Mech

If your bike has an eight wire cdi.. I think I have a diagram for that too..

Yup, the plain black wire is an earth that runs all through the bike, and the handlebar kill switch has a single wire connector going to it. The other kill switch wire is black with a white stripe. If you count the number of wires going into the cdi you should find either Gw's diagram or mine will fit. The two diagrams have different numbers of cdi wires..

I've seen the metal tab that fires the trigger coil dropped off rotors/flywheels before. And a flake of metal that bridges the air gap stops them working too.

I was thinking it was probably the gearbox/clutch shaft that moved, and perhaps because the clutch hubs control the end float.. Wild guess.. haha.. I suppose I should look in the book and check that theory..

Bugger.. It was a long shot anyway Gw.. Just in case it was a more modern sort, which to be honest aren't real common on pre-EFI systems. If it's easy enough to take the side case off then that's probably the next thing to do.. check the mechanical bits.

Oh ok.. good stuff. Hope that's the end of your problems for a while then..

Is it working now is it ? So can you get reverse reliably now ? From neutral ?

Dang Gw.. Your cdi has more wires than mine..

See if this seems to be like your wiring.. If the plug colours, or wire colours, or the main switch doesn't seem the same, then it's not the right one.. output.pdf

Yeah Atvguy, you need a wiring diagram.. And as Gw says, there are different switches for different models. To identify the wiring correctly, and the switch, we really need to know the exact model.. We need the whole model designation, with it's suffix.. YFB250***.. What's the *** ? If we can't find the *** they you need to look at the several wiring diagrams there are and figure out which one you have. One major difference is in how the main switch is connected up internally, and another will probably be how the starter wire branches into the cdi or comes out of it. If you can identify those two things then it narrows the possibly models it may be down.

I wonder if the owners manual would have anything to say about that.. Some supposed problems turn out to be designed in features.. Doesn't seem reasonable to have to use park before reverse, but who knows.. What does park do ? Lock a driveshaft somewhere ?

I'm having trouble downloading this and some other manuals I've tried to look at lately. I get good speeds right till the last ten or twenty seconds then the download fails. It does it repeatedly for some manuals it seems. I can download from other places. Some downloads from here work as they should. I can't work it out. Previously I've had no trouble with Quadcrazy downloads, but of the last while, a month at least, things just keep failing in the last few seconds. I'm mostly using linux but I've tried several times rebooting in windows ten but I get the same problem. Any suggestions ?

Sounds good Gw.. I wonder what people in cities enjoy.. haha. Sure not peace and quiet.

Clean it and inspect it. They are pretty tough things sprag clutches, and simple.. If the surfaces look ok I'd try it again... Given I don't have a spare bike sitting around. They sometimes come right with a good clean and blow out,,

Actually Gw.. First up, use the analogue gauge on ohms and see if it changes resistance momentarily as the crank turns. It might be that that's how it works and triggers the cdi.. Digital gauges don't pick up very brief changes.. not unless they are very good ones.

Nothing I haven't mentioned before I don't think.. Check the little metal tag is still on the outside of the rotor, and look for any tiny flakes of metal bridging the gap. The flakes of metal often lay down flat till the trigger plate gets close, then they stand up and bridge the gap.. It only takes one flake to stop them working. Oh, and the gap .. check the gap is right, though a wrong gap will normally still fire the trigger coil into life.

Yeah pulling the starter to check for damage or metal chips or flakes might be a good first step.. You can get those out with the body work still on..

That would be the most likely reason.

That's just what I use mine for too.. Though... I do ride up steep hills just because it's fun as well.

Do the spark plug first.. That alone could cause it if it's a fuel injected bike.. They are real fussy about the plug's gap.

