Mech

Oh ok, #11 explains it then. I think that bigger gear with more teeth will be lowering the overall ratio between starter and engine by quite a lot because there's a second reduction which will multiply the small difference in ratio of the first gear set, and I think that reduction in ratio should lower the strain/load on the gears.. so hopefully make them last longer. That said, I'm sure Honda will have worked it all to the umpteenth degree and their design will be quite alright when the right starter is fitted. I see also that the honda gear is quite a reasonable price.. Don't know what the aftermarket gear costs though..

Might be a replacement engine.. You could compare the engine to frame number for discrepancies. Have you checked in 87 what other parts got changed to accommodate the different longer starter ? It must be either that case or the gear that changed.. I think.

Oh ok. Getting the correct parts has always been a mechanics nightmare. Mechanics always blame the spares guy and the spares guy always blames the mechanic. Anyway.. There are two ways they can get extra teeth on a gear, make the pitch smaller or increase the diameter.. If they change the pitch the gears would wear badly, but those gears don't seem to be too badly worn, just a bit damaged. I'd have to suspect they increased the diameter, and that should, unless it bottoms the crests out in the valleys, decrease clearance and increase the depth of the pitch. That should aid the strength of the cogs. The fact it's got more teeth means it will be lower geared, and that should reduce the load. I'd probably be ok with the aftermarket gear as long as it looked well made and finished. I'd be pretty sure the longer pinion starter will cure the problem.

Whoo That sounds like the problem then.. And where'd you find that bit of information about the two different starter pinons ?

Read what I've said Lester.. The cdi does have a lot to do with the starting circuit.

Well I don't agree... The modern manuals are excellent, well most of the jap ones anyway, and availiable, which they weren't years ago. We are lucky ! Compared to forty years ago, when only dealers had manuals, and the manuals were terrible, the manuals these days are brilliant, well laid out, well written, good diagrams and photos, and they do tell you everything you need to know. They don't say reassembly is a reverse of disassembly, if there are in fact detail that need attention, such as timing marks or critical clearances. They do generally mention everything you are going to need to know, but they are written for mechanics that are familiar with the systems involved. And even mechanics have to read them carefully. Things are more complicated these days and so we need to browse right through the manual familiarising ourselves with the layout and what is in each section. EFI for instance will be covered in it's physical components in the fuel section, but the diagnosis and trouble shooting will be covered in the EFI section, and the electrical details will likely be found in the electrical section. It's best if we have noted that if we want to get the best out of the manual. It's also best idea to check if there is an appendix for your particular year or model, and have a look in there before reading the rest of the manual, noting which parts or operations are going to be different for your bike compared to the general model the manual covers. The manuals are written for mechanics as I said (and the manuals say too), and they do assume you are familiar with common workshop practice. There are more detailed manuals called "technical training manuals", and they are what dealer mechanics get when they do the courses. The technical training manuals are very detailed and explain design and operation in great detail. Some of those can be found online. There are also often other manuals mentioned at the beginning of a service manual, and those mentioned manuals cover the special components, such as an automatic trans for instance. There are alternatives to the genuine service manuals, such as Clymer or Haynes, which are aimed at the home handyman, and they do suggest tips and the sort of practical advice about how to do certain steps that a mechanic would take for granted, and the genuine manuals don't mention. Those are probably a better option, or a handy addition, for some people.

Yeah good point about first being at the bottom, that does make it much easier to find neutral. And yeah, it was those old machines I was thinking of. I still always try to slip things into neutral while It;s still rolling if it's convenient, or blipping the throttle before putting things out of gear if they are reluctant. I don't know about the yamaha switches but I've seen hondas and suzuki with worn switches that behaved as you say. Sometimes jiggling the shift lever with your hand just enough to make the shift barrel move a little makes the light flicker.

The broken gear has not been fully meshed with the starter pinion. The starter seems like it should be moved across left or right so it meshes full width of the gear teeth. I doubt that alone would break gears repeatedly though, or not that fast anyway. Too much ignition advance would strain the gear. I'd check the ignition timing and advance, and try to ascertain how much it retarded as it went down to low revs. The cdi is really old and it probably gets advanced timing, and more ignition advance as it revs than it's meant to, if the air-gap on the pulse coil is too small.,

Yeah I always thought a front brake did it on most bikes, but in that diagram I noticed it says it's the back brake switch, and I notice that bike has no brake lights shown in the diagram.. So perhaps this is a different model than the diagram.. Check the wiring diagrams against what's actually fitted to the bike Lester. They wire their relays etc in several different ways, and there are several different CDI, stators, pickup coils. The wiring diagrams show the plastic plug shapes and colours and pin locations, all of which they change from year to year and/or market to market. Sometimes they change things half way through a year. The bike always needs checking against the wiring diagram no matter how sure we are about the model and suffix etc.

Thought you'd know that technique from old two-wheelers Gw.

If that is the right diagram then you should check that relay 8 has power to it on the R/W wires, and that the Y/B wire is getting shorted to earth when the brake lights or the neutral lights are on. If both those things are right, then check that the L/W wire on the start relay is 12v, and that it's getting 12v to the start solenoid 6. If the 12v is getting to the L/W wire at the solenoid, check that 12v is getting to the L/B wire on the start button, and that that 12v drops to zero volts when you push the start button.

Ok, and so does it have 11 wires on the cdi, and are the plastic plugs just as shown in that diagram ?

https://www.partzilla.com/catalog/yamaha/atv/1990/moto-4-yfm350era/drive-shaft The genuine service manuals are designed for trained mechanics. They assume a certain level of competency.

