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Orvis25

Trx300FW - Timing Chain Replacement Takedown Guide (Right Side Crankcase & Rocker Box)

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Posted (edited)

Howdy everyone, 

 

Bringing you all another tutorial, this time on how to disassemble a 1994 Trx300fw right side crank case all the way down for a timing chain replacement. 

Special thanks to @shadetree for guiding me though this process when I did mine, now I will be paying it forward in the form of a guide for all to use. 

 

Note: This guide is mainly for those who need to do a timing chain replacement, and need to take the right side crank case apart for that purpose. It can be used for general disassembly help, but keep that in mind as that is how I will be structuring the steps for disassembly. 

 

Ok with that said, lets get started! 
 

Note:
I do not remember everything exactly, so there may be some missing info in the explanations.
Take this guide as a addition/alternative to the manuals break down of disassembly in some ways. Some details like bolt sizes may be updated over time. 

If you find an error, please PM me and i will change it (do not clog up the thread with the corrections)
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Tools: 
metric wrenches and sockets (8, 10, 12 and 27mm)
Impact
Gasket scraper
Flathead screwdriver
Clutch puller 

_____________________________________________


Step 1) 
Unbolt and remove the timing chain automatic tensioner (located on front right side of the engine jug)

                         - 2x 8mm bolts + 10mm head cover. insert flathead screwdriver and turn to the right to retract the tension rod. 

Remove the front bumper, and plastics, and airbox plastic feed tube. 

 

1.jpg

 

2.jpg

 

Step 2) 
Unbolt the rocker box cover/head (13 bolts) and remove. 
                         - mix of 8mm and 10mm bolts. 

Unbolt the oil line and remove (the black thing connecting the crank case to the head on right side)

 

3.jpg

 

4.jpg

 

Step 3) 

Unbolt the 2 bolts on the cam sprocket (10mm) (you will need to turn the engine, to do this, use the 8mm allen wrench (or socket) on the inspection port for the electric starter and turn to the right)
                         - Do NOT drop the bolt in the engine. I recommend stuffing a rag in the gap just in case. 

Once unbolted, slide the sprocket forward, so the sprocket drips down onto the lower part of the cam shaft, which will allow the chain to be loose and come off the sprocket. 
Take the chain, and using metal wire, string it tightly to the frame so it will not fall into the engine. 
Then remove the cam and sprocket assembly. 

 

5.jpg

 

 

6.jpg

 

Step 4) 
Flip ATV onto its left side, so the right crank case is up. 

Unbolt the right footpeg (12mm) and swing the foot break out of the way (I recommend unhooking the cable too)

 

7.jpg

 

8.jpg

 

Step 5) 
Unbolt the 4 bolts covering & holding the neutral, reverse and temperature sensors. (8 & 10mm mix) 

Once unbolted and loose, remove (unplug) the sensor connectors and tuck to the side. 
Remove kick starter from its shaft (12mm)

 

9.jpg

 

10.jpg

 

Step 6) 
Unbolt the right side crank case (all 8mm)
Remove right crank case cover
                         - Important! Keep pressure on the kick starter shaft as you pull the case off. DO NOT LET IT MOVE AT ALL.

                           If it slips outward (with he case as you pull it off), there is a very high chance the washer on the back side will fall off the shaft and into the center part of your crank case.

                         See This thread I made on how to recover the washer without pulling the engine if you do mess up. 

Remove the observe the shifter orientation and the triangle shifter system over the secondary clutch. (note that the dot on the shifter shaft lines up with the arrow on theface of the case for reassembly) 

 

11.jpg

 

12.jpg

 

Step 7) 
Remove the primary clutch nut (27mm bolt) with an impact. This is reverse thread, so right is loose, and left if tight. 
Once the nut and washer is off, use a clutch puller to pull the assembly out.
Remove the assembly cup.
Unbolt and remove the splash flap/guard (2 bolts)

 

13.jpg

 

14.jpg

 

15.jpg

 

Step 8 )
Loosen the 4 bolts (10mm) on the secondary clutch in a criss-cross pattern until you can remove the plate and springs. 
Remove the nut (27mm, normal thread) and washer holding the clutch assembly on.
Pull the assembly out.

  

16.jpg

 

17.jpg

 

18.jpg

 

Step 9) 
Unbolt and remove the internal oil line (10mm)
Unbolt and remove the oil pump (10mm)

 

19.jpg

 

20.jpg

 

Step 10) 
Remove the gear adapter piece.
Untie chain, and fish it out. 

 

21.jpg

 

22.jpg

 

_____________________________________________

And that's it! 


You can now replace your chain with a new one. 

 

I really hope it helps someone else who needs to break their engine down to replace the timing chain. 


Let me know if it helped!
 

This post took quite a while to write up, in addition get the pictures taken, organized, edited, and compressed for this thread. 

So if you like it, how about hitting that like 🙂 


_____________________________________________

Here are some tips for reassembly:
- Make sure to tie the new chain up just like you did the old so when you flip the bike upright to re-install the cam and sprocket, the chain does not fall back into the engine. 

- double check the orientation of the reverse shifter and kick starter shaft before reinstalling the crank case cover. 
- When installing the cam, make sure the piston is on the T mark on the inspection timing port, then install it with the cam lobes down (at the 7 and 4 o'clock position or so). This will automatically make the valves/piston be at top dead center compression stroke (TDCCS) for when you check the alignment & timing of the system. 
- Ensure the 2 hash marks on the timing gear are in line with the top of the cylinder jug edge, and that the punch mark is at the 12 o'clock position. When the piston is at TDCCS, the T timing mark (timing inspection port) should be alighted, and at the same time, so should the 2 lines and the punch on the timing chain sprocket. 

 

_____________________________________________

update: 

So honored to have my post pinned! 

Glad it helped 🙂

Edited by Orvis25
Clean Up & Corrections
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Great write up Orvis.  Thanks for putting that here!

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49 minutes ago, jeepwm69 said:

Great write up Orvis.  Thanks for putting that here!

Glad to help where I can. 

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Posted (edited)

Me again… so I got everything back together after installing the new timing chain. The Kickstarter never came out and it stayed in place(wound up), lined up shifter on the secondary clutch(dot, arrow, the triangle bearing piece) put the reverse lever back on to what I though was correct.
 

The Bike won’t go into any gear and the Kickstarter doesnt have the resistance it did and won’t start the bike. She starts and purrs great just won’t move. Feel like I’m gonna have to go back in the crankcase. 
 

Pretty sure I did something incorrectly.
 

Anyone have experience with this? 

Edited by JR_TRX

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4 hours ago, JR_TRX said:

Me again… so I got everything back together after installing the new timing chain. The Kickstarter never came out and it stayed in place(wound up), lined up shifter on the secondary clutch(dot, arrow, the triangle bearing piece) put the reverse lever back on to what I though was correct.
 

The Bike won’t go into any gear and the Kickstarter doesnt have the resistance it did and won’t start the bike. She starts and purrs great just won’t move. Feel like I’m gonna have to go back in the crankcase. 
 

Pretty sure I did something incorrectly.
 

Anyone have experience with this? 

Well the kick start no resistance sounds like the spring is not under tension. When you pull the crank case back off, put the peg back on the shaft and crank it and look if its under tension. 

In terms of the shifting thing, I am going to defer to @shadetree

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