Home Forums 2-Cycle Racing KT100 can vs pipe -50-60lb weight advantage for can, what to choose?

This topic contains 8 replies, has 5 voices, and was last updated by  patrick hubbell 1 year, 9 months ago.

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  • #76707

    Caleb Gilbert

    The rules for the KT100 around these parts (Northern California F100) have have minimum weight limits of 300lbs for kart and driver if 4-hole can, and a 360lbs minimum weight limit for a Formula-Y (direct drive) pipe. Considering that I can almost meet the minimum weight for can, I’m wondering if it’s actually possible that I’d have outright faster lap times with the can than suffering the 55 or so additional pounds and mounting the pipe (which I’ve already bought, fwiw). It’s would be quite a bit of work and money to test this as I don’t currently have any weights handy to add, so I thought I’d get opinion here as to whether a pipe with that much weight would still be faster than a can. The track this will mostly be raced on is .44 miles with 11 turns – mostly low to medium speed corners and not many long straights. Thanks!

  • #76730

    Will McDonough

    Hi there.  I am running a direct drive kart on a 3/8 mile track with 7 turns.  The gearing on my kart is 10/93.  And this kart will spin the tires coming out of the hairpin.  It has plenty of power.  Its all about the driver on a direct drive kart.  Direct drives love a lot of fuel so you have to constantly keep adjusting the carb to give it some more.  If you are a newbie clutch will be a lot easier to drive.  But direct drive will be faster even with more weight.

    • #88675

      patrick hubbell

      I would go with the pipe. A good RLV A2, you will have more fun when the clutch locks at 10,000 rpm. The non-sense that a pipe will cause increased engine wear is not true at least in my experience.

      The can mufflers have a couple of problems. First there is a baffle plate inside the can. Notorious for cracking. A cracked inner plate is a DQ. Two, They don’t help to scavenge the exhaust gasses. Because they don’t help to evacuate the gasses they have a tendency to load up with fuel making it difficult to start the next time your on the grid.

      The expansion chamber(pipe) helps scavenge the exhaust gasses. Yes there is more maintenance. You will need a good clutch too. I prefer the L&T 3 disc 4 spring or 6 spring.


  • #76731

    Caleb Gilbert

    Sorry, Will – I guess my wording was confusing, but my kart is a clutch kart it just uses the Formula-Y pipe (which is the direct drive pipe re-named by RLV I guess). I’m just wondering if a pipe exhaust is so much faster than a 4-hole can that it’s worth suffering 50-60lbs for it.

  • #77010

    Walt Gifford

    My experience is that the heavier more powerful kart will have an advantage at top end only. The game is to hold everyone off with tricky driving then get a good run onto the straight where you will pass everybody after you hit the main jet. If your track is all tight and you have to gear low you’re in for a real hurky jerky ride.

    If you can make the lower weight I would go for it. 4 hole @ 300# would be faster most of the track depending on the lay out plus easier to get back on the kart stand. Just keep the throttle open, keep the fire burning and smoothly drive around the track with great precision. Keep to the inside coming off the straight.

    We had a class with 4 different set ups, 2 different engines. Yamaha 4 hole was winning and they kept adding weight to it until it got to 390# then everybody quit. Combined classes are not good because you get the Jeff Gorden effect. Jeffs Chevy goes fast so penalize all Chevys.


    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

  • #77015

    Caleb Gilbert

    Couldn’t ask for a better explanation of what to expect than that Walt, thanks. I started doing some calculating on the information I could find regarding weight and it’s effect on lap times and it seems like on this particular short and tight track that at best it’d be a wash between the pipe and the can, which is pretty much what you’re pointing to as well. Then it becomes which is the simpler solution and obviously just keeping the can, not having to buy and place the weights and then adjust my setup for the new weight is so much more simple.

    That said, I wanted to get that darn soup can off the back of my kart *so* badly! lol

    I’ve enjoyed having the KT100 for getting my start with 4 wheels and think I would have gotten in trouble a few times in something faster, but now that I’m adjusting I also miss my 2 wheel days where there was no such thing as adding weight, and rider skill was so much more important than horsepower, that horsepower to a large extent didn’t really matter much (within limits of course, but it is a regular sight to see a fast rider on a small horsepower bike leaving everyone else in the dust just because *they* were quick). I image the same thing could be said of 125 shifter karts (and beyond) as well.

    • #77460

      Aaron Hachmeister

      Do you mean the RLV SR-Y pipe? I don’t have experience with the Formula Y, but a SR-Y was designed to give the senior Yamaha karts a speed advantage over the junior classes, which were about 50 pounds lighter. If the two pipes are comparable, you’d likely be faster in the pipe than a can

  • #77492

    Caleb Gilbert

    Thanks for that feedback Aaron, that makes sense and more food for thought. The SR-Y is a different pipe than Formula Y, with different characteristics. Based on looking at several photos and the description at this site http://www.out2win.com/catalog/2exhaust.html which includes the words ‘direct drive’ in for the Formula Y pipe – I believe “Formula Y” was just a new name RLV gave the same pipe they’ve been making for a while. Possibly because many people are actually using it with a clutch. So I’m guessing the Formula Y pipe gives a lot more low end power curve, and the SR-Y a top end curve.

    • #77653

      Aaron Hachmeister

      I just saw a version on the RLV website, I see how they’re different now. Perhaps if you email RLV you can ask about the differences between the Formula-Y pipe and a can to see what they think would go better

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