Apparently my G/S was designed to run on leaded petrol. What happens if I run the bike on unleaded? Will the engine go bang? Will the valves wreck the heads? Is it really necessary to use a lead replacement additive?
Running a G/S on unleaded Petrol
- Thread starter Devon
- Start date
In theory, under constant heavy running, the valve may weld to the seat every time they contact, pulling bits off as they part.
On the other hand, they may have some "lead memory" that will protect them for a while at least whe switching to unleaded.
General advice seems to be, run as you are but keep a close eye on valve clearances. Any sign of them closing up quickly indicates trouble.
If you're keeping it, unleaded seats are the answer.
Some late g/s do have them from the factory, but how you can tell without removing the heads seems something of a mystery.
On the other hand, they may have some "lead memory" that will protect them for a while at least whe switching to unleaded.
General advice seems to be, run as you are but keep a close eye on valve clearances. Any sign of them closing up quickly indicates trouble.
If you're keeping it, unleaded seats are the answer.
Some late g/s do have them from the factory, but how you can tell without removing the heads seems something of a mystery.
Beemerboff
Registered user
If they havent failed by now they probably never will.
When leaded was withdrawn in Oz some bikes failed PDQ, while other of a similar vintage had no problems whatsoever - my 1977 R75/7 is still on the original seats after 10 years of 91 unleaded and the vales rarely need adjusting, but I saw some seats which were scrap after 3 months.
When leaded was withdrawn in Oz some bikes failed PDQ, while other of a similar vintage had no problems whatsoever - my 1977 R75/7 is still on the original seats after 10 years of 91 unleaded and the vales rarely need adjusting, but I saw some seats which were scrap after 3 months.
I've had a couple of early bikes that have been ok for years and then failed. They go pretty quickly when they go. I'd just ride it if I was you my 78 100/7 was just short of 200,000 miles when the seats gave up.
Early unleaded heads have a blue spot painted on underside of the head..
i've got a pic' somewhere.
BUT, IIRC... Little 'un had her heads done as soon as Tony got her.. soon check if heads are off as you can see where the seats have been fitted
..
Gertie has not had valve seats done, but I do put a dash of 2 stroke oil in the tank occasionally..
added info >>
Unleaded Fuel
R80 (UK) unleaded from chassis number 6440512 (1985)
R80RT (UK) unleaded from chassis number 6470498 (1985)
R80G/S (UK) unleaded from chassis number 6283306 (1985)
All unleaded head have a blue paint spot near the bottom head nut.
I have no information regarding the exact time that the other R Series machines were changed to unleaded. ALL twin shock machines were designed for leaded fuel and MOST monoshock machines are built for unleaded fuel.
i've got a pic' somewhere.
BUT, IIRC... Little 'un had her heads done as soon as Tony got her.. soon check if heads are off as you can see where the seats have been fitted
..Gertie has not had valve seats done, but I do put a dash of 2 stroke oil in the tank occasionally..
added info >>
Unleaded Fuel
R80 (UK) unleaded from chassis number 6440512 (1985)
R80RT (UK) unleaded from chassis number 6470498 (1985)
R80G/S (UK) unleaded from chassis number 6283306 (1985)
All unleaded head have a blue paint spot near the bottom head nut.
I have no information regarding the exact time that the other R Series machines were changed to unleaded. ALL twin shock machines were designed for leaded fuel and MOST monoshock machines are built for unleaded fuel.
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I think it coincided with the introduction of the Mono road bikes which would be September 84 onwards. Not definite though.
Does that mean a R80ST does have unleaded valves from birth? The previous owner had dropped a 'broquet' fuel catalyst into the tank.....
http://www.broquet.co.uk/
Regards,
Jonathan
Thank's for all the advice I will get the bike back together and run it through the summer. The push rod tubes are corroded so I will check the heads and valves when I eventually get around to replacing them.
I will get the bike back together and run it through the summer. The push rod tubes are corroded so I will check the heads and valves when I eventually get around to replacing them.Solo Lobo
Registered user
My '81 ran on unleaded for more than 20 years and when the valves were done there were no seat issues.... The bike had only clocked up 20,000 miles, and I am in the US where leaded became unavailable long ago...
Mick13
Registered user
My 80 G/S Run unlead from many years without any problem
pray tell, which GS do you have ?.
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