Gearing for Avon

[Michael Drechnowicz]

I was wondering what the recommended gearing would be for Avon. I have two engines, not sure which I will use, an MC-9 or a modern US Motor 820. Both have a 9 tooth dry clutch. I have a Bug rear-engine kart and weigh about 175. Any suggestion would be appreciated.

Thanks,

Michael

[Romero Llamas]

When I ran the mini bike / Kart fun event I Ran 9/66. 1963 Rupp Brand X with a Mc91. Gave Steve Miller a good run. I weigh 150. There is one super tight corner before start finish straight, but you just have to fight through that. Wish I was attending Avon VKA event, super FUN track !!

[Kurt Bogerman]

My kart is a 65 Rupp Grand Prix. I have a Mc90 and Margay gearbox, so a little heavier than chain drive. I also weigh about 190. I settled on 7.6:1 gearing last month at Avon, which would be 9/68 or 9/69.

[Brett Mallory]

I'm at 9/70 on my A-Bone/MC90.  If they run the new track layout - and I'm pretty sure they are - you might want to gear a tad higher than that, like 68 or 69.  Like Romero says, the hairpin before the finish line prevents gearing too tall, it can be a clutch killer if you are.

Personally, I'd like to see you run the US 820 just so I can see how they work on that track - but that's just me....

[John Wolkiewicz]

i just looked at the VKA flyer for Avon and it suggests 9-62? this seems like a big difference than what has been posted here

[David Luciani]

what you have on there now should be fine to just go and run at the track.

9-62 doesn't sound good to me 
btw i couldn't find that on the avon flyer where did you see it??

 i rarely change gearing.typically i'm around 9-66 with a mc91
not the best gear at some tracks but usable and typically i am not racing anyway.
so if it was me i'd follow advise here to gear for avon.

i tend to hang out in the fun zone myself.

mostly imho gear advise should be used to gear for unusual tracks like new castle and to some extent cuddyback.
at new castle the straight is long enough to hurt a vintage engine without correct gearing.
at cuddeback not so much and i've heard the new layout has a hairpin you need to consider.


really what you have to decide is what you're trying to accomplish at the track. 
do you want to run your kart at speed with others or are you racing?

if you're racing bring a box o gears tools and alot of time.
you'll need to time your laps be consistant and swap out gears til you find the right ba1ance. 
you'll get all sweaty have no time to visit people and risk blowing up stuff if you get it wrong. 
that's racing.

or just stick on a good general gear run the kart at speed and have fun.

read this if you want to go deeper into gearing

comet article on kart gearing

d

[Kurt Bogerman]

I think that the "9-62" reference is in the VKA newsletter and/or on the schedule on the website: I've seen it, too. I assumed that the 9-62 gearing was for later models or more modified engines with pipes and slippy clutches? My Margay gearbox makes adjustment easy!

[steve miller]

I think that the "9-62" reference is in the VKA newsletter and/or on the schedule on the website:  I've seen it, too.  I assumed that the 9-62 gearing was for later models or more modified engines with pipes and slippy clutches?  My Margay gearbox makes adjustment easy!

I don't think any kart will work with 9-62..

9-68 with driver 160lbs and under
9-70 anyone over 160..
will get you real close ..

[Kurt Bogerman]

Steve, does that advice apply to both dry and oil clutches, or would you go bigger for dry clutches? Or does it vary based on how any particular clutch is set up? My Jim Donovan Max Torque is dry and hooks up pretty tight ( he set it to engage around 5k RPM) and I had a hard time keeping momentum through that final hairpin into the straight past the starting grid. It was for this turn that I went with the 7.6:1 gearset, and I would have gone bigger, if I wasn't concerned about over-revving down the long straight. Technique through the last corner might have something to do with this, too, I suppose!

[Michael Drechnowicz]

I currently am running a 9-66 with both engines. I am not aiming to race and win, just have fun at the track.
Not planning on swapping gears at the track, what I come with is what I am going to run with. Just wanted to make sure I was not far off.

Michael