1999 Yamaha 350 Big Bear 2 wheel - NO SPARK

[thatoneguy12345]

Hello All, 

 

Just got my hands on a project ATV. Its a 1999 yamaha big bear 350 2 wheel drive only. I thought I had a manual to diagnose everything, but the numbers are not seeming to match the manual I found online. I have replaced the coils based on the original diagnostics I completed. I can not seem to find an accurate manual for this bike. Anyone help? 

 

I'm trying to get a wiring diagram that actaully matches the correct wire colors on this bike to assist in diagnostics. 

 

Thanks! 

[Mech]

Yeah they are rather difficult to get a good match with the wiring diagrams and the actual bike quite often..  You need to get the full definition model number..   One way to do that is to use some online parts place like partzilla and look into all the models of 1999 big bear 350..

Here's what they say came out in that year..  https://www.partzilla.com/catalog/yamaha/atv/1999

What you need to do is start looking at specific parts like the carb, or body work or drive line/shafts, and figure which one you have..  UL, or ULC..  If neither though seems to be exactly like your's, then you should look a year earlier and later....  model years vary around the world. In 2000 your options would be M or MC..  You need that specific M, MC, Ul, ULC....  then we might be able to find the right diagram.

 

[thatoneguy12345]

So based on the VIN, and a few decoders it comes back as a YM350UB. I believe this lines up to the UL version. Is there a diagram with colors for this one available? 

When I try and start the atv, start button does engage the starter, so I'm assuming that means all of the relevant systems to the starter are good to go? Is this fair? Am I only needing to chase the coil, magneto pickups and CDI itself? Is there something else, another relay, that is triggered after the starter to allow the CDI/pickups etc to function and fire the coil? Are there anyways to test the CDI through the PINS? They are $500 now for a new one and awfully expensive to replace unless I'm absolutely sure its bad. For the history, this bike was ran 2 years ago without issue. Parked in a non heated sealed barn. When they took it out this summer, new battery, no spark no start. 

 

[Gwbarm]

You have power to the starter so your cutoff relay is working. You can check your start stop switch to see if its working like it's supposed too. There should be a black to ground and a black and white that goes to the cdi. What I always do when I have no spark , is check to make sure you have 12 v going to CDI should be R/W wire make sure you have a good ground at CDI make sure you have 12v going to coil from CDI orange wire. Check to make sure you have correct resistance at the pickup coil, not sure on the 350 but on the 400 W/G wire and W/R wire, you can also check to make sure the pickup coil is actually putting out voltage as you are cranking. There is no test to make sure the CDI is good, the manual tells you to check all these systems and if they are all in spec and still no spark replace the CDI. I don't have a manual for the 350. I will see if I can find one and take a look to see how different wiring is from the 400 which I am quoting from memory.

[Mech]

Can't find any manual for a U/B/L model..  Looks like you are going to have to improvise..

Some things to check are..

How many wires the ignition switch has, and how it operates. Some are duel circuit and some are single.

The number of wires going into the cdi unit.

The number of wires coming out of the stator.

How the start button is interconnected with the cdi unit. Some feed a 12 volt signal into the cdi unit when the starter is being operated, and others have 12 volt going into the cdi unit and then coming out and to the start button.

If you suss those points it will narrow the likely candidate wiring diagrams down a lot.. 

 

If you can answer as many of those points as possible then I, and probably Gw, will have several different wiring diagrams that might suit.. with a few colour changes.

Oh.. another little trick they like to play, but which helps find the right diagram, is they change the shape of the plastic plugs the wires go in.. They are too hard to describe, but it's worth checking the bike against the pictures in the diagrams you eventually look at.

[thatoneguy12345]

Let me try and get some pictures/details tomorrow. Right now, from the side of the engine, there are 7 wires. 3 white wires go to the rectifier. The other 4 (red, green, white/red line and white/green line) go into a single plug that then go somewhere into the bigger harness all taped together. If I measure Ohms across the green/red there is 300 ohms, but the other 2 wires have nothing. 

When you mention the ignition switch, are you referring to the start button itself? I replaced the ignition coil already with a brand new OEM. Is the VR sensor/stator all a single assembly? I'm assuming 2 of the 4 wires are for the vr sensor, but not sure what the other 2 would be for. Looks like only one pickup (vr) is used on this engine. 

