VALVE GUIDES
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Squid
Joined: Jan 2012
Posts: 38
From: Vancouver, WA
VALVE GUIDES
so i just had ne valve guides pressed in. now the new valves will not fit in the guides. is this normal the guy at the maxhine shop said thaty the guides may need to be honed out to fit the valves, is this normal? i would think that sinxe both the guides and valves are new the should fit togeather. i'm not sure what to do other then have brand new $30 a set valve guides honed out.
Senior Member
SuperBike
Joined: Aug 2005
Posts: 1,864
From: Fort Wayne, IN
They should have reamed them after pressing. My advice: find a different machine shop. You should never have to tweak anything after the parts come back from the machine shop. That is their job!
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MotoGP
Joined: Apr 2006
Posts: 4,402
From: Kempner, TX
Yes after heating the head and installing the guides to to proper height, the head is allowed to cool and valve guides should be honed.
Honing the guides is PART of the install... not something additional or optional.
Honing the guides is PART of the install... not something additional or optional.
Thread Starter
Member
Squid
Joined: Jan 2012
Posts: 38
From: Vancouver, WA
thanks for the answers i took the head back to the shop with the parts and they honed the guides. just one more question when setting the timming are the lobes of the cams supposed to be pointed away from each other or towards each other? i ask because i followed the instructions for cam replacement and timming from the manual bu when i started it agter it was back together there is a clanking sound so i immediately shut it down as to hopefully not bend the valves again.
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MotoGP
Joined: Apr 2006
Posts: 4,402
From: Kempner, TX
thanks for the answers i took the head back to the shop with the parts and they honed the guides. just one more question when setting the timming are the lobes of the cams supposed to be pointed away from each other or towards each other? i ask because i followed the instructions for cam replacement and timming from the manual bu when i started it agter it was back together there is a clanking sound so i immediately shut it down as to hopefully not bend the valves again.
Senior Member
Superstock
Joined: Jul 2013
Posts: 458
From: Rome, GA
a clanking or ticking sound can also be caused by the cam chain or too much clearance in the valve shims. one persons clank is another persons click, hard to know exactly what a noise is without hearing it yourself. When I put new valves in my bike the old shims were way too large (machine shop had to do a little work on the head because the old bent valves dinged it up some so without the machining the new valves wouldn't seal properly) and if you didn't do your valve clearances and just reused the old shims that could be where your noise is coming from. also the machining process to make the valves isn't perfect and one may be a couple tenths of a mm off from another. They are closer than the human eye can tell, but when your talking valve clearances in the hundreth of a millimeter the bike will let you know
Senior Member
MotoGP
Joined: Jul 2010
Posts: 3,871
From: Phoenix, AZ
To answer the other part of the question, when you are setting the timing of the valves, the front cylinder cams will be pointing out from each other and slightly up, and the rear ones will be pointing in towards each other and up. It's not the same for each cylinder. This method should be used for reference... when making sure it's exact you should line up the cam marks on the sprockets to set the timing...
This is a pic of lining up the FI (front intake) with the top of the cylinder head using a straight edge.
This is a pic of lining up the FI (front intake) with the top of the cylinder head using a straight edge.
Rex Kramer-Thrill Seeker
SuperBike
Joined: Jan 2011
Posts: 2,312
From: Brookfield, WI
thanks for the answers i took the head back to the shop with the parts and they honed the guides. just one more question when setting the timming are the lobes of the cams supposed to be pointed away from each other or towards each other? i ask because i followed the instructions for cam replacement and timming from the manual bu when i started it agter it was back together there is a clanking sound so i immediately shut it down as to hopefully not bend the valves again.
Thread Starter
Member
Squid
Joined: Jan 2012
Posts: 38
From: Vancouver, WA
yes i did it did not make the sound then. and i measured the lifter tolerances with feeler gauges and had to do some grinding on the shims i'm just wondering if i put the cams back in the wrong spot if you set the xams to the proper timing marks the lobes on the cams are pointing away from each other at about a 125 degree angle from the head.
this happened to the rear cylinder about a year ago and i rebuilt it and put it back together and it fired up without a problem. i had found a photo of the right side of the head that showed wich way the lobes are supposed to be pointing but i can not find one for the front head. just moving the lobes from a 135 degree (exhaust cam) and 45 degree (intake cam) angle to the top of the head prospectively to a 45 degree (ex) and 135 (int) xan make it far enough out of time to bend the valves.
this happened to the rear cylinder about a year ago and i rebuilt it and put it back together and it fired up without a problem. i had found a photo of the right side of the head that showed wich way the lobes are supposed to be pointing but i can not find one for the front head. just moving the lobes from a 135 degree (exhaust cam) and 45 degree (intake cam) angle to the top of the head prospectively to a 45 degree (ex) and 135 (int) xan make it far enough out of time to bend the valves.
Senior Member
SuperBike
Joined: Dec 2005
Posts: 1,689
From: South Lake Tahoe, CA, USA
As Jamie said, a reamer is the preferred tool for sizing the valve guides after installation. It produces a very accurate, straight bore, sized perfectly (if you use the correct reamer). Honing creates a bellmouthed bore. It will be fine, but also more time consuming.
After the valve guides are installed, the valve seats should be cut to make the valve seats concentric with the guides. Yours are probably close, but not perfect. Since the valve guide clearance is tightened up, the concentricity error is more significant. Probably better to have loose-fitting valve guides with good concentricity.
An engine is a very high precision machine. The details make the difference.
After the valve guides are installed, the valve seats should be cut to make the valve seats concentric with the guides. Yours are probably close, but not perfect. Since the valve guide clearance is tightened up, the concentricity error is more significant. Probably better to have loose-fitting valve guides with good concentricity.
An engine is a very high precision machine. The details make the difference.
Thread Starter
Member
Squid
Joined: Jan 2012
Posts: 38
From: Vancouver, WA
thanks for all the help everyone, i finally got the time to work on the hawk today i pulled the valve cover off and followed the steps in the manual to time it again and when I got it all back together she fired right up. it had to be human error i think when i set the timing the first time i went from the f mark and not the ft mark.
good news is it seems throatier that it was before and it has more power ( impersonates tim the tool-man taylor) after i got the carbs some what dialed back in i went for a ride and ended up pulling a wheelie while spinning the back tire. boy was that an experience.
anyway again thanks for all the help and if anyone is in the vancouver WA. area send me a pm i'm ready for a nice fall ride.
good news is it seems throatier that it was before and it has more power ( impersonates tim the tool-man taylor) after i got the carbs some what dialed back in i went for a ride and ended up pulling a wheelie while spinning the back tire. boy was that an experience.
anyway again thanks for all the help and if anyone is in the vancouver WA. area send me a pm i'm ready for a nice fall ride.
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