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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Valve grinding... Not allowed or...? /cgi-bin/YaBB.pl?num=1478805130 Message started by Mekh on 11/10/16 at 11:12:10 |
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Title: Valve grinding... Not allowed or...? Post by Mekh on 11/10/16 at 11:12:10 My exhaust valves looks like they would benefit from being lapped/ground, but... in Clymers manual it says they cannot be ground and must be replaced if defective. Really? I have to replace them if they are not ok? Bonus question: how do I remove the valve seal correctly? Just pull them off with a plier? |
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Title: Re: Valve grinding... Not allowed or...? Post by Dave on 11/10/16 at 12:16:06 The valves cannot be ground. The valves are made very light and thin, and I believe they have a very thin hardening layer applied. If you grind them the edges get too thin, and they exhaust valves will burn away. The valve seal pulls off....don't get them crooked and pry, get them off as straight as possible or you can break the valve guide. |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/10/16 at 13:10:43 Thanks. Seals came off fine. Just did not dare pulling or prying much, when I was not sure how they were fixed in place. So... If I cannot grind the valves, can I expect a tight seal between new exhaust valves and the valve seats? |
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Title: Re: Valve grinding... Not allowed or...? Post by Dave on 11/10/16 at 13:17:55 You can lap the seals with "Valve Grinding Compound" paste to confirm they are bedded into the seats - you should not put a valve in a valve grinding machine and take any metal off the valve with a grinding wheel or cutter. |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/10/16 at 13:49:34 Ahh, ok... That was actually what I meant. Good to hear, since the renovation costs seems to be going up a bit too much to my liking. Something like this is what I have in mind: https://youtu.be/5a71QWTogmE |
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Title: Re: Valve grinding... Not allowed or...? Post by Dave on 11/10/16 at 13:59:35 That fellow is overdoing it.....he said he had been grinding for about 5 minutes! You just want to scuff the valves in to confirm the valves are seating. Use a black marker to die the surface of the valve (or Prussian blue if you have it). Then use the grinding past just until the color is scrubbed off where the valve is touching the seat. If you have any areas that don't clean up with 15-20 second of grinding - the valve most likely will need to be replaced. When you begin to grind you will hear the rough sound, then after a few seconds the sound will smooth out - lif the valve up and it will pull the compound back into the surface between the valve and seat, then grind again until the gritty sound goes away.....repeat this just 4 or 5 times and then pull the valve out and wipe it off and look at the valve....it should have a dull silver strip all the way around. (Mower valves are different - they are thick and heavy and can be ground easily, as there is plenty of material that can be removed). |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/10/16 at 20:52:13 Thanks, appreciate the tips a lot. [ch9786][ch65039] |
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Title: Re: Valve grinding... Not allowed or...? Post by justin_o_guy2 on 11/11/16 at 05:54:30 Such technique and advice deserves a place in the tech section. |
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Title: Re: Valve grinding... Not allowed or...? Post by Ruttly on 11/11/16 at 10:28:02 Don't forget grinding of valve and seat changes installed height of valve ! The seats can be lightly ground if needed , but grinding the valves is asking for trouble , replace them ! Once the valve has been cleaned and checked in guide for wear and your ok with reusing them , just lap them in as per what Dave (SuperDave) described. Lapping valves gives a view of how well valve is contacting the seat. A lot of people don't do it,I guess it's an old school thing,I won't assemble a head without doing it ! And when using lapping compound be very careful NOT to get it on the stem of the valve or anywhere near the guide and wash all parts before assembly and blow out the guides with air ! |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/12/16 at 01:29:35 A thing confusing me here is the word "lapped". To my previous knowledge and according to translators the "correct" word should be grinding/ground. It seems that in the context of valves, grinding involves a machine (milling, drilling, lathe) of some kind. Where using a grinding compound to grind valves lightly is called "lapping" the valves and valve seat. Reason for writing the above is to better understand this, and to help others that may find this grinding/lapping confusing. Please let me know if the above is incorrect. English is my second/third language, so... :) |