[thatoneguy12345]

Is there an aftermarket stator/vr sensor available if that is the problem? I can't seem to find anything as a replacement.....

[NRA4LIFE]

Hello. I will try to guide you through the steps to diagnose your Yamaha. First off when you check the spark, make sure you are using a new plug or at least one that is working in another machine (sorry, I had to say that). If you still have no spark, then unscrew the plug cap and hold the plug wire a tiny bit from a good ground. Sometimes people are dealing with a spark so weak it won`t jump .025"-.035". If you have confirmed that you have no spark, then In my experience (about 40 years) on these particular Atvs, the mag coils fail more often than anything else. BUT, given the fact it ran when parked in a barn, I would suspect that mice may have damaged the wiring. First off, I would do a continuity test to make sure the mag coils are actually making it to the CDI unit. So do your tests right at the CDI connection. The manual I have for the 1999 shows the source coil (brown to green wires) having 270-330 ohms. The pick up coil (white/green to white/red) should have 460-560 ohms. Let me know what you come up with and I`ll try to respond when I get a minute.

[Gwbarm]

This is the only manual I could find not very impressed with the wiring diagram but it might help. You might have already seen this one.

Key, Wire colors are different from what I quoted you on the 400

 

Sorry for the bad photos I couldn't get it to copy and paste from the manual.

[Mech]

That stator has three lots of cdi windings Gw..  It's not the right diagram.

[Gwbarm]

I wasn't sure it's the only one I have been able to find for the 350 I thought it would be easier to find than the 400. 

[Mech]

Yeah 350 doesn't seem to be well supported..  I dare say some other model will be wired the same way..  but which one ..

If the OP lets us know the answer to the questions earlier, I'll post up the diagram options I have..

[thatoneguy12345]

NRA4Life, on the white plug in the image below, I have 300 ohms between the left (brown and green). I have nothing on the right which is the two white/red white/green wires. Is this the VR sensor that has gone bad? From what I can find online the stator and VR sensor (pickup) were made together.... Any thoughts? 

[thatoneguy12345]

Here are some other images of various plugs etc on this atv. There are 10 wires that go into the CDI. 3 in one plug and 7 in the other. I checked them all for voltage when the ignition switch was on. I had 11.9 volts on one wire and 0.4 V on another wire. battery was reading 12.25 at source. 

[NRA4LIFE]

The W/R to W/G should show 460-560 ohms, so that is a problem. Yamaha (and others) call that a pick up coil. As far as Yamaha is concerned it`s all one piece, but if you are good at soldering you can get a quality 500 ohm pick-up coil from Ricks Motorsports (part # 21-503) and install it. I have used Rick`s products for decades and they are very good quality. Don`t waste your time on a Chinese stator or pick up coil, they are usually junk. One nice thing about that engine is, the stator is mounted outboard of the flywheel and not under it. This keeps you from having to pull the flywheel. It can be patched in either inside the engine or by running the wires through the rubber grommet where the wires exit the engine cases. If you go with Rick`s coil, because it can work on other brands, the color of the wires likely won`t match. To get the polarity right, I just set the coils next to one another and note what color wire comes out which corner and match that to the new one. Don`t worry, if you get it wrong just switch the wires at the stator plug. If you decide to run the wires through the grommet, you might want to temporarily twist the wires together and confirm spark before soldering them. 

As an aside, I think one thing that was causing confusion was the fact it appears Yamaha only used that stator on the Big Bear 350 one year. The way Yamaha does some of their manuals tends to be confusing. They make a manual and they put all the yearly changes they`ve made at the end as supplements. That machine came out in 1987 and it saw a fair amount of ignition system changes, so you would have to jump back and forth to make sure you are using the correct info, especially on your 1999 model.  

[NRA4LIFE]

One other thing, when you pull the stator cover, disconnect the battery. This helps insure you finish the job with the same number of fingers that you started it with 🙂

[Gwbarm]

Just looking at your wiring it looks very similar to the 400 I have been working on, but you do have a few different color wires than I didn't have. The W/G and W/R did go to the pickup coil and you should have had some resistance there, your stator plug looked the same as the 400, pick up coil is attached to the rest of the stator. 

