Engine needle/ball bearings 400/4

[Fogdevil]

Hello everyone,
Having got into the guts of the engine and decided to replace all the roller type bearings I have discovered that of the 6 that could be replaced
one is discontinued(part ref 265) and another is prohibitively expensive(part ref 264).
From your collective knowledge,which bearings would NEED to be replaced and, if all of them, can anyone suggest a reputable bearing supplier.
The engine has done approx. 27k
One more question-The damper on the cam chain tensioner(part ref 51) is 1mm thicker on one side than t'other.Does the 'thicker' side go towards the front or back of the engine?
I hope the photo shows it
Cheers
Peter

[Laverda Dave]

I'm no expert but I've rebuilt 3 400/4s over the years and have never had to replace an engine bearing, they were all smooth running and had no side play. All the engines were higher milage than yours. Did you hear the engine running before you stripped it, did it rumble at all and is there any marking on the rollers or signs of overheating?

[Fogdevil]

Hello Laverda 120
To be honest, I started this project about 3yrs ago. From what I remember there were no rumbly noises and all the bearings I have taken out appear to be unmarked and normal.
From everything I have read/absorbed about restoration seem to suggest replacing every replaceable part going-bearings being one of them.
I don't know if replacing the most likely bearings to wear is a sensible option.Which bearings are more susceptible to wear?
I know I don't want to go back into the engine 6 months later to replace a failed part,but is replacing as many as possible a bit overkill(and expensive)?
Hmmmm!!
Any advice welcome
Cheers

[Bryanj]

The ball and roller bearings rarely fail unless rusted so dont bother

[Laverda Dave]

I agree with Bryan, The roller bearings are very strong and don't wear. If you want to see if the engine has had a hard life with a lack of oil changes the best indication will be to check the condition of the mains and big end shells. You will need to use plastigauge to check these. There's lots of previous threads on this subject if you use the search box.
One bearing to replace is the swingarm, don't use the OEM plastic type though they wear quickly. Someone on ebay sells phosphor bronze bearings for 400/4's, I think they are based in Germany.
Good luck with the rebuild.
Dave

[Fogdevil]

Thanks for the info.
That has made my mind up and saved me a few quid.
Cheers