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Instead o'lead?

Before I recently had my heads converted to unleaded, I was running a number of products. One was "ValvTect" which I used to get at West Marine, then on-line, but that seemed to dry up. Then I found a product called "Relead" which I used up until the conversion. When I popped the heads, I was real surprised to see all the build up inside the combustion chamber...most likely from the deposits left behind with these additives.
 
Before I recently had my heads converted to unleaded, I was running a number of products. One was "ValvTect" which I used to get at West Marine, then on-line, but that seemed to dry up. Then I found a product called "Relead" which I used up until the conversion. When I popped the heads, I was real surprised to see all the build up inside the combustion chamber...most likely from the deposits left behind with these additives.


What changes to the heads are done to make them unleaded compatible?

I presume the reason for using additives in place of leaded gasoline is to provide the lube that lead used to provide?
 
When my heads were converted they added hardened valve seats and replaced the valves. I am not sure the valves need to be replaced, but mine were done anyway since they did so much to everything else, like dual plugs, etc.
 
I thought all air cooled engines had hardened valve seats because of the higher operating temps.
 
I add a cup of 100 Low lead aviation gas at every fill up. Easy for me since I have an airplane and just drain a cup from the sumps and dump it in the bike.

Most airports will sell you a gallon or two (or more) of avgas without any hassle.
 
What changes to the heads are done to make them unleaded compatible?

I presume the reason for using additives in place of leaded gasoline is to provide the lube that lead used to provide?

What toooldtocare said...it basically converted the heads to the same components that are in the '85-on heads. I had Ted Porter do the work.
 
I add a cup of 100 Low lead aviation gas at every fill up. Easy for me since I have an airplane and just drain a cup from the sumps and dump it in the bike.

Most airports will sell you a gallon or two (or more) of avgas without any hassle.

I don't want to start a ruckus or get into the politics of things, but it is my understanding that using avgas in road vehicles may be illegal, since the proper taxes haven't been paid. It might depend on local laws. :dunno Years ago, I bought a 5-gallon container of leaded racing fuel made by VP from my local motorcycle shop (not BMW). I used the same cup or so in each tank to add back in the lead. Got to be a bit dicey, dealing with leaded gas out in the open. I'm glad, now, that I've had the conversion done on my /7. I just freed up some space in my saddlebags since I don't have to carry around anymore additives. :thumb
 
so... ya'all are basically saying that the lead helped the valves to seat?

It isn't a upper end lube issue? That' s what I always heard.
 
so... ya'all are basically saying that the lead helped the valves to seat?

It isn't a upper end lube issue? That' s what I always heard.

From https://en.wikipedia.org/wiki/Tetraethyllead "Tetraethyl lead was extensively used as an additive to gasoline, wherein it served as an effective antiknock agent and prevented exhaust valve and seat wear."

and

"Tetraethyl lead works as a buffer against microwelds forming between the hot exhaust valves and their seats. Once these valves reopen, the microwelds pull apart and leave the valves with a rough surface that would abrade the seats, leading to valve recession. When lead began to be phased out of motor fuel, the automotive industry began specifying hardened valve seats and upgraded exhaust valve materials to prevent valve recession without lead."
 
There have a number of posts over the past few years that discuss the three basic periods of head metallurgy for Airheads. The period thru the 1980 models will have cast iron seats and eventually will face some sort of valve seat recession. From 1981 to 1984, BMW got smarter (or is that dumber?) and installed seats that didn't transfer heat very well, thus the heat stayed more in the valve. That lead to valve face plastic deformation (VFPD) where the part of the valve that sat on the seat began to deform and tulip. The consequences in both types resulted in rapid closure of valve clearances. BMW finally got the metallurgy right for the 1985 models. Nowadays, any head work will be done using this type of valves, seats, and guides. There are still some choices out there, but what BMW came up with pretty much works. You'll still need a valve job sometime in the future...hopefully it will be a long time. :thumb
 
Thanks for the info.

I had heard that the primary reason (only one, actually) was upper end lube that the lead provided.

I have been a huge devotee of Lucas Products and I use their gasoline additive (purchased in gallon jug - has a 400:1 mixture ratio) which I thought added back the lubrication and also helped clean the fuel system (I know, I know, my '78 R100/7 bike doesn't have fuel injectors!!). I have used it regularly in my Toyota car, and even though it was only rated around 35 highway MPG, I am getting over 40! Measured rigidly on many trips to South Carolina and back.

So, I am hoping that this will also help any valve/seat "welding" issues as described in your provided articles!
 
Lead in the gas acted as a lubricant for the valve heads and seats. BMW began using hardened valve seats (or maybe extra hardened valve seats) in the early 1980s. Earlier Airheads had valve seats that would wear in the absence of lead in the fuel. The 1981 through 1984 models, especially the 100cc bikes, suffered a different problem though. The valve seats were extremely hard and didn't wear. But they were very poor at conducting heat so the heads of the exhaust valves would deform. Like seat wear, this required frequent valve adjustment. The two problems are completely different however. Most 81 through 84 100cc bikes have probably had the valve seats replaced by now. Many of the 800s have too.

By 1985 BMW bagan using the second generation of hardened seats in Airheads and there have been few problems with these models.
 
Dang. Have only half a bottle of CD2

Just ordered 3 bottles of Redline lead substitute from Amazon. Plan to re-use the CD2 measuring bottle as the Redline bottle is straight up. Same mixture of 1oz/10 gallons


I have Porterized heads due to exhaust valve recession but still think a lead substitute is worth the trouble if only for anti-knock in the Texas heat.
 
I'm old, so I can remember when unleaded fuel came on the scene.

Two statements I recall from the era are ...

1. If an engine has EVER had leaded fuel run through it, it has enough lead deposits to protect valves for the rest of the engine's life.

2. Mercedes stated at the time it had never built an engine that required leaded fuel.

For a fun but rather shrill read on leaded fuel, see ... http://www.thenation.com/article/secret-history-lead
 
The discussion boils down to this--do you want to spend the money to change to hardened valve seats? If you ride your Airhead 1000 miles per year, the answer is probably no--just check the valve clearances periodically and adjust as necessary. If you ride your Airhead 20,000 miles per year and are adjusting valves 5 times per riding season, you proabably want to make the change.
 
True, riding mileage may help make the decision. I'm not a big rider...100K miles in the little over 30 years I've had my /7. Pretty far short of 5K per year. But the last few years, I've really been wondering what was down there...was she going to make it the next season. What was that noise? What if...? I'm glad I've done it...I have good confidence in the change over. Peace of mind from here on out...until I have to worry about something else...like the timing chain!

I read something that Tom Cutter posted on the Airheads email list. People were discussing the idea of just monitoring the clearances and making the decision that way. Some have wondered about how many threads were showing on the rocker adjuster. He pointed out that the thread pitch is 1mm on the adjuster. So, if you've had to make one revolution of that adjuster, the valve has slid 1mm...which Tom said is one-half the width of the valve face. Think about that! That doesn't sound like much, but that picture in my mind screams problems and it might be sooner than one thinks.
 
leaded fuels, valves problems, .....etc

A rather article that covers the various valves and seat problems with the Airheads, and includes a lot of information
on leaded fuels, and aircraft gas as an additive, ETC (LOTS of "ETC") is here:
http://bmwmotorcycletech.info/valves.htm

snowbum (who rarely is on the MOA.org forums)
 
you an still get Bardhal Instead of lead gold, it contains MMT as an octane booster which also protects valves. I have used this for years before a got some modern stuff, and it works very well as octane booster and as a valve protector.

Rod
 
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