New engine or rebuild

What’s he general consensus on buying new engines or having them rebuilt? I’ve had my KA for a handful of years now, fairly rigorous rebuild schedule… but on the fence about just buying a new one for next season… On one hand if you buy a new one you get a fresh exhaust/carb, on the other I guess you could just keep rebuilding and buy those separately… do engine loose performance after x amount of years regardless if they have been rebuilt?

I would just do the rebuild and buy a new exhaust just for race days and still be money ahead. Carbs shouldn’t go bad. Only moving parts are the diaphragms that can easily be replaced. If you’ve got a good motor and carb combo hold onto it. Nothing has changed on the KA in awhile.

Also you can always refresh the exhaust with a bit of oven cleaner or a hot fire to get rid of the residual carbon buildup.

Engines get better with age and as you hone them out ‘em with each rebuild.

Depending on how much material is left will determine how many times a motor can be redone. In the US I think the KA has only been around for 5 maybe 6 years so I would think you still have some life left. You can also buy parts individually but they are pricy. The pipe can be decarbonized with heat or chemicals and as long as the carb has been cleaned and rebuilt it should work fine.

I think a good motor builder should be able to keep the performance as good or better than a new motor.

Could you just replace the cylinder head? Does the crankshaft and case also lose material as fast as the head?

Thanks for the input, validates my thinking on new vs rebuilding. If there was a major update then it would be a no brainer.

So is there a point when new would be better based on age?

Yes, you can replace the cylinder but with a caveat, a new one is $641 and may be going up too. If you have to replace the cylinder and crankshaft then it might make sense to buy a whole new motor. As long as your bearings don’t fail I would think a case should last quite some time.

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Only if the engine tears itself apart to such a point that it’s cheaper to replace vs rebuild. But for normal maintenance, generally not.