New to this now...

[David Hedderick]

A friend and I aquired a 01 CRG of some sort with a YZ125 motor. I've run it up and down the street and it seems to run as good as the old CR125 I ran last year in Mineral Wells at the Pro Solo so that's good. Feels solid and starts with a strap around the tire on the first pull.

The guy we got it from said he never touched or tuned anything because it always ran great for him...

Questions, since I don't know squat and I just want seat time should I just do the regular maitnance of new fluids and inspect for safety and go from there? Anything I should know?

Thanks and it's good to be back in a Kart.

Running a Boxster S in AS for this year and the next probably in national competition so I proably not build a motor till 09 at the earliest and just learn to drive till then. I'll be using the kart at practice days and on days when AS runs the morning groups.
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David Hedderick
Houston, TX
01 CRG Heron Plus YZ125
06 Jetta GLI (DD fun car)
02 Protege LX (kart tow vehicle)

[Bob Monday]

How much of a gambling man are you?

Find out what you can about he motor's maintenance history. Has it been run for 2 (or more!) years at several sprint tracks, track days, etc. with the same crank? When cranks (or more often, crank bearings) go, they do it all at once and result in a lot of damage. All the "trash" goes into the cylinder, bounces around a bit, catches on the exhaust ports as it tries to get out, and makes a mess of things. 2 years of sprint track racing on a crankshaft (rod, etc.) is the max even on a relatively stock engine. How modded is yours? More mods = more power = more maintenance. If nobody can provide you with maintenance history, assume the worst. It's less disappointing.

I run a CR125, but I'd assume that you can pull the cylinder off (at the base) to inspect the piston and ring. Replace the ring. If you don't know how to do that, get a book or an expert. (The Honda RS piston has an up/down side to the ring and a locator pin. Does the YZ?) If the piston looks bad, replace it too and be even more suspicious of the crankshaft bearing. Can you see any damage to the crankshaft bearing or tabs between the rollers when you have the cylinder off? Look up into the cylinder and see if it is smooth, or full of crud and divots. Lube (wipe on piston, ring and cylinder with fingers, maybe even drip some onto the crank bearing) with Marvel Mystery Oil before reassembly.

Check brake pads. Get a brake bleeder and completely replace the brake fluid, purging air/water (?) from the system. NAPA has affordable DOT4 fluid, but purge the lines well if replacing DOT3. Check the pivots on the brake bias adjuster and master cylinder actuators: they can wear. Disassemble and clean any axle bearing, front and rear, in a parts cleaner, lube, etc. Check for bearing noise after you lube again. Slightly loosen and then rotate the kingpin bolts watching for wobble. Make sure that they have e-clips on the bottom of them. Replace trans oil with whatever is recommended for that motor. Replace the chain and check the sprocket and axle gear(s) for wear. Make sure that the rear axle is straight. Align and corner weight the kart (bent frame? spindles? axles?) on scales at the kart shop. If possible, use aluminum alignment discs rather than tires when corner weighting since tire circumference (diameter) can vary. Adjust the seat as required for your weight and body proportions. Make sure that you are at legal weight while remembering that it's the scales at the track, not the shop, that count. Flush the cooling system and fill with distilled water and water wetter. Water and aluminum generally don't like each other, especially if other metals (like the water pump parts in a CR125) are present. Take all jets out of the carb and make sure that they are not blocked with crud. Check the float bowl for same. Make sure that you have a fuel filter in the line between tank and fuel pump. Make sure that there's no oil in the pulse line and that it drains back via gravity into the motor (no sags, pump higher than pulse port). Keep the pulse line as short as possible, and use line with stiff sidewall (you want the pump to take the pulse, not the line!). Remove and clean the fuel tank: water has a way of getting into the bottom of it and accumulating. Make sure all bolts are tight everywhere, everything safety wired or e-clipped that should be.

Autocross doesn't put a lot of wear on a kart and motor, but track days (as you get seat time) and former owners will. Preventive maintenance is a lot cheaper than repairs, and usually happen at a better time.

Bob

[David Hedderick]

Well the previous owner said the motor could probably use a piston ring. As for how much it's been run, in the last 2 years it was started every few weeks to keep it running good.

Its got all new water and WW in the radiator and I'll be blushing the brake fluid this week. Also, I'd like to replace the gearbox oil. I assume the local kart shops have something adequate.

I have an autocross practice coming up soon in a couple saturdays and I'd like to do a shakedown there.

The previous owner is a friend that I trust was good to it. He said they ran it at a few track events each year.
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David Hedderick
Houston, TX
01 CRG Heron Plus YZ125
06 Jetta GLI (DD fun car)
02 Protege LX (kart tow vehicle)

[Bob Monday]

Or.. yeah, you could just do that.

Bob

[Nathan Fowler]

I'd highly suggest that you follow Bob's advice. Kart motors are not toasters, they will explode (sometimes literally) and cost you more in the end than a little preventative maintenance up front. Oh, and the engines aren't on dirt bikes anymore so you can't follow the same maintenance intervals or jet it the same as the dirt diggers.
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#96 - 2000 Trackmagic Demon / Stock Honda

[richard watson]

David,

We have a growing F-125 class here in San Antonio (4 karts). We will be making the Houston Tour and the SW Divisionals, some SPOKES events in Austin and if you feel like the drive, our local event schedule is at www.sasportscar.com. We all have Hondas, so I cant comment on the Yamaha specifically, but I change the piston once a year (autocross and sprint racing), the ring twice a year, and plan on changing the crank at a year and a half.

Richard

2007 SASCA President

[Bob Monday]

I just felt like the time to make sure that things are as right as possible is from the beginning.

When we get new toys, especially when it's getting warmer out (80 degrees in Indy today!), we want to get on track. I did that last year and started out with little maintenance. It plagued me until half-way through the summer when I finally did what I should have been doing all winter, and I ended up with a lot of extra maintenance (including a cracked cylinder and overheating) that wasted a lot of good days!

You can't learn to drive a poorly handling kart. It's wasted time. Take the time and money to set it up properly with the help available NOW (it's not so much during racing season) and go out prepared to do well.

Good luck!

Bob

[Daniel Morency]

There is nothing more frustrating than problems when at an event. My whole family autocrosses clutch karts here in Maine... Our season starts the end of April so my to do list starting next week is to put each of my three karts up on the stand and go through them just as Bob has indicated. It's so easy and enjoyable I might add to work your way from front to back on a kart in the garage listening to classic rock!

It is frustating as all getout to have a problem at the event when you paid for an adrenaline rush and end up with sweaty, greasy hands and broken parts....

Follow Bob's advice and do it right, it couyld save you tons of greif! Keep your fingers crossed and maybe you only need to purchase a few gaskets and a set of rings... If not smile and be thankful that you checked before it blows up....

And yes I have blown one up at an event. Luckily I had my wife there and we finished our runs in DS in my sweet 67,000 mile BMW 325IC

Luckily it was my kart and not my sons or daughter's since they can't drive the BMW yet!

Dan