i just got done rebuilding the top end on one of my blasters and cleaned the carb. it started up no problem and was idleing great, but when i am just putting around on it at half throttle or less it kind bogs and sputters but doesn't die. when i just gas it full throttle and jam through every gear it runs pretty good, not noticing any kind of hesitation. when the quad is in neutral and i gas it its revs fine and great with no hesitation at all. the quad is all stock besides the piston(which isnt much bigger than the stock piston cause i would like to get as many rebuilds as i can out of it), and the air box has a bunch of holes drilled into it, and i believe the main jet in the carb is a 280. i'm about to put an uni air filter on it, but i don't think that it will make too much of a difference. i'm wondering if the jet may be too big or too small for the mods done. any one have any ideas of what can be causing this?
blaster boggs at half throttle but doesnt die.
- Thread starter 08curranc
- Start date
no i havent air leak tested it. and no i havent plug chopped it. i dont really have the tools or equipment to do so. i think it may have been hangin revs but not positive on that. ill pay a little more attention next time i start it. can i buy and air leak tester at a local auto store or is it a specialty item that would have to be ordered? what would the revs hanging mean if that was the case? thanks for the quick response! i dont want to ride it untill i figure out what could be wrong cause i dont want to mess it up anymore than it already is.
if its hangin revs then my guess is airleak, you can build a tester for under 25 $
If you have rebuilt then you really need to test to see if it is leak free.
Have you set the float level and correctly adjusted the idle as per manual.
The symptoms describe an air leak or a needle and idle setting problem, what needle position is it at.
Have you set the float level and correctly adjusted the idle as per manual.
The symptoms describe an air leak or a needle and idle setting problem, what needle position is it at.
not sure what setting the needle is at i bought the quad used so i guess ill have to check that out. im pretty positive that the float is correctly adjusted cause i adjusted it before the top end blew. im gonna see if i can build a leak tester today and see how that turns out. if there isnt a leak im gonna pull the carb out and check it. what would i want the needle position to be at(what does the needle position do and how does it effect the carb? does it allow more or less gas?)? thanks guys if you have any more advice or tips let me know!
The needle controls the AFR between 1/4 and 3/4 throttle.
Up to 1/4 throttle the idle setting adds a little.
At 3/4 throttle the main jet takes over using very little if any of the needles settings.
The needle is usually set on the middle clip, lowering the clip gives more gas, and vice versa.
The float level affects all the carby circuits.
Correct jetting can be ascertained by doing a plug chop and reading the plug.
Up to 1/4 throttle the idle setting adds a little.
At 3/4 throttle the main jet takes over using very little if any of the needles settings.
The needle is usually set on the middle clip, lowering the clip gives more gas, and vice versa.
The float level affects all the carby circuits.
Correct jetting can be ascertained by doing a plug chop and reading the plug.
So I made an air leak tester and tested it and found a leak on the bottom of the intake boot connected to the Reed cage. I didn't have a gasket in between them cause from what I read there is one built into the intake boot. Does this mean I need to replace the intake boot? Or do I need some type of sealant?
Leaking at the boot is very common, it is usually caused by incorrect tensioning of the bolts which causes it to warp.
You are correct there is no gasket there but there is a rubber insert there but it usually leaks.
Some put on a gasket, but the leak can be usually be cured with a RTV sealant.
Tension the bolts to 5.8 ft lb gradually, diagonally, incrementally, a little bit on each at a time.
You are correct there is no gasket there but there is a rubber insert there but it usually leaks.
Some put on a gasket, but the leak can be usually be cured with a RTV sealant.
Tension the bolts to 5.8 ft lb gradually, diagonally, incrementally, a little bit on each at a time.
any specific rtv? and how much should i apply?i dont have a torq wrench or anything so how do i know how much im tightening them?
A copper heat resistant sealant works best, but you must let it cure before you start the motor.
Tightening without a tourque wrench is risky, that is what warps the boot.
5.8 ft lb is about as much as you can squeeze a testicle without bringing tears to ones eyes.
A copper heat resistant sealant works best, but you must let it cure before you start the motor.
Tightening without a tourque wrench is risky, that is what warps the boot.
5.8 ft lb is about as much as you can squeeze a testicle without bringing tears to ones eyes.
I must be a pansy, mine only tolerate 5.6 before I cry !!
Sure, for a DOLLAR !! Either my mind went somewhere else or yours did
Just a method to not KING KONG a little fastener. Boys, there are some instances where tighter isn't better
A copper heat resistant sealant works best, but you must let it cure before you start the motor.
Tightening without a tourque wrench is risky, that is what warps the boot.
