Rpm & Fuel Issues (New Guy)

Very cool. Is this street race new or been around?

Been around a long time. Ran as part of the Clyde fair.

Check your float!
We have experienced issues similar to what you describe from a float sticking twice now. Once when we first started karting, the kart would lose power at the top end of straights during practice session. The other cost us a couple rounds at TSRS Amarillo this summer, the kart would lose power and even die out. Both occasions, the kart tested fine on the stand, but under load would fuel starve. Float was sticking both times.
1st one was the float drop tab was binding and preventing the float coming up at the end of long straights. The motor was actually flooding out when the driver lifted at corner entry. Bent the tab and reduced the float drop a little, float stop sticking at the bottom of the drop. If you look close at the post and tab, you can see how excessive drop could cause this.
2nd one was a slightly twisted float that made the floats not drop properly in left hand turns. The track happened to have some high load on power lefts, so the kart would fuel starve and die in the lefts. Took a penalty and put a whole new carb on at the race. Got home and diagnosed the twisted floats. Only thing we can figure is that I somehow did it putting the bowl back on after post qualifying tech inspection, because it ran fine before that?

Check to make sure your catch can has proper ventilation as well.


^^ Heres your winner. I would bet $1.73 that this is the problem


19 driver of course would be a much higher (taller) ratio and exacerbate whatever issue you have.

+1 on checking floats and catch can (Thought we said already) as I had the exact same issue with a brand new carb only a couple of weeks ago. Although my symptoms were more a long pause in power delivery when getting back on the power and less about a loss of top end power. In my case the needle itself seemed to be catching it’s housing just a slight amount. I exercised it by hand with some WD40 in there, cleaned it with carb cleaner and sent it down the road.


Yep! This is the Sunday main event at the Clyde Fair. this is the 31st year. The track has one long straight and the famous/infamous ‘Shitcane’ to slow the karts at the end of the back straight, the site of an epic party. 206 drivers will hit ~60 mph on the front straight. @Caleb_Schindler, fwiw the guy who organizes the race suggested a 17 or 18 tooth driver and a 63 or 64 tooth axle sprocket. As always, YMMV.
Below is my son Conor (the 0 kart) navigating the ‘Shitcane’ when we raced there last year.


I know you said YMMV but 18:63 (3.556) is 53 MPH at 6050 RPM (Leaving 50RPM to stay off the limiter if that works for the track, leaves about .5MPH on the table)

If the karts are truly hitting 60 in the draft by the finals, you’d need to be at 3.120, which is somewhere around 20:63 or 21:66

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Fair point. I didn’t do the math, I was going on what I was told. My guess is the fast 206 guys (two of which cleaned up at the Elkhart GP) will be approaching that speed since they seem to be operating in a different universe. We mere mortals will probably be closer to what you calculated.

18/56 puts you at 3.11 ratio

Yes but only possible with 35 chain of course. (The specific rear sprocket, not the ratio)
I was trying to accommodate both 219 and 35 pitches.

Not true. I’m running a 15/56 219 right now.

This might be my inexperience showing. If I don’t have the optimal drive ratio 17/18 to 63/64 (anywhere between 3.5 & 3.7 ratio), can I swap this for a smaller drive / output and achieve the same ratio (ie 15/54 = 3.6)?

Edit: Im running 35 chain

Know that you mention the Shitcane, I remember this. Have a grand old time and don’t collect too many hay bales!

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You can change the front or rear sprockets to meet the ratio. There are some limits in sizes of course.

How are you getting a 56t on a carrier? Smallest I’ve been able to get was around 62 from memory and at that the chain was riding on the carrier.

I switched over to Sharp mini gears.

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OK that’s good to know… but I’d say about 99.997% of people are running regular carriers.

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So I figure this is a good place to remind those in the Ohio-Indiana-Michigan-Pennsylvania area and beyond to come to Clyde and enjoy the fun this Sunday! I know they’re still accepting entries. @Caleb_Schindler look us up at Clyde! We’ll be easy to find… look for the flags!

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Gear ratios won’t change the load on the engine. If the engine can make x lb-ft of torque at a given rpm, it will do so every time you floor it, whatever your gear ratio is. Different ratios will change the amount of time the engine spends at an rpm and rpm ranges but it won’t change the load on the engine at a given rpm.

Now, if you are traction limited, a bigger rear gear can mean more slip, but even then the engine will deploy all its torque it can. That torque that didn’t make it to the ground just then turns into flywheel and crankshaft inertia.

Im not seeing anything that speaks to load on the engine with respect to gearing changes? :man_shrugging: