Carb cap and oil injection line leak free? Or exhaust connection to engine possibly? Really sound like an air leak, could also be starving for fuel, or a sticky/poorly routed throttle cable causing it to hang
What changes do I have to do?
- Thread starter BrianHemphill
- Start date
New seal on carb cap and oil block off kit installed so it's blocked off and throttle cable is not sticky.
Is the factory pilot installed? Did you plug the hole in the slide? Those were 2 of the many problems I (we) identified with my wife's Blaster.
I don't remember where I read it, but the hole on the slide is suppose to be open, not covered. It's a vent for the carb. It shouldn't create an air leak there if the cap seal is new and leak free.
Not sure how much it will effect the engine if closed. Others have ran it that way with good results.
Not sure how much it will effect the engine if closed. Others have ran it that way with good results.
If the throttle cable is in working order, the vent hole isn't a problem. As my wife's wasn't, I plugged it. Never knew that's what it was for though.
So must of been the boyseen Reeds causing the hanging idle, they are starting to split into two right down the middle and has a gap. How long are they suppose to last got about 40hrs out of them. And I did a plug chop wit a 320 and looked lean so put 330 in aND looks leaner.
320 is on left 330 is on right
So I got new reeds and cleaned the carb thoroughly new spark plug..it runs semi ok when you floor it but you can tell all the powers not there and when you cruise it sputters and dies then kicks back on?????
If you are doubly sure that there are no air leaks, bump the main up 2 sizes.
When you do the plug chop, is the engine pulling hard?
When you do the plug chop, is the engine pulling hard?
I have a 330 in it now so a 350?
And when I do the plug chop I warm it up, change plug on a straight away, floor it 1 thru 6 and hold it 10-15 secs and kill it and coast to a stop.
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 WOT 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.
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 circuit.
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.
WHEN ALL OF THE ABOVE ARE CORRECT PROCEED WITH THE FOLLOWING.
Warm up motor to operating temp.
Fit new B8ES plug, ride WOT 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.
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 circuit.
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.
Can it be getting to much fuel? Plug is wet when I take it out. It's fine when you floor it or gaining constant speed but when you try to coast at a steady speed it sputters..any chance it could be a bad CDI??? I'm dying just spent so much money on a complete motor rebuild... ran fine then out of no where starts doing this... Thanks!!!!!!!!
A sudden symptom is not jetting, unless the temps have gone up a whole lot from original jetting/plug chops.
CDI (for the most part) are a go/no go item. Spark issues will show the most at high RPM/loads.
At what throttle opening are you getting the sputter?
When you cleaned the carb did you remove the emulsion tube/main jet holder? There are holes on side that must be open. While you have carb apart double check pilot jet.
I know you did a leak test couple monts ago, but another might be a good idea if this isn't resolved quickly.
A quick and dirty test is at the throttle opening where it sputters, pull choke half way. If it gets worse, you're rich, gets better, you're lean.
CDI (for the most part) are a go/no go item. Spark issues will show the most at high RPM/loads.
At what throttle opening are you getting the sputter?
When you cleaned the carb did you remove the emulsion tube/main jet holder? There are holes on side that must be open. While you have carb apart double check pilot jet.
I know you did a leak test couple monts ago, but another might be a good idea if this isn't resolved quickly.
A quick and dirty test is at the throttle opening where it sputters, pull choke half way. If it gets worse, you're rich, gets better, you're lean.
Sorry for the delay. After reading all three pages and writeing above post my computer froze. Somehow it saved my draft.
Red flag is I think there is something serious going on. JMO.
Red flag is I think there is something serious going on. JMO.
Thank you the main jet holder is what I'm am going to hope for (bought a rebuild kit )
I got vforce 4 reeds and it ran better but still having that little sputter 1-4 under a quater throttle. Over half throttle and more it runs crisp. And now it has a hanging idle when slowing down with clutch in. Thanks man I appreciate it!
Hanging idle? Did you set your air screw / idle properly ? That could cause that condition. I had a hanging idle twice. Once was an air leak and once was improper setting on air screw / too small pilot jet.
Popping or backfiring on engine overrun is caused by a lean idle setting.
You may need to reset your idle speed and or leak test, as a small air leak will produce an identical symptom.
You may need to reset your idle speed and or leak test, as a small air leak will produce an identical symptom.
I going to do a leak down this weekend again and I have the air screw 3 half turns out. Think I should try next Sze pilot jet?
