KX80 swapped KX60

[Rlopatic99]

Hey Guys!
I am bringing back a thread for my engine swapped KX60 after almost two years. It sat in my basement on financial hold for so long. I actually started to do something with it. In the past few months I have been slowly restoring the engine and bike itself. So far I have the rear wheel respoked, new tires front and back, new kx65 clutch cable with custom cable holder, new klx110 front brake cable, klx110 front fender, all the rear brake pieces that were missing, a new chain, throttle cable and throttle. I had the motor apart and it is still somewhat apart, but I got a lot done. I put a new shifter shaft and shifter springs, tusk shift lever, water pump rebuild kit, clutch cover gasket, new boyesen power reeds, new mikuni carb, pod filter, new spark plug, and i have a brand new wiseco piston kit for it. Unfortunately the cylinder walls are badly worn, so I am on hold until I feel like throwing around $200 to get it replated by Powerseal USA. Once that is done, the motor should run like new again. I am very excited. In the mean time, I am planning on just running a stock KX60 radiator, so I need to purchase a radiator and tank with the shroud. The frame is a 1985, the last year that it was air cooled, so I do not have the correct tank. The other major issue I have been thinking about is the exhaust. I still have the stock kx80 expansion chamber, but it is huge and would have to be trimmed down. One problem it might pose is that the KX60 exhaust goes over the head and through the frame to the right side of the frame, but the KX80 expansion chamber would kinda be up against your leg on the left side. So I am weighing my options, I am almost thinking that I may just try to fit up a KX60 expansion chamber, but what kind of affect could that have on the powerband? The biggest thing is that I am making progress. I hope to get it done by spring. If anyone has any advice, I would love to hear it.

[motopunk]

it would run with the kx60 pipe, but you loose the top end power of the kx80 engine. you have to cut and reweld the pipe, that it fits the kx60 frame ...   it would be a lot easier to find an kx60 /65 engine and install the athena 80cc cylinder kit .. 

[Rlopatic99]

Its not like im looking for the easy way to do it. Im a welder and feel i have the skill to modify an exhaust, but modification is different than having a completely different expansion chamber. I am weighing my options of even getting some software and designing one and tig welding it. I have the stock kx80 exhaust and it is modified , but the kx60 exhaust goes through the frame whereas the 80 is much different. Im already too far into the 80 engine to just scrap it., let alone the fact that the kx80 engine will suit a larger rider much better and actually last.

[Rlopatic99]

I have not given up on this build. Its getting very close to being done. Hopefully it will be done within a month. I just got the cylinder back from Powerseal USA and got the top end back together. It needed to have the Nikaseal coating done. I just need reweld the motor mounts, modify the outlet on the radiator, find the final position for the radiator, fix the oil drain threads and finish the exhaust. I have a kx60 stock exhaust and will weld the 80 head pipe to the 60 expansion chamber and then either weld or coupler the kx80 fmf silencer i got. It has all new plastics, 2003 kx60 fuel tank so that it fits a radiator, fresh fork oil, new brake shoes, new riser bars, new cables, new wiseco piston kit, new mikuni carb, new boyesen power reeds, new shifter shaft and spring, 2003 kx60 radiator, new tires, new spokes in rear wheel, new chain, recovered seat, protaper grips, tusk shift lever, oversized klx110 footpegs, and rebuilt water pump. I will be finishing paint on the frame, swingarm and other small parts after i know everything is working properly.

[Rlopatic99]

So it is very very close to being done. It is running almost perfect and everything is where it needs to be, but i believe it needs a stator. Once I rip some hotlaps around my pitbike track for about 10 minutes, it starts to cut out and lose power which seems to me like an electrical problem. Anyways, I finished the exhaust and actually had to use the 80 expansion chamber and made it fit in the frame just like the original 60 chamber did. The muffler is mounted to the stock location but I slightly modified the mid pipe on a KX 80 fmf powercore 2 and was able to fit that really nicely. Took a lot of cutting, welding, and some denting here and there to get the exhaust good enough and I am not sure if im totally happy with it yet, but it works. I may make the 4 hour drive to NY state to see Rich at DynoPort to have him build a custom expansion chamber for it. I got the engine to sit as low as possible in the frame with the new mounts. Welded mounts for the radiator where it clears the exhaust port on the engine and sits where it should for the shroud to look right. I welded around the broken oil drain plug hole and rethreaded it without troubles. I had to put heavier clutch springs in and adjust those. Overall this bike is just as good if not better than I thought it would be. I love having a 2 stroke pitbike. The powerband rips this thing pretty hard and the suspension and brakes are everything I could ask for, which is much better than a chinese pit bike haha.