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Discussion Starter · #1 · (Edited)
I started tearing down my 400AT's engine to check the condition of the internal components. (2990 miles and 895 hours.)

So far, so good. I did find that the exhaust gasket was pretty smashed, so that could be the source of my 'knock'. Everything else so far mics out well within specs. BTW - The engine weighs 111 lbs and it took me four hours to pull it out of the frame while following the manual. I could probably do it in two from now on.

- Clutch has a lot of material left (.112" - service limit is .08") and the clutch drum has no unusual wear or gouges. I've decided not to change the weights/springs.

- All bearings are smooth and notch-free. One-way bearings are also smooth and quiet.

- Chain has stretched slightly, but still serviceable. However, I am going to change it and the tensioner.

- Piston and cylinder head had a decent build-up of carbon. I've cleaned the piston really well and the cylinder head is also better. The piston mics out properly and there has been no blow-by past the second ring.

- Cylinder walls are very smooth and scratch-free. The also mic out to proper specs.

- I'm going to have one of the local Honda mechanics rebuild my cylinder head and add new valves - just for grins.

TIP - Make note of which side each lifter and push rod comes from, and install them back into their original locations when rebuilding.

- The big end bearing has no discernible play, and the crank shaft bearings are very smooth.

- The Hondamatic tranny feels smooth and the bearings are good.

-Oil seals are all in good shape, so I'm going to leave them alone.

- One note - the lower cylinder gasket is stuck really tight. I don't want to scrape with a razor scraper and my plastic scraper doesn't even get close. Any thoughts?

Going to order my parts tonight, so I can get this thing back together. Any input is appreciated.

Melsman
 

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Discussion Starter · #2 ·
Well, I just spent a joyous afternoon scraping some sadist's idea of gasket sealing off of the lower cylinder surface, and the alternator cover. Apparently, they used Hondabond on one side of those green gaskets, which made removal a real bear.

Plus, by using Hondabond on the gaskets and the side covers (without gaskets), they permanently secured the little dowel pins into the case. No big deal, I guess. But scraping gaskets all day is no fun.

Melsman
 

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x2, nice write up! That 111lb's feels a lot heavier when your trying to yank it out of a frame huh? lol
 

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Discussion Starter · #5 ·
Thanks, Manny and Dan G!

Yes - Taking it down was easier than I thought and it does give me peace of mind and the realization that it is supposed to sound like a sewing machine...

And you're right Dan G - the hardest part was pulling that 111 lbs out of the frame and putting it on my 40" high workbench. My 50 year old back wasn't too happy with me.

Now I have to resist the urge to mess with it too much while I wait for parts!

Melsman
 

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Discussion Starter · #6 · (Edited)
Update...

So, here's how things are going -

- Parts should finally get here on Thursday. Engine sub-harness was holding up the order. I had found the dust seals on the harness had cracked pretty badly, so I figured for $21 I should replace it. Well, it delayed the order for five days.

- Used the 3 1/2" (89mm) Flex-hone (ball-hone) today (discussed here) and honed the cylinder with some light-weight oil. Came out pretty good. (The camera flash really reflected off of the hone marks. They're really not as deep as the picture makes it look.) I decided not to use a three arm hone first - would've been overkill for a light hone such as this. Plus, my cylinder was not out of round, so it wasn't necessary. The ball hone made short work of the carbon band around the squish zone on the top of the cylinder.

As for technique, basically, all I did was coat the ball hone and the cylinder walls with light-weight oil (3-in-1 oil in my case), chucked-up the hone in my drill (on low speed), started it spinning BEFORE inserting it, then ran it in and out of the cylinder bore for 30 seconds - about one complete in-and-out stroke cycle per second. That gave me the roughly 60 degree cross-hatch. Each stroke had the hone exit the cylinder ends by about 25%. Then, on the last stroke, while the hone was still spinning, pulled it out of the cylinder. Then I cleaned the cylinder walls with soap and warm water, dried it, and re-coated walls with the light oil.

- Decided to lap my own valves (might as well learn...), so I took apart the head and cleaned the carbon out of the head.

- Cleaned the carbon deposits off of the piston top and the cylinder head with a brass dremel brush and light oil. I also used some 600 grit wet/dry sand paper with light oil to finish the job. There's a small dent mark on top of the piston that lines up with the sparkplug hole. Not worried about it, but it makes you think, "hmmm..."

- I'm using a 75-25 mix of engine oil and lucas stabilizer as an assembly oil, as well as a 50-50 mix of moly grease and oil (as stated by the manual). I've been dribbling some assembly oil in the bearings to keep them oiled while I wait for the parts to arrive.

Should be able to get this thing back together by the end of this weekend. Or did I just jinx myself?

