Leaded Gas and Valve Seats

[SumtinCoo]

Alright I know this has been beat to death.....but I havent quite found the answer I'm looking for by searching. I have a 06 CRF250R and I just had the head redone with oem titanium valves. I heard that leaded gas can make the valve seats harder and making the valves not last as long. I thought that lead was softer than the head material so how could it make it harder? I was either going to use 104 leaded that i can get at a terminal, 100LL, or lead additives to pump gas.

Overall, will leaded gas be beneficial to Ti valves?

[SubTexel]

Alright I know this has been beat to death.....but I havent quite found the answer I'm looking for by searching. I have a 06 CRF250R and I just had the head redone with oem titanium valves. I heard that leaded gas can make the valve seats harder and making the valves not last as long. I thought that lead was softer than the head material so how could it make it harder? I was either going to use 104 leaded that i can get at a terminal, 100LL, or lead additives to pump gas.

Overall, will leaded gas be beneficial to Ti valves?

I ran a 50/50 mix of 110 leaded and 93 pump gas on my RMZ it's whole life (well, up until I moved back to SoCal and was stuck with 91 with torco). Valves never moved, and when tore apart the valve seats were fine.

Run 50/50 or less with 91/93 pump gas. You'd probably be better off with Torco (I run it in my SRT8 with a KB 2.8/392 and it brings the 91 pump gas inline to around ~96 octane), I buy it in bulk and end up mixing it in with the premix before I fill the 5 gallon jugs up.

[SumtinCoo]

I ran a 50/50 mix of 110 leaded and 93 pump gas on my RMZ it's whole life (well, up until I moved back to SoCal and was stuck with 91 with torco). Valves never moved, and when tore apart the valve seats were fine.

Run 50/50 or less with 91/93 pump gas. You'd probably be better off with Torco (I run it in my SRT8 with a KB 2.8/392 and it brings the 91 pump gas inline to around ~96 octane), I buy it in bulk and end up mixing it in with the premix before I fill the 5 gallon jugs up.

Is torco a fuel additive?

[SubTexel]

Is torco a fuel additive?

yeah, octane booster (actually works too). I never really paid any attention to them but Kenne Bell recommends it over 9lbs boost on my car. Works great, never had any knock retard when I run it (if I don't it pulls timing like a mofo from spark knock) (I'm @ 10lbs right now).

You can order it online or get it at most speed shops, I think Autozone and the like sell it (I know they do the NOS octane booster, which works just as well. Have used that in a pinch before. Uses MMT and whatever else to bring the octane up).

[SumtinCoo]

yeah, octane booster (actually works too). I never really paid any attention to them but Kenne Bell recommends it over 9lbs boost on my car. Works great, never had any knock retard when I run it (if I don't it pulls timing like a mofo from spark knock) (I'm @ 10lbs right now).

You can order it online or get it at most speed shops, I think Autozone and the like sell it (I know they do the NOS octane booster, which works just as well. Have used that in a pinch before. Uses MMT and whatever else to bring the octane up).

i'm really just looking for something that will help the valves last longer and not really more octane.

[donwann]

The lead in leaded gasoline amoung other things acts as a lubricant/cushion for the old school valves and seats. Once unleaded fuel became available its use in vehicles designed for leaded gas would lead to the early demise of the valves and valve seats. You should be fine running it with your Ti valves, but I think it would be best to question the manufacturer.

[donwann]

Regularly checking the valve adjustment and keeping them within specs will go a long way to extending valve life.

[CamP]

I run 100LL in all my bikes, even the lawn mower and power washer. Works great. It has 2 grams of lead per gallon. About half the lead of VP C12 and pretty close to VP Red. It's less hassle than mixing fuels and I would hate to mix anything good with pump gas anyway. 100LL runs $3.50 a gallon around here.

[SumtinCoo]

I run 100LL in all my bikes, even the lawn mower and power washer. Works great. It has 2 grams of lead per gallon. About half the lead of VP C12 and pretty close to VP Red. It's less hassle than mixing fuels and I would hate to mix anything good with pump gas anyway. 100LL runs $3.50 a gallon around here.

Thats what I've been thinking about doing, its around $4 a gallon here. I'm pretty sure the 104 leaded stuff here is not too cheap, around 5-6 a gallon. I know regular 110 at the same place is 6 a gallon.

I'll probably go out and try the 100LL, if I like it next rebuild i do, i just might put in a 14:1 piston since it wouldnt hurt.

[SumtinCoo]

bump....

[slow hand]

Modern engines that were designed after the widespread introduction of unleaded gas have hardened valve seats, so, theoretically, no need for lead to cushion.

However, I don't see as how it could hurt anything, especially in a modern Honda motocrosser, known for valve problems.

[OLD TIME BIKER]

Amazing how a little information in the wrong order can become a massive amount of misinformation!!!

Tetraethyl lead was added to gasoline as an antiknock compound as engines became more advanced with higher compression and horsepower. One effect of the lead was that it lubricated the valve train and prevented undue wear. (Those who used lowcost fuels like what was known as "white gas" which was much cheaper for economy would add top oil to the gas to get the lubrication without the added pump price that the lead package cost.)

In the '70's when environmental concerns started to be addressed by reducing (and ultimately eliminating lead altogether in the '90's) advanced wear to valve componants, especially the valve seats became a problem because the extra lubrication that the lead provided allowed valve seats to be made from softer metals. Manufacturers solved the problem for newer vehicles by making the seats from harder material, but that left owners of vehicles with softer valve seats with a problem. Some just went with the top oil or lead replcements and that worked, some had valve jobs done and had new harder seats installed and eventually engines with soft valve seats either became obsolete and disappeared or were rebuilt with hard seats.

Leaded fuel is still available as a racing fuel and for aircraft and such and modern engines will run fine on it...it still provides anti knock protection and added lubrication for the valve seats...it even helps 2 strokes to run a tad cooler, but except for putting miniscule amounts of lead into the environment, it shouldn't be a problem at all for any engine.