Yamaha Grizzly and Bruin 350 repairs

[BruinBeater]

I got asked to work on a pair of Yamaha 350's.  One has grizzly stickers, one has bruin stickers.  Both are 2wd, straight rear axle.  Not sure what year.  I'd guess '04-'08.

Both have a no start condition.  Both have been sitting 2+ years.  One came with box of parts the owners 15 year old kid removed to try and get it running.

Started working on one last night.  Pulled the rack, front plastic, fuel tank, recoil starter, carburetor.  

Removed petcock from tank, cleaned screens, made sure if flows air, reinstalled.

Drained fuel tank, put in fresh fuel, swirled it around, letting is soak and will drain and check it later.

Cleaned up the motor a bit since its covered in mud.  Checked the valves.  The intake had less zero, actually, probably less than zero clearance.  The valve seems like it was hanging open just a touch even at TDC.

The exhaust had maybe .004 clearance.  I assume that went to zero once running.  

Adjust intake to .008.  Adjusted exhaust to .018

Scrubbed the carb in a sink with a toothbrush, dawn, and water.  It looked like a mudball.

After that, sprayed it down with carb clean and took it to the bench.  A/F screw was 1.75 turns out.  I'm thinking this is a factory setting.  It seems like this machine was never touched by a mechanic.  All the jets actually seemed clear.  The bowl had minimal residue in it.

That about as far as I made it for the night.  Going to get a fresh plug, clean the air filter, add some fresh gas, and see if it will run.  If so, I'll probably clean up the oil cooler before putting it back together.  Maybe change the engine oil  and rear diff fluid too.  

[Gwbarm]

Grreat work! Sounds like you have got it ready to go, hopefully it has spark and you will be up and running.

[BruinBeater]

Got a chance to work on this again.  Put the carb back together.  Cleaned up the boots on both sides.  Installed carb.  Dumped the fuel that was sitting in the tank.  Looked and smelled bad.  Put some fresh in and swirled it around a bit and dumped that.  Came out looking ok this time.  Threw the tank on, put a lawn tractor battery in the storage box and hooked it up.  Hit the start button and it fired right up!  Fuel was leaking everywhere.  The float was stuck and the bowl drain tube fell off.   I shook the bike to see if that would dislodge the float.  No luck but when I shake the bike, it bogs down severely.  Weird.....  

Tap on the carb a bit with a screwdriver handle and it quits leaking fuel.  1 problem solved.  Cut a 1/2" off the drain hose and reinstall.  Now it wont fall off.  2 problems solved.  I was scratching my head over the bogging when shaking the bike deal.  Even if I just gave it a little jiggle with the handlebars it changed how it ran.  After staring at it a few minutes I noticed that the choke cable is pulling out of the boot that screws into the carb.  Surely this can't be the issue.  I pushed the cable back in, started it up, and the bogging went away.   Took it for a test ride and adjusted the A/F screw a bit.  By now, its running pretty good.  I cleaned up the oil cooler, pulled it back in the garage and changed the oil, the diff fluid, and started putting the plastic back on.  

Time to move on the 2nd quad.

[Gwbarm]

You have been busy, Great Work, you came out lucky, a lot of these bikes  get neglected so long people just dont want to mess with them and sell thgem for cheap.

[BruinBeater]

While working on quad #1, I found that the rear brake shoes need to be replaced.  The lining had totally come off the shoes when the drum was removed.  I found a set of NOS EBC shoes for $20 shipped! 

While the shoes are in transit, I pulled it out of the garage and pulled in quad #2.  I gave it the same treatment.  New plug, carb clean, valve adjust.  Test run went well, its a bit cold blooded compared to quad #1.  Maybe I'll back out the AF screw a bit to see if it changes anything.  #2 needed front pad, they were totally gone.  Rotors are actually scored a bit.  Found the lower A-Arm took a big hit.  Its all bent up.  Don't want to take a chance of a malfunction when kids are riding it so I recommended replacement.  Bought a new one and 2 new bushings.   Ended up buying new air filters for both machines.  They are pretty dry rotted.   

 

Took a look at #1 and noticed a tiny drip out the carb overflow.  So I ordered a new needle and seat for it.

 

Waiting on parts now.  

[BruinBeater]

Rear brake shoes and the needle and seat came in for machine #1.  The rear shoe swap went easy.  I always cut the old springs out.  Cleaned up the posts that the shoes swivel on, and the cam that rotates to spread the shoes.  Applied molybdenum paste to those surfaces.  Cleaned out the drum.  Cleaned the splines, applied molybdenum paste to the splines too.  Brakes not only work, but the shoes retract now so, no more drag.

Pulled the carb, replaced the needle and seat.  Love these carbs with the set screw and o-ring to hold them in vs pressed in seats.

Reset the AF scre to 2.25 turns out.  I previously adjusted it when it was idling weird due to the choke cable boot not being in place.

Felt confident enough to put it all back together vs be testing it with the fuel tak sitting there. Turned on the gas and it was leaking everywhere!  I forget to install the float bowl drain screw.  I removed it to polish up the tip with some maroon scotch brite.

Put that back in and then started it up.  Runing great, stopping, and no more leaking from the overflow hose.  I parked it outside overnight with the drain hose on the floorboard for easy detection.

New A Arm, bushings, air filters and some misc stuff got delivered this AM. Will probably wait till Tuesday to install all that then hopefully be done.  We'll, not true, 1 needs a battery for sure.  One is still working but its 5 years old.  Figure ill just swap them both 

 

Edited August 30, 2025 by BruinBeater

[Gwbarm]

Excellent, sounds like you are moving right along with no problems.