I have written several comments on this topic in the past, but I think it bears a repeat, because there are two possible reasons why your clutch is smoking. I usually look at one of the most likely reasons, but in this article let’s talk about the two possible causes of your go kart’s clutch smoking.

First you need the fundamental understanding of karts.. The driveline usually consists of a clutch driver and the sprocket of the driven shaft. The drive shaft sprocket is mounted directly to the rear drive shaft which turns the drive wheels. This is a one step system, or a one ratio system.

The centrifugal clutch used in most go-karts uses weights that are mounted internally to the clutch that are thrown out and pressed against the clutch bell. The bell housing, in turn, moves the teeth of the sprocket drive sprocket.

The typical clutch has 10 to 12 sprocket teeth. As a general rule of thumb, any clutch that has more than 10 to 12 sprocket teeth will cause driveline problems. Problems like in smoking clutch.

Engagement of the weights to the clutch bell occurs at a certain rpm. Usually these rpm are around 1800 to 2000 rpm. The engine needs to get above this rpm level and cause the clutch pack to stick and eventually hook to the walls of the clutch housing. The smoky look occurs when the clutch engages but does not fully engage. If prolonged engagement occurs for too long the clutch will start to smoke and eventually damage it until the weights just slip and perhaps even crack and break.

As I said at the beginning of the article.Long commit occurs due to two possible reasons:

1.) The engine is not powerful enough to pass the engagement stage

2.) Clutch weight rpm not high enough.

The engine is not powerful it is usually the result of a mismatch in the proportions of the rear drive wheels. So the real reason is that the ratio is not steep enough and therefore the engine smokes the clutch.

(Another possible problem can occur and that is if the clutch is made to engage at less rpm than the engine can achieve, the engine may not have enough power, and the engine will suddenly (more like violently) shudder and it will stop. It is not uncommon for the motor to have so much power that it spins backwards momentarily).

The second way the clutch will smoke. It is if the clutch rpm never reaches engage speed, or is close to engage speed, but not high enough above engage speed to get a lockup. This will smoke the clutch and is prevalent in mismatched output shaft systems.

The remedy for the first smoking clutch. The problem is altering the driveline so the overall ratio is steeper. The simple method is to increase the diameter of the rear sprocket. Programs have been written that will estimate whether or not your clutch will smoke, usually found on websites or available for purchase through various websites. Usually what happens is that the hp ratio simply won’t be possible using the simple system of a ratio. Therefore, a jack shaft must be added to make the ratio even more pronounced. In other words, making it a two-proportion system.

This is where the guys installing jackshafts need to keep in mind. Usually the clutch cannot be placed on the output shaft drive, with a forward ratio. This will cause the clutch to spin too slowly, even though the overall ratio is correct. Therefore, the clutch engagement rpm must be taken into account; otherwise the clutch will smoke at the secondary intermediate shaft mounting position.

The bottom line is if the clutch does not engage due to too little power or too slow clutch speed, then the system must be changed by altering the ratios behind the clutch or ahead of the clutch.