Melsman
 

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So, here's how things are going -

- Parts should finally get here on Thursday. Engine sub-harness was holding up the order. I had found the dust seals on the harness had cracked pretty badly, so I figured for $21 I should replace it. Well, it delayed the order for five days.

- Used the Flex-hone (ball-hone) today and honed the cylinder with some light-weight oil. Came out pretty good. (The camera flash really reflected off of the hone marks. They're really not as deep as the picture makes it look.)

- Decided to lap my own valves (might as well learn...), so I took apart the head and cleaned the carbon out of the head.

- I'm using a 75-25 mix of engine oil and lucas stabilizer as an assembly oil, as well as a 50-50 mix of moly grease and oil (as stated by the manual). I've been dribbling some assembly oil in the bearings to keep them oiled while I wait for the parts to arrive.

Should be able to get this thing back together by the end of this weekend. Or did I just jinx myself?

Melsman
your cylinder looks great too me !. as for scraping old gaskets off ?.( base gasket is what your talking about ? )....i scrape mine off with a razor blade..works pretty good for me..ya just gotta be real careful !..lol. you can also buy some gasket removing stuff in a can from autozone..advanced auto parts..napa..ppl use it..me ?..i've never had any luck with it !..maybe it was too old ?..don't know !. in a few day's..i'll be doing the same thing to this '05 trx400FA at the shop !..lol.
 

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but i'm doing mine in the frame !..lol.
 

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Discussion Starter · #9 ·
( base gasket is what your talking about ? )
Yes- Hondabond on one side made it a real bear to scrape off. I also had to use a razor blade scraper.

That flex-hone really made short work of the honing. Worked really well.

Doing all of this in-frame would be a PITA!

Melsman
 

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( base gasket is what your talking about ? )
Yes- Hondabond on one side made it a real bear to scrape off. I also had to use a razor blade scraper.

That flex-hone really made short work of the honing. Worked really well.

Doing all of this in-frame would be a PITA!

Melsman
i did not see any hondabond on the base of the bike at the shop i tore down today ????..just a base gasket. and noooo..you can't do all the work your doing if your getting to the front and back ?..then yes...it's easier to pull the motor..but with the one i'm doing..it's just the cam chain...and top end rebuild....so far !!!..lmfao.
 

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I should have said... Doing ANY of this in-frame would be a PITA! LOL!
it's not as bad as you think..not for the back part anyway...they don't give you much room in the front side of the motor..but the back side ?..easy..once the swing arm is droped..it's all down hill from there. and the cylinder is easy to work on also with the motor in the frame..i did not have any trouble removing the top end.
 

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Discussion Starter · #13 · (Edited)
well, crap!

I did jinx myself!!

I was prepping my case covers tonight, cleaning everything up in anticipation of getting my parts tomorrow (or so FedEx tracking says...). I started spinning through the bearings, dribbling a little oil on them and double-checking, still kinda wondering what the noise was that I heard when the engine was last run. Sounded a bit like a bad bearing to me, but upon inspection, none of the bearings were notchy or noisy... until tonight.

As I spun the large bearing that supports the front of the hondamatic (pump side), I noticed that it made a faint metallic "scraping" sound. I turned down my music and noticed that the sound was fairly pronounced. How the heck did I miss that? This was definitely the sound I had heard coming from the engine. But the bearing still felt smooth - although it was noisy. Then, I put extra inward pressure on the inner race and, yep... there they were! Notches! I could feel them plain as day. The bearing is bad! Crap.

Now I get to wait another five or six days for a $53 bearing (that I got for $39 to my door. But I gotta wait...)

Geez...

Melsman
 

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I was prepping my case covers tonight, cleaning everything up in anticipation of getting my parts tomorrow (or so FedEx tracking says...). I started spinning through the bearings, dribbling a little oil on them and double-checking, still kinda wondering what the noise was that I heard when the engine was last run. Sounded a bit like a bad bearing to me, but upon inspection, none of the bearings were notchy or noisy... until tonight.

As I spun the large bearing that supports the front of the hondamatic (pump side), I noticed that it made a faint metallic "scraping" sound. I turned down my music and noticed that the sound was fairly pronounced. How the heck did I miss that? This was definitely the sound I had heard coming from the engine. But the bearing still felt smooth - although it was noisy. Then, I put extra inward pressure on the inner race and, yep... there they were! Notches! I could feel them plain as day. The bearing is bad! Crap.

Now I get to wait another five or six days for a $53 bearing (that I got for $39 to my door. But I gotta wait...)

Geez...

Melsman
don't ya just love working on it though !!!!...lol. i feal your pain bro..i reallyyyyy do !..try going though that bs noise i had with my rancher..and 100 bucks later..i find out it was the valves and valve seats !..lmfao..i tore that damn back in apart prob 5 times ??..and still heard it after it got hot !!..then i decided..hell..only thing left is the damn head !..lol..changed it out..noise was gone !!!!..sooooo..your not the only one to find these odd noises !!..lmfaoooo. it's allllll part of working on these...now you know why dealer ships charge out the ying yang for working on them !..lmfao.
 
