J-Madd

Carb slides could be in backwards. It'll run like crap until it cleans out (about 3rd or 4th gear) then start pulling.

That's what I did. After I cold seized my cub back in January, I was fed up and boxed it up and sent it to Jeff. As mentioned, I felt safe knowing everything was checked out and a pressure test was performed. I've been having problems w/my YFZ motor(s) and got pissed and finally took then entire 4 wheeler to a shop and said FIX IT AND MAKE IT FAST!! I can work on things my self, but I get frustrated pretty easy, and probably drink too much beer putting things back together. LOL :yelrotflmao:

I saw a dyno chart from Klotz that showed a significant increase in horsepower over VP with the same claimed octane level, on the same engine just minutes apart. I know a Klotz distributer and his cost on the gas is almost $100 higher than the retail price for my last drum of 112. BTW I bought a drum of 108 Klotz.

I know this is old, but I have an important update: Even though I've sync'd the carbs a million times, that was the problem. The cable is in some kind of bind, though I don't SEE a bind. I can hold the throttle about 1/2 open and barely tap it some more and 1 slide will barely move, and the other won't. Once each slide is raised, both should always move at the exact same time, regardless of whether they're actually in sinc, right? I wonder if the spring tension could be higher in one carb??????? Anyway, I just have to re-sync my carbs several times a day while riding. They won't stay. The carb tops and cable holders are tight. It runs a hell of a lot better now. Ju

Thanks for all the info! :beer:

Gotcha. It runs cool enough now. I'll stay w/112 or 110. Thanks.

I've been running 112, but my drum is empty. I've got a friend that sells 118. Is there any added benefit at all to running 118 if it's running fine on 112. Mods are in my sig. Compression and elevation are about 160 psi and 300ft, respectively.

I forgot to mention that it smokes more out of the RIGHT when I give it gas in neutral. When it warms up, I can't tell b/c it barely smokes at all. If I had an air leak, I'd think it would smoke less, but I'm not ruling that out. Could it be an air leak on the LEFT SIDE and my pilots are too rich for the right side, but the LEFT is compensating with the air leak?? Just a crazy thought.

UPDATE: I changed the 48 pilots to 52s (couldn't find my 50s). It idles now, but that didn't fix the problem. However, by the end of the day Sunday both cylinders seemed to be acting normal, but my hydraulic clutch lost all pressure...............don't know what's up with that yet. At first I could pump it up and get it to work, then it finally quit all together.

Here's a list: Change plugs Unplug TORS Check choke tube Unplug parking brake Swap plug wires left to right Clean carbs thoroughly Check Compression in both cylinders Check for air leaks Check these things in that order until you find the problem. Good luck.

Mine is shaved 0.020 And I have around 145 psi, +4 or 5 timing and run 93 octane. Runs great. This same stock crank has, in the past, had a top end with aound 180 psi for a while also.

As for your idle issue: you can adjust it on the throttle cable at the thumb throttle.

What FMFs? Fattys, SSTs, Gnarlys? 220 Mains are too lean for any pipe and K&N w/no lid unless your elevation is way up there. What's the temp and elevation? You have to check the (fresh) plugs after a WOT 6th gear run to read them.

RMATV sells them. If there out of stock try Fulllerton Sand Sports. I bought the same tires from them a couple months ago., but mine were 10 paddle.

Unplug the TORS. Black box under left side of gas tank.

iI'm at a loss on this one. I've got an active thread now about an annoying right cylinder issue on mine that has no answer. Ya could try replacing the plugs and gapping them both to 0.020 inches.

FMF SSTs are good MX pipes. Good throttle response and midrange, but fall off a little sooner than T5s.

I'd check the reeds in that cylinder.

I would like to ad, on the motor that I've seen w/this problem. It persisted for a little while even after we ringed it and replaced the gaskets. We tried to blow all of the water out of the case as best we could, but some moisture remained. We finally got it cleaned out, just stayed on the gas until it cleared up. Good luck!!

I'm pretty sure I've used a half link in a 520 chain on a blaster years ago. But I've also heard bad things about using them.

I agree. The difference in an old corroded cable and a new one is very noticeable. Another option would be the Magura hydraulic cable. I have on w/ all HD springs and love it. Kinda pricey, though.

Blown head gasket or base gasket could let a little water in the cylinder, just enough to cause that problem. The water will bead up on the end of the plug, though, and you haven't mentioned that. If that's not the problem, I'd borrow another carb and try it. I worked on one that we couldn't get a cylinder to run. We cleaned the carbs w/no change. I finally gave him one of my spares and it fired right up. There is no chance your problem is electrical, though.

Richening your gas/oil mix will lean out your jetting a tad. 188 main seems huge. I run 175s in my Cub w/the same carbs, but maybe I'm a little lean.

I have actually swapped entire CARBS left to right, but at this point I'll try anything. Plugs are NGK br8eix (iridium) gapped at approximately 0.020. They were at 0.018 and I gapped them the next size feeler gauge..I could only find my metric gauges and didn't calculate the inch to mm conversion. I think it might have been 0.5 mm, not sure.

I'd guess the temperature had dropped and maybe the needle clip needs to be richened.