tri z gearbox

[izzy]

Hi,Im having problems with my 85 tri z 250 gearbox jumping out of 2nd 3rd and 4th gear,im in the process of splitting the cases now but its finding the time,can anyone tell me what i should be looking for when i get to the gearbox

[just ben]

I am not familiar with these engines but I would take a look at the parts that hold the shift drum. It should be a star looking part on the end of the shift drum,a little arm with a bearing on the end the "rides" on the star thing and a spring that holds the arm tight. You should be able to inspect these parts by pulling the right engine cover. If everything there checks out good then split the cases and look for worn or bent shift forks,worn shift drum, worn dawgs on the gears,missing shims. It could be a number of things but my best guess would be the shift drum isn't staying in position.

[3 Wheel Drive]

Perhaps it could be your clutch that needs to be serviced? The transmission is very basic, when i bought my first tri z it was missing 5th gear. Im pretty sure the last owner had the shift forks reversed. You never can tell for sure untill you actually pull it apart and have a look.

Here is a link to my thread, ive got some pics of my tri z being split open.

http://www.3wheelerworld.com/showthread.php/147229-TRI-Z-250...Seized-Motor....Need-Help/page2

When you put it back together read this thread too, it helps with the 5th gear install.

http://www.3wheelerworld.com/showthread.php/144805-tri-z-transmission-problems?highlight=tri-z+gear

It could be that all you need is a new set of clutch plates and springs? Ask Mosh or Raffa they know their stuff!

[izzy]

Thanks 3 wheel the link was what i needed (YOU CANT BEAT PICTURES) is there a knack to splitting the cases without a crankcase splitter

[Bryan Raffa]

Thanks 3 wheel the link was what i needed (YOU CANT BEAT PICTURES) is there a knack to splitting the cases without a crankcase splitter

Heat and a rubber mallet.. start with a sharp thin chisel on the front motor mount hole and at the swing arm pivot hole to get your cases to open up .

if your splitting it.... might as well replace the crank bearings and seals.....

[Mosh]

Thanks 3 wheel the link was what i needed (YOU CANT BEAT PICTURES) is there a knack to splitting the cases without a crankcase splitter
Get a case splitter like this..
http://www.ebay.com/itm/Crankcase-Splitter-Separator-Tool-Motorcycle-ATV-Crank-/110951209865?forcev4exp=true&forceRpt=true

OR
Buy a harmonic balancer puller for cars at your local auto store. They are cheaper but a little harder to use..Like this one below, and then go to the hardware store and buy 2 long 8mm Bolts for the bolt holes behind the flywheel on the engine..

http://www.ebay.com/itm/Harmonic-Balancer-Steering-Wheel-Gear-Puller-Kit-46pcs-with-case-/370651099938?pt=LH_DefaultDomain_0&hash=item564c86f322

You will also need a flywheel puller...Like this.
http://www.ebay.com/itm/1987-2006-YAMAHA-350-BANSHEE-MOTION-PRO-FLYWHEEL-PULLER-08-0026-/330796246873?pt=Motors_ATV_Parts_Accessories&hash=item4d04fe2759&vxp=mtr

Remove your flywheel on the shifter side with the special tool and an impact air wrench. Once the flyhweel is off you will see 2 bare holes near the crank bearing.
Install the Harmmonic balancer puller tool, with the longer bolts, or the case splitter tool, and drive the center forcing bolt with a hand ratchet while gently tapping the rear of the cases with a rubber mallet to keep the cases even during removal..

When you are ready to reassemble, get all your trans cluster in and make sure it shifts correctly apply your case sealer to one half..I put the crank in the freezer for a few hours. It shrinks the crank and lets it drop right in the new bearings much easier. when you are ready to install, get the frozen crank out and set it in the right case half with the trans cluster installed, and lightly tap the crank into the new bearing before it thaws out. Then install the left case as quickly as possible and tap it with a plastick mallet until you can use the case bolts to pull the cases together. Once you torque the case bolts, gently tap on bothe ends of the crank shaft to center it up in the cases so it spins nice and free.

Use these vids also I posted in this quote also before starting the job..They will help alot..


I see alot of questions from guys new to ATV's on how to Rebuild your engine,or install a new crank or splitting cases.
I stumbled across these vids that are very helpful.
Some of the methods used in these vids I dont approve of (Specifically, using a hammer for bearing removal, and torches on the engine),Generally the same results can be acheived safer with a press, and I have never had to heat a case above 130 degrees to install bearings.But there are many VERY good tips here. It is a 3 part series,and applies to many standard engine procedures.

Gotta Hand it to Rocky Mountain Atv for posting these vids.
Part 1
http://www.youtube.com/watch?v=kYX-bOG9vR4&feature=related


Part 2

http://www.youtube.com/watch?v=vVKeT8Mh2dQ&feature=related


Part 3
http://www.youtube.com/watch?v=ti_UkR3XjyE&feature=related

They dont hit all bases of the rebuild.The common sense things they leave out.
But using this video series combined with the proper service manual, you should be able to do this operation if you are mechanically inclined.
In their related vids links they also cover topend replacement as well.

Hope this helps some of you.

[TimSr]

I am not familiar with these engines but I would take a look at the parts that hold the shift drum. It should be a star looking part on the end of the shift drum,a little arm with a bearing on the end the "rides" on the star thing and a spring that holds the arm tight. You should be able to inspect these parts by pulling the right engine cover. If everything there checks out good then split the cases and look for worn or bent shift forks,worn shift drum, worn dawgs on the gears,missing shims. It could be a number of things but my best guess would be the shift drum isn't staying in position.

X2

Could be as simple as the little screw that holds the roller arm coming off, or a spring popped off. Very easy to check before splitting the cases.