Gwbarm

I would check for partially clogged main jet.

The 450 is a bear to pull over i think to check if the decompression valve is working i would do a compression test and see what you get service manual will tell you what it should be. The valve should be located in the head maybe an access panel not sure about that.

That doesnt concern me sitting on pulleys for years it will conform to that shape just inspect it for cracks and fraying. Im assuming the pulleys are moving correctly and not gunked up you might clean them up while replacing the belt.

Spins with no power is normally a commuter problem i have ran into this on several occasions something seems to short internally causing this. I have replaced the commuter on starters and its good to go never could really figure out the problem with it, and on other occasions i have replaced it with no change, so i just chaulked it up as weak magnets. As starters have gotten cheaper over the years i really dont mess with it if it doesnt start i replace it.

Loosing a little pressure somewhere if it takes 2 weeks thats minimal ,6 year old seals and hoses not surprising. Takes a minute to build pressure backup.

After you have run it for a bit after sitting is it still taking longer to start.

image.pdf It appears that the rubber line is all put together with spring clamps and then there is the crossover line between the two cylinders if yours is crimped on you can cut it and use a spring clamp to reattach depending on how it aattaaches to the cylinders you buy. image 1.pdf

Thats interesting been a while since i worked on a non caliper hydrawlic brake system. The rubber line should screw into the wheel cylinder if not it must be made onto it, if you look further down the line it should unccrew somewhere, you can cut it and clamp it, i dont like doing that just somewhere else to leak, but it needs to screw into the new cylinder or does the new ones come with the hose built in or just a place for it. I will see if i can look at a manual later today. That seems aa little pricy for chinese wheel cylinders, but if it comes with the hose thats OK but they should work fine. It may be only a few years that they were made that way which drives the part price up.

Very good!

Head should be fine unless you see discolored areas from extreme heat, make sure the gasket surfaace is flat and the head fits on with no big gaps if its not perfectly flat you can get some aggresive sandpaper and lay the head on it going back and forth to flatten it back out and replace the gasket do not put gasket sealer on the new head gasket it keeps the head gasket from sealing correctly resulting in failure, maybe not immediately but at some point make sure head bolts aare torqued correctly.

Everything looks very clean in there, like they may have been replaced recently , whats going on, are the cylinders leaking or just wont build pressure or stuck. IF the seals are jusy stuck you may be able to keep working with them with fresh fluid to free them up, if you have to take them apart put in a kit or replace them , you can usually find aftermarket wheel cylinders cheaper than the kit and the aftermarket ones work fine. You just have to remove the old one replace it and reinstall the brake line. If you use the kit you have to take it all apart hone the cylinder clean it all up and reinstall the rubber parts and spring that comes in the kit.

CF Moto has been around for a while, they have increased in popularity as a reliable machine, i dont think parts availability will be a problem, unlike some other chinese brands, i am consistaantly seeing one i have never seen or heard of and parts availability is fairly non existant.

No! The 400 head will not fit the 366 Kymco.

Rotate the engine to top dead center on the compression stroke remove the cam gear cover make sure the marks are straight across find the T mark on the flywheel make sure it is lined with the pointer if everything lines up you are in time. They very rarely jump time but its possible. A sservice manual would better explain it.

CF Motos had some quality issues early on, but lately i have not heard anything bad about them. Most were minor sensor issues and bolts coming loose, but the engines are very robust.

Welcome! Glad to have you, a good place to learn and share knowledge.

That is a lot of weight!

I have had a few of those, the last one was long and slinder shaped like a bat, infact it was called a Bat Light. The problem i had with the last 2 i owned the battery would coorode in there and had lots of trouble getting the batterys out, didnt know if it was the aluminun causing it or bad batterys.

It sounds like it may be trying to backfire when turning over have you went through the carb to make sure all is good.

Top end or full rebuild, engine come out, it sounds like linkage adjustments are needed, which would be typical if engine came out.

It is tight on the side i have done it several ways, you can usually get a couple of fingers on the top and pull up but easy to loose your grip and it will fall back down it is very heavy. You can pry up one side with a screwdriver and get a grip on it and pull it up, but dont pry against the plastic may crack use a board under it.. If you are replacing it get pliers on each terminal and pull up, but i dont pull on the terminals with the new battery dont want to change them breaking loose.

That could definately be your problem, i would fix that so its working the way it should and see if thats it, if not them go from there. When you pull the choke off it may be going too far leaning it out so much it dies. I have seen this before with partially clogged jets but you cleaned those so i would fix the choke .

It does sound like timing, does it blow gas out the carb or just smoke, put your hand over the carb inlet while turning it over you should feel suction on your hand as it approches the firing stroke then it will let go and you will feel it again, it you feel a weird pressure against your hand trying to blow it off the carb something is not right.

I figured you had done that already , i really dont think its timing, just stated an old school way of double checking. If it was 180 off it would not try to start. I still think it is aa fuel delivery issue, not sure what since you have tried multiple carbs and not sure why you cant keep it running with starting fluid. It still could be an electric glitch you said the CDI has been replaced is it an OEM or aftermarket sometimes the aftermarket ones are not exact and the CDI does control the timing to some degree. Another thought would be a glitch in the pick up coil they can get debris on them to caause not to function properly , but again you have checked all that. So im not sure at this point i would keep trying to start it and see if anything else happens to give a clue as to what is going on. Being that its a 98 it shouldnt have sensors and electronic devises causing this problem.

Rotate engine to top dead center, timing marks should be lined up, cam lobes should be pointing toward the ground, valves should be loose. It you really want to make sure its the compression stroke take out plug put your finger over the hole rotate the engine, when you feel pressure on your finger stop and continue up to top dead center by hand, you can put a straw or piece of ridgid wire in the hole, move it until it stops going up, see if your timing marks line up and check that valves are loose.