85 moto4 lack of spark.
 

I have never owned an atv before this - so please bear with me. I used the cyclepedia vin decoder, and I for sure have a 1985 Yamaha YFM200N-S Moto-4. That being said, please bear with me. I know this kind of post comes up often, but I am at best a newbie to atv mechanics.

I HAVE NO IDEA WHAT I'M DOING. I have worked on outboards, cars, etc, including some larger projects (rebuilding auto trans and transplanting a chevy drivetrain into a jeep... had help with wiring. My nemesis.) but I don't have the "mechanics eye" for ATV just yet. I don't even know if I'm trying to start this thing the right way.

I took on this TURD (I love yamaha, but this thing is a pile.) for about what the tires under it are worth. That being said, I have found that the trans finally does in fact shift after thawing out the poor waterlogged/(read: iced up) gear case. new oil that i circulated as best I could by pulling the recoil to keep rust at bay until I can get it pumping oil under it's own power. The trans was my main concern, I didn't want to tackle this project if i knew it had grenaded for sure.


waiting on my manual to come in the mail, the suspense is killing me. I cant seem to achieve spark. This thing is a debonair basket case. all the cables need to be unfrozen or replaced, the brakes probably need redoing, i have a feeling the wiring is to blame. PO put a fancy switch in to turn the lights on when the quad was turned off... I should have saved my money, but now it's a challenge, and you know how we all are about a challenge... tough to back down at this point. that would mean admitting defeat.


If someone has a rundown on what things I should check in a waterfall fashion to see why I can get spark (I also can't get the starter to engage.) I'd really appreciate it. Do I have to have the "dual range" shifter in a certain positon for startup? It appears to only have two positions.

All help is greatly appreciated. I will try to respond to questions and insights as fast as I can. :)

nevermind!
 

I achieved spark, and then LIFTOFF with starting fluid last night after lots of dinking around. Got the gearcase freed up, etc. now I move on to fuel... this beast of a project is starting to shape up. I even got the starter to run after ding donging around with its guts a bit.

I searched and did not find an answer, can I simply slap an 86 carb onto this machine, and will it work with the slide that is attached to my throttle currently? The only reason I ask is carb parts for an 85 are a lot less plentiful than an 86 and up machine. I can get what I need directly from Yamaha or partzilla.


Thank you all!

And I already have to carb apart and cleaned, blew all the jets and passages out clean as a whistle, if anyone can help me with any settings or issues I may run into in the guts of this thing, it appears I can adjust only a few things in there. I love fixed jets if they work right...

Not exactly fixed jet, as that long tapered needle, below the carburettor slide, varies the size of the main jet as you open the throttle. The only adjusters are idle mixture and idle speed. I make it a rule never to alter idle mixture screw, and idle speed screw just alters how far down the carb slide can go when the cable is slack, you set it fast enough not to stall, but slow enough not to engage the centrifugal clutch. On some you can alter the main jet by putting the circlip on the aforementioned long needle into a different groove, but best not to alter it unless the bike is running rich, or weak, once you have got some miles on your nice clean carb.

Thank you. this is my first experience with a slide style carb. Should be an adventure, the kit is on its way...

i'm in the same boat with my beater 1987 moto 4 - 350 project, following your progress.

Finally got the carb back together, re-installed - I have no idea what I should be doing with the (air screw?) Up front as far as setting goes.

I heard it take off ONCE with starting fluid pulling the crap out of it before I had fixed the elec start. I don't think any fuel is getting to the engine which makes no sense to me, I know it's getting into the carb because it was damp around the fuel bowl, even with the brand new gasket. going to try and tighten that up. Will try again tonight perhaps and see if the plug is even getting wet.

I don't like basket case projects!! I cant wait to get the ol turd running though...

i hear ya, keep at it i'm sure you'll get it working.

Can anyone coach me on setting the air screw correctly and the "idle" jet (I know it isn't called this - primary perhaps?) correctly on this? Do I have to low speed fuel flow by turning that low speed jet outwards on the inside of the carb? How many turns should I be giving both of these to get them close to factory starting points?


thank you all