Anybody got information about low tech/low cost valve seat grinding?

v30magna

v30magna

Been Around the Block
It has come to the point that I think I would like to learn how to grind valve seats, and pick up some tools. I'm kind of poor (too poor to pay for all the valve jobs I need on all my toys), and I like doing things myself. I basically have a small atv/dirtbike graveyard full of lab rats to learn on too.



I'd like info on something like entry level equipment, and what size and types of grind stones I'll need. I want to start with my '83 XR200r. I've lapped valves before, but never had a seat grind set. I want to install new valves in old heads and lap as necesary. I've seen a video of a guy use a guide shaft, stone, and holder, hooked to a cordless drill going slow. That's all i really need, just something to get an old head to seal new valves.

How do i figure out what stuff to buy? I want to try to get just the stuff i need, possibly used, to save money. If I can get my 200 going, I'll need to do an atc70, a 300ex, and a 250 big red. My cb77 305 might be another I'dlike to do. I really would like to end up with a simple valve seat grind setup that i can use to do all 4 of these vehicles. What are the least tools i could buy to get a valve grind setup to do these 5 vehicles? Anybody else low tech like me?
 
It would take several different stones to grind the seats. I know in cars there are several angles that are used between manufacturers and a way to set and grind the valves at the same angle.

If you could get the stones onto a shaft you could use the valve guides to hold it straight on a drill and do the seats.

As for the valves you could look into a drill bit grinding setup and modify that since you can set those to grind specific angles onto the bits.

Kinda thinking out loud there but hope its a start.
 
you're going to need to cut the valves as well, otherwise regrinding or recutting the seats is pretty pointless. all in all, it's a pretty good investment in tools, you can buy used stuff but if you don't know how or lack the tools to make sure the used stuff is accurate, then it's a bit of a waste. a generic seat and valve cutting setup will likely cost you at least $500, which will take care of a size range of valves and seats, if you have dramatically different size valves, then you'll need additional tools
 
neway makes cutter sets for less than $500, that would be an inexpensive way to go
i am not aware of a cheap method to do it right it is a precision operation
 
And the Neway cutter is still hand operated, so you're looking at having to combat chatter until you develop the knack.
 
If you're going to use new valves then you don't need to face the old ones - you just need to cut the seats.

Having said that, by the time you buy the cutters and the new valves you're probably going to be around the same price point as getting a shop to re-face the old valves and cut the seats.

Also, if you have to replace the seats / valve guides then it's a shop job anyway.

Most of the cutting kits you see on eBay aren't small enough for small bike motors (mainly the guides are too large in diameter).
 
Thanks for all the replies so far guys, exactly the info I'm looking for.

In any case which I'd be grinding the seat, I'll be using new valves. New valves shouldn't need a grind, just a lap (where it applies). The guy who tought me what I know about engines tought me how to lap in valves, but I've got a pile of stuff that is just gonna need the seats ground, too far out to lap. I'd like to start out cheap and get better stuff as I go along if it's possible. If I need new guides or seats on most of the stuff I'll be working on, it'll be easier and cheaper for me to just use another head and sell the old one for a core. That's why I primarily work on small vintage Honda stuff (50-250cc), because of parts availability/prices.

I've been looking around a little, and found 2 systems that suit my application.

The Neway kit uses a cutting head with blades, appears to do 3 angles at once, and rides on a guide. You rotate it a few times by hand and you got a seat (got to practice to get the skills, but it's pretty strait forward). Fairly expensive.

Then there is the Souix and Black and Decker grinding stone system. You use stones instead of a cutter, each stone cuts one angle. stone is screwed onto a "holder", which rides on a guide. The holder is rotated by a big electric tool that isn't much more than a specialized rotary tool. Head has to be in a vice (original souix kits had a dedicated vice) Even more expensive if you have the whole setup.


The cheap method I'm pursuing seems to be to collect only the exact stones and guides you need for the jobs you have, get a stone holder, and run it with an electric drill using your own vice. At this point you do have to combat chatter, and you have to be sure you got exactly the right guides and stones to insure accuracy.


That's what I got so far.

Is it ok to just grind the primary valve angle and lap it in, or is it manditory to have three angles?

