I added in a ridge in the intake to stop the piston rocking.
I left the bottom of the sleeve in place till after honing to stop the
I have a very good boring system so I only needed to remove 0.04 mm to get a
good honed finish.
The sandpaper hone was precision turned and I can adjust each side to make
sure it is parallel or correct for any taper in the bore. It is very slow so I
removed some material with the stone hone but there are points in the cylinder
where it rattled, so i went on either side of the bad spots and then cleaned
it up with the sandpaper hone (80 Grit paper). I did this a few times to keet
it all true.
I've looked through a few posts and I cant really see one specifically for this. Piston/Sleeve wear. This is in a KR150 CC 2 Stroke Kawasaki. 1989-2007
I'm at a loose end here. Both KR150s exhibit the same wear patterns after an hour or less of racing.
Bike 1 new pistons (x2) in the original coated bore with a loose fit but within spec
Bike 2 new piston in a new cast iron bore with new tight (correct 0.05mm) fit.
Bottom of pistons shows no signs of overheating underneath the piston crown.
Bike 2 also had a really serious deep score mark where the rings ends meet.
Bike 1 uses TTS and bike 2 uses Spectro Platinum XS. Both bikes are using the standard auto lube system.
New bearings, conrod and crank seals in both motors. The first worn piston was from the original motor, seals etc.
The original bike had 40K on the clock and the piston and bore looked ok. As these are still running the standard ignition, ie no retard at max RPM, (I think) could it be that this is causing the overheating issue when used as a race bike and max RPM most of the time?
PS this is at Ruapuna full track so they are being given a good workout. 3.6km track with an average speed of 100 kph.
You could probably use a better curvature on the tops & bottoms of the exhaust port. The port width does appear a little excessive.
A skosh more skirt clearance might be in order; perhaps closer to .006mm. Maybe converting to a good grade of (Bean) Castor ol mix.
Back in the old days; there was a brand of (Green Label) castor oil which only used 4oz. per gallon of alcohol. Everything ran clean & slick. Only problem is with castor oil the carb must be drained after each days ride.
I don't have my close-up glasses on, but I'll ask do you think you have sufficient ring end gap, side clearance, and back clearance? In outboard racing I ran into a set of factory racing pistons (Mercury, in the 1970s) that had the side-clearance (ring-to-groove) so tight that the ring dragged in the groove. Graham Bell's 2-stroke guidebook isn't infallible, but his assertion that you can't trust ANY new part that you haven't completely miked yourself is right on the money.
I think Tice has stated this before, but filing the rings for a little more end-gap, even on a one-ring piston, is a good safety factor and doesn't effect performance. This is argued all the time, so nobody has to believe it, but back when John was a handsome young lad racing his kart, McCullogh Corp., maker of tens of thousands of 2-stroke kart engines, dyno tested one of their motors with no changes other than increasing the ring end-gap. They didn't start seeing significant power losses until they were at around a tenth of an inch gap. This was a two-ring engine, so I wouldn't go anywhere near that much gap, but you see the point.
The 60’s & 70’s were the Wild West for 2 strokes. Converting from cross to loop scavenging. I’d truly love to bring the Mac times back again. They were first starting to use tuned pipes on the new Italian Sieta engines, the first time I’d seen a slide valve carb on a Kart engine.
This brings up another subject, How about using a pumper carb on a Quad? They work great and have been ignored over the years. Smitty& I are the old farts who’d seen most all of the changes.
Maybe in the next life, we can do it over again.
Talking specifically for the LT500, Lectron carbs are semi popular for the drag racing crowd (about as popular as the LT500/Quadzilla itself ). For a wide open application (drag racing) they are great and easy to tune, but they are not that great running in a dune environment... IMO.
I had a Lectron 44mm carb when I built my Quadzilla back in 2010. I had nothing but problems that took about a year to solve. My quad felt like it was draining the carb bowl after extended 4th and 5th gear large dune bowl runs, so I kept improving the flow from the tank to the carb, but never licked it. It was not until I watched my quad take some pulls on a dyno that I truly discovered that my stock bowl (its clear plastic) on the Lectron 44 drain the fuel on a run in about 8 seconds.
Switched to a Mikuni TM38 tapor bored to 40.5mm and that condition disappeared. IMO, the Mikuni carb is more adjustable then the Lectron. I'm not a drag racer, so I want good low/mid/and high RPM response.
I'm hoping that the new lathe & mill will be delivered next week.
I've been in the cylinder business since 1971 & am anxious to pass along all of what I know about the trade
Cylinder machine work is close & must be extremely accurate. Most any of you people can learn the trade.
Give me a call if you've got any questions.
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