5.8 ft lb is about as much as you can squeeze a testicle without bringing tears to ones eyes.
so i seal it all up and and all is good there. now its still bogging around 1/4-1/2 throttle. it doesn't die, but comes close i thought it was gonna die but i just held it and i just chuggs real slow. seems to be a bit hesitant from 1/4-1/2 throttle. so now im thinking it may be the carb. i have a new a new FORGED piston (i forget what size it is but its only a hair bigger than the stock piston so i don't think that should effect the jetting right?i have the tors cut off so i pre mix 32:1. the air box lid is removed and on the rear side of the actual air box the previous owner drilled a bunch of little tiny holes , and it has an uni air filter so i assume i would want to be near a 270 main. there was a 340 main in it from previous owner so i took it out and replaced it with a 280 and thats when the bike had fatty fmf and exhaust. i put the stock exhaust on it now so i figure i would want to jump down a size on the jet so i removed it and put a 270 in. now i am still trying to keep it rich for now but do you think that would be too rich or too lean from your knowledge(im located pretty close to sea level right outside of san diego... if that makes a difference)? still with the smaller jet it acts the same still rides fast and good at wot, doesn't die, and idles great. i am going to attempt playing with the carb needle and see if that makes a difference. from what i said does it seem like its starving for gas or getting too much? should i start by going up a notch on the needle?
and i tested again for leaks today after i sealed it up yesterday. so there are no air leaks. the carb is very clean. i am going to recheck the carb float and make sure thats sitting right too. any more suggestions if its not the carb float or the needle position? oh and i checked the needle position yesterday and it was in the middle incase anyone wanted to know. thanks again for the help
I notice you run a forged piston, are you warming up the motor fully before you put the bike into gear, or do you just start and ride.
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Now it is time for a plug chop. You will have to do it at 1/2 and 3/4 throttle to also test the needle position.
Before you make the plug chop run it is important that the float level is correct, the idle is set correctly and there are no air leaks in the system, otherwise the smoke ring may lie about the AFR.
WHEN ALL OF THE ABOVE ARE CORRECT PROCEED WITH THE FOLLOWING.
Warm up motor to operating temp.
Fit new B8ES plug, ride through the gears and hold WOT in 5th or 6th gear for 10 seconds, or as long as you can safely.
Switch off the motor and pull in the clutch, apply brakes to come to a stop quickly.
Take the plug out and replace the old one for the ride home.
Carefully cut the threaded end off the plug to expose the insulator.
There should be a smoke ring of a cardboard or biscuit colour around the insulator.
If it is non existant or a very light colour, you are lean and require a larger main jet.
If it is a lot darker you are rich and may go down a size in main.
I prefer to run a little on the darker side, I may loose a little power but it is worth it for the peace of mind that I won't need a rebuild so soon.
http://www.blasterforum.com/do-yourself-20/how-plug-chop-38674/
http://www.blasterforum.com/engine-13/plug-chop-how-vid-48226/
This is a good to go plug.
This one is a little rich, but I would run it, I like to be on the safe side.
You have to get up a reasonable speed so that you can get the motor to pull strongly.
Then hold it Wide Open Throttle (WOT) for 10 secs or as long as you can.
The idea is not to get speed but to make it pull strong at full throttle to get onto the main jet curcuit.
I find I can safely do it on a short run by applying the brakes some.
If you have not enough room you can use 4th or 5th gear with good results.
.................................................................................................................................................................................
Now it is time for a plug chop. You will have to do it at 1/2 and 3/4 throttle to also test the needle position.
Before you make the plug chop run it is important that the float level is correct, the idle is set correctly and there are no air leaks in the system, otherwise the smoke ring may lie about the AFR.
WHEN ALL OF THE ABOVE ARE CORRECT PROCEED WITH THE FOLLOWING.
Warm up motor to operating temp.
Fit new B8ES plug, ride through the gears and hold WOT in 5th or 6th gear for 10 seconds, or as long as you can safely.
Switch off the motor and pull in the clutch, apply brakes to come to a stop quickly.
Take the plug out and replace the old one for the ride home.
Carefully cut the threaded end off the plug to expose the insulator.
There should be a smoke ring of a cardboard or biscuit colour around the insulator.
If it is non existant or a very light colour, you are lean and require a larger main jet.
If it is a lot darker you are rich and may go down a size in main.
I prefer to run a little on the darker side, I may loose a little power but it is worth it for the peace of mind that I won't need a rebuild so soon.
http://www.blasterforum.com/do-yourself-20/how-plug-chop-38674/
http://www.blasterforum.com/engine-13/plug-chop-how-vid-48226/
This is a good to go plug.
This one is a little rich, but I would run it, I like to be on the safe side.
You have to get up a reasonable speed so that you can get the motor to pull strongly.
Then hold it Wide Open Throttle (WOT) for 10 secs or as long as you can.
The idea is not to get speed but to make it pull strong at full throttle to get onto the main jet curcuit.
I find I can safely do it on a short run by applying the brakes some.
If you have not enough room you can use 4th or 5th gear with good results.
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We need to make it a rule that every time blaaster post the plug chop directions it automatically gives him some green.
