96 TRx400fw rebuild

[SilentBob 3]

Started work on my 400 foreman today. Got the engine out which is not as simple as the service manual makes it seem.  I've  had this bike for about 3 years now and it always smoked a bit but got worse and finally wouldn't crank anymore. I don't plan on doing a full restoration on this but plans for it is to tear it open and clean it all out, get the head and bore cleaned up with a new piston. And if there's budget left over upgrade the font brakes to disc. 

 

Question for all you experienced guys on here, what tools would you recommend to make life easier with the rebuild? Any recommendations on getting a broken bolt out of a hole? I have some threads sticking up might try welding a nut on it. Also what do you guys use to clean your parts? 

 

Thanks!    

[jeepwm69 7,721]

I still use starter fluid in a spray can to clean out the inside of the crankcases.   It's not cheap anymore, and I have a parts washer, but the starter fluid cuts the gunk better than anything else I've tried.

 

If you want to scrub the outside of the engine down I'd soak it in a parts washer or diesel, and then scrub with a wire brush, then use some alumabright or similar on it.

 

If you're tearing down the bottom end (which probably isn't really necessary if you know the history of the machine, and know it hasn't been sunk), you'll need a flywheel puller and a 3 jaw puller for the centrifugal clutch.  I use a cheap Motion Pro flywheel puller from ebay.

 

If you can weld a nut on the end of a broken off bolt that's definitely the way to go.

 

A 450 jug and piston bolts right onto a 400.  Keep the 400 head and everything else.

 

Also, disc brakes from an 05-11 Foreman, 05-14 Rubicon, or 06-23 Rincon will all bolt on at the ball joints.

[SilentBob 3]

12 minutes ago, jeepwm69 said:

I still use starter fluid in a spray can to clean out the inside of the crankcases.   It's not cheap anymore, and I have a parts washer, but the starter fluid cuts the gunk better than anything else I've tried.

 

If you want to scrub the outside of the engine down I'd soak it in a parts washer or diesel, and then scrub with a wire brush, then use some alumabright or similar on it.

 

If you're tearing down the bottom end (which probably isn't really necessary if you know the history of the machine, and know it hasn't been sunk), you'll need a flywheel puller and a 3 jaw puller for the centrifugal clutch.  I use a cheap Motion Pro flywheel puller from ebay.

 

If you can weld a nut on the end of a broken off bolt that's definitely the way to go.

 

A 450 jug and piston bolts right onto a 400.  Keep the 400 head and everything else.

 

Also, disc brakes from an 05-11 Foreman, 05-14 Rubicon, or 06-23 Rincon will all bolt on at the ball joints.

 

Thanks for the info jeep! As for the history I only know how it was used from the time my father in law owned it and he used to put used motor oil from his truck in it. Though I don't really want to split the case I think it will be better for the long run.

 

For the 450 jug are they available from a reputable brand or is honda the way to go?

[jeepwm69 7,721]

If that's the case, and you feel comfortable doing it, I'd definitely split cases and clean it out then.

 

If you look at my 05-11 Foreman 500 engine rebuild thread, your 400 engine will be very similar.  Not exact, but pretty close to the same.

 

You can get OEM Honda new, which will be $$$.   You can get a used 450 OEM jug and have it bored oversized, which is probably what I'd do.  You'll have to have your 400 jug bored anyway, so the only additional expense would be buying a used 450 jug. 

 

Or you can get new aftermarket which are cheap.  I put one on my neighbor's 450 and it's been fine so far, but he doesn't have a tremendous amount of time on it since the rebuild.   I think @shadetree sent me the link to the one I used on the meighbor's bike.

[SilentBob 3]

Got some more work done on the atv yesterday. A previous owner for some reason drilled a bunch of holes into the bottom of the muffler, took out the welder and made some real ugly welds but hey it closed the holes up. Got the welds and surrounding metal cleaned up just need to get some hi temp paint for it. Tried everything I could think of to get my broken bolt out but no luck so I have some heli-coils coming tomorrow. Also ordered all new oils seals for the output shafts, new DiD chain, gasket set, new honda one way bearing coming from Japan, and random bolts and a bracket. Talked to a guy over at G&H and i'll be sending both the jug and head to get worked on. 

