Hitchcocks Forum

Reading Stelam92's Topic on tuning his Electra X. i have done similar over the years, my bike has our hosts English made Exhaust pipe, small universal "silencer". Pod Filter. 19T gearbox sprocket.
Carb Jetting is 117.5. (std is !!0) and the needle maybe raised a notch (can't Remember).
My next stage is to fit larger carb, not sure what yet, but am thinking 32/34mm, the forums advice is most welcome. As covered on other posts on this forum, the inlet casting on the cylinder head is huge, masked by the inlet rubber assembly.
looking at the exhaust port, there is a crescent shape which i am looking to grind away to match the exhaust pipe . Would doing this spoil the port shape and exhaust gas flow?


Stelan92 115 Main Jet part number 112180/115
117.5 """"""""""""""""""""""""/1175
120""""""""""""""""""""""""""/120

I haven't seen an Electra-X exhaust port that WASN'T a badly finished mess. My guess has always been that with the narrow bore of the inner exhaust pipe (part of the factory lean-burn set up) there wasn't much point spending worker's time (and therefore company money) having a nicely finished exhaust port. Once you fit one of our hosts' full bore unobstructed exhaust pipes there is more point to it.

As far aftermarket carbs are concerned, you're spoilt for choice, any properly jetted 4 stroke Amal, Dell'Orto or Mikuni of the required size will do the job, even one of the el-cheapo Chinese clones of the Kehin PWK if it's set up right, and you're not limited to 34mm.

1. That inlet is also very easily ported to 36 or even 38mm,



2. Larger carbs can actually work very well on street bikes. My stuff is on Dell'Orto PHF36s, at the moment, but my old Electra-X also ran very nicely with a big Mikuni TM36-31 pumper carb - once I'd managed to squeeze it in under the tank.



The current Electra-X based project has a number of options in the 38mm carb department...





and with a bit of work...



A.

Just noticed mine is the same as yours, well on the wonk!!

I see you have a copper ring as gasket/seal, I have always used the flat fibre washer but do have some copper rings, which is best?

Looking at the photo of the exhaust port, the step looks quite badly aligned, but at least it is the “right” way, I.e. it doesn’t form a narrowing downstream and might even be beneficial at low gas flow. What does the other side look like? Is there a step going the “wrong” way? If so, I would want that blending in.

Most of them look like this. The sooty black crescent-shape is the area that should have been opened out, so it clearly does not even match the opening offered by the more restrictive original exhaust pipe.

A.

Where’s my Dremel?

Die grinder and tungsten carbide bit, more like! It looks even worse on a new head.



That's more the sort of thing...



A.

That’s more like it! Why couldn’t the factory have done it like that in the first place?

When I first gas flowed my 350 I concentrated on the inlet side and didn’t do much to tidy up the exhaust port. But the next time I had the head off I did some proper gas flowing. Opening it up and smoothing it made a lot more difference than I expected.

Well, they COULD have, but like I said above, the small bore inner exhaust pipe of the Electra-X and other lean-burn models meant that there wasn't really much point, just leave the exhaust ports rough and save a few rupees labour cost on every bike.

A.

I’d say more than rough….the core in the mould used to form the exhaust port was too small for the job and badly placed.