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Title: Re: Valve grinding... Not allowed or...? Post by Dave on 11/12/16 at 03:14:02 When you grind the valves or valve seats (hardened metal inserts in the aluminum head), you create a new surface by removing metal with a grinding wheel or cutter. This process leaves some very small grinding marks/scratches in the surface. The valve grinding paste does not "grind" the valves or seats.....it is called that because the product is used after the valve grinding is completed using machinery. The valve grinding paste is used to smooth out and remove the scratches the grinding left in the surface. This process is called "lapping in the valves". What you are doing is using the paste to smooth the surface and look for imperfections....you are not "grinding" the valves or seats with the paste. |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/12/16 at 05:38:19 Thank you for the explanation. As mentioned by justin_o_guy2, the subject regarding grinding/lapping valves really should be condensed into a how-to with tips and tricks in the tech section. I'm willing to try and make a post with a write-up, but guess I will need help from someone to actually place it in the right place and so on. Should I give it a go, and then send it to.... who? |
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Title: Re: Valve grinding... Not allowed or...? Post by Papa Bear on 11/12/16 at 07:43:50 "My exhaust valves looks like they would benefit from being lapped/ground," Explain the words "Looks like they would benefit" .... I would often say something like that just before I open a can of worms that never needed opening ;) |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/12/16 at 08:39:04 Uneven carbon deposits around the valves and valve stems. I do not intend to just grind/lap away for the "fun" of it. :) I intend to check with color on the surface of the valve seat first, then insert valve, rotate it back and forth a few degrees to get a feel of how oval and/or uneven it is. If all looks fine I will not do much if anything. If however it looks like it's oval and/or uneven I will lap it a bit, then re-check... Rinse/repeat... |
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Title: Re: Valve grinding... Not allowed or...? Post by Ruttly on 11/13/16 at 07:58:30 While you have the valves out you might want to do a little work on the exhaust port too. For the fun or it Even the most dreaded & difficult jobs when building a bike are done just for the fun of it !!! |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/13/16 at 12:03:17 I'm considering it, but I really, really, really love the low end torque in this engine and would hate to compromise that. Haven't gotten around to ask into this yet. |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/19/16 at 06:33:16 Yesterday I lapped my valves and wanted to show a few photos of it. http://https://dl.dropboxusercontent.com/u/295041/billeder/SuzukiSavage/2016-11-18%2021.43.34.jpg http://https://dl.dropboxusercontent.com/u/295041/billeder/SuzukiSavage/2016-11-18%2022.01.30.jpg http://https://dl.dropboxusercontent.com/u/295041/billeder/SuzukiSavage/2016-11-18%2022.19.18.jpg |
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Title: Re: Valve grinding... Not allowed or...? Post by Ruttly on 11/19/16 at 11:28:57 Looks good from what I can see,great way to see how well your valves will seal. It's a task but an easy one, kinda fun |
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Title: Re: Valve grinding... Not allowed or...? Post by LANCER on 11/19/16 at 13:42:32 The valve pictured in the middle photo, has that one been lapped ? If so, what is with all the spottiness ? |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/19/16 at 13:53:16 The spotted one was only lapped a bit, took a photo to show just how uneven the surface was. Afterwards I finished it. |
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Title: Re: Valve grinding... Not allowed or...? Post by justin_o_guy2 on 11/22/16 at 02:48:48 Before I even pull a valve spring I put the head upside down and level and dump gas in it. Leaky valves will be exposed. |
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Title: Re: Valve grinding... Not allowed or...? Post by Mekh on 11/22/16 at 11:26:39 I tried that and the exhaust valves leaked quite a bit. The inlet valves not so much. The exhaust valves required a bit more work, while I just lapped the inlet valves a bit with the fine grinding paste. |
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Title: Re: Valve grinding... Not allowed or...? Post by LANCER on 11/22/16 at 12:20:28 I recently got a tool to help speed up the lapping process. It is hand operated. It has 3 heads for various valve sizes. The head attaches to the valve by a built in vacuum pump. It cost a few bucks and is pretty well made. The body is a tough plastic material. Just one push on the top while holding it firmly to the valve head and it is attached. The valve head does need to be clean of course. I purchased it from Goodson Tools and Supplies for Engine Builders It is called a VLV-50 Vacuum-Style Lapping Stick It was $32.99, and $42.58 with shipping. http://https://s26.postimg.org/nwivjgbkp/DSCN0094.jpg |
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Title: Re: Valve grinding... Not allowed or...? Post by Kenny G on 11/22/16 at 13:22:23 Lancer, That tool sure beats that darned old thing KD tools made. Do you remember, they were painted orange with a suction cup on both ends. The good old days. Kenny G |
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Title: Re: Valve grinding... Not allowed or...? Post by LANCER on 11/22/16 at 13:28:28 4D6368457467756E060 wrote:
I've got the old style but with a brown handle, and yes, I like this one much more. The old style rubber stoppers on each end just DID NOT hold at all. I would take a piece of Gorilla tape and fold it and use that to keep the thing stuck to the valve. It would work ... sort of. |
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Title: Re: Valve grinding... Not allowed or...? Post by Ruttly on 11/22/16 at 21:06:39 I just use a rubber hose that fits tight at top of the valve stem and my trusty can of coarse & fine lapping compound and BEER ! ;D |
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