help with 240 big bore kit

wolf1

wolf1

Member
Jan 19, 2008
270
4
49
Ringgold Georgia
www.quadclass.com
i just purchased a vito's 240 big bore kit, i have tried every jet they sent in the kit and runs rich on every one of them.

i have to run the fuel/air mixture screw all the way in just to get it to idle.


the only jets that it will run half way decent with are the stock jets which iam told will damage the engine.

the airbox is removed.
my blaster has the vito's 3mm stroker crank, a set of boyeson pro series dual stage reeds with the stock reed cage, 4 degree timing advance, 247cc slip on silencer with the stock pipe.

anyone know how to get this thing to tuned in?

thanks in advance
 
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im willing to bed the stock pipe has something to do with it.. running rich since your motor needs plenty of fuel, but the stock pipe is killing it and messing with it.. 2 streokes depend on the pipe big time..
 
1st, leakdown test,
2nd. the engine isn't balanced, an engine is nothing more than an airpump. your let a little more in the intake, you opend the middle of the pump with te vitos kit, and you have choked down the flow with the stock exhaust..I take it since you removed the airbox you have a pod filter stuck on the end of the carb. get a piece of tubing and space the pod at least 4 inches back from the carb so youhave a decent pulse velocity thru the carb.
 
the exhaust may be the problem, but then vito's advertises that it is a bolt on and go kit. which should mean that you didn't need anything else but to "bolt it on and go"

the crank balancer is dead on. (line up the marks pointing toward each other.)

the compression is a steady 135psi with no leak down.

i have removed the exhaust as suggested by vito's and it still bogs down running too rich with the smallest jet in the kit in it.

the dealer went through the carb 2 days ago and said it was in perfect working order, and they tried to jet it and tune it with the kit and said it wasn't possible to get it done right with the kit they supplied.

I have tried everything and am out of ideas.

the only way it will run right is with the stock jets in it but they say that the stock jets will damage the engine.

iam lost
 
well.... for sake of arguement.... whats the plug look like when you have the stock jets in??? if for some odd reason your plugs show your good/safe just run them.. like everyone says every quad is differant
 
wolf1 said:
i have removed the exhaust as suggested by vito's and it still bogs down running too rich with the smallest jet in the kit in it.
Click to expand...


he told you that ? gee thats scary :(

my question is why did you spend all that money on fancy engine bolt on mods and still use a stock piece of crap pipe and tiny oem carb ? im sure it is rich the mods you have can make it run more rich and the jet kits they give you in the kit are a joke and usually super rich for libaility reasons .the 26mm mikuni carb isnt desigend for a 72mm stroked 244cc quad engine.
 
wait a minute ...your sig says a 30mm keihin style carb but your post says your using vitos jets ..so what carb is this? this doesnt add up ?in your sig ..how is your stock pipe a custom exhaust ? what is a 247 slip on silencer? ..never heard of this
 
Ill bet if you change off the garbage stock pipe and get an aftermarket since the rest of you motor is modded pretty much and you will probally see your problems go away
 
i run a 148 and have a 30mm cpw carb and it runs great. i have almost the same mods just not the stroker. hope this helps
 
wolf1 said:
the exhaust may be the problem, but then vito's advertises that it is a bolt on and go kit. which should mean that you didn't need anything else but to "bolt it on and go"

the crank balancer is dead on. (line up the marks pointing toward each other.)

the compression is a steady 135psi with no leak down.

i have removed the exhaust as suggested by vito's and it still bogs down running too rich with the smallest jet in the kit in it.

the dealer went through the carb 2 days ago and said it was in perfect working order, and they tried to jet it and tune it with the kit and said it wasn't possible to get it done right with the kit they supplied.

I have tried everything and am out of ideas.

the only way it will run right is with the stock jets in it but they say that the stock jets will damage the engine.

iam lost
Click to expand...

what he ment by balenced is the engine system. big intake, big displacement, little exit. so it is like a bottleneck. thats the definition, but in a clearer veiw.

just get a pipe. your going to think the 240 kit did nothing without the pipe anyway.
 
i agree with flotek your saying the jets vitos gave you (stock 26mm carb) and your runing a 30mm carb... well as long as its the same brand carb itll work..i can take a jet from my zr800 and put it in my blasty but than agains its a like 570 main
 
FLOTEK said:
wait a minute ...your sig says a 30mm keihin style carb but your post says your using vitos jets ..so what carb is this? this doesnt add up ?in your sig ..how is your stock pipe a custom exhaust ? what is a 247 slip on silencer? ..never heard of this
Click to expand...


it's not on mine, it's on my sons blaster, he is using the stock carburetor.

the only reason i didn't purchase a better carb was that the vito's big bore kit advertises that it will work with it.
if i had known it would have problems running with the vito's big bore kit i would have bought a pj or something for him.
but their advertisement said it would work.
so by all rights it should. at least you'd think it would.
 
FLOTEK said:
he told you that ? gee thats scary :(

my question is why did you spend all that money on fancy engine bolt on mods and still use a stock piece of crap pipe and tiny oem carb ? im sure it is rich the mods you have can make it run more rich and the jet kits they give you in the kit are a joke and usually super rich for libaility reasons .the 26mm mikuni carb isnt desigend for a 72mm stroked 244cc quad engine.
Click to expand...

yes but only as a test to see if the exhuast was choking it off.

it didn't make any difference.

....hmmm, the over-rev switches and module you know the one in the tors, and the one in the thumb throttle, could they be killing the power?
 
yes, there are some electrical issues that could cause it not to rev...but if it revs with smaller jets its not electrical. i have a bb with 34mm carb and my main is around300-330 same with wifes but on stock carb with stroker..have you moved the lil c-clip on the needle? this will also make a big difference. if the mixture screw is all the way in ur pilot is off.i think u should have a 35 pilot in there?maybe 40...first idle,throttle response, midrange then top end..but i dont think u will have much top end...i think with the set up u have it will be a low end torquey bike..u need a new pipe for sure and a carb...my carb is off stock lt250r , not the best but it was freee and works good
 
wolf1 said:
yes but only as a test to see if the exhuast was choking it off.

it didn't make any difference.

....hmmm, the over-rev switches and module you know the one in the tors, and the one in the thumb throttle, could they be killing the power?
Click to expand...
What do you mean by "it didnt make ne differance"?? An aftermarket didnt make a differance over stock?? If so, you have some other problems cause you should see a big differance with an aftermarket pipe
 
Vito's is working with me and so far they have been great! we still haven't figured it out yet, but as the tech at vito's pointed out it could be the over-rev switches.
so iam going to go and disable all of those, and give it a whirl.
then do a fuel drain test to see if it is getting enough fuel from the tank.

Paul at vito's is awesome!!

they are doing well at customer service so far (even took their time to call me to make suggestions.)

hsure hope we can get this figured out. i'd love to get the 240 kit dialed in.

but anyone who has run across this issue or has an idea i'd be glad to hear it!!

thanks guys
 
If its running lean do a leak down test to see if you have an airleak that is causeing it to lean out. Could be this but maybe not. Never a bad idea to do a leak down test ne way. Ecspecially after you had your top end off. This should always be done after the top end was off your motor.
 
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