How to set Valve clearances on horizontal engines.

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thump*140

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Ladies and Gentlemens, may I have your attention please??
Is your bike hard to start?
Have you been chasing a carby issue you just cant fix?
Has your engine recently lost a bit of compression?
Is your bike running a bit hot?
Is your missus dis-satisfied with your “performance”?
Do you kids no longer think you’re “cool”?
Has your dog stopped coming when you call it?

Chances are, your valves clearances are WRONG!!!!
The above symptoms can all be effected by poorly gapped valves, and despite “doing your valve clearances” sounding scary, it is actually a very simple process, and hard to get it wrong…
With the right tools, you can do valve clearances in under fifteen minutes with a bit of practice, just like Uncle Thump…
Your missus will once again find you attractive, the kids will go riding with you again, and the dog will stop stealing your stubbie holders..

Naturally you will need a bike first up, and remember.. you’re working on the head… make sure it’s clean…and the following tools…

 17mm ring spanner.
 Large flathead screwdriver.
 8, 10, and 14mm sockets, extension bar and ratchet.
 Feeler gauges (.003 and .004 for inlet and exhaust valves respectively)
 9mm ring spanner
 Needle-nose pliers (or special valve-tool thingy if you are fortunate enough to have one.)
 15-20 minutes of shed time away from the kids and missus if you have them, or PS3/X-Box 360 if you’re a young fella.

Not all engines are equal in the valve caps or engine cases used. The engine I have used for the tute, is a 107cc FYM motor, as found in 04 Hungeten Thumpstars. It has the CRF style “screw-in” valve caps, and the stator cover has removeable plugs for the stator nut, and timing marks. Other “solid” type stator covers will need to be removed beforehand to allow you to find TDC.

 

thump*140

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 Step 1: Find TDC. Remove all inspection plugs or stator cover.

 Step 2: Remove cam cover. The bolt that allows you to do this, is on the other side of the motor, and goes right through the head. Using a 10 or 12mm socket, loosen this bolt until you can remove the cam cover.

 Step 3: using a 14mm socket on the stator nut, turn the motor over until you have lined up the “T” mark on the flywheel, and the TDC “Dot” on the cam sprocket, with the TDC “Groove” on the head. See pics below.
 

thump*140

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 Step four. Remove the valve caps, using either a 17mm ring spanner (CRF-style) or 8/10mm ring spanner if you have bolt on type caps. You will now be able to see the rocker arms, and adjusting nuts for the tappets.

 Step 5: There are two ways of going from here. You can either CHECK the clearances as they are, or you can loosen the nuts off, then SET the clearances from scratch. I have always started from scratch, but it’s up to you.

 Step 6: using your .003’’ feeler gauge, slide it under and between the rocker arm and the top of the INLET valve. This is the one closest to the carby, and is at the “top” of the motor. If the clearance is right, it should be slightly tricky to get the feeler gauge in there… if you cant slide it between the rocker and valve, your clearance is too low. If it slides in there easily, and moves easily, your clearance is too high. This is why I always start from scratch, rather than checking the clearance first. Saves a bit of time..
 Step 7: Using a 9mm ring spanner, loosen off the nut on top of the rocker arm.
 Step 8: Using needle nose pliers ( or your fingers is you are dextrous enough) LIGHTLY tighten the small square “bolt” that the locking nut is on, with the feeler gauge still in place, until the feeler gauge only juuuuuust slides in and out.

 Step 9: Once you have the gap set right, using the 9mm ring spanner and needle nose pliers, tighten the locking nut on the rocker arm.
 

thump*140

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 Step 10: repeat Steps 7-9 on the exhaust valve, using a .004” feeler gauge. Loosen locking nut, set the gap, and tighten locking nut.

 Step 11: Replace all valve caps, cam cover and inspection port caps/stator cover.

 Step 12: With the kill switch off, slowly turn the motor over with the kickstarter by hand. You should have decent compression, and no “knocking” noise coming from the piston, which would indicate valves hitting piston etc.
 Step 13: You have now set your valve clearances, and your motor is good to go, and you can start chasing carby problems, wifey problems, kid/dog problems etc etc, which by doing your valve clearances, you have eliminated one source of problem, and if problems still persist, you can see your doctor, or start playing with the carby…

 

mboyg1

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great work thump, top job on all the effort and detail you have gone into and it was easy reading.
 

thump*140

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Thanks Milfboy, i pride myself on making things as difficult as possible.. heh heh.. :)
 

tomy251

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Sweet write up mate!!!

Im sure it will help A LOT of people including myself.

Cheers ;)
 

thump*140

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pffft ring spanner and pliers is for losers :p
tappet adjusting tools make life so much easier ;)

nice guide by the way :cool:
screw you DVDrip, those tools are for pussies, Homo Honda riders, and clumsy people... ha ha ha ha!!!
Real men use needle nose pliers and ring spanners. they also undo wheel nuts on landcruisers with their teeth!!!! ;)

Hope it helps kiddies, this might be the next automatic link that goes into all noob posts...
 

thump*140

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^^^that is true, but i gave up smoking rollies when i moved to the city... so i can now no longer set the points in a points-ignition distributor either... Tally-ho's had so many uses aside from just cigarettes..
I can however, still fix broken swingarms with fencing wire and binder-twine from a haybale.... ;)
 

DvDRip

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heheh pwnt, thanks sean01 :D

dammit thump I was gonna say pliers n ring spanners are for homo's but decided to stay out of that war, then you use that card on me :(:p
 

thump*140

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lol, the war applies to everyone DVDrip... Yamaha or Homo, sorry, i mean Honda... choose your side gentlemen...

ha ha ha. ;)

New rule.

Thou shalt not pwnd Mods. ;)
 

DvDRip

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I choose yammies, I never owned either but I just like them and when pigs fly and I buy a brand spanking yz250f I won't have to replace homo red bits straight away ;)
 

t00l

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sorry for the beginner question, i just set my clearances to .003 in .004 exh, i'm now getting a much louder tapping noise than before, just wondering if this is because i have set them too tight or does this sound normal?

video
 

DvDRip

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sorry for the beginner question, i just set my clearances to .003 in .004 exh, i'm now getting a much louder tapping noise than before, just wondering if this is because i have set them too tight or does this sound normal?

video
tapping is normal but that does sound a bit excessive, the looser they are the louder it taps, maybe you should do them again just incase
 

t00l

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we did check the clearance after tightening back up but i did notice it was a lot louder!

when you say the feelers should just fit, they need a bit of a wiggle and jiggle to get in right?
we did a check on the exhaust before we set it, but we could only fit a .002 in there
or do the feelers need a fair push to get in there?
 

DvDRip

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the feeler should only just slide in there, you should be able to feel resistance and hear it scraping when you move it in and out
 

skruba

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wicked rite up will be doin this l8r fingers crossed it eliminates problems with my dog/girlfriend and kiddies lol
 

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