She'll start right up with the recoil pull start (with only 1 or 2 pulls) but the electric start is not so easy. It turns the motor over no problem but will not crank unless you choke it (Half Choke or Full Choke). Even when using the choke it's not a guarantee it will crank.

I read here on the forums that if the air space is too wide between the pickup coil and magnet on the flywheel, it could start with recoil but not with electric start. I double checked this just in case and I see no adjustment for the pickup coil as it only mounts in one position.

NOTE: The original issue was no spark. Troubleshooting lead to the CDI. We replaced it along with a new ignition coil, pickup coil, and stator. The old carburetor was gummed up pretty bad and the diaphragm looked worn so we also replaced it and the fuel pump.

The speed limiter and regulator is MIA but according to the schematic I don't see how it's affecting the starter.

Something else that seems unusual; when the motor is warmed up and you choke it, the engine revs up. I would think at full choke it would kill the motor. A vacuum leak somewhere...maybe?

Thanks! WesTech

 

Pulling the choke on a warm engine should choke it down. Check the intake manifold for any cracks,plus should have a 140 main jet and a 40 or 42.5 pilot jet depending on build date. Limiter is better of missing as it caused trouble any way,BUT you need the regulator as it keeps the battery charged. Battery doesn't affect ignition on this model,but does need a fully charged one for the starter and lights. Pick up coil still could be the problem even if it's new. May need to be "tapped" in gently towards the flywheel and then see if electric start works. Her's the original post on one that the pick up was out of place.no spark to plug when using electric starter - Page 3 - ATVConnection.com ATV Enthusiast Community

 

Super Fast Response!

I'm actually using a FatMax jumper box connected directly to the Positive/Negative leads for power. This is of course temporary until we get a new regulator and battery. Super easy to charge up with an AC adapter. I have plenty of power and the starter sounds strong.

Regarding the Pickup Coil, if that is the issue, how can you explain the electric starter working with the choke out vs choke in? Are these two somehow related?

I will check intake manifold for possible cracks.

Thanks!

 

Just eliminate any carb problem,running lean or cracked manifold first. Pick up coil is not related to the starting system whether on choke or not. Only thing is that with the recoil you can actually get a better spark in most cases as you can put more torque on the flywheel than the electric starter can.That's why a lot of 500s especially had this problem as they got older,would pull start easily but wouldn't electric start. Thes engines still had the old magneto triggered ignition system.The Magnum 425 is basically the same engine. If the carb/manifold checks out,just try tapping the pick up coil bracket lightly inward towards the flywheel and see if it helps.

 

I checked the intake manifold and the rubber boot the carb connects to. Everything looks good, no cracks. It starts up every time with the recoil without even choking it. When you flip the choke (Half Choke) it revs up and actually seems to run better although the RPM's are high. When testing the electric start, as you hold the start button in and flip the choke to Half Choke it will eventually start up. I also tried tapping the pick up coil inward as you suggested. It's very sturdy and didn't seem to move at all. I lined the flywheel magnet up with the coil and there's very little gap between the two.

I'm starting to think maybe this is a carb problem. It's a new aftermarket carb ordered online. We've tried adjusting the idle screw on the bottom but that's it. I didn't see any other adjustments. Any further suggestions would be greatly appreciated! We're pleased to get this far considering she hasn't run in nearly 15 years!

 

If this aftermarket carb is similar to the oem Mikuni,should have a block off plug at bottom of the carb at the front of the bowl.This is the pilot or fuel mixture screw for idle purposes mainly and can affect starting also if set too lean. Just drill carefully through the block of plug,use a drywall screw and wiggle the plug out. Count the number of turns to a lightly seated position.If less than 2 turns out,set it to 2 to 2 1/4 turns out.Best to warn the engine up and use a small flat screw driver or carb adjusting tool to fine tune the idle.

 

Here's the carb:

 

It's an Aisin carb similar to the Mikuni,but I'd still check for the block off plug.

 

I located the pilot jet screw but it's a pain to get to with the carb installed. The original Mikuni we replaced did not have a block off plug and I can see the screw. In your experience, does that usually have to be adjusted with a new carb?

I'm a noob to working on carbs and motors so this is a learning experience. I also have another question, non starter related. Can I ask here or should I start a new thread?

 

Kinda figured it didn't have the block off plug as many aftermarket ones don't. Plus if the Mikuni didn't have one either then someone has been messing with it before. I'd still check that it is set at least a minimum of two turns out. May help on starting and idle. That's why they make tools like this.http://www.ebay.com/itm/Motion-Pro-Carburetor-Pilot-Screw-Adjustment-Tool-Carb-Air-Fuel-Mixture-Yamaha-/201339804052?hash=item2ee0c99994&vxp=mtr