If a bike doesn't want to come out of gear and into neutral, the easiest way to get it out is to blip the throttle so the bike starts to roll, and then as you throttle off and the load on the gears from driving the bike comes off the gears, they will generally slide out of mesh. Works on two wheels, quads, and 4WD trucks stuck in 4WD.

Yamaha change their wiring often. I think we need to get the RIGHT service manual and wiring diagram for that bike. Here are two that both claim to be your year and BB. Check how many wires the cdi has and let me know and I'll see how many wiring diagrams I can find with the right cdi.. Or, if you have the YMF400 suffix it would help. 00-05bigbear-kodiak400.pdf 2000-2001BB400.pdf For the lack of power now, after jumping the starter, check the earth contacts and the battery cable to terminals connections, and battery to cable.

Oh the knurled screw might be a mixture screw, in which case it will be either forward or back of the slide by a half inch or so. I think that is in the center-line of the slide and touches under the slide to hold it up to idle position.

If you put the brake lights on by using the brake lever, then it should be able to start in gear, so that tests all the rest of the circuit except for the neutral switch and relay/relays.

There will likely be an adjustment for the cable on the throttle hand-piece as well. If the cable outer can be pulled out of the throttle hand-piece by a couple of mm or more it should be enough, then try adjusting the idle speed screw to slow the idle, then adjust the mixture screw to best slow idle then slow it with the speed screw and recheck the mixture screw. Keep doing that slowing it down to it's best slow steady best mixture position, then wind the speed screw in a little to give the proper idle speed. Oh, and when checking the free play in the cable, swing the steering hard left and right and check the free play there and compare it with the center position.. The free play can alter when the bars are moved.

That's a different carb Gw.. This looks like an old cable on slide carb. That knurled knob on the side of the carb is the idle speed screw, and the idle mixture screw will be underneath at the front I think, pointing downwards and up a tube/drilling. Where that screwdriver is pointing to.

Are you sure the choke plunger is going right in ? I'd double check the idle speed screw and the initial setting of the idle mixture screw for that bike, and then try adjusting it to best slow idle, which would be a bit slower than we'd mostly have it idling at. They need adjusting right down to a slow idle and the best mixture setting, then sped up with the speed screw to a good idle speed. It can happen that people get into a circle of adjusting the mixture too lean or too rich and then speeding it up to compensate.. That circle can end up with things being adjusted right to the end of their range, and then the spring holding the screw from vibrating out, becoming loose, and the screw dropping out.. If it didn't come right then I'd pull the idle mixture screw out and make sure it's O ring and spring and washer was on right, and that the taper was in good condition and looked the same as the original(check the shape carefully !),, then pull the slide and check/inspect the discharge tube down in the venturi was poking up a little, and I'd check the slide needle was secured in the slide properly. If all that looked right I think I'd take the carb off and check the float height and jets hadn't been muddled, though it's generally pretty difficult to get them muddled. When the carb is set up right the idle mixture screw should be about two turns out as a starting point, and then you adjust it when it's warmed up. It shouldn't go right in to a stop without leaning the mixture so much the engine dies, and you shouldn't wind it out till the retaining spring has stopped holding the screw, and at that stage it should be too rich.

Engines, if they are too rich, tend to chug and run irregular and rough for some time, either a second or three or more than a minute, before they get slower and slower and finally die. Engines that are too lean tend to idle quite regularly except every few seconds they give one single miss, then go straight back to a steady idle till the next one miss. They can sit idling with that intermittent single misfire sometimes without dieing, but if they are going to die it will generally be idling fine then suddenly cut right out. Doesn't always show up like that, but mostly a single cylinder engine with an idle mixture that's not right will behave like that..

I think the mixture at idle is too rich. That would explain it idling cold but then cutting out once it warmed up. And winding the idle mixture screw in doesn't make it too lean by the sound of it... Both things point to a rich mixture. Check the air filter is clean and oiled, and not over-oiled. Check the breather hoses on the tank and carb are fitted correctly and not blocked. The dieing when warm could also be a tight valve clearance so it would be a good idea to check those. The idle mixture needs to be adjusted at the slowest idle speed it will idle steadily at. So you slow it with the idle speed screw then wind the mixture screw in and out till it is in the place that gives the highest idle speed, then you wind the speed screw out to slow it right down and you adjust the mixture to it's best idle again, then slow it, then adjust it, and you keep going around in a circle slowing it and adjusting the mixture. Once it's idling slow and steady then you can speed it up if you want to but leave the mixture where it's best at the place where it will run nicely with the least amount of butterfly opening. If it doesn't come right, if the idle can't be adjusted in both directions with similar rev changes, and/or it keeps dieing once warm then I'd check the float level, which can probably be checked with the carb in place using a bit of clear hose, and I'd check the jetting.

You should put the hoses back to how they are meant to be. The sump might have too much oil in it, or the oil may have fuel in it, or the engine may need an overhaul. Those are the usual reasons oil gets into the airbox. Your bike may have a PCV valve somewhere, and that maybe clogged and need cleaning.

One year later and a DC cdi. Coil Primary 0.1-0.5, secondary 12-20K ohm with cap. Pickup coil 90-140 Ohm. They recommend a peak voltage test of at least 2.5v.

Coil primary 0.5Ohm, secondary 10-16K Ohm. Pickup/trigger coil 90-140 Ohm, cdi charge coil 106-160 Ohm.