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By PeteF
#35077
"The changes you have described are not real performance changers"
Well, they sort of are on these bikes Mike. As standard the air filter and silencer are very restrictive, so letting them breathe a bit better will release a horse or two that they are choking on.
Pony, do you have decent compression? You should just about be able to stand on the K/S of a 500
By Pony
#35079
OK Alan R, will start at the beginning and try to be as clear as I can.

the bike is a 2007 model Bullet 500 with 4 speed box. I'm guessing you could say there are only 4 gears un;ess you include the huge false neutral between 2nd and third which I like to think of as my fifth gear. Got the bike at the tail end of last year and it was just supposed to be my winter hack whilst I was building my workshop in preparation for my Triumph bobber build. The plan was to leave it alone and just ride it. Kinda developed a soft spot for the little 500 though but was inevitably a little disappointed with performance and reliability so started to tinker.

I replaced the rock hard (might be stuffed with bricks?) dual seat and added a large sprung solo seat just for comfort and the look of the thing.

Due to the poor performance I decided to get rid of the Pulsed Air Valve system on the exhaust. For this I removed the very heavy Header pipe (possibly manufactured from a left over piece of scaffold pole) and the very heavy muffler. I replaced these with a Hitchcock's straight through header and turned out muffler. The air box and air filter where also removed and replaced with a steel gauze conical sports filter.

At this point things went wrong. I tried to start the bike (although far too lean)just to see how lean it was. The timing was a little too advanced and the bike kicked back against the starter and stripped six teeth off the sprag clutch!!! :(

Having done some research into sprag clutch replacement and the quality/longevity of said piece of rubbish I decided I might as well do myself and the bike a favour and convert to kickstart only. Ordered the new inner primary from Hitchcock's and went to work. Whilst the primary was off, seemed like the opportune moment to change out the front sprocket so upgraded to an 18 Tooth.

The conversion went well and I'm guessing shaved at least 5 KG off the bikes weight. The original kickstart primary case weight about 3 times what the new one did, even without the starter motor. I also removed all of the wiring associated with the starter motor.

Bought the fiberglass cover to cover the gap where the air box had been and neatened up all of the wiring. Rejetted the carb as per the chart in the Hitchcock's catalogue and after a couple of calls to make sure the jets and slide where right for my set up. I'm using the standard 28mm Micarb.

I set up the timing and adjusted the pushrods whilst at it.

Started the bike up with colour tune plug and tried all different combinations of jets and needle positions just swapping one jet at a time. I was unable to get a good clean blue flame at any revs. So just fitted whole set of jets and the new slide as recommended.

The bike now starts first or second kick every time without using the choke at all and so in combination with the sooty plug I'm sure the bike is far too rich. Smells rich too! I have a spare Amal 930 and manifold which I'm going to try once I've got a choke cable. Would like to sort the mixture as is though, just because I don't like not being able to. I did mess with the airscrew to introduce more air, but all this did was make the idle uneven. Idle kept picking up and then dropping off so followed the manual and wound it back in until it was idling smoothly. This said, the bike takes a while for the idle to drop when stopping at lights etc. Plug is a bog standard NC3 copper cored item.

Bike fell of it's centre stand on the soft ground in the back garden and smashed the back light. At this point I decided to finish lightening the bike with some mods to the back end. I removed all of the scaffolding supporting the rear mudguard and rear foot pegs and fitted Hitchcock's scrambler steel loop and polished alloy mudguard. To this I have attached a number plate holder and rear light from a 1967 Triumph T120 and but very small projector LED indicators mounter directly on the number plate holder. So small, you wouldn't know they were there unless you looked but blindingly bright! So Dropped another few kilo's off the rear end.

The mirrors have gone from the front and I've fitted a pair of smaller lighter pre 1940 bars which are swept back and much more comfortable.

Acceleration is OK through 1st, 2nd and 3rd. Struggles to pick up a little when first going into 4th unless your really giving it beans in 3rd before changing. Acceleration in 4th is slow and the top achievable speed is just around 65mph. I'm using the standard speedo to measure this. I did put a new speedo cable in (the old one used to act like a windscreen wiper then snapped) Greased the cable thoroughly before fitting it and the needle now gives a very steady indication. However my wife followed me up the dual carriage way yesterday and says I didn't manage to get above 65mph.

So where am I going wrong? The bike is much lighter, Timing is spot on, free flowing exhaust and Air filter. 18T sprocket. Wheels and Tyres are standard. I would like to change the rear as it's a very square profile, presumablt better suited to lugging a sidecar. Fuel is a little rich. I am 6ft 1 and weigh 16 stone so that is clearly a contributing factor, but this thing can supposedly lug a sidecar around so my weight shouldn't phase it. This bike should easily be hitting 80 and it's not. Please help!!!!
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By PeteF
#35080
Couple of things.
You didn't lose the washer under the main jet while you were re-jetting?
Have you checked fuel height in the bowl?
By MadMike
#35083
Pony little or nothing you have done will increase power except by a marginal amount. A couple of horses you tjink? more like a couple of kittens I am afraid. The engine mods may eventually make it breathe better BUT to in crease power you will have to burn more fuel, more often and more efficiently. Like I said before it is simply the laws of physics. Simply put you cannot get out more than you put in. You again refer to an expected top end of 80mph. What was it doing before the mods? Did you measure it either accurately or by exactly the same way that you checked after the mods? I am not trying to decry what you have done but all too often people "tune" their engines in an inexact way and are disappointed with the results. More speed and more grunt both demand more BHP and torque. You need to consider more drastic action if you want to get huge, relatively speaking, power increases. Again your "weight saving2 will not add more MPH. Simply because as I said earlier road speed is a function of engine speed and/or gearing (usually both).
By Pony
#35084
I had hoped that in terms of power to weight coefficient, there would be some improvement. I need to be able to keep up with dual carriageway traffic and hopefully motorway traffic to make this bike viable for my needs. How about the swap to the Amal 930? worth it or not?
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By PeteF
#35089
Must agree with Norm.
As you say, it should get to 80 or somewhere near but if you did it for any length of time you would be courting disaster. It's not like a modern bike where top speed and cruising speed are pretty close. On this design a regular steady 60 is more realistic.

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