Kart having a problem, could use some help.

David Benson · Joined: 02 Apr 2012 Posts: 14

So my kart was running ok a week ago. Just seemed very rich. So I pulled the carb out, cleaned it, changed the jet to a 155 instead of a 160 since for weather conditions it seemed I was right on the edge of needing a 158 or 155 and I did not have a 158 jet. I cleaned the oil out of my airbox, cleaned the clutch housing (it had a little grease in it), lubed the chain, cleaned the RAVE, etc... Also of note, my friend tweaked the float level up a tiny amount. So tiny I could not see that it moved, but he says he moved it. And to get the thing to idle I had to completely tighten the slide stop screw thing and turn the idle air screw (I think that's what it is called) out like 4 full turns from closed.

Then this weekend rolls around and I am all excited to see if my carb work paid off. Start good, idles well, seems to run fine, but not really much better. Then I hit the front straight. 11,800 RPM it sounds like VTEC kicks in but all my power is gone and I can not accelerate past 11,900 RPM. That's weird, keep driving. Same thing happen going into the sweeper this time. Now every lap, it does this wherever I can get up to 11,800 RPM, it takes a dump. I pull it in, check the plug, it looks fine. Next session I change back to the 160 jet thinking maybe that was the issue. Exact same thing happens. And it doesn't appear to run any better or any worse. Bring it in. Changed to a new spark plug as it looked like it had been running rich for a while. I checked the plug gap before putting it in.

Now it gets weird. Kart dies going onto the track. I finally get it going again and now instead of 11,800 RPM, it is doing it at 11,400 RPM and I can't get past 11,700 by the end of the straight. All that changed was the spark plug. And to add even more oddity to it, Every time I hit a fast right hand turn that is immediately after a left hand turn, I would hit the throttle and the engine sounds like it is dead, like it loses spark or fuel or something. But once that fast turn is over, the engine comes back to life. It only happens on that one turn, but does it every lap.

I pull back into the pits to play with idle since now it won't idle as well with that bigger main jet (thought that had nothing to do with it...) and when I start it, I notice on constant drip of fuel coming out of the fuel pump. It looks like the fuel is coming out of the gasket rather than a hose. I talked to the guy in the kart shop at the track about my issues, the only thing he could think of is maybe the stuffing on the muffler. I pulled that out to check it and it is fine. I will buy new stuffing, and a new fuel pump. But as I am very new to this (2 test and tunes is all now) I really question if there is something else I need to investigate.

Shannon Schmidt · Posted: Mon May 21, 2012 8:34 am Post subject:

Dave,

Couple of initial thoughts on your issue:

1. Welcome to Rotax. They can be more moody that most women.
2. Don't worry about the motor idling. They don't need to. Use your foot to keep the motor running. They actually run better if they don't idle.
3. Change your fuel pump. Get a new one, not a kit. (did you run it after the new fuel pump?)
4. What did you use to clean the air filter? Don't lube it after you've cleaned it. The carb will self lube the filter. Most filter lubes actully clog the damn thing up.
5. Put your float setting back. Sounds like its flooding to me.

If you ever run into a problem with this motor, go back to how you had it when it ran well and start over.

Sounds like your buddy buggered up your carb.
_________________
Miller Motorsport Park
2006 Rotax Masters Champion
2007 Rotax Masters Runner-Up
2009 F200 Champion
Monza Z32C #7

"Don't brake till you see God!"
"A great racing driver has his head in communication with his balls." -Richie Evans

David Benson · Joined: 02 Apr 2012 Posts: 14

Shannon Schmidt · Posted: Mon May 21, 2012 9:21 am Post subject:

Dave,

I'd clean that air filter out also.
_________________
Miller Motorsport Park
2006 Rotax Masters Champion
2007 Rotax Masters Runner-Up
2009 F200 Champion
Monza Z32C #7

"Don't brake till you see God!"
"A great racing driver has his head in communication with his balls." -Richie Evans

Scott Falcone · Posted: Mon May 21, 2012 9:16 pm Post subject:

When is the last time you charged the battery?

Rotax batteries go bad and could cause these issues.

Check it with a voltage meter fully charged should
Be around 13.6- 13.8 or so anything under 12.5 is no good.

David Benson · Joined: 02 Apr 2012 Posts: 14

Ihor Bilyy · Posted: Tue May 22, 2012 7:59 am Post subject:

Were floats put back correctly?

David Benson · Joined: 02 Apr 2012 Posts: 14

Shannon Schmidt · Posted: Tue May 22, 2012 10:06 am Post subject:

Alta means top. Very easy mistake to make. Great point.
_________________
Miller Motorsport Park
2006 Rotax Masters Champion
2007 Rotax Masters Runner-Up
2009 F200 Champion
Monza Z32C #7

"Don't brake till you see God!"
"A great racing driver has his head in communication with his balls." -Richie Evans

Devin Smith · Joined: 08 Feb 2009 Posts: 87

It will not even run if you have the floats in backwards. Been there done that.

Marshall Martin · Posted: Wed May 23, 2012 3:06 am Post subject:

Check the Power Valve to make sure it is not sticking. You cleaned it and probably when you put it back in cocked it just enough so it is not free from the sides of the chamber it works in.
_________________
Marshall Martin
LSR Motorsports
www.lsrmotorsports.com

marshall@lsrmotorsports.com

David Benson · Joined: 02 Apr 2012 Posts: 14

Proper jet and fuel pump should be here today. So I will be heading out to the track to check floats and RAVE and give the kart a general douching and install new muffler matting. Probably clean the filter while I am at it.

Is it OK to use regular dish soap to clean the filter?

Shannon Schmidt · Posted: Wed May 23, 2012 2:34 pm Post subject:

Dish soap = good.

Also, you may have a cracked float. Check to see if they are full of fuel.
_________________
Miller Motorsport Park
2006 Rotax Masters Champion
2007 Rotax Masters Runner-Up
2009 F200 Champion
Monza Z32C #7

"Don't brake till you see God!"
"A great racing driver has his head in communication with his balls." -Richie Evans

David Benson · Joined: 02 Apr 2012 Posts: 14

Well, went out to the track. Cleaned the air filter, put in the 158 main jet, cleaned the rave, floats were fine, put the new fuel pump on, put new matting in the muffler. The thing starts up and idles and revs better than before. I was unable to drive it around though as they are getting the track ready for Superbike stuff and it would have been too late to actually get on track anyway. But I am optimistic that it will run better.One thing I noticed was that there is now no air in the fuel line. With the old fuel pump, their was always air pockets in the fuel line.

John Savage · Posted: Wed May 23, 2012 9:52 pm Post subject: