ATV burning oil 2 months after rebuild - Honda ATV Forum
Repair & Maintenance Having problems? Doing a rebuild? All Repair/Maintenance Discussions here.

LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old 05-19-2019, 06:24 PM Thread Starter
Junior Member
KelPas's Avatar
Join Date: Sep 2016
Posts: 1
ATV burning oil 2 months after rebuild

Did the top end of a customers(neighbor) 08 Honda Rancher 420 last summer. He said it worked fine for 2 months of steady driving by his son and then one day it started smoking pretty good and using oil. He drove it for the rest of the summer and fall. Took it out this spring and it's still burning/using oil so he brought it to me to check it out.

We thought maybe the valve seals took a crap but when I removed the head and valves the seals look fine and no oil on top of the valves. Oil breather system is clean and working.

Combustion chamber and top of piston is clean. Rotated the engine to BDC to check the cyl walls and the cyl is glazed and no cross hatch visible.

Now this engine was rebuilt properly and I have done probably a hundred. I take the cyl to an engine machine shop and they measure it and do a rough bore and then tell me what size of oversize piston and rings I need to order. When they are in I bring them to the machine shop and they do a final bore and hone after measuring the new piston.

I install the rings according to the shop manual after measuring ring end gaps and clearances.

Used Honda oil and the owner broke it in properly by warming it up and driving it somewhat hard and no babying it. full throttle but not reving to high then off the throttle and repeat several times to seat the rings. After 5 hours he changed the oil and the bike ran fine for 2 months and did not burn or use oil in that time then just suddenly started burning.

He's not hard on his stuff and if I messed up a ring or something it should have done this right away and not 2 months down the road. I've never had this happen before as I always use OEM pistons/rings/gaskets and not aftermarket parts. Engine had never overheated as far as I know. Picture doesn't really show how shiny it is but does show no cross hatching. Wierd thing is he brought this to me last summer for the same thing- burning/using oil and now it's doing it again

ATV burning oil 2 months after rebuild-img_0886.jpg
KelPas is offline  
Sponsored Links
post #2 of 12 (permalink) Old 05-19-2019, 07:00 PM
Gold Supporting Member
Supporting Member
fishfiles's Avatar
Join Date: Jul 2013
Location: Bayou La'combe , Louisiana
Posts: 11,657
Liked: 6568 times
Garage thoughts , the connecting rod has slack , the piston is wobbling and the bore is egg shaped ------ or you machinist did a bunk job ........ try G+H next time around , hard to beat them price wise and work wise
cmanningjr and Jeepwm69 like this.
fishfiles is offline  
post #3 of 12 (permalink) Old 05-19-2019, 10:32 PM
Gold Supporting Member
Supporting Member
wheeler's Avatar
Join Date: Apr 2010
Location: Canadian Ice Box!
Posts: 990
Liked: 442 times
I wanna know why the piston is so clean? I've never seen one that clean with the time frame u mention.... & yes the cross hatching isn't visible.
_Wilson_ and retro like this.

1995 Honda 300, 355bbk, 40b Webcam, Springs & Hardened Rockers, 300ex Carb, Ricks CDI, FMF Full Exhaust, EBC DRC Clutch Kit, Outlaw Clutch Springs, Twin Air Filter, HL Disc Brake Conversion, Wide Open 424 kit, HL 2" lift, Bronco Shocks, 26" Zillas, Terra 35 Super Winch, Heat Demon Hand/Thumb Warmers, Powermadd Hand Guards, PIAA 35w Bulbs
wheeler is offline  
Sponsored Links
post #4 of 12 (permalink) Old 05-20-2019, 09:59 AM
Senior Member
Jeepwm69's Avatar
Join Date: Sep 2013
Location: Eastern Arkansas
Posts: 6,294
Liked: 3099 times
420 cranks don't hold up well at all. I'm with Fish on the bad crank/rod. ANY play at all in the wrist pin to small hole on the end of the rod? ANY up/down play in the rod at all?
Jeepwm69 is offline  
post #5 of 12 (permalink) Old 05-20-2019, 06:19 PM
Super Moderator
Supporting Member
retro's Avatar
Join Date: Mar 2017
Location: Ojibwe Gichigami
Posts: 5,554
Liked: 2979 times
The piston crown looks like its been water blasted clean. I see the cylinder wall shows water scuff/burnished smooth evidence too. I imagine the combustion chamber looks the same...? water implosion carbon removal... very efficient. The piston ring will tell a more complete story if thats the case.

My guess is the kid has been back in that same water hole/creek that trashed the motor the 1st time. The rod might be bent or hammered at the top by now, so I'd replace that before fixing the topend. If the motor was sunk its gotta be yanked and split for cleaning and the crank rebuilt anyway...

retro is offline  
post #6 of 12 (permalink) Old 05-20-2019, 08:44 PM
Super Moderator
Supporting Member
SlammedRanger's Avatar
Join Date: Feb 2010
Location: Norwalk,OH
Posts: 4,241
Liked: 1238 times
My first thought was exactly what retro said. The grit in the water it sucked in sand blasted the piston top clean. No gas combustion is ever that clean. Thats like nitro engine clean. The same grit removed the crosshatching on the cylinder walls. You would have a hard time convincing me otherwise. My .02

07 416ex
To many mods to list in signature(ran out of space lol)

Check out garage for full list
SlammedRanger is offline  
post #7 of 12 (permalink) Old 05-21-2019, 09:14 AM
Super Moderator
Supporting Member
retro's Avatar
Join Date: Mar 2017
Location: Ojibwe Gichigami
Posts: 5,554
Liked: 2979 times
On liquid cooled motors the first thing to check for anytime you find the piston/chamber cleaned by imploding water droplets is a coolant leak. That could be from bad/warped gasket surface or blown gasket, a cracked casting, a porous (defective cast) casting etc. Whatever it was allowing moisture into the chamber looks like it was slow 'n steady... classic signs of a crack or porous leak somewhere.

Check the top piston ring for extremely sharpened upper & lower edges (sharp enough to cut ya like a new razor blade) and inspect the lower surface of that top ring land for evidence of hammering... the land will be sharp around its edge (chamfer hammered away) and in extreme cases that outer land edge might be rolled out slightly. The lower surface of the ring will look hammered and work-stressed with an uneven surface matching the hammered ring land. Sometimes the upper ring land surface will have a gazillion tiny pits (look like it was media blasted, like the top of the piston looks, only finer) caused by imploding water molecules. That ring land clearance will be very sloppy and way out of spec, of course, and the 2nd ring land will show signs of deterioration along its top edge... likely becoming sharp, but still having a more normal looking bottom edge.

Break-in/seating procedure of new iron or iron/moly rings & bores should be RPM limited to a max piston velocity of 1500 feet per second during the first hour of operation, with continually varying/alternating pressure loading & unloading of the rings. Unless a new flat-tappet cam & lifters were installed at the same time as the fresh bore, brief shutdown/cooldown periods of a couple minutes or less are advised during the first 15-20 minutes of life. Don't allow the motor to idle for long, or at all if possible in either case to keep the oiling supply high. Beyond thar' be evil 'n destructive dragons... :-)
misterclean59 likes this.

retro is offline  
post #8 of 12 (permalink) Old 05-22-2019, 04:11 AM
Gold Supporting Member
Supporting Member
fishfiles's Avatar
Join Date: Jul 2013
Location: Bayou La'combe , Louisiana
Posts: 11,657
Liked: 6568 times
I find it hard to believe that a piston that is that clean is burning oil , did you clean it up before you took that picture ? ----- another thing I noticed is the mark at the top of the bore , it is kind of wider than I seem to being use to , is the piston coming all the way up to the top of the deck , if there is a bend in the rod , it won't come all the way up and make the mark wider
fishfiles is offline  
post #9 of 12 (permalink) Old 05-22-2019, 06:00 AM
Rocketman5144's Avatar
Join Date: Oct 2017
Posts: 45
Liked: 15 times
First thing I thought when I saw the picture is man that piston is clean.
I'm with the others its been getting water in it some how. Please let us know what you figure out.
Rocketman5144 is offline  
post #10 of 12 (permalink) Old 05-22-2019, 08:27 AM
Senior Member
mrbb's Avatar
Join Date: Oct 2011
Location: NE Pa
Posts: 7,925
Liked: 1992 times
I think the OP went MIA on us here! LOL
mrbb is offline  

  Lower Navigation
Go Back   Honda ATV Forum > Honda ATV Technical Discussions > Repair & Maintenance

Quick Reply

Register Now

In order to be able to post messages on the Honda ATV Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
1987 350 starter rebuild Jillian Honda FourTrax 6 12-19-2018 10:15 AM
86-89 TRX350 starter rebuild Goober Repair & Maintenance 5 10-21-2018 09:49 PM
Top end rebuild videos 09z71 Repair & Maintenance 2 05-21-2018 10:19 AM
1995 TRX300FW Rebuild in Australia 4stroker Builds, Projects & DIY 23 11-27-2016 03:37 AM
2007 trx400ex top end rebuild kits BussTD Repair & Maintenance 8 06-24-2016 09:44 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome