07 Rubicon Stuck in Low Gear

[07Rubicons4Life 5]

It’s alive!  I moved the cam back to where the line on the sprocket was parallel to the case, then installed an after market tensioner. The chain has significantly stretched which I find remarkable on a machine with only 1,300 miles. The aftermarket tensioner doesn’t have a spring and is able to push the guide in further, I’ve read a lot of people who race dirt bikes use them. 
 

The gasket set didn’t come with o-rings for the water pump and I tried to reuse the original ones and the pump is leaking really bad, I’ll pull that off tomorrow and replace the o-rings. Anyone know the size for that?  Sucks I just dumped $40 in Honda coolant in it. 
 

I jacked up the rear tires and it cycles through all the gears and shifts great so fingers crossed on that. 
 

Only bad part of the progress today was that now that it’s running holy smokes does it smoke. Smells like burning oil. I’m going to do an oil change tomorrow and coolant flush and just let it run for a while. I didn’t a compression test and it is holding steady at 100 PSI now so really hope it’s just a bunch of junk that needs to burn off. 
 

 

[jeepwm69 7,686]

My guess?  Your machine is the same as the basketcase I bought; sunk, engine filled with grit, and prematurely wore out the engine.

 

If it's smoking top end is likely done.  If you want the thing to be right/ plan on keeping it, I'd pull it, tear it down, CLEAN CLEAN CLEAN, and then reassemble.  

 

The one I bought had 2K miles on it, but had already had at least one top end rebuild (had an aftermarket oversized piston installed) so no way it wasn't sunk at some point.  That's likely why your front plastics were missing.....to hide the snorkel hole.

 

Get a new timing chain, new OEM tensioner (get rid of that aftermarket tensioner!) and have the cylinder bored to an ovesized new piston.

 

I see these around here with 10K miles on them on a regular basis that have never had engine work.   Once you sink them you have to tear down and clean out or you just keep throwing new parts at it.

[07Rubicons4Life 5]

Thanks for the input @jeepwm69!  You might be right, I'm at a stopping point right now as I assess my next moves.  I did take the smoke monster out for a short ride yesterday and it shifts through all the gears great and got it up to 30 mph, the gear shift linkage still is tough to move around but once it's in gear it's fine.  Anyone ever send their jug off to G&H ATV supply?  I've read nothing but great reviews and I talked to the guy who answered the phone yesterday.  He said they would bore it out slightly larger than stock and then include a matching Namura piston and rings, plus all the top end gaskets to put the top end back together, all for $193.95 plus $15 shipping so a total of $208.95 and back to me in a week.  He said the stock bore is 92MM, and they would bore it to 92.5MM so just slightly larger that way no changes to exhaust or carb would be needed like if you were going to a big bore.  I'm not going to waste the money to have that done and not just rebuild the thing because in short time anything in the engine will just destroy the newly rebuilt top end. I've added a new tab to my spreadsheet (wife is not happy about it) and am working through pricing of pulling the engine for the rebuild.  So I'll start by rebuilding the top end with new valves, push rods, and rocker arms, then send the jug off to be machined and new piston/rings, buy new timing chain and then the lower portion I'm a bit fuzzy on what I need.  I know I need that puller tool, what else should I get for the lower end of the engine once I crack that open?

[jeepwm69 7,686]

You shouldn't need new valves, rods, or rocker arms unless you can find issues with what you have.  

 

G&H does good work.   I've used them for several top ends.  And you won't need any changes to exhaust or carb.

 

The biggest thing you have going for you is the Hondamatic is apparently good.  That's the pricey part on these Rubicons, so the fact that it drives and shifts through all the gears tells you that the Hondamatic is good.

 

Normally what I do is pull the top end for a bore and new piston.   You'll then need to check the connecting rod.   If they wear it's usually at the top of the connecting rod, so take the wrist pin, stick it through the rod until one end of the wrist pin is flush with the side of the small end of the connecting rod, and then wiggle.  If you get more than a tiny bit of play, the connecting rod is shot and you'll need a crank rebuild (around $235 including the new rod).   If there is little to no play in the wrist pin to connecting rod, then your crank should be fine, but you also need to pull up and down on the rod and see if you have any up/down play in the bottom of the rod.   If so, crank rebuild, if not, crank is fine.  I've never had a bad bottom bearing in a crank, I've always had to rebuild cranks due to the top end wearing at the wrist pin.

