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Rebuilding heads aka valve jobs
In this installment of the Q ship saga, we are going to talk about valve jobs. A lot of time is spent jawing on the internet about things like carbs, cams, and exhaust, but relatively little attention is paid to valve jobs. A lot of this has to do with misinformation about valve jobs and it seems an even bigger portion has to do with the cost. Most machine shops charge a minimum of $150 per head plus parts to do a true valve job – with the price rising fast if you want special work done. Once you toss in valves, springs, guides, and other hard parts – the price easily hits $250-$300 per head. That starts getting to be too much for the average biker and they find “work arounds” until they can’t do so any longer.
The purpose of this write up is not to give you a step-by-step guide to doing your own valve jobs. To do so is to literally write a book. Instead, we are giving a 50,000 foot overview with highlights of the basic steps. There is quite a bit of skill and experience that goes into a full on valve job that is very difficult to capture in the written word – or even through photos. Long story made short – nothing beats experience when doing a valve job.
What we aren’t going to talk about here are full on performance valve jobs where we are concerned about spring pressure, seat pressure, coil bind, rocker geometry, etc. That is another level and more than we have room for in this simple overview.
So, why is it so expensive to get heads rebuilt and why don’t more people do their own valve jobs? The answer is simple – cost. Much like boring cylinders, a proper valve job requires a set of specialty tools. These tools are not only for the job at hand, but you may need a whole range of them to work on various types/brands of motor. As a result, it is almost never cost effective for the DIY/home mechanic to purchase these tools. And, be wary of used valve servicing tools. Unless you know for sure how they were cared for . . . you may wind up causing more grief than you prevent. Many, many heads have been seriously screwed up by shade tree wrenches beating guides in an out till “it felt right.” This is especially true of alloy heads. So, tread lightly if this is your first rodeo and consider a practice set of heads before you work on something you really can’t afford to screw up.
Before we get to the tools, let’s define what we mean by “valve job.” For a lot of folks, a valve job is nothing more than getting the valves to seal. Easy peasy. For clarity, we are going to split this term into five stages from Zero to Four.
Stage Zero is the baseline. This is where you simply clean the valves and “lap ‘em in” with compound. All the parts are reused – right down to springs. It is the oldest and the least effective “valve job.” Yes, it restores some seal, and leaves a ton on the table. In particular, “lapping ‘em in” tends to only truly work on the bench. Put simply, in the first seconds of operation, a valve heats up considerably. This causes its outside diameter (OD) to expand noticeably. This in turn causes the valve to ride higher on the seat – generally above that band you just spent time lapping in. So, while they seal on the bench . . . many a rider has experienced a bike that mysteriously “loses” power when hot. Usually the ring seal is blamed or a tight push rod, but often a prime culprit is a leaky valve that is fine cold . . . but cruddy hot. In short, avoid stage zero unless you have no choice on a back road in the third world. Or you hate your lawn mower. Stage Zero is sort of the high school shop class manifesto for small engines!
Stage One is where you reuse the existing guides, but pair them with new or reground valves and freshen the valve seats. This is one of the most common valve jobs. If the guides are straight and in spec (relatively rare above 30K miles on a motorbike) then this can be an effective method. Chuck has found it is generally best to start with new valves and to grind, as opposed to cutting, the freshened seats. Our goal is only to remove enough pitting to get a good seal.
Stage Two is where we fit new guides, valves, and cut new seats. This is a much more involved process and where skill as well as tools starts becoming important. This is the most common valve job from a professional machine shop.
Stage Three is much like Stage Two, but we go further. The valve guide bore is honed to a mirror finish, the exact ID mic’d, and guides selected or machined for the correct interference fit. Guides are sized and then honed mirror smooth, valves are polished, and often the valve head is back cut at a 30 (and sometimes a 30 and 15 degree angle) to smooth the flow. Oversize valves may be fitted. All edges are radiused, etc. This is more of a “performance” valve job and is overkill for stock bikes on the street. Sort of like hunting rabbits with a .303. If you have a stroker . . . well, this might be where we start.
Stage Four is Stage Three but with relieving/radius work, maybe some port work, and certainly valve lightening. This is for the all-out person . . . and like taking the space shuttle to visit California if you have a stock bike.
