G16 running slow

[Jhall33]

We got a 97 Yamaha g16 and it used to run around 21mph. Turns out it was burning oil and seized up. I had the engine rebuilt here recently by a reputable mechanic. Once I got it back, with the governor bolt turned all the way in, with this fresh engine she is maxing out at 17 mph. I’m pretty disappointed with that! I ordered a K&N air filter for it, but regardless, anything I should look at to determine why it slowed down?

[rstacy]

21 is too fast for a stock car. No surprise that the engine gave out but I'm sure it tried until the end.
My guess is that the mechanic set the governor and cables properly which will limit your top end speed. The good news is that the fresh engine should last for many many years.

[Dave in VA]

Originally Posted by Jhall33

We got a 97 Yamaha g16 and it used to run around 21mph. Turns out it was burning oil and seized up. I had the engine rebuilt here recently by a reputable mechanic. Once I got it back, with the governor bolt turned all the way in, with this fresh engine she is maxing out at 17 mph. I’m pretty disappointed with that! I ordered a K&N air filter for it, but regardless, anything I should look at to determine why it slowed down?

Put the stock air filter assy back on if you've got it. There's no performance gain with the K&N to speak of, and you'll probably need to change jets in the carb to compensate for the increased air flow. Check compression and valve clearance. Valves .004 cold. Compression maybe 160?

With the governor turned all the way in, the cart should run in the 20's, without a problem. Running in the 20's isn't going hurt the cart, as long as you know how to govern with your right foot. A properly maintained G16 is hard to kill.

[smallblock450sl]

Maybe accelerator cable #2 got out of adjustment and is not opening the carb throttle shaft all the way?

[Jhall33]

I’ve read about two different governor adjustments around here. Using the long cable to just go throttle to carb OR the bypass involving drilling out the governor and what not (from the sticky). Would either be viable routes if one of the two cables are stretched?

[Jhall33]

With the K&N would the higher flow jets for the carb help out? That’s only like a $35 upgrade so just wondering. And it’s on 20” tires with 2 inch lift, I could probably go to 22 or 23 for a little speed, right? Still learning and reading a lot on this site.

[Dave in VA]

Originally Posted by smallblock450sl

Maybe accelerator cable #2 got out of adjustment and is not opening the carb throttle shaft all the way?

Check this^^. A K&N will not speed up the cart, and adding bigger tires just to increase speed isn't the way to go, either.

Drilling out the governor arm is the way to go IMO, and will give you a higher speed. It eliminates the land speed governor while maintaining both cables. Your right foot becomes the governor. There is no governor on the engine. Cranking the governor nut all the way in is the most used option vs drilling the arm, and the land speed governor is still in play.

A properly running G16 on 20" tires should be in the mid 20's mph range with the nut cranked all the way in. Go back to the mechanic who did the work if there's any question about the performance of the rebuild.

[slonomo]

I would not think your cable is stretched enough to cause an issue, but it should have enough adjustment to compensate for that.

There were some good suggestions here, cable adjustment, throttle plate open all the way?, governor modification, all good stuff. The stock air box setup is your best bet, provided it's not broken or torn. Basic things like spark plugs and carb adjustment can also make a difference.

What about the rest of the drive train? Clutches and belt can make a huge difference in speed. Comparing a cart with worn out clutches and belt with one that has new/good clutches and belt is like night and day. Definitely could be leaving 3-5 mph on the table there.

[sho305]

Larger tires will help a little but you should figure out what happened here first. Yes clutches and belt can affect speed, also if the engine was put back in and moved somehow, most factory mounts don't adjust but I would check it just the same. If the belt is tight that will slow it down, it needs some play at rest around 1.5 inch if pressing down on the top center of belt. Or the engine is not aligned properly.