Durability of engine

[trailer01]

I have a 1981 650 special, I would say it has about 35 to 40 thousand miles on it, and it well mainted and not driven hard at all, was wondering how long these engines can last Can the make 70000 miles or more?

Thanks

 

[5twins]

Well, maybe 20 years ago but now, most of these are suffering from failed front cam chain guides. It's not a mileage thing, it's age. The glue is failing and the rubber strip is falling off. All the other parts in there may be fine and might do the 70K but that front guide will probably need replacing.

 

[trailer01]

I replaced the cam chain and guides due to a leaking head gasket a few years ago.
It has always had a rattle or knock at highway speeds when its under load about 3 to 4000 rpm , when you let off it goes away, never could figure out what that noise is.

Thanks

 

[gggGary]

Cam chain adjustment is very finicky a little movement of the rod but not TOO much. The BS34s like the needle shimmed up with a couple of washers, you might be getting lean enough to have some pre-ignition going on?
The bottom ends are usually considered to be good for 60K plus if the bike has been maintained.

 

[kaimojurgis1]

This will sound stupid, but... Let's say you have a bike with 80k miles on. Is is even worth trying to work on it? To what level can it be restored? I've just recently got this crazy idea of buying an xs650, tearing it down, and trying to do something cafe-racer-like with it, but in Europe they start at EUR 1500 with 70-80k km. This would be my first project EVER, so xs650 seems like a reasonable choice due to the resources and help available online. However, spending 1500 for the bike, then another few hundreds for the missing tools/parts just to rebuild the engine and realise that it will do another 500km before dying sounds slightly discouraging..

 

[xjwmx]

One place I worked they would try to estimate the lifetime of a thing now and then and one of the ways of simulating age was to heat it up.

Now with the front guide, the normal temp for it is 300F or more. So I wonder if age itself would have a significant effect on its lifetime, since it normally operates in a condition of extreme heat. If you follow the logic.

 

[trailer01]

The reason I ask how long it can it last is because I really enjoy riding this bikeI used to have a yamaha v star, but I actually liked this bike better, i had my bike for 10 years and put 20000 thousand miles and never had one break down, i would like to some day to a complete restoration of it.

Thanks