 

It sounds more complicated than it is, so don't freak out.

 

If you look back at my thread on that 2012 I went through, it has some pics of tearing down one of these engines to clean out.   Depending on what you find when you remove the front and rear covers, you might want to just clean what you can see and bolt the covers back on.  I would advise on going ahead and pulling it apart, simply so you KNOW that everything is good and clean, and you also get to inspect for wear while you have it apart.   You'll need a flywheel puller ($10-15 on ebay, motionpro) and for the front clutch a 3 jaw puller with some big hose clamps or a Rubicon specific clutch puller.   The specific tool would be easier, but they cost more, and I can use my 3 jaw puller for lots of things so I stick with that.

 

The problem with just putting a top end on the machine is IF it's been sunk, you probably have residual grit in the bottom end.   You put a new top end on the engine, and that grit is pumped up to your freshly bored cylinder and new piston, and eats it up and you're back where you started.  Again, depending on what you find when you pull the front and rear engine covers, you could possibly get by with just cleaning what you can see, and flushing out the center section as best you can with the cases still bolted together.  I'd advise against that, but some people do that rather than a "proper" clean out.

 

Going through one of these engines won't cost you a ton of money, it's mainly just time and effort as cleaning everything out is the main goal.

 

The only parts I normally replace are timing chain and seals, have the cylinder bored with a new piston with a top end gasket set, and if needed, a crank rebuild.   The rest is just labor.  

 

It can be daunting if you've never done one before, BUT once you learn, you have that knowledge and if you need to tear into either one of your Rubicons again, you can do it again.

 

I like to know that I can fix/ maintain my stuff in the future, so I try to keep learning.

 

First step I'd do is pull the top end and see if the piston is still the OEM standard size, or if it's already been rebuilt.   If it's already been rebuilt, I'd definitely go all the way in.  With those miles, if it's been rebuilt once already, you can almost guarantee there's grit in the bottom end.

[07Rubicons4Life 5]

I read through the threads this morning and see you sent that one to G&H so cool glad others have used them.  The exhaust valves were hitting the piston which was the cause of the knocking noise when I first got it started, I inspected and cleaned them but I'm concerned they are bent or not seating right.  I have a new set of OEM exhaust valves and valve seals coming tomorrow from Motosport.   Before I removed the valve cover this machine had never been wrenched on so I'm very confident that it's the original piston.  It has marked HN2 on the Exhaust side, and IN on the intake side of the piston, not sure if that is enough to identify whether it's factory or not but I do have a digital caliper somewhere if not.

 

Can't I just start by removing the front cover?  Also, guess I have to remove the clutch and flywheel to replace the timing chain so could do that while the front cover was off.  .  

[jeepwm69 7,686]

Yep, in that case, probably not a bad idea to replace valves. 

 

If oversized you should see .25, .50 etc on it.  If not marked it's likely a std piston.

 

And yes, front oil tank, then front cover to access the clutch, which comes off and then you'll see the oil pump chain and timing chain.

[07Rubicons4Life 5]

Ok so I've decided my next step is to take the valve cover back off and replace the exhaust valves, and also replace the valve seals for both intake and exhaust valves while it's out and do a very solid cleaning.  Then I'll button it back up and if it's still smoking (like I'm basically sure of already) then I'm going to tear the top end off and send it to G&H to have them bore the cylinder out to 92.5MM and a new piston.  While waiting for that I'll take the oil tank off, remove the shift linkage, and then crack the front case off.  That way I can see what the inside of the engine looks like and if there is any grit/dirt.  If that and/or the oil tank is dirty and showing signs of it being swamped I will pull the engine.  If not then I'll remove the clutch and replace the timing chain while I have the front cover off.  I don't have the space or even a bench to really pull the motor so I'll have to do some more prep and get a proper space together at that point. If I end up having to even crack the front cover I'll start a new thread as well.  

