[William Martin]

Fuel dribbling out the lower fitting on the carb while starting? That sounds like too much pressure in the fuel system. I see there is a tiny vent in the fuel tank cap, likely not enough for the size of pumps used on shifter karts. Guessing your pump is a 52mm Mikuni, can’t see it in the pictures. Did you check the needle & seat carefully for any sign of wear? If it’s leaking, that could be part of your over-rich condition.

 

[William Martin]

Don’t know about an on-line parts source for this stuff, unless someone bought up the inventory from Wally Wallen’s shop. I have heard that a YZ125 piston is a very close match for the Pavesi piston, may have to play with cylinder base gasket thickness a little to get proper squish measurement. I guess that would not be a legal ICC engine, but probably no one cares any more.

 

[William Martin]

Manny,

That looks like a DIY version of the old “magic can” fuel system. The can is just a reservoir to simulate a gravity feed like on a bike. One thing that seems wrong about the carb plumbing: the line looped under the carb, from side to side, should go over the top of the carb, and have an air vent snipped in the center of the loop. The way it is now, there is no venting of the float bowl. Not sure what that bottom hose is about, never have seen one of those on a shifter engine carb.

 

[William Martin]

Wrong part of the country for me, but your suggestion is sensible and well presented. Well done!

bill

 

[William Martin]

When you want a slightly stiffer front end…or just want to use hub-mount wheels you might have lying about.

 

bill

 

[William Martin]

Not such popular stuff these days…maybe you could post some prices?

 

[William Martin]

You could also braze a sleeve around the break.

 

[William Martin]

The idea of being in front of a cell-phone happy suv driver makes me shudder!

 

[William Martin]

Nigel,

Intuition is not your friend here…it may look like a solid mount will keep everything together, but it won’t. Vibration will have all kinds of things flexing or trying to flex, but you need to absorb the vibration as best you can in order not to crack the pipe. The rubber isolator wins.

Bill

 

[William Martin]

Steve,

Does the rod look like it got really hot on the bottom end, blue discoloration of the metal? If so, it was too tight possibly not enough thrust washer clearance. That is suspect since you say you see pieces of thrust washer in strange places…

 

Bill

 

[William Martin]

Woah! there’s a blast from the past. :-)

 

[William Martin]

Is it always this unwatchable on the live feed? I took a look at a couple of the archived events, worked great. Once the live coverage started, I got nothing but delay, delay, delay… on the streaming. Uploading from a cell phone?

bill

 

[William Martin]

No, only karts with front brakes “require” dual master cylinders. Way better if front brakes were required on everything…

 

[William Martin]

You might try Comet karts, they often have some older stock on hand.

 

[William Martin]

King pin bearings are most likely 8mm ID, inline skate bearings fit nicely, or have for me. You can buy as much quality as you like with those…

Stub axle bearings are most likely 17mm ID, find an industrial bearing supplier for those. Take an old one with you when you go shopping, and don’t be afraid to get the equivalent size with “seals”, not shields, if you want them to last a long time.

The spacers are kind of unique, they are not plain washers, the little step on one side is there to keep them from dragging on the side of the king pin bearings.

Hope this a little helpful!

Bill M

[William Martin]

The front connection looks like a Heim joint, but the rear is maybe some kind of compressible thing. So if that’s the case, it’s tuning the front flex…I think. Like making the tubing stiffer in the waist area. Or something :-)

 

[William Martin]

That’s more like an “implosion”…parts flying together, not apart. I’m just in envy…wish I could put an engine together that fast!

-bill

[William Martin]

How about a picture of one that exploded? :-)

[William Martin]

along these lines of “specs” how does one tell the difference between a normal production crank/rod assembly and the “factory” parts?
-bill

[William Martin]

[quote quote=18449]I’m kinda in the same boat I just bought a kart and it looks like some minor surface rust on the axle and front hubs. Any suggestions to get that off?[/quote]

Wire brush or ScotchBrite scrubbing pads…plus elbow grease.

 

[William Martin]

Any update on recovery process? Hoping it’s looking positive!

 

[William Martin]

You need my top secret mini-JATO bottle…but I can’t tell you about it, it’s top secret you know…

[William Martin]

OMG! That is amazingly funny…used tires, anyone? Just one race day on them…. :-)

[William Martin]

Another simple thing to check: make sure your spark plug is not wet. If you stall with the throttle open, it’s possible to have a cylinder full of unfired mixture.

-bill

[William Martin]

Top end rebuild is straightforward…not necessarily “easy”, as it takes some care to get it right. You will want a flat plate with a slot in it to slide under the piston so you can pull it down to the plate, helping you not twist the connecting rod while you extract the wrist pin. You really need a pin puller, but it can be removed by heating the top of the piston with a propane torch until the pin can be pushed out with “very little” side force on the piston. Never force it…that’s how rods get bent. When you have the old piston removed, use it to push your new ring into the bore about a half inch down the bore. Measure the end gap of the ring (feeler gauge), make sure it is within the specs that should be on the paper that comes with your replacement piston/ring/pin kit. If it’s too tight you might have a ring “stick” when it gets hot. If you don’t have a tool to insert the new clips in the piston pin bore grooves, be really careful not to nick up the piston or shoot the clips off into space…it is tricky. Pay attention to the markings on the piston top so as to get the new one in pointing in the right direction. Put some of that gooey pre-lube oil on the wrist pin bearing prior to reassembly, as well as on the piston skirt. Keep everything very clean, including your fingers while you do this work! Put a non-fuzzy towel over the open top of the engine crankcase, no extra stuff wants to be falling in there. That’s all that comes to mind…if you already knew all this, apologies for boring you…if I left out anything important, someone should feel free to chime in here and add information.

Good Luck,

Bill

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