Hang on guys, it wasn't me looking as such, the OP said he needed new rods and I merely mentioned a recent post I'd seen from Seager Eng regarding some new rods for Trumpy 750's from Hepolite. My intention was purely to impart info not to make any recommendations, and currently my rods are still OK...as far as I can tell...until it goes bang!
Which leads me to a point here. The way I see it, these bikes are not getting any younger and we know the accumulation of fatigue stress cycles in aluminium alloy is something that can build up over the years with no outward signs of distress until one day boom a rod lets go. Every missed gear, slight over rev, changing down instead up etc. may not cause a failure at the time but it does add to the fatigue bill that ultimately might result in a catastrophic failure, without warning. I know they can be refurbished to an extent, crack detected, polished, resized...resized that's a good one. Why would they need resizing? Because they've stretched that's why, its not wear, its movement! Either taken past their elastic limit resulting in permanent deformation or slow creep either way it ain't good!
There is no way of knowing even with x-ray etc. unless a crack exists. So all these old units are essentially ticking time bombs in this regard. These bikes were never originally conceived to last 70 years plus and I see the alloy rods as one of the weak areas where it is probably worth renewing, if you have your engine down, rather than substituting someone else's previously enjoyed unknowns into the mix. Just my 2c and we all have to make our own decisions on this but if I was doing my engine again from scratch, I'd be going for new rods.
Meanwhile until that day comes, I'll try not to think about it too much, have fun and ride sympathetically.
