Chain length vs engine position

Never really put much thought to this before. I picked a chain length that positioned the engine “about right” and in a location for the already drilled starter hole on my old kart. When I’d change sprockets I’d never change chain length just move the engine an inch or two to make it all work

I’m thinking about it now should the engine position be based on what’s optimal when scaling the kart and whenever possible should I be changing chain length. Not engine position, to acomodate gear changes?

Is this a complete over-analysis of the whole topic?

@Andy_Kutscher awesome question.

To say that engine position doesn’t matter is akin to saying seat position doesn’t matter, which as we know many fervently and religiously obsess over, for good reason. Fundamentally, moving the motor forward or back will of course change front to rear weight percentage. I’ve pondered this question before, and I’d love to see what others think!

From my thoughts, realistically you can only move a motor forward or back 1-2 inches before it rubs on things or the chain lengths available are simply too long or too short. So, overall the amount it changes front to rear weight is not enormous, although certainly measurable.

The other factor to consider is that karts do not necessarily react to changes in front to rear weight the same way a car does, as in a car we have more limited points to adjust behavior. In a kart, the entire chassis is active, which to me means there are more opportunities to compensate for a motor forward, or more rearward.

I’m very, very curious what others may think on this subject, tho.

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I’ll tag on with a related question. Is there an advantage to having a shorter or longer chain? Shorter chain is less weight to rotate, but a longer chain has more links to spread heat/wear over. Or is it completely moot when we’re likely only talking about 4-6 links difference?

Rotating mass is always important. However, what needs to be decided is if the handling - as a result of shifting the engine’s weight around - outweighs the gains of less rotating mass. I assume it will be scenario dependent, honestly. A shorter chain will also retain a bit more heat as there’s less thermal mass there; so, make sure everything is clean and well lubed.

I would say the differences are negligible.


I was thinking about this too. Since the chassis is so active, maybe a little longer chain will have more give or flex? Less binding than with a shorter chain?

@ssiever3 perhaps? Open to others thoughts, although my thought is unless you are running a chain extremely tight the tension in the chain vs. the magnitude of the flex of the chassis I would think would be negligible.

Chassis flex tends to happen across the waist. I can’t imagine a lot of flex happening between the bearing carrier and axle.

When we talk about axle flex, it’s really resonance and damping that’s happening.

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