This post is not about how much fuel you wish to use but more about how well the engine is using it. Also the following MPG numbers are only for town work, London traffic, as this is mostly what I am doing at the moment . I will try a run later to see what happens.

With the bike STD I used to get 43 mpg using STD 95 RON fuel. At 5K I fitted a Remus can, Remus Powerizer, K&N air filter and moded the airbox. This, with 95 RON fuel, cut the MPG to 38. At about 10K I then tried 97 RON fuel and the bike run better, but not perfect, and the MPG went up to 42.

Now that the Earth problems, that had effected the ECM and starting, have been sorted the bike is now giving an average of 43 mpg and runs as smooth as a nut. That was over 2 tanks, 300 miles and the last tank gave 148.7 miles with more than 1L left. Very good IMO given that aftermarket cans and wot-not do tend to cut MPG.

Some of this is due to fact that I can now just "ride the torque" and need to use less revs/clutch slip to control the engine because it was fecking about before. Massive power and torque across the whole rev range, no flat spots, no poping and no ECM map changes. I also suspect that using 97 RON fuel will be even better .

The point of this post is that the Thunderstorm engine can "walk-the-walk" it just needs a bit of thought and TLC to get the best from it. As it is I am amazed at what it can do given its "model-T" era base design.

Ok. So whats its about with your lumpy engine problems. If mine can run right then why not yours. A good point and apart from any mecanical probs it should be fine. Also given that I have had to make no map changes, apart from the Powerizer, makes me wonder a bit.

I guess a map mod might be needed in other cases.

Still getting 43 mpg in 100% town traffic on 95 RON fuel.

I have just put in 97 RON fuel and the bike has really come to life now. It seems to rev eaiser, the mid range is much beefer, engine "pick-up" is faster and the overal response from the engine is very crisp in all gears. The engine also labours a lot less if you happen to be in the wrong gear at some point.

An amazing all-round bike.

V-POWER Is your friend.

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Drinking Rum before noon makes you a Pirate ! Not an alchoholic.

I used it before, wene the engine was not right, and it did help a lot but it was not a "cure-all" for the situation. The engine problem still needed to be sorted. The engine does run great now on 95 RON fuel (as Buell states) so not a problem as long as the engine is right.

The use of 97 RON fuel helps even more if the engine is right in the first place. In other words it should not be used to overcome engine problems that should not be there in the first place.

If the engine will not run smooth on 95 then there is still a problem and that is, in part, the point of this post.

Yep the bike runs better on 97 RON, over 95 RON, but the mpg was the same, 100% town work, @ 43 mpg. I would say, on my bike anyway, use 95 for normal roadwork but if your out for a good ride use the 97. Much nicer on a good thrash