martyq8 Posted September 13, 2010 Report Share Posted September 13, 2010 Hi to all, Just recently acquired a Bultaco 250 1978 198 and to be honest I dont have a great deal of experience or knowledge of the bike. Hopefully with time this will improve. My question is a simple one really, could some one give me the fuel/2 stroke oil ratio that I should be running with this bike. I have read 20:1 in an old manual, is this correct? Please forgive such a simple question. Many thanks. Marty Dunn Quote Link to comment Share on other sites More sharing options...
twinshockdude Posted September 13, 2010 Report Share Posted September 13, 2010 use castrol TTS at 50 to 1. Quote Link to comment Share on other sites More sharing options...
martyq8 Posted September 13, 2010 Author Report Share Posted September 13, 2010 Twinshockdude, Many thanks for your reply. I have lots of questions I need to ask regarding this bike but I wont bother you just yet with them. Just one more if I may, what is the best way to clean out the exhaust system as I believe it will be full of oily goo - hence previous question. Thanks again, Marty Quote Link to comment Share on other sites More sharing options...
twinshockdude Posted September 13, 2010 Report Share Posted September 13, 2010 there are as many answers to that as there are owners !! my prefered method is caustic,others set it on fire,others cut it open and clean manually take your pick Quote Link to comment Share on other sites More sharing options...
pedronicman Posted September 13, 2010 Report Share Posted September 13, 2010 Use a semi synthetic or castor oil NOT castrol TTS which is fully synthetic and run at 40:1 not 50:1. Use super unleaded fuel. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted September 14, 2010 Report Share Posted September 14, 2010 (edited) It is possible to avoid oily gunk depositing in the exhaust by running with very little oil in the fuel. Trouble is, it is not kind to the motor to run with so little oil. It will run fine but will wear out much faster than it would with adequate oil in the fuel. How little oil you mix with the fuel depends on what life you want to achieve from your motor. Because of this, you will find a variety of opinion about what is the ideal amount of oil to add. I use 40:1 semi-synthetic If your M198 has a standard exhaust and you burn out the gunk, the main (first) muffler section will need repacking to run properly. It will run but not very well without packing around the inner tube. To repack the main muffler it will need to be opened and there are many ways to do this. Edited September 14, 2010 by feetupfun Quote Link to comment Share on other sites More sharing options...
legs Posted September 14, 2010 Report Share Posted September 14, 2010 Please do NOT use TTS Fully Synthetic as it is to good for old boreable barrels, use a Castor based oil.... Quote Link to comment Share on other sites More sharing options...
big john Posted September 15, 2010 Report Share Posted September 15, 2010 Like Castrol A747, caster based semi synthetic at 40:1. That's 125cc per 5 liters of fuel! Big John Quote Link to comment Share on other sites More sharing options...
martyq8 Posted September 23, 2010 Author Report Share Posted September 23, 2010 Thanks guys for the advice. What about clutch oil - I have heard that Automatic Transmission Fluid is the stuff to use. What kind, quantity etc whats your advice on this. Cheers Marty Quote Link to comment Share on other sites More sharing options...
big john Posted October 5, 2010 Report Share Posted October 5, 2010 Thanks guys for the advice. What about clutch oil - I have heard that Automatic Transmission Fluid is the stuff to use. What kind, quantity etc whats your advice on this. Cheers Marty ATF is OK for primary drive 300cc. I'll try to reply to your PM as soon as possible, been a bit busy recently! Big John Quote Link to comment Share on other sites More sharing options...
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