Valve Clearance By adamhoyer (Read 1,803 times)

[adamhoyer]

Got a question about valve clearance. I have a 157QMJ engine, what do I adjust it at when it says 0.006-0.008 on the emissions stamp? Both at 0.006 or 0.008 or intake at 0.006 and exhaust at 0.008?

[twowheeler]

intake .006 exhaust.008

[adamhoyer]

Thanks.

[Alleyoop]

On my Trike I have the 157QMJ motor I adjust them both to .004 inchs been doing that since 2009.
Alleyoop

[rapidjim]

I also use .004 inch on both intake and exhaust.

[clonedrone]

The .004 or a loose .003 is the correct clearance.
Mine are a Tight .004 or a Loose .003,
Word Of Caution!
These Valve Spring's are Very Light, you can push the valve in with your fingers.
So light they are closer to Book Binding Windings.
This will determine the amount of feel on the feeler Gauge.
A light feel or drag is sufficient, Anything More and you Will Actually Compress the Valve.
Ride On!
Clone

[Bashan]

I personally think .006" and especially .008" are too loose. The gap has to allow for the valve to open. If it's that slack the lobe comes around and smacks the valve mechanism and doesn't push it open adequately. If it's too tight the valve doesn't get to come back against the valve seat properly and your compression sucks. The gap between the rocker and adjuster also has to allow for heat induced expansion. The gap you set is not your hot running gap. So it's tricky, how hot your engine runs can affect your ideal gap also. I still think that's mighty wide.

[cyborg]

Clone are you serious? you can open the valve with your finger???,,,i had no idea they were so soft in these engines,,,,,

[Alleyoop]

No, you need to really push down usually it will take two hands, if they are that soft then you need to replace them. That soft you will have serious Valve Float at high rpms.
Alleyoop

[Bashan]

Clonedrone's hand:

[adamhoyer]

So i'm thinking then, adjust both to 0.004 then?

[Alleyoop]

Works for me
Alleyoop

[Bashan]

Alley and JR do that, I go .005" on the exhaust. The way I do it is I set them to .004 and .005. Then, at startup I like to hear some slight valve noise. As the bike warms up I want that noise to diminish but NOT GO AWAY! If you can't hear a little valve noise they're too tight IMO. Like Alley says, a happy valve purrs or something like that. It should be almost a whir instead of ticking. If one valve is too tight the sound level is cut in half. Also, you can get a mechanics stethoscope and put it right where the valve cover meets the head right next to each valve, top and bottom. You can hear them amidst all the engine noise if you listen carefully. If you can't hear one it's too tight. If so...reset. If you ride a while, shut your engine off, try to restart while hot and it won't start, you need to set your valves.

[adamhoyer]

Know of any cheap torque wrenches 1/4 drive? Need to torque down the head bolts on my 157qmj and the valve bolts.

[clonedrone]

Apr 1, 2014 16:13:01 GMT -6 adamhoyer said:

Know of any cheap torque wrenches 1/4 drive? Need to torque down the head bolts on my 157qmj and the valve bolts.

Harbor Freight