coldwaterboater
Recruit
- Joined
- Oct 17, 2004
- Messages
- 4
Can anyone let me know how to check the valve clearance on a 03 BF50?.
.<br />sometimes if you cant educate the customer ya have to baffle themStrange way to fix worn rocker shafts.
<br /><br /> <br />coldwaterboater,<br />As per Honda Marine Shop Manuel.<br /><br />Valve clearance inspection must be performed with the engine cold.<br />1)Remove the engine cover.<br />2)Move the gearshift lever to "N" position.<br />3)Remove the four 6x25mm flange bolts and three 6mm plain washers from the flywheel cover.<br />4)Remove the flywheel cover.<br />5)Disconnect the breather tube and oil return tube from the cylinder head cover.<br />6)Remove the sparkplugs and the engine hanger bracket.<br /><br /> CAUTION! <br />.The starter stopper collar is close to the flywheel and the starter ring gear can become sharp. Avoid hand contact with the starter stopper collar or flywheel ring gear.<br />Hold the upper portion of the flywheel when rotating engine.<br />.To avoid waterpump impeller damage, always turn the crankshaft in a counterclockwise direction.<br /><br />7)Manually turn the flywheel counterclockwise in the same direction of the arrow on the flywheel. Align the "T" mark on the flywheel with the "I" mark on top of the engine hanger mounting boss. The "Tv" mark on the cam will align with the "T^" mark on the cylinder head. In this position the No.1 piston is at top dead center of its compression stroke.<br />With the engine in this position, check the intake and exaust valve clearances of #1 cylinder by inserting a feelers guage between the valve stem and the adjusting screw on the rocker arm.<br /><br /> Valve clearance, <br />IN. 0.13-0.17MM (0.005-0.007in)<br />EX. 0.21-0.25mm (0.008-0.010in)<br /><br />8)Turn the flywheel counterclockwise until the cam pully turns an additional 120deg. and the "^2" mark aligns with the "T^" mark on the cylinder head. This will put the No.2 piston at TDC of its compression stroke. Check the inatke and exaust valve clearances on the No.2 cylinder.<br />9)Turn the flywheel counterclockwise until the cam pulley turns an additional 120deg. and the "^3" mark aligns with the "T^" mark on the cylinder head. This will put the No.3 piston at TDC of its compression stroke. Check the intake and exaust valve clearances on the No.3 cylinder.<br />10)Proceed to adjustment if necessary or install the removed parts in the reverse order of disassembly.<br /><br /> Adjustment <br />1)With the cylinder at TDC of its compression stroke, loosen the adjusting screw lock nut, and turn the adjusting screw to obtain the specified intake and exaust valve clearance.<br />2)Hold the adjusting screw using a screw driver, and tighten the lock nut.<br /> Torque:23Nm (16.6 ft-lb) <br />3)Recheck valve clearance after tightening the lock nut.<br />4)Install the removed parts in reverse order of disassembly.<br />-------------------------------<br />If your going to miss a valve adjustment check, the intial 20hr isn't the one to miss. This is the break-in adjustment.<br />Checking valve adjustment deserves alot more attention then what brand oil you're using.<br /><br />I adjusted my valves at the recommended intial 20hr. service interval. I adjusted a loose #3 exaust valve clearance. At 100hrs. I adjusted a loose #1 intake valve clearance.<br />At 200hrs. no adjustment was needed.<br /> They will be checked again in another 10 or so hours, at 300 hrs.<br /><br />Valve clearances tighten substantially at cold temperatures. A valve with tight clearances on a 70deg. day is one thing. That same clearance goes away on a 20deg. day. Immediately resulting in a terrible coldstart and rough running while the engine warms up.<br />A common complaint with the BF50.<br /><br />BTW, my cambelt needs and gets an adjustment pretty regular.<br />It's a very simple proceedure also. <br />Buy the FSM. 
rodbolt pretty much covered it, but here are a few other considerations.<br /><br />The head of an exaust valve is probably the hottest single part of an engine. The only time it has an opportunity to cool is when it is resting on its seat. This is a pretty short duration, so the contact has to be positive and complete.<br />Here are a few situations that hamper that contact.<br />Say a motor has a tight valve clearance on that 70 deg. day. Then temps start to drop with the season. That already tight clearance turns into no clearance. The valve is held off its seat while the engine is brought up to operating temps. The valve seat starts to collect carbon deposits on it. This carbon hampers proper cooling and sealing of the valve. Gasses start to leak past and make the problem worse. The valve and seat are no longer sealing or cooling.<br />As a valve and seat start to burn away, the clearance starts to go away more. Really to the point that the valve never makes positive contact with the seat. At this point the damage is done, a burnt valve and valve seat.
rodbolt is correct in his answer.
<br /><br />In my own words. <br /> Generally <br />Wear in the valvetrain, camshaft, tappets or followers, shims or pads and valve stem tip result in greater clearance, loose adjustment.<br />Wear or burning at the contact face of the valve, and contact surface of the valve seat and/or low ambient temperatures cause a decrease in valve clearance, tight adjustment. . I also bought a set with the tips ground .002" smaller for the first 1/2" or so. they are also bent at a 45* angle and are desighned for valvetrain use. they are about 25 to 30 dollars a set but well worth the extra money. takes all the feel work out. just roll the engine to the proper position and insert the gauge. if the first one goes and the second step does not its correct.<br /> but yes I too have several sets that I have to check the thickness with my caliper first Nobody's going to bite on this one?