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Discussion Starter #1
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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I'd start with a compression test
how many miles/hours on atv, , have you owned it since new, or how long have you had it?
atv ever been swimming??
what other motor work was done when timing chain was replaced?
 

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Discussion Starter #3
I have to order a tester, don't have one, my friend has one but no plug adapter that fits. I just bought it last summer and it has a different engine than original. Same as it came with but the guy I bought it from also only had it a year so not sure about this engine. I don't know the history but doesn't appear to have been sunk.



When I did the timing chain I also put a cam sprocket in along with a rebuilt clutch. The head was taken to a local shop and they lapped the valves and cleaned it up.



The original engine was given to me with no discussion of what had broke on it. Along with the parts I found a new Wiseco piston kit oversize .040 for 91 mm. I may see about using that if I need these parts. I will have to take the head and get it bored.
 

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reason why I asked if sunk, as if was and dirt and crap was inside the motor, the longer you run it, the more damage that stuff does, and sooner or later a top end is gone and your smoking, a rather common issue in atv's today!
sellers SINK em, clean em up, and sell em, to guys that find out the hard way what they did!
about HOW Long have you ran motor since you got it, Hours wise that is?

and till you get a compression test, ??
 

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Discussion Starter #5
Since I got it, maybe 100 miles and 10 hours. I will report first of the week after I test.....As far as swimming no clue, it isn't horribly rusty anywhere so think maybe not....
 

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Did you have the cylinder off for the timing chain job? Wondering about carbon buildup on the rings, especially the bottom set, the oil control rings. Much carbon on the top of the piston?


Oil and fuel treatments can dissolve carbon on sticky rings. Seafoam works for me, but it takes running time. Soaking the cylinder when parked extended periods will help also.


Of course the rings could just be worn out of spec.
 

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Discussion Starter #7
Did you have the cylinder off for the timing chain job? Wondering about carbon buildup on the rings, especially the bottom set, the oil control rings. Much carbon on the top of the piston?


Oil and fuel treatments can dissolve carbon on sticky rings. Seafoam works for me, but it takes running time. Soaking the cylinder when parked extended periods will help also.


Of course the rings could just be worn out of spec.
Yes head or jug was off when the timing was repaired by the shop I had taken it to. They lapped the valves and said the piston looked good and clean. The smoking started all at once last week, never did it up to that point. Only have around 10-15 hours on it since the timing change so wouldn't think carbon should be an issue. Compression tester here tomorrow so will see what it reads....
 

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i would bet the rings are getting blowby. it should have been checked for proper tolerances while apart and bored to next size if needed or new rings and a light hone if it was was within specs. i try not to bore any bigger than needed so it can be bored again if needed later in life. if you already have the piston and rings have the cylinder bored to fit the oversized piston, that should be all that is needed.
 

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Discussion Starter #9
Should get my compression tester today and hope to get some readings that will give me an idea on the problem. But yes I feel you are correct in your thinking....
 

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Discussion Starter #12
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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I expected decent compression, since you said it starts and runs ok. But, extra oil in the cylinder will raise the compression number.



Not too many places the oil can come from. Past the rings, through the valve seals, and that's about all considering how well it runs. The head was just looked at, but maybe the valve seals weren't? Normally with bad seals, the smoke would be worse during high vacuum, as with decelerating.



I've seen Hondas run for months like that with worn rings, then the piston rocks sideways enough for the skirt to rub the cylinder wall, then it will seize. A 200x comes to mind. Or, the rider forgets to top off the oil and the bottom-end goes.
 

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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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my 2 cents, if your going to spend the time and $$ here, I would insist on a full case split and clean, clean clean, and inspect all things!

as if this motor was every sunk and all you do now is a top end and there is something in there that is eating things, you will be back at this point real soon,
done right once, and it will last for yrs and yrs
half azz things and you could be wasting more money down the road!
 

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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....

That's probably about right, I don't use shops very much, but the last cylinder bore & hone I got was $90, and I carried the cylinder in. That's been quite a while too.


Is this a different shop than the one that lapped the valves and checked the timing chain?
 

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Discussion Starter #18 (Edited)
That's probably about right, I don't use shops very much, but the last cylinder bore & hone I got was $90, and I carried the cylinder in. That's been quite a while too.


Is this a different shop than the one that lapped the valves and checked the timing chain?
Same shop, but I think I have changed my strategy. A good friend is a local auto mechanic and was talking to him about my problem, he hasn't worked on an ATV engine but done lots of car and truck engines. I have the extra engine given to me when I bought this and he said to bring the head for him to look at to get a better picture of what is involved. He said no problem, he has a valve compression tool to get things apart so I have decided with that I can replace all the valves, springs, and seal. I should be able to clean any carbon or whatever is on the head surfaces. While everything is apart I do plan on getting the cylinder bored to match the Wiseco piston kit that came with my spare parts. On their website it is listed as .040 oversized. Should save me a few hundred $$ I would think.

Where does everybody order engine parts from?? I don't want the cheap China parts with this project. Is there anything I should replace with this project besides the valve and piston parts and gaskets?? Now is the time while apart....Thanks for all the advise....
 

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If I can find it on ebay, I order from there. If not, I check amazon.


Good deal on getting the friend involved, I wasn't too impressed with that shop. Remember? They said the valve timing was good, but that's exactly why it wouldn't run.
 

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Discussion Starter #20
If I can find it on ebay, I order from there. If not, I check amazon.


Good deal on getting the friend involved, I wasn't too impressed with that shop. Remember? They said the valve timing was good, but that's exactly why it wouldn't run.
Yea kinda agree with that assessment, I looked up pretty much all the parts I should need on Partzilla to redo the head including valves, guides, and gaskets. It came to about $150 so alot of labor costs to make it close to $500!! Whether they need it going to replace most everything and also see what the piston and cylinder look like. I have that oversized Wiseco piston kit that was in the spare parts I got and will probably use it and have the bore job done for the $100. That way its pretty much all new.....
 
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