To illustrate, over the coming weeks we will do two valve jobs. The first one, illustrated here, is a Stage Two job meant for a stock 900 sportster. When we do the Q ship, we will do a Stage 3 job, minus the valve back cutting.
Before we get started, let’s talk about tools. In general, here is a list of the minimum tools you would need to do a full on valve job at home:
1) 1-inch micrometer – preferably a Vernier mic.
2) Miniature inside mic or ball gauges that can read .25 to .4
3) Reams – proper valve guide reams are piloted and NOT common sizes. They also are not inexpensive. HSS for cast iron, carbide for bronze. Generally $50 each!
4) 14/18mm thread restorer for sparkplugs
5) 7 and 8 mm ball hones – or a sunnen honing station or a sunnen portahone driving head for valve guide mandrels. Ball or flex hones are about $20 each; a sunnen station will run you about $400 used, and then another $400 for tooling. The Portas generally are $400 used -- $600 new. Stone sets are priced by size and material. They range from $15-45 set. We won’t talk about the cost of honing oil.
6) Intake and Exhaust pilots. You’ll need several solid pilots or a couple of expandables. Solids are usually around 25-30 bucks each, expandables are usually around $50 each!
7) Intake and Exhaust seat cutters or a stone grinding kit. The most common cutters in the US today are Neway, though old kwik-way and Sioux valve cutters (or sometimes called valve reams) are around. Note that if they don’t have carbide blades, you won’t be getting through stellite seats. Stone grinding kits are also widely available. They tend to be pretty beat on the used market and require quite a bit of re-supply before use. About the cheapest you can get away is around $200 for cutters and around $500 for a properly equipped grinding set. All require some skill to use. Your patience determines your craftsmanship as they are HAND tools. Really big shops have dedicated machine tools for this stuff that allow even the inexperienced to get very, very good results.
8) Dykem, Prussian blue, or sharpies for marking seats and contact patterns
9) Concentricity gauge. This is to check the run out of your valve seat – it’s a $200 tool and not strictly necessary – but it sure helps.
10) Brass brushes or a media blast cabinet for carbon removal
11) Parts washer or a good bucket of cleaner
12) Cleaning brushes
13) Double diameter drift or fixture and arbor press for removing/installing guides
14) Can of 220 lapping compound
15) Vernier calipers or a steel rule capable of measuring 32nds or 64ths.
16) Valve spring compressor – while you can disassemble without a compressor, getting things back together is a bit more challenging without one!
17) Trays or pans to hold all the parts and keep them organized.
18) Spring tension gauge (if you intend to reuse springs).
19) A good 6-10 inch vise solidly mounted to the bench
20) If you’re driving guides in and out by hand . . .a good 1.5lb peining or brass hammer
21) If you’re a press guy – a fixture and 1 ton arbor or 10 ton hydraulic press.
All in all – it’s a solid $600-1000 worth of tooling to equip yourself to do ONE valve job on one brand. Maybe you’ll get lucky and the tooling fits more than one of your scoots – but this is relatively uncommon.
Speaking of tooling; let’s talk real fast about cutters and stones. Valve seat cutters are just that – a cutting tool that pilots off the guide centerline to create a seat. Some people swear by them and many swear at them. Neway is the premier maker in North America. Currently, there is a crop of India and China made “valve reams” on the market. Please don’t buy them. If you want cutters, buy Neways and be happy. With regard to stone kits – if you don’t buy a full kit – then what are you buying? The full kit consists of a motor, driver, spring holder, seat spring, a bunch of pilots, a bunch of stones in different grits/sizes, and a diamond dressing stand. They take up a box about double the size of a large hand tool box. Common names on the used market include black and decker, blue point, van norman, and Sioux. Brand new sets are quite expensive. Chuck’s favorite was/is the Black and Decker set with the old 5 pound driver motor, which was made by Blue Point. The sets prior to the 80s were GREAT and are so robust you can still buy brand new supplies as of January 2020 – a full 40 years since B&D last offered them!
And, don't forget about Hall-Toledos . . .if you find a complete kit, consider buying it.