[shadetree 5,951]

7 hours ago, 07Rubicons4Life said:

Ok so I've decided my next step is to take the valve cover back off and replace the exhaust valves, and also replace the valve seals for both intake and exhaust valves while it's out and do a very solid cleaning.  Then I'll button it back up and if it's still smoking (like I'm basically sure of already) then I'm going to tear the top end off and send it to G&H to have them bore the cylinder out to 92.5MM and a new piston.  While waiting for that I'll take the oil tank off, remove the shift linkage, and then crack the front case off.  That way I can see what the inside of the engine looks like and if there is any grit/dirt.  If that and/or the oil tank is dirty and showing signs of it being swamped I will pull the engine.  If not then I'll remove the clutch and replace the timing chain while I have the front cover off.  I don't have the space or even a bench to really pull the motor so I'll have to do some more prep and get a proper space together at that point. If I end up having to even crack the front cover I'll start a new thread as well.  

i just gotta ask...how are you going to remove the valves, and valve guide seals..without removing the head ??..lol. psssttt..you can't !..lol.. the head has to come off, in order to do what you are speaking here ^^. sooo..this means..there goes your head gasket..NO...you can not re-use the head gasket !. ( well...you can..if you go about it right...and flat broke ? )..but no..anytime the head comes off the top end ?..it calls for a new head gasket.

[07Rubicons4Life 5]

Sorry I’m not a gear head so if I’ve mess up verbiage I’ll get there. Of course a new gasket is needed even a newbie knows that!  I actually already have the gasket set just waiting on the valves. 

[07Rubicons4Life 5]

Here are some pictures as I start the tear down. 

[07Rubicons4Life 5]

I also forgot to post the picture of what I found when I dropped the oil filter. The oil was so dark it clearly hadn’t been changed in quite a long time. 

[jeepwm69 7,686]

That cylinder doesn't look too bad.  That valve looks tweaked to me, and yikes on that oil filter housing.

 

I have to repost this thread, where @basfnb changed his oil.  

 

https://www.hondaforeman.com/threads/stripped-oil-filter-bolt.143930/#replies

[07Rubicons4Life 5]

Yeah cylinder isn't too bad but after I replaced the valves it is still smoking (and yes I lapped the valves my father-in-law who is a mechanic for 40+ years came over and helped me).  I also checked the front and rear diffs and while they are low, the fluid is clean and not milky.  When I pulled the cylinder head off this morning there was a puddle of oil on top of the piston, so I'm pretty sure the rings are bad?  I did make sure it was top dead center before I started removing anything maybe it's from the piston moving up and down a few times?  Either way pretty sure oil should not be on top of the piston head.  When I removed the cylinder the rings on the piston were not lined up they were staggered I did check that as well, pretty sure you all know what I'm trying to say.  I'm going to the post office to ship the cylinder off to G&H for machining this afternoon.  Will post after pics when I get it back.  

[shadetree 5,951]

On 5/29/2024 at 10:38 AM, 07Rubicons4Life said:

Yeah cylinder isn't too bad but after I replaced the valves it is still smoking (and yes I lapped the valves my father-in-law who is a mechanic for 40+ years came over and helped me).  I also checked the front and rear diffs and while they are low, the fluid is clean and not milky.  When I pulled the cylinder head off this morning there was a puddle of oil on top of the piston, so I'm pretty sure the rings are bad?  I did make sure it was top dead center before I started removing anything maybe it's from the piston moving up and down a few times?  Either way pretty sure oil should not be on top of the piston head.  When I removed the cylinder the rings on the piston were not lined up they were staggered I did check that as well, pretty sure you all know what I'm trying to say.  I'm going to the post office to ship the cylinder off to G&H for machining this afternoon.  Will post after pics when I get it back.  

agreed, cylinder does not look bad. you could have worn rings ?, or..bad valve guide seals ?. if the seals are bad ?, they could allow oil to seep past them, and down onto the top of piston. as for that oil filter ?..yikes !..looks like water made it into the engine at one point in time ?..looks milky too me ?. just because the main oil did not look milky, does not mean it was changed, keep in mind...an oil change cannot get all of the bad stuff out.