4 cycle engine, 2 cycle chassis, clearance issues

Adrian_Kmita · July 13, 2023, 5:46am

Hi all, new to this forum! A decade back I was a little reckless, and I bought a chassis without doing any research beforehand and it’s been in storage since. Never done karting, and decided a 4-stroke is the best option for me. After some research, I realized that I had purchased a chassis meant for a 2-stroke…

I came up with 2 options, I’d like to know if I’m on the right track with this, or if I’m completely out of my mind, again my karting knowledge is limited. From my understanding, I can’t have a briggs 206 engine with the sprocket and clutch outboard as it is now (kart will go backwards).

move the sprocket inboard, but I only got 6.5 inches of clearance. I could only fit a smaller sprocket (219 chain, 63t sprocket will BARELY clear the crossbar). This would seriously limit my range of gear ratios.
get a more expensive mount with a jackshaft, and keep the sprocket outboard, as it was with a 2- stroke. Not sure if this is a common thing to do, or how it will affect performance and maintenance.
buy a chassis designed for a 4-stroke engine, this is something I’m trying to avoid

My goals are to get this thing on the track a few times a year (senior karting class) and be “somewhat” in line with the competition. Also, I’ve never done anything besides public karting yet, my mechanical know-how is half-decent at best. Any suggestions would be super helpful!

CrocIndy · July 13, 2023, 5:53am

Use Rocket Sprocket, PMC, or Smoker Performance Mini Gears

fatboy1dh · July 13, 2023, 12:24pm

Burpo is right, for what you are doing, some mini gears would be the cheapest/easiest solution.

Shop around for price, but this is what he is referring to:

https://cometkartsales.com/-35-and-219-Mini-Sprockets-for-inboard-drive/

Adrian_Kmita · July 13, 2023, 4:22pm

thanks guys, think I’m gonna go with rocket sprocket, for #35 chain, somewhere between 38 and 50 tooth should will clear the crossbar. This still limits my options for gearing but, assuming 11t clutch, I should be able to go almost up to 5:1, down to about 3:1. think this might be an issue?

Jim_Johnstone · July 13, 2023, 4:44pm

We race on a relatively short and tight track, and we havrnt ever gotten close to needing a 5:1 gear. You should be fine with that range.

Adrian_Kmita · July 15, 2023, 3:37am

thanks for the input !! Honestly hard to believe I might live my childhood dream of racing, looks like I need a mount, measurements averaged out to 31.75 and 88.5, which seems out of the ordinary to me. I’ll take a wild guess and say it’s a 32 / 88mm chassis. All mounts except odenthal seem to have 92mm rail spacing, I know odenthal mounts are great but can’t seem to find any alternatives to it, maybe one of you guys know?

Jim_Johnstone · July 15, 2023, 4:08am

What brand is the chassis? I’d wager it’s probably supposed to be 90mm spacing, which is used by CRG and their variants.

Adrian_Kmita · July 15, 2023, 4:19am

was told it’s a margay, and it has margay branded axle bearing holders. No serial numbers that I can see, and haven’t found one that looks like it anywhere online.

CrocIndy · July 16, 2023, 1:05am

Margay will be 1 1/4" rail in this case.

You can use a cheap PMI mount with International spacing if a normal i32 or k32 clamp won’t work.

Serial number may be inside one of the spindle Cs

Adrian_Kmita · July 22, 2023, 2:22am

UPDATE: got a rocket sprocket installed on the axle, had to remove the axle and grind down the keyway just a hair, got a snug fit now. I got a PMI mount from a local shop, but turns out 8deg angle will make the motor collide with the tire so now waiting to exchange it next week. rocket sprocket clears the crossbar just fine, thanks guys!!