Mech

So you just need a key and bolt it back together ? It looks like the seat where the star washer sits or the shift drum is a bit worn ? As long as the washer sits nicely on the shift-drum again it looks like it should be ok. And yes I've seen the bolt loose, and those pins the ratchet works on can come out in some bikes. It's good nothing got down into the sump.

Can't find any reference anywhere to a 300 bayou being water cooled.. Looked back and forwards several years in the parts lists, and looked at the model development..

Hmmm.. We have a problem.. Here are the parts listings for that model from Babbits and Partzilla. They both think it's an air cooled engine. https://www.babbittsonline.com/oemparts/l/kaw/500ae675f8700209983b6416/1996-bayou-300-4x4-klf300-c8-parts https://www.partzilla.com/catalog/kawasaki/atv/1996/bayou-300-4x4-klf300-c8 I see the 400 is watercooled..

I'm in New Zealand. I've been riding suzukis for years.

Well I looked up that bike in the parts sites and it shows it as having a "Double Clutch Transmission", which is described as DCT. Then I tried to find a manual and the nearest manual I could find is the owners manual for the same bike from 2020, so I looked up the 2020 model, and it has the same running gear, a DTC transmission. So.. that bit I posted is describing what to do about faulty gear shifts in the 2020 model, which, as far as I can figure, is the same as your bike.

The manual I have covers from 1986, and so this supplement is saying that most of the your bike, apart from the things mentioned in this supplement, is the same as the 1986 model service manual. It's worth noting though that this manual is not a genuine yamaha manual.. I think it's a trustworthy manual though.. output.pdf

Could only find an owners manual so far.. But it's for the 2020.. Probably right.. Check this pdf and see if it is the same as your model. Try the tests they say.. 2020 Rubicon 520.pdf And I see it doesn't say you can drive it home.. That was older models.

You should check the shift cable is moving the shift lever down on the engine full travel. I don't think that will be the problem though because that bike has a power shift (electrical/hydraulic). I think it might have a place on the left side of the engine where you can fit a foot shift lever to test the gears and to get you home if the electrical or hydraulic systems that do the normal shifting plays up. They say to fit that lever and try manual shifting early on in the long and complicated diagnosis process.. So if that lever is in the tool kit, fit that and try driving manually. I'll see if I can find a service manual.

When you are pulling the cylinder up, wrap a rag around the con-rod to stop broken ring falling into the crankcase !!

Some carbs have a short straight screw in fitting for the cable too.. That cable might be meant for that..

That's right Anthony.. Welcome along. What country are you in, and what do you ride ?

Do you have the old cable to compare length to ? Are you sure the outer cable is pushed right in to the fittings ? Can you get the plunger on without the spring ? Does the spring perhaps need to go up inside the elbow ? Perhaps it needs a skinnier spring, Perhaps it needs a different elbow. Maybe that cable is made for a model without the elbow.. Guessing here.. haha.

Oh.. Now you need a spares bike to fix that one up. I'm familiar with the problem.

Bad rings.. or badly blown cylinder head into the chain case.

They are (comparatively speaking) fairly simple. And the access is better than some. Yell out if you have any doubts about any of it. Check and/or test things at every stage of the reassembly, and backtrack if you think you need to, sooner than later.

Good weather to read the manual then...

I can't think how it would/could cause it, but I think I'd suspect the neutral light switch. I'd test that idea by by-passing the switch with a piece of wire I could earth out. If it worked normally with the wire earthed then I'd figure the switch was not making proper contact.

Ok, too tight at least means the valve isn't bent.. haha.. or stuck open. Probably burnt.

https://www.babbittsonline.com/oemparts/a/hon/5053de37f870021c54bddb6f/front-crankcase-cover-trx500fe-fpe Part 21 is attached to the gear shift mechanism and when the shift lever moves any direction it swings part 13 left or right. Part 17 is a housing with three ball bearings in it, and it, and parts 13 and 15, all work together to lever 13 and 15 apart. Part 13 pushes against the cover and 15 has the adjuster screw in it's center. The adjustment screw presses and disengages the clutch. So yeah, it looks like it may be needed to take that cover off. If you have it off and are putting it together again, use a bit of vaseline to stick the bits in place while you fit the cover.. It saves/stops then falling out of position.

At such low pressures it's almost certain that the rings and the valves are at fault here. You say the valves were not to spec.. so were they too tight or too loose ? And I suppose there's no sign or sound of the head gasket beingreally badly blown ? No whistling or whooshing (haha) sounds ?

Yeah compression that low it will be a valve problem. If the/one valve has a lot of clearance it might be that valve sticking open.. Try tapping it and/or turning it ..

Check the valve clearance.. Check the cam timing. Then check the compression with a gauge, then put about two teaspoons of oil down the spark-plug hole and check the compression again. If it comes up by more than about twenty pounds (depends on what the first figure was) then it's an indication the rings are leaking/weak, if the two figures are almost the same then it's probably a valve. If it has more than a hundred pounds then it should run, just, but be hard to start.. Less than eighty and it's unlikely to start at all.

Yeah ok. So when you get the new rings, check the holes in the back of the oil groove are clear, check the side clearance of the rings (that's the clearance top or bottom of the ring), and check the ring gap of course. When you get the bike together, check it all over before you start it, then when you do start it, check the oil is getting to the head, then start riding straight away, don't let it sit idling, and when you are riding it, put a heavy load on it until it's built up about 3/4 revs, then let the throttle right off till it's slowed to just above idle revs then give it about 3/4 throttle again and keep it there till about 3/4 revs.. repeat that cycle about ten minutes or so and the rings will bed in.. That first few minutes is more important than hundreds of miles of careful running in.If you bed the rings like that, the engine doesn't need any running in. Let it sit idling and the rings might never bed in. The rings have to have a heavy load on them in the first few minutes.. That means letting the engine labour slightly..

You could check the engine breathers. They generally run from the crankcase to a branch where one hose goes up the front, around the fuel filler and then down a little, and the other branch goes onto a restricted vent into the air box. The restricted vent in the airbox is only to stop water getting drawn up the main breather if you drive into deep water. it breaks the vacuum. They also often have a short branch going down the bottom of the bike somewhere with a plug on it, that's to drain water out if any does get drawn in. The main vent hose can get blocked by dust and oil, and then if you undo the filler while it's running there will be pressure. You could test that and/or check the main vent hose going up front and high is clean.. If the filler plug gets pressure, the vent isn't clean.

Ha.. Very good. You said you used a barrel and piston and rings off another bike that didn't smoke.. Then later you say you think the head must be good because the bike didn't smoke.. So you did swap the head off the other bike too ? The cam timing being a tiny bit off wouldn't make it smoke.