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[Dampking]

Well... I am going to go for more power output from my bike. I know that the inlet port needs some porting work, it should match the 36mm carb's manifold and that's what I will do--- not only that but some other stuff too. But I just wanted to know which one will give me better combustion, value for money, better power output. Also, these modifications I am going to do for my own satisfaction but not to show off.--- Thanks again for valuable info! ----Regards,
Sanket

[Kristof]

Hi,

I have been experimenting lots with different carbs for both bullet std and Electra. There is no question of superiority of Mikuni vs Amal. Amal looks nice but both the quality of performance are way below Mikuni. I think that 34mm is a bit too big for Electra. I use 32mm Mikuni, VM and TM. TM flat slide is much better than VM. Amal is more difficult to tune and the jetting system for Mikuni is more precise. So it all comes down to whether you want to have the original look or performance and trouble free use.

Kristof

[Les H]

Hi Sanket. To be honest there is not much difference between any of them certainly performance wise v bore size. Only the GP carb has a remote needle that does not impede the air flow. All the others use a needle. The Mikuni 28mm carb does ¬its job just the same as a Monobloc and Concentric does. I would say your choice of 34 mm seems excessively large if you are still using standard cams and standard inlet valve diameter. The inlet tract needs to flow smoothly from the carb open bore right the way through to the inlet valve port with only a very small amount of tapering which should be uniform right the way through. If the cam is only allowing small sips at the fuel charge then there is no shortage of fuel with the standard carb size. You also need to have the gas flowing at a high speed into the combustion chamber to encourage swirl, so the fuel burns thoroughly and can produce the most power contained in the charge. The bigger the tract size, the slower the gas speed will be which is not a good thing. With too big a carb the air flow at low revs is going to be too slow to create good fuel atomisation and distribution so you might have poor throttle response with little increase in full bore power. As you now have the 34mm carb I would splash out and get the head ported with the bigger inlet valve, sports cams and high comp piston...Then when the bottom end blows….a new steel rod & roller big end....or the special Hitchcocks Crank...oh yes don’t forget the 5 plate clutch...yes loads o' money but that’s what happens when you start the tuning trip the wrong way round.

[John L]

Everything Les H says.............

[Alan R]

-------------and there's more !! More powerful engine = "go faster" = upgrade the brakes = upgrade the suspension = and tyres to cope = "self-cleaning" saddle (optional) = 'evenin all! Is this your bike, Sir ??. (Get the idea??)

[Dampking]

Les H - Yes, I am planning to do something similar. Will get the inlet ported to match a 36mm. For now I will stick to VM34, later go for a TM36.. I think I go for Mikuni instead of Amal. Also I had plans to increase the bore to 87mm(535cc big bore kit) but I asked few guys who did that recently and it seems that the compression went up by loads! the stock Electra has 150psi compression I guess and after 535 kit it was 180+ which is not good I believe.. Once again... when he put "S" cams in his bike.. the compression went down to 173 it seems. He tried a bunch of cams and according to him.. without racing cams the high compression doesn't help much. So I think for now I will just stick to Free flow exhaust, Free flow airfilter and bigger carb + the porting work..I was also thinking of opening up the exhaust port by 2mm(Internal Diameter).
I think these are pretty reliable mods..

[Dampking]

I also hear a lot of stuff about the lower end of the engine blowing up. But why does that happen? when the compression is too much and when the bike runs at higher rpm because of high lift cams? So in order to counter these what can we do? I don't mind saving up for better alloy parts (For the lower end). It's always fun to ride a vintage bike at it's peak performance figures rather than a superbike! That's fun hehe

[simon]

Les is right 36 you were talking is too big and unless you you put substantially hotter cams in won't increase the performance. An 11/8" is a good sized carb around 28mm and the word on porting is that you make it so the carb joins seamlessly but that it has a waist in the middle so that the gas speed is increased. I did mine with a die grinder and a tungsten burr and you've got to be very careful not to remove too much. A tube of engineer's blue is useful too. There are some rather good pics online of a nicely ported head that are usefull but there are some seriously obvious spots that need to go. On my head the factory suck a 1" milling cutter in on the inlet side but left a jutting shelf either side further in.

[Dampking]

Very true! The port job done by RE is real pathetic. When I opened up my engine.. I was checking out the ports.. both exhaust and inlet. Man! That's soo messed up. I will try to get that fixed. Will surely let my bike breathe way lot better. Also - I heard that Cast Iron 500 bullet's cams can be used on AVL 500? like the electra X and machismo? A friend used Cast Iron 500's cams on his Machismo 500(AVL engine) and he says that there was a good amount of performance boost. I wonder how much extra work that will require tho.

-Sanket

[Kristof]

Increasing ports in std 500 is not a good idea, because the ports are already way too big, disturbing the lower end torque. Some polishing is enough. With high compression, a steel conrod is a must, or the crank will fail with devastating results. With high compression piston, retarding the inlet cam can help, by 1 tooth and putting an extra gasket or 2 under the barrel. Racing cams, or high performance cams, are good only for high revving, and they do require high compression to work, or otherwise power is lost.

Kristof