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Discussion Starter #1
Hi, i have a 1994 Honda Fourtrax, and i got a smoking issue but.. in the front end! The problem occur when i pull something for example last week i pull some firewood by a hot day and when a i pull a log it starts smoking real bad from the front end between the handle bar and the gas tank, when i stop pulling, and the quad is idling the smoke stop. Yesterday i went for a ride with my Buddy and he stay stuck, try to pull him out with a rope and again in first gear on charge my atv starts smoking same place.

I can't see where the smoke come from but it seems to happens on charge everytime. Runs Great, shift great, no smoke at the exhaust at all, it smells like burning oïl. Maybe clutch slipping ? Maybe crankcase Vent ?

Help me !
 

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It could be a vent, they all end just below your handlebars.
 

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Pull your gas tank off and check your rocker box cover for leaks.. probably leaking on the exhaust and burning away...


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Discussion Starter #6
Pull your gas tank off and check your rocker box cover for leaks.. probably leaking on the exhaust and burning away...


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Just when i pull something ? because if i juste take a ride it do not smoke at all
 

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Yep, cmanningjr is right. When you put the motor under heavy load pulling something, pressure under the rocker cover and inside the crankcase increases quite a bit. Any gasket that may be slightly leaking will leak a lot more under load. If your rocker cover is weeping oil directly above the exhaust pipe coming out of the head it will leak faster under load and be burned off as soon as it touches the hot exhaust.

The higher pressures seen in the crankcase during heavily loaded conditions are caused by combustion gases escaping the cylinder past the piston & rings. All motors do it to some degree, because nothing is ever perfect. As the motor wears cylinder leakage past the rings increases until the increased blowby becomes obvious, as possibly is your case.

While you have the fuel tank off to check for a leaking rocker cover, take the crankcase breather hoses off and see if any motor oil is wetting the inside of those hoses. If so, check to make sure that the motor is not overfilled with oil. If the oil level is correct it may be time to rebuild the topend of the motor. You can confirm that diagnosis by performing a leakdown test on it.

Do you have a copy of the FSM yet?

Welcome to the forums!
 

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Mine smoked a lot last week when I was hauling wood. It was a very hot and humid day. However, I seem to have oil deposits on my cylinder head coming from the muffler flange... That seemed to be the culprit of the smoking issue.
 

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Discussion Starter #9
Yep, cmanningjr is right. When you put the motor under heavy load pulling something, pressure under the rocker cover and inside the crankcase increases quite a bit. Any gasket that may be slightly leaking will leak a lot more under load. If your rocker cover is weeping oil directly above the exhaust pipe coming out of the head it will leak faster under load and be burned off as soon as it touches the hot exhaust.

The higher pressures seen in the crankcase during heavily loaded conditions are caused by combustion gases escaping the cylinder past the piston & rings. All motors do it to some degree, because nothing is ever perfect. As the motor wears cylinder leakage past the rings increases until the increased blowby becomes obvious, as possibly is your case.

While you have the fuel tank off to check for a leaking rocker cover, take the crankcase breather hoses off and see if any motor oil is wetting the inside of those hoses. If so, check to make sure that the motor is not overfilled with oil. If the oil level is correct it may be time to rebuild the topend of the motor. You can confirm that diagnosis by performing a leakdown test on it.

Do you have a copy of the FSM yet?

Welcome to the forums!
Thanks a lot for the rapid answer ! I'm gonna check all these possibility tonight !!
 

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You could yes but you'd just be hiding the problem not fixing it.
 

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if I had to guess I would say the smoke is coming from the crankcase vent tube and it is blow-by from around the rings
if it's the case, can i run the vent tube in the intake to collect that smoke ?
Vents normally run into air box. Since it's a guessing game I'm going with leaking valve cover dripping on exhaust.

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if I had to guess I would say the smoke is coming from the crankcase vent tube and it is blow-by from around the rings
if it's the case, can i run the vent tube in the intake to collect that smoke ?
Vents normally run into air box. Since it's a guessing game I'm going with leaking valve cover dripping on exhaust.

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the crankcase vent part is not a guessing game , as the 88 is the only 300 where the vent tube goes into the air box , after that the crankcase vent ran up the frame under the air intake tube , from reading his post he don't have an 88 , so his vent is not in the air box
 

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I think I was right... lol

Get you some new gaskets and some Hondabond (if the rocker cover is leaking) fix it and call it a day..


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Looks like you would benefit removing the cam cover completely and reseal it along with the valve adjustment covers.
Also, I was completely wrong about it being a crank case breather! The crank breather doesn't exit by the handlebars (or at least mine didn't) it ends under the seat!
Been a while since I looked at an OEM crank breather.

Apologies for the false info.
 
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