Colasonojon9

On 9/10/2013 at 2:32 PM, Doug said:

Hi, I'm new to the forum but used this site extensively to solve a problem a friend had with his bike so I thought I should at least share a little problem solver I discovered.

He bought the bike knowing there was no spark. He replaced the stator and primary coil also known as pulser coil or exciter coil or rotational etc., as well as the CDI, secondary coil (the one attached to the spark plug wire) along with the wire and plug. Still no spark.

He dropped it off at my place a month ago to see if I could figure out what was wrong. I did all the recommended tests and everything was within specs. I checked all connections and switches, all okay. So everything was perfect but still no spark.

Here's the problem solver, I devised my own test and pushed "Bell wire" beside the positive and negative pins of the primary coil inside the plug of the ATV wiring harness (see below for wire identification) leading to the CDI box. I touched the wires to the ends of a "Double A" battery observing polarity. The spark plug sparked. So I knew right away everything in the ignition wiring was good and there was a problem with the primary coil. So there you go, no ohms and crap to test, you'll know right away where to look for the problem.

I pulled the stator housing and found that the primary coil (or what ever you might call it) was mounted upside down, I removed it, turned it over, remounted it and now the machine runs perfectly.

Here is some info I could not find on line regarding the primary coil:

The after market stator on this machine:

Blue with yellow stripe is positive from the primary coil

Green with white stripe is negative from the primary coil.

ATV wiring harness:

White with blue stripe is positive from the primary coil pin to CDI.

White with red stripe is negative from the primary coil pin to CDI.

I hope this information helps somebody.

I tried this on my 99 big bear 350 2wd and no spark but my wire colors are different  I have white wire green stripe, white wire pink stripe maybe red, brown wire white stripe and green wire to CDI for pickup coil and Source coil

@DirtDemon I am having a similar issue with my 99 Big Bear 350 2wd my stator has three bolts on the inside of the case Phillips head three screws on the outside star bit also has the bearing on the inside of the cover in the middle of the stator I just need to be able to remove the stator so I can replace the source coil still waiting on my service manual to show up  I have attached a picture of my stator

@Rebel50 Rejet the carb i bought a carb new/refirbished from zoom and it came with too small a pilot jet it had like a 25 in it i had a 30 just laying around got better but still not right i ordered the stick size a 42.5 from pjmotorsports huge difference runs like a scalded dog but I have other issues now like stop sparking once hot replaced all coils beside the primary coil only because I can't figure out how to get my stator off and now it only Sparks Once when you first hit the starter anyway hope that helped

Rejet the carb i bought a carb new/refirbished from zoom and it came with too small a pilot jet it had like a 25 in it i had a 30 just laying around got better but still not right i ordered the stick size a 42.5 from pjmotorsports huge difference runs like a scalded dog but I have other issues now like stop sparking once hot replaced all coils beside the primary coil only because I can't figure out how to get my stator off and now it only Sparks Once when you first hit the starter anyway hope that helped

Atached is said crack in starter clutch

@davefrombc update: installed new starter clutch sound is gone. The starter clutch had a crack in it. I imagine thats why it was clacking during turnover. Just wanted to update in case this was helpful. Also changed pick-up coil and ignition coil. I have the primary/source coil but cant figure out how to remove the stator need to be able to flip stator over and tap the source out cant find any info anywhere. Do i need a special tool dont want to break stator windings. After assembly without changing source the bb only sparks once when you start to turn over wil spark once everytime if you wait a few sec inbetween engaging starter. Please help 

Well i never 100% figured out the grinding after removing stator cover and replacing starter but i do know what the loud clack is its one way bearing i turn magneto by hand and seems to work correctly then i enguage starter and hear sound clack the magneto/flywheel lock both ways deffinately the bearing.

Just to touch base ended up ordering the stock pilot jet for the brand new carburetor size 42.5 at least 2 sizes bigger than what was in carb brand new i can actually drive now still trying to tune carb in after about 20 mins of riding it wants to shut off and not start but this could either be float level or electrical heat problem ill keep you guys posted

On 11/26/2017 at 9:12 PM, davefrombc said:

I don't  think  the idler  gear  could  fall  out  without the  cases  being split apart.  If   you  couldn't find anything else loose in there  that  could  have  fallen  down  and interfered  with rotor  and one  way  clutch  behind  it . I  don't  know where  the noise  would  have been  coming from..  As  I  said, I've never  had to tear one  apart,  so  I can  only  make semi-educated guesses  from  my  automotive experience.  Try  rotating  the  gear  train  that  makes  the  clutch  engage  to   start  the  engine  and  see if  you  notice  any   noise or roughness there ..  I  doubt  it  will  engage  the motor  and  lock up  to  start  since the  rotation speed would be  so  slow  and  I  think the  one way  clutch  would  need a  fairly  fast rotation to  engage.

