So, I'm running a 1mm jet and think I may need to go bigger....

put a piece of tape on your air filter. If you improve performance where you describe having a problem, then you need to go to a larger jet.
 
Might give that a crack tomorrow Foximus. I picked up a few extra drill bits today including one that 0.8mm and another which is 1.2mm. I can move either way with a bit of solder :p
 
Today I drilled the jet out to 1.2mm. She's a real screamer now. After raising the clip a notch I would say the bike is running perfectly. Seems to be reving out absolutely no worries at all and the acceleration it has now compared to before I had the new head and air filter is astounding. I can't wait till I take it back into the suburbs on some smooth roads to give it a power run and see what speed I can manage. PB so far is 63kmh and that was before I changed the jet and filter. I will take some footage of the computer in next few days so I can depict how she accelerates.

Just for reference this is some footage I took not long after I set the bike up and had it run in.

http://www.youtube.com/watch?v=ZjWOki4FbtY&feature=channel
 
Sweet!


Shift kit sounds really appitizing... might actually have to put one on my first or second bike.

Sounds like you could get some more revs out of that though....

You could try shortening your head pipe a bit, get your chamber tucked in real close to the frame. The shorter your exhaust track the higher your powerband will be.
 
http://www.youtube.com/watch?v=pE3TWpL2ZcY

Took this video this afternoon. I tried beating my top speed of 63kmh but ran out of road. I need to take it out on the long flat stretch in the suburbs that I hit 63kmh on last time.

Just now I have shortened the head pipe about another 10mm and removed the extra lawn mower muffler from the expansion pipe to see if it goes any better but that will have to wait till the morning. Unfortunately the silicone rubbers supplied with the exhaust don't seem to have coped very well as they basically crumbled when I took them off. Hopefully the high temp copper silicone I used instead will hold up.
 
Acreeguy: It is definitely making good power but I still feel it should be doing more in the higher RPMs. It just doesn't rev like it used to at WOT but I think its very close to perfect. I can just feel it struggling with fuel supply. Loads of grunt throughout the rest of the range though.

Pablo: The engine is a Skyhawk GT5 badboy 66cc/"80cc"

Apart from your shift kit it has the following...

-Velocity stack and UFO style filter
-Boost Bottle
-Rocksolidengines Billet Head
-Your expansion chamber exhaust
-Shaved and side cut BPH6s

Fuel is BP Ultimate 98 RON mixed at 30:1 with FUCHS Silkolene Comp 2 Pre-Mix Synthetic Ester.

Other than that it is still wired the way described in the supplied instructions using the crappy little bullet connectors and standard plug wire. When I initially assembled the motor I cleaned up the manifolds and also the expansion chamber with my dremel to try and match the ports as much as possible without actually touching the jug itself.


I should mention that when I rode the bike the other day it was only about 13 degrees Celsius outside.

silkolene is grade a oil comp 2 is good stuff
 
what do the actual jets look like pics? anybody? I have a bunch of dynojet jets from many kits when i worked in bike shops. round head with flat slot?
 
hex head but I think there are a few different styles that fit. When I went looking around at carbuettor shops they showed me ones like you described that came from a webber carb I think. These fit but their smallest was way too big but I can't remember what size exactly.
 
Hey people. After running the bike for a few weeks with the 1.2mm jet I decided I still wasn't happy with it as it was still bogging at WOT. So I am now running a 1.5mm jet! Bike seems almost perfect now and I have hit 66kmh or around 41mph! Fuel economy isn't that much worse either :D
 
I love these bikes. Upgrading the fuel supply is a simple matter of getting drill bits instead of shelling over hundreds for new injectors on a car!

Nice setup. It looks like a shift kit is worth it. Are you thinking about adding some NOS for a boost? You might be able to reach 50 mph on a suicide run!
 
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