Jeffin, I havent touched anything, Honda did a full rebuild except they bored the existing cylinder 0.50 over.
My guess is that something in the bore went wrong.

They are putting a factory fresh cylinder, and piston in.

Cluby, The orginal motor never failed ,but was smoking ,and ticking badly cause of my own mistake.
I left the crankcase breather off ,and got alot of mud ,and sand water in the engine.

Also the 420 does not have a oil cooler.
It is liquid cooled ,and I have read that the liquid cooling eliminated the need for a seperate oilcooler.

 

Sounds to me like the dealer only bored the cylinder and nothing else. All the crap from the breather hose being off was still in the bottom and came up and worn out the new piston and rings.

 

No they split the cases ,and replaced everything.
New 0.50 over piston, and rings, crank, oil pump, clutches even though mine were fine I requested new ones while it was down.

Gear position sensor, ,and of course all gaskets.

I have all the old parts.
It never ran bad ,but oviosly after replacing all that it was practically a new motor ,and a new motor should not smoke.

They said I should have it next week so we will see.
Im ready to ride!!!

 

Cluby -

Along the way while diagnosing the cold start issues with customers on 420's, I ran across this problem of units that smoked like abmobil is having. I cured the smoking issue real easy. His dealer is way off base and are wasting their time installing the new top end. The smoking will return. Actually, I would be shocked if it does cure the problem. Been wrong before though, I have.
I will pm you my thoughts
Where is this Honda service manager who said I was some wacked garage mechanic ? He will probably tell us the battery bolts are loose.... hehehe

----- Gimpster -----

 

Gimpster-Share your thought with us as well if you will.....

 

I mentioned to Cluby how many of the 420's we had issues with starting in cold weather, had the same smoke problem. Blue smoke. While trying new ECMs I noticed the units would stop smoking blue. Like I mentioned to him in the PM. I felt the ECMs on these units could have been mapped wrong for timing, fuel or the accelerator function. Many of these quads when they came in were way overfull of oil. When the dipstick was pulled, how I could smell raw fuel real bad in the oil. They were real rich to get this much gas in the oil.
Also mentioned how on many bikes or quads over the years that would smoke, adjusting the valves and cam chain would make them quit smoking. This all has to do with negative and positive vacuum in the cylinder. If the piston is in one direction of movement when a valve should be closed, and the valve is hanging open because of improper valve adjustment, stretched cam chain, or the timing is off so that it will suck oil past the rings as they are not sealed and on the other hand how fuel can be transfered past the rings into the crankcase as well as there is not enough vacuum to seal the rings to the cylinder walls at certain times when fuel is drawn into the cylinder. Now days this will change since we are working with fuel injection which adds forced fuel into the intake system instead of relying on lower vacuum in the cylinder to draw fuel in during the intake stroke. Diagnostics may sway a little here now from a carbed unit to a fuel injected unit because of the pressured pulse of fuel and issues with valves, ignition timing etc... may be affected/magnified as compared to carbed engines. Another thing to take into account is the new engine platforms which run higher exhaust temps to burn the fuel we have now days. That is another topic though.
Getting back to my thoughts, If an ecm is not programed just right, It will change timing or fuel pulse which in turn directly affects the vacume within the cylinder at any point, which in turn will affect the ring sealability directly contributing to fuel in the oil, or oil in the combustion chamber when it should not be. This is where our forum user, Mr. abmobil could be seeing the smoking from his 420 although it has been overhauled. I felt the origional diagnosis of him needing a complete rebuild was far fetched to begin with as the issue has existed within his quad before they blamed the crank breather hose as being at fault. Believe me, in over 25 years of being in this industry, I have seen worse dirt particle sucked into engines and this result not happening.
Here is some more food for thought. Honda's decompressor system. It is a moveable lobe on the heal side of the cam lobe. Now what happens to the cylinder vacuum when this decompressor wears to the point to where it holds the valve relieving compression open too long (late timing) from continual side thrust wear from the lifter bucket. This may be a factor also, as many cams I replaced from decompressor failures over the years. I will dismiss it on the 420 though. If it plays into the resulting symptoms of the 420 as issues I have addressed, it would have minimal effect on the area of at hand issues. As where it opens and closes, late or not should not cause smoking.
This all leads me back to my origional reply on this topic. Replace the ECM. The timing mapping, fuel injection mapping is off. The rings in the cylinder will not reseal as they are washing out or poor cylinder vacuum is sucking oil past the rings or not letting them reseal.
My customers here do not stop riding their quads because of cold weather. I feel that others will not ride their quad when it gets this cold out. They will eather not try to start it at all, try it and give up thinking it is cold. The issue with 420's is not showing up in warm weather other than backfiring until the exhaust is totally sooty to where it will not get hot enough to allow backfiring inside of it. I feel that my customers demand to get their units started as they rely on them for checking cattle in any weather, has brought forth a issue that will surface in all 420's sooner or later.
I have been wrong before, but I will advise 420 owners to watch their spark plugs. They will be black around the outside and it will build until eventually fouling build up reaches and shorts the center electrode. Something is not right and some units are way worse than others. By the way, I have tried 2 heat ranges hotter and 2 colder on spark plugs, normal and iridium with the same blackness build up noted. I think it will show up in the future.


----- Gimpster -----

 

Thanks for the reply!

 

Interesting...

Since this thing had just been rebuilt, though, I'd hesitiate to name a cause without looking at it. Over the years I've found rings in upside down, piston clearance way off, and other things like that on engines that had been worked on previously...

What you said was interesting, though, as I've heard about some Ranchers with really bad looking oil...

 

Exactly, the sleeve could have slipped during boring or they might not have replaced the o-ring at the bottom of the cylinder (which many new techs to the field do not know exist) or something dumb like that

----- Gimpster -----

 

The Ecm thing makes since ,but mine ran flawlessly before my own personal screw up.

Hopfully it is done tommorow.