First time post.

[Midian Yoshi]

Hello to all. Joined the forum sometime back, have found lots of useful info, this is great. I have some kart questions that I have not been able to find answers to. Where do I start?

 

[Poboy kartman]

Welcome to the forum.....Thanks for filling out a profile.....and.......ummmmmmmn.......how should I put this????

Ask the questions?????

 

[chancer]

Welcome what are your questions?

 

[Midian Yoshi]

First of all, thanks to the many posts on this forum, I have found what we are running for clutches is way wrong for the power we make. I say we, meaning my Shriners unit, Yoshi. We are a go Kart unit that routinely performs in parades around the state.
Current set up is a Briggs Animal, beyond stock form, Comet 30 Series Driver/7" Driven w/ Yellow Spring set to position #3. #35 chain-10T at Jackshaft/75T Sprocket. 6" Rims with 15x6 tires. Actual tire height measures 14 1/2" high.
My question: is this gear ratio excessive?
I was running a 10T/60T then to a 66T, looking for low-end launch. The 10T/75T combo launches like no other. But, it sounds like I have alot of engine braking when you drop off the throttle??

 

[chancer]

That is a long way from the Shriners "Tin Lizzie" Parade cars I am used to seeing. Way Cool! Usually 6:1 or 60 and 10 tooth is your standard best all around Ratio for Karting around. You can take off normally and get a decent top speed. I imagine you like the 7.5:1 for messing around during the Parade. So yes You are experiencing engine braking. The Kart accelerates fast and so do the Rpm. At 7.5:1 you will have a lower top speed and excellent launch. Sounds like everything you are doing is correct.

 

[OzFab]

it sounds like I have alot of engine braking when you drop off the throttle??

You get that with a low ratio; I can't explain why, it's all very technical but, you get the same thing with any vehicle, something to do with rotating mass & whatnot...

For low end launch, you're heading in the right direction...

Welcome to the forum...

 

[Midian Yoshi]

Great. I did sacrifice top speed. Although it was not much of a sacrifice, not alot of room to hit top speed during a parade. Now after the parade, that's when the Animals cut loose heading back to point A. The 6:1 and even 6.6:1 Ratio was great. I first went to 7:1 at the beginning of this season, which was a big difference. Now to the 7.5:1 and man what a launch. This is my 2nd year with Yoshi, and after losing the coveted Fastest on 4 Wheels run by .48 seconds last year, I am taking it this year in Golden Colorado. The course has a couple nice curves with a full 180 at the end then basically run it reverse back to the start. Low gearing is seeming to be my Ace. I posted a pdf of the course, or tried anyway. Not sure if it made it. Also another pic of the Kart.

 

[OzFab]

The low gearing will definitely help through the bends, you can push it a bit harder without the threat of "losing it"... which should help you close the half a second gap...

 

[chancer]

With the supped up motor you have described you should be able to really push the RPMs and still achieve a respectable top speed. I know there is some kind of tachometer that is sold on ebay like ten/fifteen bucks. Member kartfab knows about it. easy to install wrap a wire around the spark plug. If you go testing you can calculate your speed by RPM using this https://www.affordablegokarts.com/SpeedCalc.php. Then you can swap out gears 7:1 and 7.5:1 and see which will be best on that course. Figuring straightaway speeds0 to 100 feet vs. launch speeds etc. Hope this helps