[SilentBob 3]

Got all my supplies in this week, just waiting on the one way bearing from Japan. Split the case today and I'm glad I did. Found a bunch of muck in the bottom of the case and the oil screen had junk in it to. Not sure if someone split the case before as the oil screen wasn't set in the grove on one side.

[jeepwm69 7,721]

Yuck.  Good decision to split cases!

[SilentBob 3]

Finished cleaning the bottom end up and started putting it back together today. Had to stop when I got to the starter gear, I was missing the two washers that go with the gears. It was odd as I had all the gears and pins for it together but no washers. Searched all over the garage for them but never found them so I went through my pictures and didn't see the smaller one in the pics so I'm guessing they were never in there to begin with. I'm more certain now that someone has been into the case at some point. Ordered the two washers and waiting on the head and jug to come back from the machine shop.

 

Any recommendations on break-in oil? Been using shell T6 since I got it but didn't know if its an adequate break-in oil.   

[jeepwm69 7,721]

On 8/24/2024 at 8:00 PM, SilentBob said:

Finished cleaning the bottom end up and started putting it back together today. Had to stop when I got to the starter gear, I was missing the two washers that go with the gears. It was odd as I had all the gears and pins for it together but no washers. Searched all over the garage for them but never found them so I went through my pictures and didn't see the smaller one in the pics so I'm guessing they were never in there to begin with. I'm more certain now that someone has been into the case at some point. Ordered the two washers and waiting on the head and jug to come back from the machine shop.

 

Any recommendations on break-in oil? Been using shell T6 since I got it but didn't know if its an adequate break-in oil.   

 

I use T4 for break in, and then use T6 after break-in.

 

I've heard full synthetic is too slippery for rings to seat.  Don't know if it's true or not, but my T4 break in and switch to T6 has worked well for me.

[SilentBob 3]

4 hours ago, jeepwm69 said:

 

I use T4 for break in, and then use T6 after break-in.

 

I've heard full synthetic is too slippery for rings to seat.  Don't know if it's true or not, but my T4 break in and switch to T6 has worked well for me.

 

Do you use the 15w-40 or 10w-30? What kind of break in procedure do you use? 

[jeepwm69 7,721]

15W40 in the T4, I just ride it normally.  Normal riding for me requires lots of speed changes due to the terrain on our farm, but everyone has their own opinion on break in. 

 

I think the main thing is varying throttle/ engine speed.

 

I put in 15W40 T4 for 50-100 miles, then switch to T6 in 5W40.

 

I think @retro suggested letting the machine warm up for a few minutes, cutting it off and letting it cool down, and doing that heat cycle on and off a few times before riding it for any extended amount of time.

 

[SilentBob 3]

Got everything back together and in the atv but ran into an issue. When I turn the key on the reverse light is on. Doesn't matter if I go up or down in the gears the reverse light stays on. Another symptom is the wheels will not go forward or in a counter clockwise rotation seems like it locks up. Maybe I put the one way bearing in wrong? It will go clockwise in all gears though.

 

Any suggestions?

[jeepwm69 7,721]

The reverse light should be your gear position switch.
Did you align the slot in the rear of the shift drum with the T-shaped post on the gear position switch, when you reinstalled the rear engine cover?

[SilentBob 3]

7 hours ago, jeepwm69 said:

The reverse light should be your gear position switch.
Did you align the slot in the rear of the shift drum with the T-shaped post on the gear position switch, when you reinstalled the rear engine cover?

 

Yes I made sure the longer part of the T was over the N on the switch. After leaving this weekend and coming back to it the light will go off and if I shift through the gears I can get the neutral light to come on for a brief second then goes out. I think the bigger issue is the fact that unless it's in neutral the wheels will not go forward. When I put it in gear and move the wheels forward they move slightly then I hear a click and they will not move forward anymore but they will move backwards no problem.

 

[jeepwm69 7,721]

I think I would ground the light green with red tracer wire which should illuminate your neutral light, allowing it to start.  Then see what you have. 
 

You should be able to roll it both ways even in gear, it's just hard to do when it's not in neutral.

 

you could always pull the front cover and try rolling it and see what you see. 
 

I hope you didn't get a gear in the transmission backwards.  Been there, done that