Lead Replacement Additive

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Duccout
Posts: 1285
Joined: Wed Feb 05, 2020 1:20 pm
Location: Essex UK

Lead Replacement Additive

Postby Duccout » Mon Nov 23, 2020 9:23 pm

Has anyone on here done any research, or have any personal experience of the best lead replacement additive? I ask because I am currently refreshing my 900 S2 desmo top-end, and was dismayed to find pretty bad pitting of the exhaust valve and seat. Just before my engine was made, Ducati switched from bronze to cast iron for the seats (no idea why) and the cast iron seems to suffer worse than bronze from the lack of lead.

I have used Castrol Valvemaster Plus in the fuel ever since the demise of LRP, but obviously it is not the answer, so I'm wondering if another product will be better? Obviously, the oil companies will all claim that their product is the best....

I wrote in my saga of the resurrection of my 250 Mototrans about the wear on the valves, where both had suffered a thinning of the seat area until it had reached a knife edge, and they were close to being pulled into the port, although the bronze seats were in good condition; Nigel suggested that the cause may have been running on unleaded petrol, and I watched a You Tube video the other day of an American mechanic investigating lack of compression on a car engine, caused by running on unleaded, and the valves were in exactly the same condition as mine.

cooperplace
Posts: 334
Joined: Fri Apr 25, 2014 12:49 pm
Location: down under

Re: Lead Replacement Additive

Postby cooperplace » Mon Nov 23, 2020 10:42 pm

I will watch this with interest as I have an S2 as well, 1982. What year is yours? Can the seats be changed for bronze?
be nice, I'm not very bright.

graeme
Posts: 938
Joined: Sun Mar 25, 2012 12:00 am
Location: Tasmania Australia

Re: Lead Replacement Additive

Postby graeme » Mon Nov 23, 2020 11:59 pm

I thought the seats were changed to cast iron because of unleaded fuel ?

Graeme

Duccout
Posts: 1285
Joined: Wed Feb 05, 2020 1:20 pm
Location: Essex UK

Re: Lead Replacement Additive

Postby Duccout » Tue Nov 24, 2020 7:25 am

My S2 is registered in 1984, but according to Ian Falloon it is one of the first made. It should have had iron seats and iron guides, but the guides are phosphor bronze.

Cast iron has no resistance to seat erosion and neither does bronze, although possibly, from my own observation, bronze does not undergo microscopic welding of the seat to the valve like iron, but I'm not an expert in metallurgy.

To cure the problem requires hard valve seats from something like beryllium copper, but this is fraught with difficulties because it is a highly specialised job and many engine builders promise much but deliver a mess, and once ruined it is a lot of hassle to repair a damaged head. I am currently waiting for my barrels to be returned from a rebore, and am fully expecting them to be ruined, but I can't do it myself, so someone has to! I only do about 1000 miles a year now on my 900, and probably won't be able to ride it much longer due to the weight and my advancing years, so it is not worth the risk of an unleaded conversion.

cooperplace
Posts: 334
Joined: Fri Apr 25, 2014 12:49 pm
Location: down under

Re: Lead Replacement Additive

Postby cooperplace » Tue Nov 24, 2020 8:27 am

Re weight and advancing years, I know what you mean. When I had a 900SS in my mid-20s I rode it everywhere without a seconds thought. Now, 40 yrs later, i find it hard to ride and hard to get on the stand. My VTR250 Honda is easy to ride in comparison. It has no soul of course.
be nice, I'm not very bright.

Duccout
Posts: 1285
Joined: Wed Feb 05, 2020 1:20 pm
Location: Essex UK

Re: Lead Replacement Additive

Postby Duccout » Tue Nov 24, 2020 8:56 am

That was one of the reasons why I recently bought a 250 Ducati, for the riding that I do now (along small lanes to the cafe and back) it is perfectly adequate.

Duccout
Posts: 1285
Joined: Wed Feb 05, 2020 1:20 pm
Location: Essex UK

Re: Lead Replacement Additive

Postby Duccout » Tue Dec 01, 2020 6:44 pm

I went to collect my rebored barrels from the engine reconditioners today, expecting the worst, but while I was there I discovered that they actually carry out the engineering for Ducati specialists Ray Petty Motorcycles, and regularly do rebores for him, so perhaps it will be ok. I haven't had time to inspect the job, but fingers crossed!


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