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4 Answers
- 1 decade agoFavorite Answer
Fit a harder exhaust valve and seat, and retard the ignition timing by about two degrees. If you still get pre-ignition you may need to add an extra cylinder base gasket to reduce compression.
Source(s): 41 years riding and maintaining British motorcycles. (BSA, Triumph, Excelsior, Norton, Panther, Royal Enfield .... Okay, so the Royal Enfield was made in India, you wouldn't know by riding it). - Anonymous1 decade ago
Your 250 BSA will run fine without modification. You are not likely to rack up enough miles to damage your valve seats. Indeed there are not enough of them running around to find out if they are susceptible to damage from unleaded fuel, unlike BMWs, which were racking up huge mileages during the years when fuels were in transition to unleaded.
- Anonymous1 decade ago
Lead coats the exhaust valve to protect the valve seat in the head. You can have the head modified by having the valve seat machined out and an insert put in made of harder steel. They do this on vintage BMWs so they can handle unleaded gas.
Or you can use lead substitute, which you can get at an auto store. About 1 oz. added to each tank of gas.
- 1 decade ago
it will run fine im sure , but i remember buying a kit for my series one landrover to be able for it to take unleaded might be able to get one for a bike
