RacerAlex.com

From Basket Case to Bitchin
By Mike Kojima @ MotoIQ.com

Lately the MotoIQ staff has been Karting a lot to get our speed fix for few bucks.  Running MotoIQ is an expensive endeavor and we have had to mostly give up racing cars for now to keep MotoIQ growing and strong. Looking for cheap used Kart parts on Craigslist one day, we happened upon an ad for what seemed like a lost cause.

 We thought that the kart was pretty rough and in poor condition but noticed that the engine looked pretty new.  Turning the crank by hand showed it to have good compression.  Basically we first bought the kart thinking it could be a source of spare parts for Christa’s race program but now its just too nice.  It is way too big for Christa to drive though!

There was an early 2000’s vintage CRG Heron kart for sale for the very tempting price of $300, super cheap for such a machine.  The ad stated that it didn’t run but for $300, the picture looked like it was complete, straight and equipped with an IAME HPV engine of some sort and a Mychron III electronic dash.  Well we figured, it was worth a look since Italian CRG karts have an excellent reputation, the kart was new enough so its technology would not be too out of date and the parts on the kart were worth way more than $300. Used HPV engines usually go for around $1000 if they are in decent shape for instance.  Worst case we could use the engine as a spare for Christa.

The main reason why we bought the Kart was for its Parilla IAME HPV-4 engine (no it does not stand for Human Papillomavirus Vaccine ).  The engine looked to be in pretty good shape compared to the rest of the Kart.  An HPV engine usually goes for around $1800-2000 dollars new and around $1000 used.  The differences between the HPV-4 engine and the HPV-1 used in Christa’s kart is a pipe tuned for more top end power and a larger WB3A Walbro carb.  The HPV-1 puts out around 8 hp and the HPV-4 puts out around 18 hp in stock form.

Checking the Kart out we found it to be very weathered but in OK shape, the frame was straight, by spinning the crank by hand, the engine had decent compression, but the brakes didn’t work.  The engine was an HPV-4, the most powerful variant of the venerable piston port two stroke IAME Parilla HPV engine range that pumps out 18-20 hp at around 16,000 rpm. The HPV race classes use a spec clutch and a spec pipe which we like because clutch and pipe tuning in other classes like the Yamaha KT100 classes are a major hassle and expense. The cool thing is the engine looked to be in good shape; it looked newer than the rest of the kart. The frame looked like it had been repainted in some parts with house paint. The steering wheel was oxidizing apart as was the old plastic bodywork, every part on the kart was rusted, especially the axle and fasteners but everything was there.  If anything we could use the kart for spare parts.

The other reason we bought the Kart was this Mychron electronic dash which was worth about the price of the Kart!

The owner told us he had bought the kart used a few years ago from a racer and had wanted to use it but could not figure out how to start it and had lost interest in it.  He pushed it out into the patio/back yard to rot and wanted to get rid of it as it was taking up too much room around his house.

The Walbro WB3A carburetor is a diaphragm pumper type that uses crankcase pressure pulses to pump the fuel.  It was hopelessly gummed up with old fuel and oil residue.  This was the reason why the engine would not run for the previous owner.  A good cleaning and an $18 rebuild kit make the engine a strong runner.  We added a foam filter from Empire Karts inside the airbox.

The expansion chamber used on the HPV-4 engine is a lot shorter than the one used on the restricted for kids, HPV-1 engine.  The shorted length means that the reflected wave is timed better for high rpm use.  Embee Performance coated our chamber with their satin black thermo barrier coating.  HPV racing classes do not allow the switching of chambers and all racers must use a spec chamber.  This eliminates a lot of expense due to pipe tuning like the Yamaha KT100 classes must have if you want to be competitive.  The flexible slip joints and spring mounts keep the pipe from cracking due to fierce two stroke vibrations.

Getting the kart home we decided to see if it could be made to run.  Spinning the engine with the starter proved that we had spark, but looking in the oxidized and crusty fuel tank confirmed that the fuel system was hopelessly gummed up.  Opening the master cylinder showed that the brake fluid had also turned into a gummy mess.  We did a little research and found that Acceleration Kart Racing in Las Vegas seemed to have the best selection and prices on CRG OEM parts so we gave them a call and found them to be quite friendly and helpful.

The HPV engine class rules state you must use this spec Horstman clutch.  The KT100 rules allow clutch tuning and this is a big part of being competitive.  The HPV rules don’t allow this and thus saves a lot of time and expense.  We broke the stock chain and ruined the sprockets so we replaced these parts with an Empire Karts sprocket and a more compact and lighter Top Kart sprocket carrier.  A gold DID roller chain is long lasting and low friction.

A few emails and some photo swapping identified our parts and a package with fuel line, a new fuel tank, caliper, master cylinder and carb rebuild parts arrived two days later.  We cleaned out, honed and rebuilt our brake system which was really quite easy and carefully cleaned and rebuilt our carb, changing our spark plug for good measure.  We bled the brake system with fresh Motul 660, freed the gummy axle bearings by soaking them with tri-flow, and filled the tank with some premix VP MS98 fuel blended with Motul Kart synthetic mixed at 30:1 and gave the starter a whirl.

The brake is a CRG twin piston with a floating vented iron rotor.  We rebuilt the caliper.  All of the silver parts on the Kart are billet magnesium and they were badly corroded and frozen to the bolts and bearings.  Magnesium is highly reactive and corrodes really easily.  We bead blasted them all and sent them to Embee for clear powder coating.  The rusted hardware was replaced with stainless allen bolts with trick nut retaining clips from Baller Bolts.  We straightened and polished the bent and rusty axle and cleaned, repacked and honed out the bearings.  Embee blasted and powder coated the frame which had been painted with latex house paint!

To our surprise, the HPV started instantly. Blipping the throttle, the engine was sharp and responsive.  We put air in the tires and blasted down the street, the thing was fast!  Apparently this was a fresh almost new engine and it didn’t run simply because it had sat and the fuel system gummed up with stale pre mix residue, a best case scenario.  The brakes also worked well now.

The master cylinder was full of gummy old brake fluid residue and white corrosion.  We cleaned and honed out the bore and rebuilt the old and dry seals.  The brakes now work really well. The adjustment rod was rusted solid and had to be replaced as well.