Mech

Thanks Gw. Ah well then Shadow, that starts to make sense.. lets hope it's only the diode.. Trouble is, if the diode goes it's meant to set a code. It may have blown something else, like obviously the PS unit or the control, or even the power supply module those things have.. We hope not. The diode is shown in that pdf as being in with the fuses and relays, third column from the left and the top two. They are both shown as diodes. Your bike appears to have fuses in there.. Check if they are blown. And.. you know how to test a diode huh ... One of the manuals I was reading said that all the relays in the fuse box are the same and can be interchanged. I'd try swapping the EPS relay.

You wouldn't think the flooding etc would cause a problem. I'm pretty sure that the decompressor will operate like most do and not force the valve open, but only hold it open after the cam has opened it. Hard to see how that could damage anything. Good luck in there. They are good to work on. I'd recommend you get some "loctite master gasket" to reseal the top up.. Brilliant stuff.. Way better than silicon or anything else on the market. Clean, economic, doesn't block selves or filters, never leaks, doesn't harden till the parts are clamped together so you don't need to rush, and if you have it apart again the old stuff is easy to get off.

Oh, ok. Well I can't identify the make or find anything about it either. If you find a vehicle identifying tab with something like a frame or vin number on it, it may tell us something useful.

We need to bear in mind that this only developed after you'd changed the battery.. Right ? Or had it been playing up with the old battery ? I think I'd pull all the relays and see which one cut the power to the unit, then do the same with the fuses. That would confirm what was what. The fuse is lower center and the relay should be lower left. You did see that last pdf I posted ? Then I'd try and find that diode it mentions. It should be right top or second down. If the battery had been connected backwards for an instance it could have blown the diode, and when the old battery was low voltage that can cause excess current draw which might have damaged the diode. I'd check the kill switch carefully. It may be a double pole switch and one pole/contact might not be working. Most of that though should have set a code. About the only thing not listed as a code is a worn or stuck brush in the PS motor, though it may be a stepper/brushless motor anyway.. The common cause in cars when there is no code set is either that it's a mechanical fault, or the power supply or earth is the problem and at the instant it's occurring the computer isn't powered and can't log a code ! So... I'd check the 14.4v didn't drop when it got a load on it. To put an electrical load on the EPS unit you have to put some force on the steering. I'd do that and see if the voltage dropped right down, which would mean there's a bad connection in the power or earth supply( you have checked all earths ?), or if it dropped slightly which would indicate the unit is trying to work but perhaps the motor's brushes are stuck or worn out, or if it didn't drop voltage at all in which case it would mean there was something wrong with the control unit or the EPS electronics. I'd check for voltage drop at the EPS control unit too when it had a load being applied to the EPS

You should repair or copy the old wiring.

Any idea where or what the diode they mention is ?

Hmmm.. You're right. It's mighty hard to find the wiring for the EPS. It's shown in later model wiring where it was fitted by default but I wouldn't depend on those. I found this though... 2010_Power_Steering_Addendum.pdf

Ok.. arctic cat but the same engine I think.. output.pdf

How much does it cost to buy a genuine service manual over there ? For the price of a subscription you can download all the manuals for your bike, and more.....

No trouble. If you need the wiring diagram yell out.

It's also possible that there is something wrong with the electrics such that the coil sparks one last spark after the engine bounces backwards off the compression. Something like a bad connection in a key switch, a bad earth on the cdi or the coil, or a bad kill switch. The easy way to eliminate it being a spark at the plug doing it, is to watch a timing light as the engine comes to a rest after the kill switch is flicked. Check the easy things first. If you run through those questions in #2 and #4 it will lead us in the right direction I think..

Parts diagrams are normally helpful, but not this time.. https://www.partzilla.com/catalog/suzuki/atv/1998/quadrunner-4wd-lt-f500f/cam-shaft-valve The service manual doesn't tell us anything. It looks very simple and similar to other one's I've seen. At start revs the weight falls down towards the cam shaft, and once it starts spinning faster the weight flies out. When it's in there will, I think, be a steel pin bumping the rocker up, lifting the valve. It looks like you might be able to poke a screwdriver in through the valve adjuster holes and flick the weight.. output.pdf

Here.. It's only three pages. This is from the 2016 Alterra 500,550,700. I think it will be the same. output.pdf

You should be able to get the manual now.. I think you only need ten posts and you are up to fifteen.. Have a try at downloading. If it won't allow it I'll cut the chapter out of the manual and post it for you.

Ok, read through the text of another manual and it says the centrifugal/one-way clutch nut 72.5lbft, and generator rotor nut 115.5lbft..

Oh.. I'll check in another book.. Forty sounds good to me too.

Is this the one-way over-run clutch for engine braking ? That's called the clutch shoe nut in the book, and it's 101.5 lbft. There's also the starter clutch, which is the generator rotor nut, and it's 115.5 lbft. I wouldn't do either of those nuts up that tight though, not on an old bike. The nut might strip, the threads on the shaft might strip, and it's probably possible that either hub could get forced down on their taper or splines and cause problems. I'd do them up carefully, to about 65-70.. It will be plenty as long as the stator is clean and sitting nicely on the taper.

Yup, go to partzilla and find what your bike's model suffix is, then find a service manual.. The suffix will be either AM, AMC, FAM or FAMC

Yup Huapakechi is right, a broken key in the flywheel could do it, but if/when you get around to checking the cam timing it will eliminate or point to that. Check the cam timing first, it's easier and checks cam and ignition timing at the same time.

If you can't keep your finger in the plug hole when you turn it over it should be enough compression. Yeah well it's backfiring so it's getting spark. The spark timing might be out. It was going till it got switched off.. so check the switch perhaps.. The key switches differ but they all send 12v into the cdi, and a signal into the cdi when the start button's being pushed, it retards the timing I thing to take the load off the starter. The noise when the throttle's opened might be the starter straining. You could check that signal is getting into the cdi. It's a bit tricky though because some send 12v through the cdi then to the start button and on to the start solenoid, and others have 12v to the start button, and it then branches to the cdi and the start solenoid when the start button's pushed. That retard function though isn't used when pull starting.. so.. perhaps try a pull start... Or.. a tow start.

#8.. Absolutely right about knowing what's what before you go see a mechanic.. I've told lots of young fellahs, mates of my sons or children of my peers, that learning how things work, and to fix them, is a good idea even if you eventually decide to let someone else take care of your cars/bikes. It keeps them out of the clutches of rouge mechanics. And if you know how to fix your bike or quad.. it makes you al lot more adventurous. Adventures are always good..

Ok, found the manual.. It says to check for 12v at the control module and at the power steering unit. It does say though that not all models have power steer, so.. Does the power steering connect to the battery with it's own separate wires ? Did you get those wires reconnected when you had the battery out ? Have you checked those wires for breaks right where the wire enters it's metal terminal ?

Have you checked the fuses and relays ? Is the dash flashing at you, or got lights on ?

Are you sure it's compression ? Have you checked it with a gauge, or a finger in the plug hole ? It might be the piston hitting a valve you are feeling. It was going till it got turned off. "New plug has lots of spark against frame .Poured a little fuel down the head installed plug and nothing.when turning it over it keeps backfiring but wont go.".

And did you try the choke(without any throttle. The choke doesn't work with throttle.), and did the plug come out wet ?