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Discussion Starter #1 (Edited)
OK need some more advise, she is now blowing smoke out the muffler. It has been running swell since the timing chain replacement and had her out last couple weeks pulling some logs for cutting. She did a great job. A couple days ago I was helping my son pull some brush out that was overgrown and on one pull I looked back and had smoke behind me. It is the whitish I guess blue smoke. Still seems to run fine and doesn't smoke right away when starting until I give her some throttle or slight load. I have tried adjusting the carb with no success. I pulled the plug and it was wet and pretty cruddy looking. The air filter is clean and no fuel in that area which is good. I am now going out to check the valves, but probably figure it is something worse. After I check valves where should I start? I surprised myself with the timing chain replacement and would like to do what is needed this time also. I will post results from the valves later.


Also the color of smoke, if it was fuel related would it not be a darker blackish color? This much lighter in color....Fun times....


Update: valves are good at .006, so any ideas much appreciated....
 

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Ya, I think the adapter it takes is 12mm. When you buy an adapter it won't have a schrader valve in the end of it so your readings will be slightly lower than reality, but close enough that you can make a decent judgement call on the condition of the cylinder.
 

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Discussion Starter #6
Ya, I think the adapter it takes is 12mm. When you buy an adapter it won't have a schrader valve in the end of it so your readings will be slightly lower than reality, but close enough that you can make a decent judgement call on the condition of the cylinder.

OK thanks, will do some reading here on how to test, never tried before...should give me an idea of what is wrong hopefully...
 

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Its easy... warm the motor up to operating temp, yank the spark plug and ground the plug wire, screw in the compression gauge, hold the throttle wide open and hold the starter button down until the gauge stops climbing.

Make sure you are getting a good pressure seal where the adapter meets the head and mates with the pressure hose. I use an old spark plug gasket on those wherever possible, cause rubber o-rings squeeze out and can't be trusted.
 

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Discussion Starter #9
Almost certainly a worn top end unless it is too full of oil and or fuel leaked into the crankcase and overfilled the level. I can't imagine a worn valve stem seal leaking that much oil to make that much smoke.

Oil level is good, right at top of fill stick mark when placed on top, not screwed in.
 

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Oil looks good changed a month or so ago. I have to get a compression tester, nobody I know has the right size adapter.
Following your recent oil change did you use a similar grade oil or maybe a thinner viscocity? Is your motor original spec or has it been rebuilt/rebored in the past? Cylinder/piston ring age/mileage related wear maybe making itself known.
 

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Discussion Starter #11
Oil looks good changed a month or so ago. I have to get a compression tester, nobody I know has the right size adapter.
Following your recent oil change did you use a similar grade oil or maybe a thinner viscocity? Is your motor original spec or has it been rebuilt/rebored in the past? Cylinder/piston ring age/mileage related wear maybe making itself known.
I wish I knew the history of this engine but alas I don't only having purchased last summer. Seeing as tho it isn't the original engine I would assume it has not been rebuilt/rebored....
 

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Oil looks good changed a month or so ago. I have to get a compression tester, nobody I know has the right size adapter.
Following your recent oil change did you use a similar grade oil or maybe a thinner viscocity? Is your motor original spec or has it been rebuilt/rebored in the past? Cylinder/piston ring age/mileage related wear maybe making itself known.
I wish I knew the history of this engine but alas I don't only having purchased last summer. Seeing as tho it isn't the original engine I would assume it has not been rebuilt/rebored....
I would never count on this, as this isn't that old of a motor, and unless it had a TON or miles and hours on it, there is suspect as WHY the first one failed, , if not a lot of excessive use, odds are it failed due to owner miss use or care, ever few or NO pm's
and they let it go, and or they sank it,
if they sank it, then odds are high they also used NEW motor the same way, and or treated it the same, NO to few pm's and possibly sank it too!

there are tons of honda atv's much older than this, on there original motors and running just fine, due to proper care of there owners!
just as well as there are tons of honda atv's that have had there motors torn apart a bunch of times due to , how there owners used and abused them!
 

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Discussion Starter #13
OK got tester yesterday and ran it today. I started the engine and ran to warm it up. I then removed the plug, screwed the adapter in, attached the hose and gauge. Also grounded the plug wire, opened the throttle and cranked. It registered 160 psi and stayed there after 5-6 times over. Manual says 78-121 psi normal but if below on the check to loosen the exhaust valve lock nut and adjust 1 1/2 turns and recheck. It should then read 178-206 psi. My check is between both the readings so not sure what that means. Any ideas here would be appreciated...
 

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One reading is for the compression release working properly and the other reading is an actual reading with auto decomp. disabled. I'm guessing the top end is worn out. Just tear it down and inspect. You will probably find it needs an oversized piston. Check the valves and valve train good. Done correctly this may be the last top end this engine will ever need.
 

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Discussion Starter #15
Went to talk to our local small engine shop today. Told him about having 160 psi and what the normal should be. Also said it has all of a sudden started smoking from the exhaust lately, mostly after warming up, never right after starting. Obviously he said it is getting oil from somewhere that shouldn't be there, said to check any hoses running to the engine, the only one I see comes from the bottom of the air cleaner box. Took that off and no oil on the end. Other than that said it would need the valves and piston/cylinder torn apart to check. So looks like I prolly am at that point. He said having the valves and assemblies new, gaskets, and boring the cylinder to fit my .040 piston I have would be around $500-600. I have no way of removing valves or boring so does this sound reasonable? Just don't know any other reason it's burning oil but having higher than normal compression....
 

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The high compression reading is probably caused by two things going at the same time... for one, there is an oily cylinder and two, your compression gauge is probably imported.

You'll have to take the topend apart for inspection, check the rod etc., then buy the parts that are needed to restore it to new. Once you get your list made take the cylinder to a notable machinist to be measured, then buy the oversize piston and give it to the machinist so the piston clearance can be set properly during final honing. You can do all of the teardown & reassembly work yourself provided that you can find a valve spring compressor you can borrow.

So the price you were quoted is a blue-sky figure including labor... should cost ya much less if you do the majority of the work yourself on your pushrod single.
 

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Do top end rebuild but check head and cylinder surface have seen many before leaking oil where comes up stud bolt to feed rocker box leak in combustion chamber-between head and cylinder only like 8-10mm from stud hole in gasket to cylinder .surface both
 

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never assume anything. i got this advice from an old TV show. felix, not oscar.
or was it the other way around.
make's an ass, out of u, or, me. ass u me.
god spelled back word's, is dog. forget where that came from, maybe the same place.
the aluminum in my brain must be kicking in. either Alzheimer's, or the connection's are getting better..
since i alway's been a little drifty, ya'll never know.. :grin
what is in your muffler, how old is it? ya might be cooking up an old batch.
 

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I have seen it take 3 hours of running it hard to make all the oil from a upper job burn off all the oil that got into the exhaust , but I do't think that is the problem , seen the valve guide seals leak into the cylinder , usually when that happens you get a lot of smoke on crank up and then it slows down after it has ran a while , unless they were totally shot , but then I would think it would smoke on crank up bad ----and seen the cylinder wall get egg shaped from the piston wobbling from a worn out rod , would think since it gets worst after warming up , the jug is expanding and letting oil by-pass the rings ---if you do an upper job on a bad rod , it is not going to last but maybe 50-100 hours and be worn out again ---I think the last crank for my red 450 I bought was close to $400
 
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