XS-1 Topend Rod bearing

[sethhazuga]

I have a new Project. Its an 1970 XS-1. i just tore down the topend and found it has topend needle bearings. I was excited to see the bearings, but now I have read in multiple places that the rods fail in some cases. I can rebuild the crank with 447 rods and use other pistons, but I want to keep things original. This bike already had 40,000 miles on the odometer and has lasted this long. My question to you all is what do you think? Nothing has happend in 40000 miles, so why not keep it? Also this wil be a restoration that takes Sunday afternoon drives.
Thank you, Seth Hazuga

 

[Jan_P]

What I did when I suspected to much play in the topend -- not needle bearings
I took it to the dealer and the Senior Mechanic put in the piston pins Most likely new ones and he with his experience could move them and get a feel for the play Gave it a pass which was correct aka no rattle after rebuild.
Difficult to give advice .. But I would investigate refurbish not bothering about stock do the math what the cost will be
And the overall status of the machine mint or rusted dented.
40 000 miles and some day it will be sold and I would not pay much for such a bike
Perhaps ready sets are available crank and pistons ..
But again it is not an exact science ..but myself would most likely refurbish if it is a known weak point and 40 k
Here in Europe rebuilt cranks are sold a bit pricey but they are available

Thinking out loud are they not possible to replace the needle bearings at a shop ?

 

[Signal]

I have read that Yamaha used the needle rollers because of their previous expertise was in 2 strokes and the 650 was the first 4 stroke offering.
Don't know if its true or not but it's a good story.
Have you thought of using a bronze bush in the little end.
MMM long rod kits use KX500 rods with a bush in the little end and they hold up well.

 

[zrx1100]

today I was talking to MMM and we were discussing the benefits of D-ports. I asked why Yamaha did not shape the ports right from the get go. He said that Yamaha did a lot of silly things, like the needle bearings in the top end of the connecting rods on the early XS. then i brought up this discussion here and his advice: take those rods out......