In this installment of the Q ship saga, we are going to talk about valve jobs. A lot of time is spent jawing on the internet about things like carbs, cams, and exhaust, but relatively little attention is paid to valve jobs. A lot of this has to do with misinformation about valve jobs and it seems an even bigger portion has to do with the cost. Most machine shops charge a minimum of $150 per head plus parts to do a true valve job – with the price rising fast if you want special work done. Once you toss in valves, springs, guides, and other hard parts – the price easily hits $250-$300 per head. That starts getting to be too much for the average biker and they find “work arounds” until they can’t do so any longer.
The purpose of this write up is not to give you a step-by-step guide to doing your own valve jobs. To do so is to literally write a book. Instead, we are giving a 50,000 foot overview with highlights of the basic steps. There is quite a bit of skill and experience that goes into a full on valve job that is very difficult to capture in the written word – or even through photos. Long story made short – nothing beats experience when doing a valve job.
What we aren’t going to talk about here are full on performance valve jobs where we are concerned about spring pressure, seat pressure, coil bind, rocker geometry, etc. That is another level and more than we have room for in this simple overview.
So, why is it so expensive to get heads rebuilt and why don’t more people do their own valve jobs? The answer is simple – cost. Much like boring cylinders, a proper valve job requires a set of specialty tools. These tools are not only for the job at hand, but you may need a whole range of them to work on various types/brands of motor. As a result, it is almost never cost effective for the DIY/home mechanic to purchase these tools. And, be wary of used valve servicing tools. Unless you know for sure how they were cared for . . . you may wind up causing more grief than you prevent. Many, many heads have been seriously screwed up by shade tree wrenches beating guides in an out till “it felt right.” This is especially true of alloy heads. So, tread lightly if this is your first rodeo and consider a practice set of heads before you work on something you really can’t afford to screw up.
Before we get to the tools, let’s define what we mean by “valve job.” For a lot of folks, a valve job is nothing more than getting the valves to seal. Easy peasy. For clarity, we are going to split this term into five stages from Zero to Four.
Stage Zero is the baseline. This is where you simply clean the valves and “lap ‘em in” with compound. All the parts are reused – right down to springs. It is the oldest and the least effective “valve job.” Yes, it restores some seal, and leaves a ton on the table. In particular, “lapping ‘em in” tends to only truly work on the bench. Put simply, in the first seconds of operation, a valve heats up considerably. This causes its outside diameter (OD) to expand noticeably. This in turn causes the valve to ride higher on the seat – generally above that band you just spent time lapping in. So, while they seal on the bench . . . many a rider has experienced a bike that mysteriously “loses” power when hot. Usually the ring seal is blamed or a tight push rod, but often a prime culprit is a leaky valve that is fine cold . . . but cruddy hot. In short, avoid stage zero unless you have no choice on a back road in the third world. Or you hate your lawn mower. Stage Zero is sort of the high school shop class manifesto for small engines!
Stage One is where you reuse the existing guides, but pair them with new or reground valves and freshen the valve seats. This is one of the most common valve jobs. If the guides are straight and in spec (relatively rare above 30K miles on a motorbike) then this can be an effective method. Chuck has found it is generally best to start with new valves and to grind, as opposed to cutting, the freshened seats. Our goal is only to remove enough pitting to get a good seal.
Stage Two is where we fit new guides, valves, and cut new seats. This is a much more involved process and where skill as well as tools starts becoming important. This is the most common valve job from a professional machine shop.
Stage Three is much like Stage Two, but we go further. The valve guide bore is honed to a mirror finish, the exact ID mic’d, and guides selected or machined for the correct interference fit. Guides are sized and then honed mirror smooth, valves are polished, and often the valve head is back cut at a 30 (and sometimes a 30 and 15 degree angle) to smooth the flow. Oversize valves may be fitted. All edges are radiused, etc. This is more of a “performance” valve job and is overkill for stock bikes on the street. Sort of like hunting rabbits with a .303. If you have a stroker . . . well, this might be where we start.
Stage Four is Stage Three but with relieving/radius work, maybe some port work, and certainly valve lightening. This is for the all-out person . . . and like taking the space shuttle to visit California if you have a stock bike.
