carburetor/ Power loss question???

[blasterboy32]

I just bought a blaster with a vito's 240 BB kit. It also has the oil block off kit and exhaust. I rode it for about 5 minutes and noticed a lack of power after about half throttle in every gear. the gears feel really short. I have the stock carb on it with a 290 main jet. I want to know why im losing power after half throttle. Do i need bigger jets? Also does the needle in the carb make a difference? I think it has an aftermarket one because it is blue?? I attatched pics of the plug but i dont know how long it was in the bike. According to the previous owner the BB kit was only ridden on for an hour. Thanks in advance for any help. Why am i lacking power after half throttle? Ive been told that with a 240 kit i should have a 34 mm carb. Do I? Or what jet should i put in it?

 

[blasterdemon7]

Start with a compression and leak down test. That main jet may be to small. You can get away with the stock carb but a larger carb would give you more power. Learn how to do a plug chop.

 

[jaddict]

The blue needle is a vito's needle same as Banshee.

 

[blasterboy32]

Ok. so should i do a plug chop with the 290 main or get a bigger one then do a plug chop? Is the jetting the reason for the lack of power?

 

[IGottaPee]

After you leak-down and plug chop and tweak jetting and needle position follow the throttle cable to make sure there are no kinks or other issues. You may also want to consider if you are running stock sprocketry and a big bore you may want to up the front sprocket to 14t in the front and 38-40t in the rear (stock is 13-40, i think). You have to have equilibrium between the bigger jug and sprocket ratio or you will just waste a bunch of speed on ridiculous amounts of acceleration.

 

[blasterboy32]

What is a leakdown test?

 

[IGottaPee]

it is a device and procedure that tells if you have sufficient compression, i'm pretty sure there's a sticky on it

 

[Larry's Shee]

Leakdown tells you NOTHING about compression. It tells you if you are leaking air into the motor, from cases, crank seals, base or head gasket, and intake/reed assembly. Air leaks cause lean conditions, which cause excess heat, which causes piston melt down=BAD.

 

[Awk08]

what other mods on the bike will help determine what jet it needs, a stock pipe may also be holding back a bbk cylinder ???

if it were mine, i'd start with the biggest main jet i could find...like a 340 or bigger on a bbk with stock carb
needle on the middle clip, stock 32.5 pilot, airscrew at 1.5 turns out < all to start with

what pipe ya running ????
filter ???
air lid on/off ???

 

[blasterboy32]

pro circuit pipe
uni filter and the air box lid is off.
How do i see what clip the needle is at and how do i adjust it?

 

[Larry's Shee]

Pull the spring away from slide, remove clip that holds cable, remove cable, two small screws hold needle keeper. All this is covered in any manual.

 

[Awk08]

/\ yep

the manual is linked in this troubleshooting/maintenence list, go down thru it and check the basics while you're in there...........

http://www.blasterforum.com/engine-13/my-general-troubleshooting-maintenance-30347/

chances are, that if you don't know how to get to the needle, neither did the last guy, and it is still on the middle clip position, but check to be sure

get us a # on that main jet before riding it again, if it's still stock, that explains your problem, and it is gonna fry if you keep riding it like that
with those mods you should be in the 270-290 range, possibly bigger depending on elevation and temps
you'll need to buy some jets and learn to do plug chops ............

http://www.blasterforum.com/do-yourself-20/how-plug-chop-38674/

 

[blasterboy32]

what clip should the needle be at and the main jet is a 290. i only rode it 5 minutes then noticed the power loss and shut it off.