Ok so installed my starter works fine also after reassembling the grinding is gone but there is still a clack that has been there only hear when turning over and when engine stops i think i read where this is the one way bearing i have a short video of the sound its louder in person

 https://youtu.be/ePrM0Gm8TaM

New starter came in but havnt been able to get running yet. Also i thought new starter motor would stop and it still has same sound i have a video to help 

On 11/25/2017 at 10:11 AM, davefrombc said:

Likely  something  in the   gearing for the  starter.  That would  be  why it was  locking  up  with the  starter in place.

Okay i think this may have been partly human error on my part. I took the casing off the left side and one of the starter idler gears just fell out. I could be wrong but when i took the innerds of the starter out because the magnets inside the starter were swolen and causing the starter to clack and make alot of noise. I put the rest of the starter back in so it wouldnt leak oil. Without that piece inside starter would it be possible for one of the idler gears to fall out making said grinding noise i attatched photos and i dont see anything else that could be making that noise. I will be ordering a new starter tomorrow along with a new gasket for the cover, please let me know if im correct and headed in the right direction thanks

Okay havnt been able to solve previouse post about carb because before i could my starter locked up, ended up having to remove guts of starter to be able to use pull start, too much resistance with guts still in starter. Finally got it to start after this and installing air box and it started good about the third time i pull started now there is a nasty grinding sound on driver side seems like behind clutch adjustment going to tear down tomorrow and take a look any ideas?

17 minutes ago, davefrombc said:

I  haven't  had  to  mess with  the  ignition and  cam  timing  on a  quad  motor so  I  cannot be sure ,  but I believe  the  sprockets are  keyed to the  shafts  and  are  not adjustable.  I  believe  about the  only  thing that  could take  them  partially  off  center  would be  wear  on the   sprocket teeth  and  chain stretch..   Neither  should  have a  great effect  on the  timing and  how  the  engine  responds..  If  the  chain  jumped  a  tooth or  more due  to  wear  and  a  loose  slack  adjuster, I  believe  the  timing  would be  much  farther  out and the  motor  would  be  greatly effected  at  all speeds from  idle  up.

I  don't  believe  that  is  your  problem. The  most likely  is fuel  problems , with  a  much  less likely possibility  of weak  spark.

 okay that's good to hear I was rather gun-shy about messing with it anyway I like to know exactly what I'm doing before I go messing with something and the chain is very tight so I doubt it could have slipped anyway never know though. Of course my starter had to go out and I'm having a little difficulty pull starting so kind of at a standstill thanks much appreciated

20 hours ago, davefrombc said:

It  sounds like it is starving for  fuel..  I'd start  by  adjusting  the  idle  air screw.  Start  at  about  1  1/2  to  2  turns out from seated.  and  try  in 1/4 turn  adjustments  out  or  in  to  see  if that  cures the   idle  and accelerate from  idle  problem ..  also  check  for  air ( vacuum)  leaks.  If  that  doesn't  do  it  then    I'd  suggest   taking the  carb  apart  and recheck  float  height and  carb jets  and  passages  for  blockages. . Even a brand new  carb  could  hacve  some  manufacturing  debris in  it ,  and  rebuilt  could  have  a missed blockage or float  height set  wrong .

Okay I just wanted to get a good idea where everything was this morning so I started with the timing checked it, it looks like it's about 1/16 or 1/8 off is it as simple as removing the center bolt in the Top Gear and then turning the gear without turning the chain that far and bolting it back up

Thats where i was thinking of starting, the mixture screw i mean. Gonna count how many out the screw is from the factory first. Just so i can reset if need be. I also bought new screw for intake boot incase vaccume leak there. Didnt have an air box on idk if thats considered an air leak being after the carb an all but i got one now havnt started with it yet. Just trying to give all the details

I purchased and installed new zoom zoom carb on my 99 big bear 350. It starts alot easier where it used to start once or twice then you would have to wait awhile. But it needs at least half choke to run if you cut off choke it slows idle all the ways down until it dies. I tried turning in idle screw but just makes it harder to start. Also with half choke on i put in gear and it will go if you barely hit throttle anything past that it cuts out, any ideas?

12 hours ago, davefrombc said:

Downloads ok with  Firefox  too,  and opens with  my Adobe  Acrobat  no  problems. It  should  open  without  problem  in  any  .pdf reader.

Idk why im downloading via chrome and it says cant open file every other one i try works but stil im looking for 99 yfm350ul service manual with detailed description of procedures. ( dissasembly, adjustments, and reassembly)  the 4x4 man is for yfm350fml not the same as mine thanks for helping anyway fellas.

2 hours ago, Ajmboy said:

Looks in the Downloads section. There is this:

 

That one wont open in acrobat and its the 4x4 model idk if thats the same as the yfm350ul

Thanks i must have over looked it 

Hey looking for 1999 yamaha big bear 2x4 repair manual