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Thread: Instead o'lead?

  1. #1
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    Instead o'lead?

    Now that there is no more CD2 substitute, what are people using?

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    Administrator 20774's Avatar
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    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.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
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    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    Quote Originally Posted by 20774 View Post
    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?

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    Registered User toooldtocare's Avatar
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    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.

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    I thought all air cooled engines had hardened valve seats because of the higher operating temps.

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    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.

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    Administrator 20774's Avatar
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    Quote Originally Posted by jimmylee View Post
    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.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
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    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    Administrator 20774's Avatar
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    Quote Originally Posted by nc bmw driver View Post
    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. 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.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    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.

  10. #10
    Registered User toooldtocare's Avatar
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    Quote Originally Posted by jimmylee View Post
    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."

  11. #11
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    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.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    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!

  13. #13
    Benchwrenching PGlaves's Avatar
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    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.
    Paul Glaves - "Big Bend", Texas U.S.A
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  14. #14
    Registered User ebeeby's Avatar
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    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.

  15. #15
    Registered User lkchris's Avatar
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    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
    Kent Christensen
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