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

EnFlaMEd

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When I upgraded my air filter to a velocity stack + UFO style the other day I found that my bike ran a bit ****house. So I dropped the clip on the needle and found that it ran better slightly richer however at WOT the engine would die. There were no weird noises or anything associated with this, the engine simply cut out until I backed off the throttle. In order to cure this I hunted around for some larger jets but didn't really have much luck in finding anything so being the impatient ******* I am I found a 1.0mm drill bit and ran it through the jet with my fingers.
I figured that was probably going to be way to big and cause problems however that was not the case. The engine is running great now and is pretty good at WOT but it still feels like it is running a little lean. A check of the plug after a good 20km or so thrash has revealed it to be a bordering on a light tan colour whereas with my old setup it was always a dark grey. Is it possible I need to go larger again? I only doubt myself because everyone else seems to be running such smaller jets in their engines even with setups like mine. What do you guys/girls think?

 
That really does look just like my setup LOL! Suprised to see the stock wire though, easy to upgrade! I even used the same tailpipe hanger as you!

The WOT bog is a sure sign you are in the danger zone lean and closed to melting the piston. Ask me how I know :)

If you motor likes it where you are, go with it! You could tune the pipe by adjusting the length though.

Ed
 
Yes I know, thats why its good comparing notes with you and I've seen your piston with its speed hole lol :D

There is a new plug wire on its way to me from sbp. I had to order some other parts so thought I may as well get that while im paying for shipping. I hadnt really bothered to upgrade it before as I don't think I have had any spark problems. I wonder if there will be any further improvement with it. Notice anything on yours Ed?

I have thought about mucking around with the pipe some more. I trimmed it a bit when I first installed it but I can't remember how much. An inch perhaps.
 
Had the wire on my old bike, so I just moved it over when I built this one. Never tried without it, but can not hurt. I'd see what Pablo thinks on the pipe tuning, they are really sharp with this stuff!
 
WOW - 1mm? You must be getting some great power out of that combo to effectively utilize that large jet!

I usually need to go up to .82 - .85 from the stock .78, but then again, this is with a stock exhaust and intake.
 
Sounds huge.

Tell us about your other mods. What about oil and oil ratio?
 
The IDEAL color for spark plug tuning is HERSHEYS MILK CHOCOLATE.



And if your playing with advancing your timing you want the heat band parallel with the inner edge of your earth diode.
 
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.
 
Do you know your RPMs when your hitting this bog?


You could be going to rich, or on the bad side if you have a big sprocket you really could be over revving and getting ring flutter.


If you really want to see whats going on in your engine get a harbor frieght laser thermometer. get readings at sustained riding rpms, slowly going up. See what happens to your motor.


Oooooorr... If you want to get even more fancy, get something called a (if i remember correctly, its been a while since ive had one) ColorTune Spark plug.
 
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It doesn't really happen at any particular RPM its just when Ive got the taps opened right up. Like I can still rev the engine out with less throttle but it just takes longer and is harder to do in higher gears.

Gearing wise its all standard SBP Shift kit with a 11t-32t 9spd rear cassette.

I don't think I am running too rich because what I am experiencing now was far far worse before I increased the jet size.That is my reasoning anyway lol. It is now almost at the sweet spot but just not quite.
 
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