Honda Rincon

I finished up the cam shaft job on the Honda Rincon 680.  The total time for the job was 11 hours and there was about $500 in parts. 

I am always amazed at the amount of engineering that Honda puts into their machines.   Just take a look at this photo of the oil drain plug.  Could you have made a more complicated oil plug?  Note that there is a aluminium crush washer and an o-ring on it.  The service manual says that you are supposed to change both of them when you remove it!

Rather than spending all that time designing the worlds most complicated drain plug they should have figured out a better system for the oil filter.  This photo shows a typical Honda oil change.  The filter is a round paper element that goes in that hole in the side of the engine.  When you pull the cover off the oil pours out all over the place and dribbles down onto the foot well.  There is no way to change this filter without making a mess.

At least on this machine they have an element that is the same on both ends.  On some of the Honda ATVs the filter element can mistakenly be put in upside down.  If that happens it restricts all the oil flow to the engine.  I have seen a few wrecked motors from this problem (I didn't put the filter in upside down, I just fixed the engines when someone else did).

Honda Rincon 680

I got back to work on the Honda Rincon that I started on a few weeks ago.

I am installing a new cam shaft in the engine.  The first step is to press the sprocket off the old one.  I do not have a hydraulic press, but with a good setup and a careful hammer you can get it done.  This photo shows the cam supported by a notched plate under the sprocket.  The yellow thing is my "anvil".  It is a large cast iron counter weight off of an old front end loader.  It weighs around 100 pounds and makes a great foundation to pound on.

A few careful swings with a 4 lb hammer and a punch and the sprocket came right off.  Next thing to do is move the bearing to the new shaft and "press" the sprocket on.

Tomorrow I'll install it in the engine and finish the job up.

Rincon 680

 I finally got back to work on the Rincon 680.  I pulled the top off the engine and discovered that the cam is wore just like I suspected. 

I am still not sure why it wears out?  In the first photo you can see the cam sitting in the "tin bathtub" full of oil.  It is definitely getting plenty of oil.  There was no noticeable wear on any of the other parts.

Here is the cam and followers removed from the engine.  You can see the follower on the right has a definite concave shape to the contact surface, it should be flat.  Both the intake and exhaust lobes were about .075" short.

I don't know why this is happening, but it seems to be a common problem on this engine.  An after market cam is available for about the same price as a new Honda original part.   I am going to recommend that to the owner.

Honda Rincon 680

Today I have a 2007 Honda Rincon 680 in the shop.  This is supposed to be one of Honda's biggest and best ATV's.  It has a big fuel injected engine, independent suspension, and an automatic transmission.  The transmission is an actual automatic with a fluid torque converter and computer controlled solenoid shift valves.  It is just like a mini automotive transmission.  I can't imagine what it must have cost to engineer that thing!

The engine on this model is kind of odd.  The basic Hondas use a simple air cooled engine with pushrod operated valves and a cam down low in the block.  Other manufacturers high performance machines have overhead chain driven cams that operate the valves or rocker arms directly.  One the Rincon Honda decided to put a chain driven cam halfway up the cylinder and use short pushrods to move the rocker arms. It's not an "overhead" cam, it's an "along side" cam?  I guess they had to have a cool chain driven cam but just couldn't give up their traditional pushrods?



This particular machine was in my shop about 18 months ago.  Back then the machine had around 2000 miles.  The problem was that it would start and run fine at idle, but when you revved it up it just would not go.  It acted like it couldn't breath.  I checked everything out and discovered that the lobes on the cam had wore down so far that the valves hardly opened.  Everything else checked out ok.  I eventually came to the uneasy conclusion that the cam shaft must have been defective (not heat treated properly?) and it simply wore out.  I replaced the cam and everything worked fine.

Now the machine has around 4000 miles on it and it is running the same way.  I have not tore the motor apart yet, but at this point I am assuming that the cam is bad again.  Before I open up the motor I figured I should check the oil pressure.  The only place that you can access the oil system is at a small bolt with a sealing washer under it.  You are supposed to use your Honda factory authorized pressure tester with a banjo bolt fitting on it to connect to this port.

I don't have the Honda pressure tester tool so I had to improvise.  I had a few odd banjo fittings that I have collected from other machines, but they are all to big.  I made a banjo fitting out of a left over scrap of HDPE.  I also had to drill out a standard bolt to turn it into a "banjo" bolt.  In the photo you can see these two items next to a manufactured banjo fitting that is just a little bit to big.  The homemade fitting worked great, but the 1/4" hose that I stuck on the hose barb with no clamp blew off.  Turns out the machine has lots of oil pressure and a good pump.  It made a big mess in the few seconds that it took for me to turn the thing off.

Does anybody have an idea why this machine is wearing out cam shafts?