Triumph Rat Motorcycle Forums banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Bike of the Month Challenge!
1 - 10 of 10 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I have a 74 bonnie motor and was wondering if it was ok to use an octane booster. If so what brand does anyone out there use. any help would be great.

thanks in advance!
t.
 

·
Registered
Joined
·
507 Posts
Octane booster

Yes, use octane booster and lead replacement too.
I use Cartrol Valve Master Plus. It is lead replacement with octane booster combined. Cost is £10 in the UK and treats 250 litres of fuel.

Mark
 

·
Premium Member
Joined
·
487 Posts
If you can get 100LL avgas you can try mixing some in. It is exceptionally stable and seems to not form varnish like US pump gas. A little goes a long way.

Good if you store for longer times. The US EPA pump gas blends we get in cities starts breaking down down in a few weeks.
 

·
Registered
Joined
·
348 Posts
you can use all the octane booster in the world but if your engine dose not need it or have high compression your just pissing away money:D
 

·
Registered
Joined
·
625 Posts
I'm pretty sure that a '70 500 Triumph said 'recommended 97 / minimum 95 octane' ... earlier bikes called for even higher octane fuel ... highest available currently is 93 .... sounds like they ALL 'need' it ... Further, the engines were designed to run on leaded gas ...
 

·
Registered
Joined
·
411 Posts
l have been using 97 unleaded for a while but my bike is a '67 T100c. l think Nelson's book states that new head shape and piston's pushed compression to 9.75 which is fairly high ( new bikes go to 14.1) but well within the range of 97 unleaded. l have not had to do the valves yet and l use only half the reccomended dose of a popular additive when l remember to put some in. Racing a 750c.c. triton l used Avgas mixed with 98 unleaded but l never used straight unleaded so l don't really know if made any different, but my mechanic would not allow me to try. Anyone seen any real comparision data?.
 

·
Registered
Joined
·
2,993 Posts
I was told by MAP that they stopped making octane booster because it's too hard to keep up with the seasonally changing gasoline mixtures. That made sense to me.

You could just get some Sunoco "Standard" Racing fuel, 110 octane and leaded to boot, and mix it down with unleaded premium to the octane that you need. A gallon stretches pretty far when used that way and is probably less expensive than the questionable octane booster. I understand that it's also very stable with respect to long term storage.
 

·
Registered
Joined
·
2,993 Posts
you can use all the octane booster in the world but if your engine dose not need it or have high compression your just pissing away money:D
The owner's manual for my '76 specifically states 97 octane, and it has always needed it since new.
I don't think it's about compression ratio so much as ignition advance; If memory serves, it's 38 degrees, and that is pretty far out there.
 

·
Registered
Joined
·
94 Posts
The owner's manual for my '76 specifically states 97 octane, and it has always needed it since new.
I don't think it's about compression ratio so much as ignition advance; If memory serves, it's 38 degrees, and that is pretty far out there.
Beemie

You are dead on with the suggestion of mixing racing gas with the 93 octane (which is the highest available now), I mix it 3 gallons 93 to one gallon race. It is simply amazing the difference it makes.

The compression and the timing will cause problems with lower octane but the real culprit is simply the engine design. No matter how you look at it, they are nothing but air cooled Hemi's. This combustion chamber design needs a lot of advance and compression which is not a "bad" thing if you put some good fuel to it. Being air cooled makes it even worse. I have seen in other post where the guys are trying to "tune" these motors to run with the modern gas. I have always replied to them that all the tuning in the world isn't going to help. I'll agree that they could be made to "operate" with todays gasoline blends, but lower compression and back off the timing also screwing around with the carb jetting would destroy the performance.
 
1 - 10 of 10 Posts
Top