Unleaded and E5 fuel in older B&S engines

[sidevalve44]

I am wondering if my 1976 B & S 3HP engine is unleaded compatible. It probably doesn’t get used enough for it to be a real issue but, should I perhaps be putting Valvemaster or similar in the fuel ? Also, has anyone had any problems with older type engines running on the new E5 type petrol ? So far I haven’t with the Briggs but am aware of it being a problem in older motor-bikes.

[wristpin]

It will have hardened valve seat inserts so no problem there,but if you want a bit of extra protection for the valve stems and guides a drop of two-stroke oil or good old Redex will do the trick. All my old BSAs and Villiers get that treatment.
E5 won’t be a problem so long as it’s fresh and not left in the system to evaporate and deposit gum. If you are concerned about “shelf life” you can use a stabilising additive such as B&S’s Fuel Fit or Fuel Fresh (same product, different packaging) but I don’t bother and as yet have not suffered any problems. For long tern storage the advantage of a stabilising additive over “running dry” is that the tiny bit of fuel left in the dark recesses of the carb ready to cause trouble will be protected.

[sidevalve44]

Thanks for that. I had a feeling it might have hardened valve seats but wasn’t sure. I use fuel stabilizer anyway so no worries there. As it smokes a bit after running for a while It’s probably getting a fair bit of UCL anyway, although I may get some Redex for extra measure !!

[charlie]

Another product that helps counter the gumming and similar E5 issues is Ethomix available from Frost Auto Restoration, FBHVC website lists other products tested by them.

[Author]

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