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That stinks! But I'm glad you found the problem, most people would have over looked it, reassembled and ended up with an engine failure shortly after, so thats awesome you were able to catch it!

Let me know how you do lapping the valves and the difficulty of it. I've been debating to do it myself or to bring it to a shop to have it cleaned up and inspected...
 

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Discussion Starter · #16 ·
I think the parts will be here today, but I'll probably start lapping the valves on Saturday. I'll post my progress... or lack thereof!

I'm also finding trash in some of the other bearings (mostly in the rear cover subtranny bearings), so I'm going to pull the bearings and flush them out and make sure there's no permanent damage. I think that small Hondabond pieces have been floating around in the oil. There's a significant amount of "over squish" Hondabond that I've been peeling off of the case joints. The vast majority held together on the case halves like it's supposed to. But I dug out some Hondabond that had been forced into the oil transfer collar when the rear cover was last placed on the case. I found more Hondabond blocking a small oil feed orifice in the stator cover oil galley that was downstream from the oil transfer collar.

So, I'm taking my time and really going through this thing again before I put it back together.

Melsman
 

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Discussion Starter · #17 · (Edited)
Now I'm getting paranoid...

I thought I had done a good job of checking bearings...

Last night, I start spinning the other case bearings. I end up finding five more(!) bearings that where questionable. So, I pulled the bearings and cleaned them. I found three that were bad (mostly the subtranny bearings) and two that were questionable. Now, the bearings weren't horrible, but they definitely had rough spots. So, I ordered all five... why take a chance?

I received my Athena complete gasket set today, and I'm a little disappointed. The gaskets are good quality (and no end cover gaskets, Shadetree - you were right.) There are o-rings that I don't think I'll use (we'll see), and some that weren't included, i.e. the little o-rings on the oil galley collar going into the cylinder head and the oil collar on the rear cover. Plus, they included the cyl head crush washers, but nowhere did they mention that, so I had ordered additional.

And the real head scratcher... four valve stem seals - for two valves?

Anyway - I'll compile a list once I'm through so that others will know what the kit contents are.

****** UPDATE

Not real happy with the completeness of the Athena Complete Engine kit. (see photo) I couldn't find homes for about half of the o-rings, and it didn't include ANY of the internal o-rings nor the shifter fork gasket! Luckily, I was able to find o-rings that weren't included in the kit at my local hardware store. But hey... At least I have two extra valve stem seals.

Can't recommend this rebuild kit.


Melsman
 

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I thought I had done a good job of checking bearings...

Last night, I start spinning the other case bearings. I end up finding five more(!) bearings that where questionable. So, I pulled the bearings and cleaned them. I found three that were bad (mostly the subtranny bearings) and two that were questionable. Now, the bearings weren't horrible, but they definitely had rough spots. So, I ordered all five... why take a chance?

I received my Athena complete gasket set today, and I'm a little disappointed. The gaskets are good quality (and no end cover gaskets, Shadetree - you were right.) There are o-rings that I don't think I'll use (we'll see), and some that weren't included, i.e. the little o-rings on the oil galley collar going into the cylinder head and the oil collar on the rear cover. Plus, they included the cyl head crush washers, but nowhere did they mention that, so I had ordered additional.

And the real head scratcher... four valve stem seals - for two valves?

Anyway - I'll compile a list once I'm through so that others will know what the kit contents are.

Melsman
I've got 4 valves, and my kit had 3. :dry: Got one to spare? lol I ordered up some anyways, I wish they would list whats included, I have a bunch of extra parts just like you...
 

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Apparently, they used Hondabond on one side of those green gaskets, which made removal a real bear.
Yeah, on some of those gaskets, the gasket comes with sealant already on the gasket in certain places. It's used in places on the gasket that are prone to leak.
 

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your cylinder looks great too me !. as for scraping old gaskets off ?.( base gasket is what your talking about ? )....i scrape mine off with a razor blade..works pretty good for me..ya just gotta be real careful !..lol. you can also buy some gasket removing stuff in a can from autozone..advanced auto parts..napa..ppl use it..me ?..i've never had any luck with it !..maybe it was too old ?..don't know !. in a few day's..i'll be doing the same thing to this '05 trx400FA at the shop !..lol.
Most of the gasket remover that you get at the auto parts stores doesn't really do a good job, but if you get some industrial strength gasket remover, it does pretty good. You just have to be careful to not get it on any rubber seals or anything or it will dissolve them. I usually just use a razor blade, but on real stubborn gaskets, I sometimes use an industrial strength gasket remover. And yes, the cylinder looks good to me, too.
 
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