pulse adernaline 125 photo guide to main jet swap

hi guys, dont know if this should be here or in maintenance?
im sure a mod could move it if needs be.

just a basic photo set to show the simple points involved in changing a main jet on a mikuni vm22 carb

ive not included the pull the carb off the bike and chuck the carb back on the bike as its a bit of a no brainer once everything is disconnected,

tools used and a reference as to what the jets look like are included,

please feel free to comment, or add your own info as required.

thanks, james

http://farm6.static.flickr.com/5155/...d6338acdf8.jpg
fuel pipe clip by offtheclockuk, on Flickr

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carb/ airbox joint by offtheclockuk, on Flickr

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undo nuts securing carb by offtheclockuk, on Flickr

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unscrew piston cap by offtheclockuk, on Flickr

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remove piston by offtheclockuk, on Flickr

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dont damage piston or needle by offtheclockuk, on Flickr

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remove screws from bowl by offtheclockuk, on Flickr

http://farm6.static.flickr.com/5111/...a21c8b831b.jpg
remove bowl by offtheclockuk, on Flickr

http://farm7.static.flickr.com/6026/...e7c503b867.jpg
secure jet body and remove jet by offtheclockuk, on Flickr

http://farm6.static.flickr.com/5115/...97780a18d5.jpg
screw in larger jet by offtheclockuk, on Flickr

http://farm7.static.flickr.com/6035/...fedd1dd07d.jpg
check for obstruction/damage before closing up by offtheclockuk, on Flickr

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refit and check connections by offtheclockuk, on Flickr

http://farm7.static.flickr.com/6030/...3f44fe4a87.jpg
tools used by offtheclockuk, on Flickr

http://farm6.static.flickr.com/5034/...906c229a7f.jpg
112.5 left - 115 right by offtheclockuk, on Flickr

Hi
what Main Jet size are you using?
cheers

Quote:

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Originally Posted by superfamous

Hi
what Main Jet size are you using?
cheers

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At the moment 115, not had a chance to run it properly yet to see how it pulls, need to find a performance cdi really.

thank you for your quick reply!
Did you already check your plug? 115 isn't too rich?

Quote:

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Originally Posted by superfamous

thank you for your quick reply!
Did you already check your plug? 115 isn't too rich?

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I checked the plug right after I did the swap, not done a chop at wot yet, the bike pulls hard to the rev limit, but before the swap on the #112.5 jet, it went flat around 6k and didn't want to rev further, when you snap the throttle open then shut again, there's a flash of bright blue flame, that's meant to indicate complete burn so mix must be close to right.

hey man me and u have the same carb im looking changing the jet myself where can i get one and how can i find out what size i need
cheers
guy

Quote:

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Originally Posted by relentless addict

hey man me and u have the same carb im looking changing the jet myself where can i get one and how can i find out what size i need
cheers
guy

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They can be found on eBay for about £3, just search mikuni vm22 jet, as for size 97.5 was the standard jet in mine, but it's not as straight forward as pick a number, you probably need to try 2 or 3, starting at 100-105 then going up if it's not enough.

kool ive gt a race cdi and full custom stainless steel exhaust system also making a custom ram air filter for it so may need a fair bit of fuel going in what u think if i go straight to 105 then higher if i need?

I'm up as far as 115, just trying each one for a few days till I'm happy, with all that you have done to yours 105 may not be enough!

Out of interest do you know where your cdi came from as I'm looking at getting one, there is a slight miss at high revs and full throttle, also is the cdi just a rev limit raise or does it increase power/timing etc?

Thanks, james

jsut to let you know i actually have a superbyke RSR 125 same engine as yours so same general tuning i have a kamakazi cdi gives me a power band over 8 thousand revs only problem is 3rd 4th n 5th i have trouble geting over 8 thousand revs so more air/fule is needed if u can find a kamakazi one ace but there hard to get also bigger spark

Hi guys
I have a pulse adrenaline with a 150cc kit, stainless steel exhaust, custom air filter, with the vm22 mikuni carb.
Now I have a #100 main jet with a #20 pilot jet. The bike runs fine, however when I hit the 7k the bike starts to fail. If I push hard the acelerator the bike goes fine and start to gain revs. it seems that it only fails in a specific acelerator position...:confused1:
What do you think about my Spark plug?is the mix ok?

Attachment 4693Attachment 4694

thank you

its looking a bit black should be a chocolate brown colour is it moist(and smelling of petrol) or dry?? cant really tell from the pics

Quote:

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Originally Posted by relentless addict

its looking a bit black should be a chocolate brown colour is it moist(and smelling of petrol) or dry?? cant really tell from the pics

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Thank you for your reply. yes, it is a bit black...so I guess that the mixture is rich. I only use the #100 main jet right now...maybe the pilot jet is too large (i'm using a #20)? because you are using a #115 and the mix is ok!
I think that I have a good air intake, so it shouldn't be a lack of air in the mixture.
My spark it's dry and don't smell too much of petrol.
cheers

if its dry and black your probs looking at a lean mixture rather than a rich one as you would be able to smell the petrol

Quote:

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Originally Posted by relentless addict

if its dry and black your probs looking at a lean mixture rather than a rich one as you would be able to smell the petrol

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sorry about the questions. But the black colour doesn'i indicate a rich mix? I thought that a lean mixture should make the spark look brown and a rich mix should make it black.
I'll try a bigger main jet and see if it will work better!
thank you

Lean mixture spark plug should look white. Main jet is most effectively at 3/4 to full throttle opening (which means does very little effect at small throttle opening).
Carb is complex, I found main jet at #100 is good for my 150cc. I recommend this reading (LINK) for further turning.