Mech

I don't have one, but these look quite good.. There are other designs of special tools for adjusting the hard to get to bike carbs as well.. https://www.amazon.com/dp/B0BHYW1PBF?tag=qcforum-20

Look the original yamaha part number up on Babbits or Partzilla, and then put that part number into google..

The inner most bearing would be easy and cheap to machine out and fit a caged needle roller bearing, which I've done several times before on honda engines, but that sprocket flange is a problem at the other end. On a honda you can fit a common ball bearing race on that end, but not on the suzuki.. It does look like a repair or replace of the head is going to be the way to go. I'd clean it all up and go pick the brains of a competent engineer, he may be able to build the bearing surfaces up and machine them easier than you think. Other than that, I see that both versions (different years) of head listed for your model, use the same cam. Each of the two head designs get used in several other years, but it's far from clear just quite all the small differences are. In these links you'll see they say which other model bikes each head fit, and you'll notice that they aren't just earlier or later consecutive years, they jump around a lot. https://www.partzilla.com/product/suzuki/11100-19B01?ref=64703b8d4d387f224d0394c7c7e590909bddd469 https://www.partzilla.com/product/suzuki/11100-19B10?ref=64703b8d4d387f224d0394c7c7e590909bddd469

If this fuel gauge is an analogue, with a needle, then it's probably damped and so slow to move. You should get a test light or a small bulb, about two watts would be good, and use that to short the gauge wire to earth, but leave it on long enough to see if the needle works. If the gauge is digital then it's possible that the ECU could be contributing to your problem, possibly, or in any case it could be a wire broken or shorted to earth. It's hard to tell without looking at the bike, or a wiring diagram which I haven't been able to find, but the variable resistor in the tank could short towards earth potential for full or empty reading on the gauge. You really do need to get that tank unit out to be completely sure it's not the sender unit. The lock detent I was looking at was just a bit of dark metal I think. Not white. Check for locking tabs on the retaining ring, then bigger screwdrivers/levers crossed and a steady pressure. Lube helps and lube it all when it goes back together. I like the "Clydaho" too by the way.. Very good.

I'd warm it up and adjust the idle mixture and speed first, then see if it still does it after it's cooled off. It might be too rich at idle when warm, and so have the speed wound up. Then when it's cold the rich mixture is just right and the wound in idle speed screw makes it race. Could be....

In the upper left of that photo, about 11 oclock, is that an indented sort of notch you have to overcome to get the ring to move ?

As far as I can see in that photo it should just turn, but a better lit photo might reveal something.. a lock tap perhaps, though that's not usual. Two big screwdrivers normally get those undone. They can be tight though. Lube might help.

Lol... You won't need luck.

Two screwdrivers crossed above the center of the unit, with their tips hooked in behind the lugs, and then both used to lever against the other so it turns the flange thingy. Have you ascertained it is the sender unit faulty ? When you put it back in, a smear of vaseline/petroleum jelly on the seal will make it go together real nice.

Well clean it, start it up and watch it while it's running for a few minutes. If oil starts appearing then that's your leak. If it doesn't leak go for a ten minute ride and recheck for oil leaking, if it's still no leak go for a half-hour ride. Under that oil cooling pipe flange there will be a rubber O ring I'd think, or possibly a gasket. The oil filter will have a built in rubber ring for sealing so you could try turning that about a 1/8 turn if it's not already tight. The oil filter should seal at only hand tight, sort of wind it down till the rubber seal touches then about another half to one turn. If the filter was put on without a wipe of oil on it's sealing rubber it might have bunched up and not be sealing properly. If it is the filter leaking then you could undo it until the seal comes off the mating surface and then tighten it down hand tight again.

I think I'd just live with those tyres till I'd put some hours on the bike and made sure nothing more serious was wrong.

On that type you turn a big locking ring that holds the tank unit down. The rubber seal under it should be reusable.

Figure which wire on the tank unit is the gauge wire and short it to earth. The gauge should swing. Be careful not to try shorting the pump wire ! Here's the procedure for removing the tank unit. Hisun..pdf

The oil's higher up the engine than the oil pipe, so it's possible that that oil leaked from the oil filter, or got there when the filter got changed. It doesn't really look wet either, which would suggest it's not leaking now or recently. I'd use some fuel and then the garden hose to wash it clean and then keep an eye on it, it may not leak at all, and if it does you will be able to see where it's come from if you look before it's spread the oil about.

Good plan Gw..

Has this started after the bike's been siting for a while getting the repairs done ? Is the fuel fresh ? Could moisture have condensed in the carb ? Check the plug is clean and has a good blue spark, then undo the drain screw under the carb and make sure fuel keeps coming out at a good rate. Keep flowing fuel till you are sure the carb should be empty and make sure it doesn't stop delivering plenty of fuel. Catch the fuel and check there wasn't water in it. If there was water then clean the tank and test the bike again. If it's getting plenty of fuel to and right through the carb then it's probably time to take the carb off and give it a good clean. I usually start by taking the top cover off before taking the carb off the bike, and checking the diaphragm isn't split and that the slide needle hasn't come loose, or adjusting the needle (if the circumstances seem likely that it's in need of adjustment), but if the problem just arose then just that it's not jumping up and down, or dropped down through the slide. Then I'd remove the carb and strip it entirely down and clean it and reassemble it.

