Talked to Robert over at kartoramainc.com (they seemed to have a bunch of Tomar parts). He helped me find the rebuild components I need - now the clutch seems to work great. However, I couldn’t find any dimensional schematics for where this clutch should set the springs at. I measured about .040" before taking it apart and set it at that for the rebuild - but seems to not catch soon enough. Is it a matter of tightening the spring bolts to bring it in?
I also got a carb rebuild kit from Robert and now she runs much better, but still bogs at anything greater than 3/4 throttle. Messed with the slow speed needle a bit, but not much changes (runs decent at 2 turns out).
Lastly, I just noticed there may be bolts missing from this center bearing - is this anticipated?
While the low speed is often the go-to adjustment, especially on the track, you may have to slightly adjust the high speed to account for what is happening. I always would suggest going richer (out) first as leaning could end badly.
As for the clutch, adjusting the springs adjusts the engagement RPM. With the KT they like to rev so it will rev to 8-10k before fully engaging. The tighter the spring (turn in clockwise) the higher the rpms will go before engagement. With a caliper try to adjust them all about the same. These motors don’t have much torque so you do want the revs.
8-9k on a can motor, 10-11k on the big pipe, can’t remember what we ran on the Y or SSY or SSR or whatever that latest pipe was that WKA tried. I think it was in between.
Depends on the clutch a bit too. The dry clutch on the big pipe slipped and heat soaked more easily so we generally ran less engagement RPM than the wet clutches.
I never really liked driving that big pipe. What an audibly annoying motor package; sounded like a CVT. 20 of those things shooting off the grid was like nails on a chalkboard.
Thanks for the clutch details - I was going the wrong way with the adjustment. I’ll also try making the high speed needle richer and give that a shot (havent touched it yet).
You guys aren’t kidding, this thing sounds insanely loud. Almost like a 500cc’s little annoying brother.
Tires - typically 12-20psi is run with kart tires in the dry. Start at 14-or 15.
Anything else…well we could write a book. My main suggestion would be to make sure you preserve the motor. Too lean and your day is over. I’ve never tuned with alcohol but on gas run it rich. Basically, start at 2 turns on the t handle and go a little richer first time out. You want to hear it “4cycle” meaning its to rich and not firing every revolution then lean it a small amount at a time till it doesn’t 4 cycle on the longest straight.
Bob,
Just in case, describe what 4-stroking feels like to driver so he can understand. I’ve been in a kart that was doing that and Mike hopped in, (100cc vortex) twiddled the needles while driving angrily in circles, and fixed it. My description below is not good.
No idea how he fixed it. However, the 4-stroking felt like the two stroke engine was stuck and couldn’t open up the top end. So, you’d get through the midrange and it would hang there.
Yeah that is about it, especially if it is really too rich. You can feel it and with a pipe you can certainly hear it, maybe not as much with a can exhaust. Another term sometimes used is its “fat” meaning rich on fuel.
James & TJ are a wealth of information, the faster you listen to them, the better off you’ll be. If you discount their input, it will cost you time and money. You will not find anyone better in the game at getting people get started.
Took everyone’s advice and applied it last night - everything went great! Kart ran good, went 5 sessions with no issues thanks to everyone’s help. They put me in with the Rotax’s, which wasn’t too fun being so much slower - but still great to be out there. I got many “looks” when entering the track - maybe because its so freaking loud? Also got a lot of “haven’t seen those in 10 years”, haha.
One of the seasoned guys said my frame was unique in that it has 2 side frame rails - he had never seen one in person before last night.
Can’t thank you all enough! I wouldn’t mind taking it out again for fun, but I may keep this around for a friend and maybe grab a Rotax cart in the future.
If you get a pipe on the KT you’ll be able to play with some of the Rotax’s. But there’s no doubt that a Rotax is going to last longer between services.
Dual rail on the left of the chassis used to be more common alright, often with a pinch bolt between those two rails.
the SR-Y pipe (WKA’s spec pipe near the end of Yamaha’s popularity)
or the Formula Y pipe. Can’t find a pic of this one.
With the L2 you can run more RPM and slip the clutch higher and make more power. It is a bit more sensitive to carb setup though, and easier to blow up. The SR-Y pipe that WKA used is a bit less tedious but IIRC not as fast as the L2.
I didn’t enjoy driving the L2 as it was super loud and the clutch slipped at like 10k RPM as I noted in an earlier post, but we did pretty good in that class. I won a regional championship or two I think, and had success up front nationally as well. This was the top-tier Yamaha class at the time and had really strong fields.
TJ, you are a wealth of information! Looks like I need to take quite a bit into consideration if I choose to upgrade the pipe - I’ll keep a lookout for some used ones!
Also, here is one of the only pics I got. I came with a friend, he rented the kart directly in front of me. In the beginning he was lapping me more than 6 times a session, by the end it was down to just two.