[thatoneguy12345]

Thanks team! I will work on replacing the pickup coil. Has anyone heard of parts by a company called "DB Electrical" https://www.amazon.com/gp/product/B0081S8OP6/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1

The RIcks coil is about the same price as the one above. 

I had a Kawasaki Vulcan where I had to replace the pickup coil. One of the modifications that was made based on forum recommendation was to relocate it closer to the pickup on the flywheel. Is there a recommended distnace to measure between the flywheel and the pickup iron core itself? 

[Mech]

I  don't think those resistance figures are right.

I've never seen a cdi charge coil that had more than about 1.5 ohms. The trigger coils are often between 80 and about 200 ohms.

Those high resistance figures are for a different stator in a different model.. A model that has six cdi wires comimng out of the stator.

That system you have there should have one high resistance, which will be the trigger coil, and one very low resistance, which will be the cdi charge coil.

 

[Mech]

Those figures are only right for the ignition systems using three cdi windings.

All the two winding systems use figures more like what I say.

I'd recheck that coil that seems open circuit.. It might only have .085 to .1 of an ohm..  It's possible that a cheap gauge might not register it..

[NRA4LIFE]

Mech, with all due respect those figures are correct for a 1999 model. I took them right out of a factory Yamaha manual using the 1999 supplement. The lower ohm readings like you have observed are for newer machines. Rick`s also has a 500 ohm pick-up coil listed for a 1999 Big Bear 350. https://ricksmotorsportelectrics.com/Trigger-Coil:-500-OHM-21_503

[Mech]

OP..  before you condemn that stator you should try this..

Disconnect the battery's negative lead. Disconnect the stator plug. Run a wire from the negative battery terminal to the white/green wires and then use your volt gauge from the battery's positive to the white/red wire and see if it shows voltage..

If it shows voltage then there is continuity and the windings are probably ok.

[Mech]

Nra, I looked that manual up and those figures are for a stator with six wires coming out of it, this stator only has four wires for the cdi.

Could you have a look at the wiring diagram in the manual you have and confirm it has four wires for us.

And OP, you could also use two pins and poke them into the dud wires just a little way down the wires to check it's not a break right near the terminals, or dirty connections where the wires crimp into the pins.

I checked the accuracy of my middle of the price range multimeter, and the specs say it's accurate within .7%..  Which means a figure of only .018 might not register.  We should always try and confirm any conclusions we come to when diagnosing, with another system of checks or tests.

 

[Gwbarm]

Those are the same coil specs for the 2000 and it is a 6 wire CDI.

[Mech]

Yeah that's what I found, right specs, for a different stator than the one we are working on !

Or are you saying this bike is a six wire stator ?

Haha..  I'm getting confused here..

[Mech]

Nope.. post six says it has three white to the rectifier, and four to the cdi.. 

All my manuals, and experience, tell me that should have two wires with very low resistance, and two wires with higher resistance.

[Gwbarm]

Just reviewing the photos the CDI has 6 wires in one plug and 4 in the other.

[thatoneguy12345]

My multimeter has a continuity checker which sends an amerage through it to see if it comes back. If the two  W/R W/G were still whole it should have beeped. It did not beep as it does even with extremely low resistance. Based on what you were mentioning that it should be extremely low resistance, that would be approximately the same resistance as 1 ft of 12 gauge copper wire (1.5ohms per 1000 ft). It beeps with this test of copper wire. I plan on opening the stator cover tomorrow and check much closer to the pickup. Any tips/tricks for opening this cover? Could not find a youtube video for this particular year. Seems like this ATV is a tad of a frankenstien. 

 

NRA could you post the wiring diagram/manual for this ATV? Seems like as I continue to have to do other maintenance I will continue to run into a lack of documentation. 

[Gwbarm]

This is the CDI wiring on the 2000 model

 

[thatoneguy12345]

Definately pretty different. The plugs don't match either for the CDI. The 2 plugs are a 8 pin and 4 pin. For what ever reason, they have 7 in the 8 pin (there is a yellow/black wire hidden in that picture. ONly one pin is empty) and in the other 4 pin, 3 wires are there. All three are from the stator/pickup and the other wire is in the 8 pin plug.