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[Pony]

Removed air box and PAV system. Lightened bike by removing starter, starter inner primary, rear frame. fitter a rear loop from a scrambler. Straight through header pipe and muffler. 20 tooth sprocket.

Took it out on a dual carriage way. Struggled to keep to 70 with the throttle wound fully open. on a very slight incline, speed dropped to 65.

Is there anything else to do. Can't afford a big head or to spend much more on my bullet 500, but surely, this should be capable of 80mph????

[Mark M]

Have you re-jetted the carb to suit? Removing the airbox alone will require re-jetting let alone the other mods. Have a look in the Accessory Catalogue for advice on how to re-jet, otherwise there are plenty here who've done this job and can advise.
REgards, Mark

[Bullet Whisperer]

Pony, the 20 tooth gearbox sprocket is where you are going wrong. You would need over 40 BHP to get the best from a Bullet fitted with one of those. 18t at the most if you want the best top speed. If you want to chug around at 50mph all day on flat, straight roads, stick with the 20t, I would never contemplate going over 18t on any 500, except the racer we have which has well over 40 BHP. Go back to 17t if you want good acceleration, I have tuned a few which can see 90 MPH with 17t on the front and pick the front wheel up in 1st and 2nd gears - they would be dead ducks with 20t to cope with, though. regards, Paul.

[Bertie the Bullet]

Paul's right, Bertie has an 18 tooth sprocket, a re-jetted Amal and free flow Goldie exhaust (otherwise standard) and can show 80 on the clock easily, even got it there once 2 up (took a while).

[Pony]

Yep rejetted the carb as recommended by Hitchcocks, new slide too. Ran way too lean and too hot (discoloured the exhaust in just a few minutes). so put it back the way it was. Running a little rich but starting 2nd kick every time and idling smoothly. I have an Amal 930 (swapping to Mikunis on my Triumph)going spare and may give that a go.

[Pony]

Got that wrong. Did rejet as Per Hitchock's advice, because it was burning too lean. But is now too rich. across the whole range. Put a colour tune on it and was unable to get a clean blue flame at any revs.

[PeteF]

Yep, too many teeth. You'll probably go faster in 3rd (-:

[Pony]

Also am running an 18 tooth sprocket, not 20. Rechecked the order to make sure DOH!

So given that it is 18tooth, the mods I've done and the rejetting, this should easily hit 80, but won't

[Alan R]

Hi PONY-------- you don't mention which bike you actually have.......I'm guessing from the parts removed it's not an Iron-barrelled 500 ?? so must either be an Electra X or a more modern UCE-type ??...If I may make an observation and that is you are committing the beginners mistake of altering too many things all at the same time.....Let's try to be a bit more methodical about this, eh ?? So, a)----- what means are you using to calibrate your speed ?? The OE speedometer is no better than a lazy windscreen wiper !!.... suggest you have a colleague follow in a car for accuracy ( and impartiality !!)...b)----- What piston and cams are fitted ?? ( I'm guessing standard because you don't say otherwise )...c)----- What plug is fitted ( again, std ??)...d)----- What tyres are in use (ie}-- have you fitted a different size / profile on the rear along with that "loop" you mentioned) ??...e)----- what fuel and timing setting are you using ?... and finally the Amal 930--along with the appropriate air filter etc.--- is a good carb for tuning BUT remember the length of the induction tract can alter just where in the rev. band the max. torque is developed...........If you would answer the above questions then we can begin to form a mental "view" of how your machine is currently set up.......PS}----- just a thought..If you have been using a 28mm Mikcarb then the fuel enrichment handle is HORIZONTAL for normal running and DOWN for cold starting ( might account for the richness over the whole range ??)..................Let's see if we can get this sorted for you..

[MadMike]

Pony you should take note of Alans sage advice, for verily he doth speak the truth, and his words ye shall find wise and helpful. (I know but it is Easter and I have been reading that big book again. LOL). The art of tuning is to measure your bikes performance accurately, and write it down as your memory will fade within nano seconds, before you make any change. Then research the changes needed to achieve the performance that you require, more grunt in the mid-range, more top end, etc. Then make each change and re-measure the effect. You should never under any circumstances change multiple parts in one hit. You will never be able to identify what caused any change, good or bad, and so will find it difficult to remain objective and get the best results. The changes you have described are not real performance changers. Increases in capacity, high compression pistons, high lift cams, larger valves, gas flowed head compatible carb and/or Dyno-jetting, re-mapped ignition should when done correctly and together should all result in increased performance. Then we must remember a simple fact. Road speed is strictly a function of engine speed. So if you are able to get more revs then you will gain speed on your existing gearing. If you are also able to increase torque then you can raise the gearing and if you maintain the existing or increased revs then the bike will go faster. It's simple physics, however do not assume that you will be able to easily increase top speed from say 70 to 80mph, after all that is an increase in speed of 14%. Sorry to waffle on. HTH.