.

When he got back to me he told me that Yamaha used the same bearings in the FJ1200 but that the colors were different. I looked up the bearings for a 1986 FJ1200S using Yamahas online parts catalogue and found the same part numbers as my 82 XS400 but the colors were listed as different. I don’t know why they changed the colors but I do know that if some one in the future tries to order bearings for my engine based solely on the colors on them, they will get the wrong ones. Not good!

So the good news is the photocopy my dealer gave me. I has all the tolerances and specs for the 82XS400 engine.

The clearance for the con rod big end bearing is 0.021-0.045mm (0.0008-0.0018in)

The clearance for the crank bearings are 0.020-0.044mm (0.00079-0.00157in)

I hope this can help some one and clear up some of the confusion. I do have other specs for this engine. If anyone wants them just let me know.

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good bit of info, thanks for sharing. Didn't knw ththe FJ shared the same bearings

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@XS-Time 

Hi there!

I'm glad I finally found somebody with the same problem! I own a 1995 XJR400R. The bearings in my XJR's connecting rods are worn out. The problerm is, from use, the stamp numbers have faded out. Just like you, I need the stamp numbers on the connecting rods to find the correct size, color and part number of the bearings. The only manual I own is one in Japanese as the XJR400R is too rare and another one from an XJR1300. I don't know how to even begin looking, if nothing on the con rod gives me a clue.

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You may not have noticed but this thread is 8 years old. Try setting up another NEW thread in the Workshop section. Right after saying Hello in the new members section (hint).

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