To illustrate, over the coming weeks we will do two valve jobs. The first one, illustrated here, is a Stage Two job meant for a stock 900 sportster. When we do the Q ship, we will do a Stage 3 job, minus the valve back cutting.
Before we get started, let’s talk about tools. In general, here is a list of the minimum tools you would need to do a full on valve job at home:
1) 1-inch micrometer – preferably a Vernier mic.
2) Miniature inside mic or ball gauges that can read .25 to .4
3) Reams – proper valve guide reams are piloted and NOT common sizes. They also are not inexpensive. HSS for cast iron, carbide for bronze. Generally $50 each!
4) 14/18mm thread restorer for sparkplugs
5) 7 and 8 mm ball hones – or a sunnen honing station or a sunnen portahone driving head for valve guide mandrels. Ball or flex hones are about $20 each; a sunnen station will run you about $400 used, and then another $400 for tooling. The Portas generally are $400 used -- $600 new. Stone sets are priced by size and material. They range from $15-45 set. We won’t talk about the cost of honing oil.
6) Intake and Exhaust pilots. You’ll need several solid pilots or a couple of expandables. Solids are usually around 25-30 bucks each, expandables are usually around $50 each!
7) Intake and Exhaust seat cutters or a stone grinding kit. The most common cutters in the US today are Neway, though old kwik-way and Sioux valve cutters (or sometimes called valve reams) are around. Note that if they don’t have carbide blades, you won’t be getting through stellite seats. Stone grinding kits are also widely available. They tend to be pretty beat on the used market and require quite a bit of re-supply before use. About the cheapest you can get away is around $200 for cutters and around $500 for a properly equipped grinding set. All require some skill to use. Your patience determines your craftsmanship as they are HAND tools. Really big shops have dedicated machine tools for this stuff that allow even the inexperienced to get very, very good results.
8) Dykem, Prussian blue, or sharpies for marking seats and contact patterns
9) Concentricity gauge. This is to check the run out of your valve seat – it’s a $200 tool and not strictly necessary – but it sure helps.
10) Brass brushes or a media blast cabinet for carbon removal
11) Parts washer or a good bucket of cleaner
12) Cleaning brushes
13) Double diameter drift or fixture and arbor press for removing/installing guides
14) Can of 220 lapping compound
15) Vernier calipers or a steel rule capable of measuring 32nds or 64ths.
16) Valve spring compressor – while you can disassemble without a compressor, getting things back together is a bit more challenging without one!
17) Trays or pans to hold all the parts and keep them organized.
18) Spring tension gauge (if you intend to reuse springs).
19) A good 6-10 inch vise solidly mounted to the bench
20) If you’re driving guides in and out by hand . . .a good 1.5lb peining or brass hammer
21) If you’re a press guy – a fixture and 1 ton arbor or 10 ton hydraulic press.
All in all – it’s a solid $600-1000 worth of tooling to equip yourself to do ONE valve job on one brand. Maybe you’ll get lucky and the tooling fits more than one of your scoots – but this is relatively uncommon.
Speaking of tooling; let’s talk real fast about cutters and stones. Valve seat cutters are just that – a cutting tool that pilots off the guide centerline to create a seat. Some people swear by them and many swear at them. Neway is the premier maker in North America. Currently, there is a crop of India and China made “valve reams” on the market. Please don’t buy them. If you want cutters, buy Neways and be happy. With regard to stone kits – if you don’t buy a full kit – then what are you buying? The full kit consists of a motor, driver, spring holder, seat spring, a bunch of pilots, a bunch of stones in different grits/sizes, and a diamond dressing stand. They take up a box about double the size of a large hand tool box. Common names on the used market include black and decker, blue point, van norman, and Sioux. Brand new sets are quite expensive. Chuck’s favorite was/is the Black and Decker set with the old 5 pound driver motor, which was made by Blue Point. The sets prior to the 80s were GREAT and are so robust you can still buy brand new supplies as of January 2020 – a full 40 years since B&D last offered them!
And, don't forget about Hall-Toledos . . .if you find a complete kit, consider buying it.
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