I'll see if I can find some valve angles and dimensions from the stuff I need to do, and I'll post it, as well as anything else I find.
 
the valve seat contact must be the correct width and location of contact on the valve face
so the seat must be narrowed during/after grinding and the extra 2 angles do this
so you cannot just grind the seat and lap the valve
once the seat valve job is done consideration of the installed length of the valve stem stickout must be addressed most often by ginding the stem tip
 
3 angle flows much better and less reversion

with the stone system dont forget taht you need the stone dresser and diamond cutter as well

the electric driver is designed to allow the holder to float to center on the guide pin

if you try to drive the stone with a fixed chuck driver you will grind the seat off center
 
Ah, very good info. Thanks. So I guess I'll need to get a proper system either way. So right now it looks like I'll find out the specifications for each of these vehicles I have and look for a deal on a Neway kit that will work.
 
any seat grinding system needs a way to dress the wheels, and if you want to be right, you really need a way to ensure your dress angle is good, so there's more tooling. a cutter should do the angles well, carbide doesn't really wear if you're turning it by hand.
 
word. I was finally able to get in contact with my "mentor" about this issue. He agrees with pretty much everything, but he did offer one but of advice I'll share.

He explained that in the case that you just gotta get the motor to run and you're broke and aren't worried about ruining a new valve or the head, you can basically just lap a new valve in with coarse lapping compound if the old seat isn't knicked deep, severely out of round, worn or pitted, etc., even if the seat if rounded. You just lap the hell out of it until you get a band, like you would during normal lapping. The band will most likely be closer to the tip of the valve, and thinner than it is supposed to be, but he said he's had success with a variety of vehicles he has tried this on over the last 30 years (of course he's experienced enough to know when the seat is too toasted to even try it). He said you will most likely be running out of spec with this method, and you can't run the motor as hard as if it were in spec without a failure, but if it passes the "fluid test" it'll run. I had an '84 ATC200s that we built 3 years ago. Appearantly that's how he did the valves in it. I had no idea. I tried to break it for the 2 years I had it, and the guy I sold it to still rides it.
 
You can bodge anything if you try hard enough ;D

Seriously, unless you're racing and chasing an extra tenth, lapping a new valve to an old seat will still "work".
 
for a while :-\ an overly wide exhaust seat in particular can leads to carbon buildup leads to loss of heat transfer leads to burnt valve
 
well said hilsy. This method is gonna give you less time and use before failure than a good cut. Say the Honda ran 30 years with the original valve with fresh seat. With this method you can expect the time to be shorter in relation to how worn the seat was.

Also consider that most of these motors that I'm refering to are 50cc-200cc Honda 2,3, and 4 wheel bikes/atvs. Lower revolutions over the years due to lower distance traveled. The old enduros i usually see have from 1000-5000miles on the clock, in the last 30-50 years. Much less than a road bikes sees.
 
I usually do mine with a pocket knife and the ole calibrated eyeball
;)
 
at least by this method it saves all the hassle of having factory service manuals

and all those pesky specifications and measurements

and a bunch of measuring equipment and service equipment


why didnt i think of that ???
 
you take an engine outta the frame tear it all apart and fix it wrong why bother
it is not rocket science at all to do the job right,and it does not even cost a lot to buy the tools ???it is just you are too much of a cheap fucker to buy the tools :D please tell us that you won't be selling a bodged up machine ? will you tell your buyer that you did it wrong if you do ?
 
well, I didn't say do it yourself, I just said that it works. I'm gonna get a Neway kit. I was just sharing info I recieved. if you guys wanna chuckle it up go ahead, atleast I'll know I made a few people happy this holiday season.

and I'll tell everyone but you xb33bsa, everyone but you...



If you had any idea the global operation I got going here LOL! I basically have a pile of trash. I can build full Honda atvs and atcs for around $100-$300 out of pocket. Most of the stuff I have I just bomb around on until it breaks and sell it again for parts. I always practice full disclosure when selling running vehicles. My family usually buys the stuff I don't break, and I fix thier crap for next to free (gas money or dinner). The prices I charge for things that run, you guys probably pay for parking or vehicle storage fees or Homeowner's association.

If something's toast, I part it out. Sometimes it just doesn't justify the money. Say you got a Honda Clone 50-124cc pitbike you got for free (that's about what they're worth, people chuck 'em at me like fish mongers). You can pull the head and cylinder with the engine on the bike. Hone, $10 rings, "quick valves", you got a runner. Go break it... You can't throw your pocket book at every bike in the world fellas, some of them aren't worth it. Learn to appreciate things less, you'll be happier.

cxman said:
at least by this method it saves all the hassle of having factory service manuals

and all those pesky specifications and measurements

and a bunch of measuring equipment and service equipment


why didnt i think of that ???
Click to expand...

Although it's meant to sting, it's also exactly the point. Fierce.
 
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