Mech

It's not strictly putting it in gear that's making it miss.. It's putting a load on the engine that's making the miss I'd think.

It's easy to muddle the spacers and/or washers around the clip on the needle slide on some carbs. Some have spacers above and below the clip. Some of the plastic spacers are quite thick and make a big difference to the running.

Haha..

Sounds good Gw. My son's got a walk behind self drive honda and he's in love with it. I've worked on the self drives and they are a very nice machine. Easy start, super reliable, cut and drive real nice.. Just like honda quads. Hopefully you will never need to take that engine out again after a cam belt and a service.

Yeah I checked it. Thought you might be able to extrapolate somehow.. haha. There are other sites like it. It did at least confirm it's for the Bayou. It's really only the last six numbers that are the engine number. If you looked in parts books it might just, if you are lucky, find they refer to parts changes by referencing the number. That's how you discover if it was some tricky situation where the part changed half way through a model year/run.

The bad running and the smoke are almost certainly two separate problems. If the smoke is a valve seal etc leaking it will most likely be the exhaust one if it's the evaporation scenario. If it's the inlet, the oil will get burnt and it smells like burnt oil, Evaporated oil smells different, more like oil. For the bad running, the carb would be the number one suspect, and easy to check. I'd clean it and check the slide needle's position. The running from about 1/4 throttle up is controlled by the slide needle and the emulsifier tube. You need to take the emulsifier tube out and clean it carefully, especially the tiny holes up it's side.

White smoke, if it's from engine oil is oil that's being evaporated but not burnt. It's common if a turbo fails for it to chuck oil into the exhaust manifold where it gets evaporated and makes distinctly white rather than blue smoke, and lots of it. In your case NH it might be a worn out valve guide, or just a valve guide needing replacing, or, a valve guide that's loose in the head. Another thing that I've seen make amazing amounts of white smoke(from a lawnmomer) was when someone had accidentally put chain-bar oil in the sump by mistake. That thing filled my yard with smoke you could hardly even see through.. And no, I didn't put the oil in it. I figured it was the wrong oil though because it smelt wrong, and when I asked the owner.. They'd just had it serviced at the chainsaw shop.. Haha.. too funny.

There are sites/lists like... https://atvmanual.com/kawasaki/frame-vin-and-engine-serial-numbers

You could take the pull start off and try turning the crank by hand(or screwdriver through the cup's slots.).

Welcome along Lewis. (Hope I pronounced that right.). This is a friendly site. Well run too. How old are these grandchildren ? I've got grown sons, and young grandchildren, all living here on our few acres. So far we just take the grands for rides.. but it won't be long.

Braided ropes and cords come in fractions of a mill differences in diameter. It's the hardness and the no-stretch you want to get in a new cord, and heat resistance too I'd think, they make fire resistant cords and ropes(for fire rescue work). The diameter will be close to either six or eight mill I'd think, but the replacement is very likely to be some fraction of a mill different. Look in an arborist or rock climbing site and they will have good cord, or, to find heat resistant cord get a catalogue and it will have it. Page 35.. see the melting temp differences.. https://www.maximropes.com/fileadmin/Download/22-03-20_MAXIM_Climbing_Catalog_USA_2022_EN_web.pdf

Oh man, that's a bummer. Probably just got the bearing cocked over a little by banging too much on one side(yeah I read about the socket etc). You could put a big bolt, or length of threaded rod, through the socket and a plate on the far side of the hub, and pull the bearing in. Grease the housing and bearing.

Not all the bikes had brake lights Gw..

We don't know what make or model of bike it is, so it's a bit hard to advise you about what might have gone wrong. Did the workshop tell you what they had found when they fixed it ?

No trouble. There are service manuals with wiring diagrams in the manuals section.. For free download..

It's for the brake lights if the bike has them.

If an engine has 80 degrees of ignition advance... it doesn't run.

Nothing runs at 80 degrees advance. Check/test your light.

The piston's aluminium, and it would get chewed up before the plug. Put it at the T mark on the crank and use a torch down the plug hole.. I don't think a piston could chew metal away like that. They bend the electrode, seen plenty of that, but I don't recall ever seeing bits of metal worn off like that.

!25 is a bit low, but it should start. That rough looking buildup could be burnt oil or be because the compression's too low. As you say, if it warms up and has a nice ride with a bit of load on the engine it might come better.

I don't know what this bike is but I'd doubt that nick in the side of the plug was caused by the piston. If a piston hits a plug it's nearly always right on the end of the plug, and it closes up the plug gap. That might have been hit by a valve at some time, and it might have been like that for years or since new. I wouldn't worry about that, but the blackness of that plug looks like burnt oil to me. It would pay to check the compression.

My sons have spent countless hours at the dinner table discussing and debating what they were going to do next to get some bike running by a combination of slotting the mounting bolts so the trigger coil could be advanced and retarded, and then how much air gap it should need to get the right curve. It's a process I've been through probably a dozen times, and they have been through scores of times(not all as successfully as me though.. haha. I know when to quit).

Good idea, and what I'd do with any slightly newer bike. The older ones though can often be got to run pretty well with some other bike's cdi. They all(even the later ones), run very similar timing and curve. If the capacitor gets enough charge, and the trigger coil produces adequate voltage, we can tweak things and get them to run close to specs.

Too much advance breaks compression rings and destroys big end bearings.. It doesn't have much effect on temperature. Coils don't affect the timing. You have about twice the advance your bike is meant to have at idle speed, and more than it's meant to have all through the range. Manufacturers have worked out how much advance engines can stand, and what's best for them, and trying to better all the years and years of testing and accumulated knowledge isn't a good idea. You should try to tune it close as you can to specs. The consequences will be dire if you don't.

And.. Check the cam timing for signs it's jumped the cam chain, or broken the crank key putting the firing timing out..