Wiring connectors/plugs I fill up with grease so dirt/mud doesn't get into them. As long as they are good terminals, of the sliding contact type, we can separate them and smear the metal bits and then push them together and fill them from behind with more grease. It's a good idea to do the electrical connectors down by the stator engine connection like that. Other connectors that are exposed should be filled the same way. Switches, if it's something like a brake light switch and we can stop the dirt and water getting in by blocking the holes, then fine do that. Some switch contacts though will be held apart by a thin layer of grease and not make good contact. Sliding contact switches are less prone to the problem, but contacts that press together, such as a starter switch, they can easily be prevented from contacting if there is too much grease, or grease with a bit of dust in it. Switches I mainly just use the grease for lube, and only a smear on the contacts. If I do fill them up to prevent corrosion I wipe the contacts off afterwards. Ignition components have insulators that make sure things don't get close enough to short so all we have to do is make sure the water can't creep in. A thin smear of grease will do that.. You might have seen the ad for vaseline on tv where they vaseline their hands and then pick up water that doesn't creep between their fingers. I've been waterproofing bikes for the last fifty years with vaseline and like Mark.. my bikes run under water. Ya gotta have fun!!

If you shorted across the two big terminals on the starter solenoid and there wasn't even a decent spark, and the starter didn't spin, then you have a bad connection somewhere in the main big wires or their connections or a crook starter. If it's the starter it is most likely because the brushes inside are worn out or stuck in their holder from sitting too long. If you know how to do it, you could use a volt gauge as P5200 is suggesting and carry out voltage drop tests all along the starter cables, earth cable and between the starter and engine.. Or, the easier thing, which is to pull the starter motor out and test it on the bench with a battery and jumpers. Most starters come out real easily.. That's probably the easiest, and likely to be where your problem lies too. Starter brushes give a lot of trouble.

Reeds have much the same effect as a cam.. stiff reeds give better low down power, but stifle the revs, and soft reeds work the opposite. It's all compromise regarding the power. The thing I'd be looking at is the durability of the reeds.. some break or fall apart easily.. I haven't had much experience but one son loved two strokes for a few years and played around a lot. He eventually decided that steel reeds were better.

Oh it's over in another site Gw.. which I thought you visited.. must be mistaken about that. It turns out that it's been run without any battery in it, and the regulator is attached with a zip tie, and it has no air-filter.. So hardly surprising it's bedevilled with problems.. All good though. We had a laugh and Yoshi is going to get onto things.. haha. Hopefully it will be ok once things are back to as designed.

Permatex has a good name here in N.Z. Grease, whether that stuff or a petroleum grease, keep water out and off components and so maintains the existing air gap. It's the gap between wires or conductors that is maintained by varnish, rubber, plastic or grease that prevents electrical leaks and shorts. That grease, and common old vaseline, are both non-conductive and will prevent water ingress. They both prevent corrosion. It's important to understand though that there is a difference between non-conducting, and insulation. All non conducting grease can become a insulator if it prevents components from contacting. Both vaseline and silicon based greases are non conductive, they are both dielectric, and so if we apply them to poorly fitting or contacting contacts, such as non-sliding switch contacts, we do run the risk of causing a non-conduction situation. It works best to fill electrical plugs with the grease to keep dirt and water out, but switches and rubber boots really only need a smear. Vaselene, or silicon grease, will both prevent water getting into rubber boots by virtue of the water surface tension, we don't need to fill the boots on spark plug caps, just a bit rubbed over the outside of the boot right to where it contacts the porcelain works fine. Regular automotive greases would do the same job but some of them have additives that are in there to support heavy loads and provide a gap so the grease doesn't get squeezed out. Those additives can easily hold contacts apart and prevent conduction. Other automotive greases have compounds in them that can conduct electricity, so while they might waterproof, they can cause shorts. Don't use regular auto lubricating greases. The chief advantage of the silicon based greases is that they can stand higher temperatures before becoming inflammable. The silicon grease is a good lubricant in extreme temperature situations, but, we don't really get any temperatures so high as to need it any place we want to lube in the automotive world. It's high temperature benefits aren't needed for most waterproofing situations either. I fill already plugged in connectors with petroleum jelly/grease. I smear a little on switches for lubrication mainly and to water-proof them. I rub it on rubber boots and leads to prevent moisture getting in. Apart from keeping dirt out of the plug connectors, I'm depending on the water's surface tension to prevent water creeping in in most applications. Vaseline/petrolium grease is just as good as silicon grease, and more handy to have around.