It's nice and warm here in N.Z, so I'd probably go for one of those things you put on the seat behind you in a bikini..

A little leak up at the head to exhaust pipe join, or anywhere in the first few inches of pipe, will make them backfire. Tried these guys.. They have always been good exhausts at a fair price. https://www.musketmufflers.com/

A bad misfire can cause a sooty black plug, but it has to miss a lot and for a while.. I'm thinking you would notice that. If it only goes rich occasionaly, and if it was only when you throttle off hard as would be the case if the choke was stuck on, then you wouldn't particularly notice the richness.. That could also explain why the idle mixture doesn't respond to adjustment.. -

Old worn low compression engines do get a build up on their plug, but it's generally a healthy tan or grey hard build up, not sooty. Worn rings burning oil, or leaking valve stems letting oil in to be burnt, the plug goes black and oily looking .. Black soot is always rich mixture I think..

Start the bike and operate the choke.. You should be able to hear if it's working, or doing nothing. The choke only sucks fuel up when the throttle's closed. Soon as you open the throttle the vacuum drops in the choke circuit and it doesn't lift the fuel right to the top of the venturi where the discharge for the choke is. So it could be on and only go rich when you throttle off hard. It does seem unusual to have fluffy dry soot that fast. That's definitely rich though.. Oil looks wet black. You have got fresh fuel haven't you ? And a good grade ? The compression is probably meant to be nearer 175 Lb but that's warm and with a full open throttle and cranking at the right speed. If it comes up to it's 125 in the first couple of compression strokes it's a good sign. If it has to be cranked a lot and slowly creeps up with each compression stroke it's a bad sign. You could put a teaspoon of oil down the plug hole, give it a quick spin with the starter or pull start to distribute the oil, then do a compression check. If the oil raises the compression a lot it points to rings, not valves. Having a tight or leaking valve doesn't normally cause dry fluffy sooty spark plug. Leaking rings doesn't normally cause that sort of soot either.. Only fuel does that. Some bikes say what size the jets are in the parts manuals. You can look that up online, or in a service manual.

Sounds like the charging isn't working. Check the fuses and the connection between the regulator and the battery, both power and earth connections, then the next check is that the stator is putting AC power out down at the engine, or even better, that the AC is getting to the regulator.

#41 I'm not sure which sensor is fitted where on the bike. I only know one has one wire and one has two. If putting power into the fan makes the fan run then the fan is ok. My test procedure is testing which place along the wiring system the disconnect is that's preventing it from going. The most common sign of a blown head gasket is bubbles coming up in the radiator. Steam could be caused by the air being very cold ? Warm water always looks like it's steaming if the air over it is cold enough. Even a farm pond can look like steam's rising up off it. If the engine is really overheating in fifteen minutes of idling it could be the thermostat, the water pump, the head-gasket, a blocked or dirty radiator.

Have you looked at that wiring diagram I posted for you at #32? There are two temp sensor switches, one has one wire and the other has two. They use different coloured wires. If you follow the recommendations/test procedure in #34 it should find the fault with the fan, if there is a fault with the fan. Most engines won't overheat in fifteen minutes of idling from cold. It may be that you have a blown head-gasket, faulty water pump, blocked radiator, or a radiator that's dirty on the outside. If you take the radiator cap off and let it idle with a full to the brim radiator, there shouldn't be any bubbles coming up in the filler. I'd check that.

Dry black soot sure sounds like too much fuel. The mixture adjustment doing nothing is always a sign of something wrong in a carb. Since it's running good, no mention of missing or hard start etc I'd doubt the ignition is at fault. Check it's got a reasonably fat blue spark. Ignition systems with resistor caps or leads can have a skinny spark, but it should be blue. If it looks yellow it's a bad sign. If the soot is only on the porcelain tip it might pay to try a hotter plug. If it lost it's spark suddenly it might have a wet plug, but it wouldn't have black soot. I'd make sure the fuel tap was good and not filling the sump with fuel. And if it's got a vacuum controlled tap check that isn't letting fuel into the vacuum line. Then I'd start looking at the mixture. Choke's going right off, check that first because the choke only works when the throttle's shut so they run ok with a stuck on choke, till you throttle off, then air-filter, intake piping isn't crushed or blocked(mouse nest), carb breather tubes, fuel tank breather. It might be that the richness is intermittent, or caused by heat or the time run. So check the carb breathers, and tank's not presurising. Then It'd be off with the carb for another look. Check the float height(can be done before pulling the carb off) and that it isn't sinking, check the idle mixture screw tip and the seat the screw goes into for damage, check the float needle seat is sealed to the body, the breather drillings are clear, all the drillings are clear, the jets are the right size, the slide needle is the right one and attached to the slide, the slide isn't sticking. Reassemble and check the idle mixture is responsive. If it isn't then there's still something wrong in the carb.