blaster running away
- Thread starter Colton Case
- Start date
did you ever check pilot jet? as you stated above? Lets look at it like this if you have not checked something including any new parts that you put on then go check them.....you put on new reeds ...Did you check them again since your problem.....there is no way your engine is increasing its idle by itself,unless it is getting to much air and or fuel,or not enough of one or they other or your spark plug is melted to its self...
i forgot everything you wrote but what reeds are we talikng about.?
i forgot everything you wrote but what reeds are we talikng about.?
FALSE !!
A Blaster does not have a choke. It is actually a fuel enrichment circut, basically an extra jet.
ill put it this way ive had a complete diff carb and and throttle cable with and with out the tors on it. no matter what carb i use it does it. i took the carb off my brothers and put it on mine and it ran away. switched back mine still runs away and now his quit running. and yes ive checked the jets. they are clean. and your right there is no way it can do it by it self. i just cant figure it out.
Leaky header pipe.
Leaky head gasket.
Leaky crank seals.
Leaky crank collar.
Leaky crankcase. Due to damage.
Leaky base gasket. Check to see if it is blue/green paper.
Leaky reed cage. From incorrect tension settings and tightening procedure.
Leaky carb boot. They have been known to crack and leak with vibration. Did you flex it when you leak tested?
Leaky carp top.
Leaky oil injection nipple.
Incorrect idle setting. If it is incorrectly set revs can rise after warm up.
Low fuel level.
Crap in the pilot circuit. Did you ever check it?
When you leak tested where did you test from, the carb area or the spark plug hole?
What spark plug are you using?
What mods and jetting, this could have some bearing on the matter?
Is the problem consistent or only during warm up.
Why did your Brothers quit running, was the carb out of whack?
Leaky head gasket.
Leaky crank seals.
Leaky crank collar.
Leaky crankcase. Due to damage.
Leaky base gasket. Check to see if it is blue/green paper.
Leaky reed cage. From incorrect tension settings and tightening procedure.
Leaky carb boot. They have been known to crack and leak with vibration. Did you flex it when you leak tested?
Leaky carp top.
Leaky oil injection nipple.
Incorrect idle setting. If it is incorrectly set revs can rise after warm up.
Low fuel level.
Crap in the pilot circuit. Did you ever check it?
When you leak tested where did you test from, the carb area or the spark plug hole?
What spark plug are you using?
What mods and jetting, this could have some bearing on the matter?
Is the problem consistent or only during warm up.
Why did your Brothers quit running, was the carb out of whack?
Last edited:
nothing is leaking i leak down tested from the intake boot and closed of the exhaust. oil injection has been romoved and it has the oil cover. i looked at jets looked fine. didnt see anything wrong with the pilot circuit. mods are oil delete fmf fatty head pipe and silencer. im not sure what reeds the guy that rebuild it put in but they was brant new. and its got a br8es. problem is consistant on cold starts. and not sure why is quit running it was running fine and he put his carb on my bike to see if tht would fix the problem of mine running away and it didnt.
Sorry but I thought we were talking about a shee carb, which Idk much about, but as you said here:
Leak-down tested? (only two more times needed)
Also, if you used a 'shee carb, make sure nipple/hole oppisite the choke knob is plugged. It connects both 'shee carbs.
To which he responded it was plugged. And although the fuel enrichment knob and a choke knob do different things the effect is pretty similar, but I will admit I'm no expert and not near as knowledgeable as most of you guys here.
Did the leaktest hold steady for 5-10 minutes?
Does using the choke affect the problem? Try pulling it out. I don't recall seeing a list of your mods and what your jet sizes are. If you could provide this info we could probably get some idea if they're in the right ballpark. Also, you don't say where your needle clip is? If it's above center, you're set to the leaner range, below center is richer. May be fine wherever it's set but all of this matters A LOT (including your local elevation and air temp) with a 2-stroke and could help us help you.
Run-away is basically one of two things: a lean condition (possible air leak somewhere, clogged or undersized jet, ...See Blaaster's list) or throttle slide not coming back down. Since you changed the carb and cable, the slide is not likely the cause but did you try your carb on your brother's engine to confirm that it works normally there?
I hate to say this but IMHO, the stock 26mm Mikuni carbs suck (basically same on both but with a cross-over tube on the bansee as mentioned earlier). There's a well known problem with them on the banshee - when they get wet (think slamming through a puddle), some have a severe run-away condition (mine did did it reliably ). You have to pull in the clutch and feather the throttle until the thing settles down or just kill it and wait for it to dry out in the worst situations. I tried everything to figure out what caused it and finally broke down and replaced them with Keihin PWK-28's. Haven't had the problem in the 2 yrs since and my throttle response is dramatically improved as well.
Run-away is basically one of two things: a lean condition (possible air leak somewhere, clogged or undersized jet, ...See Blaaster's list) or throttle slide not coming back down. Since you changed the carb and cable, the slide is not likely the cause but did you try your carb on your brother's engine to confirm that it works normally there?
I hate to say this but IMHO, the stock 26mm Mikuni carbs suck (basically same on both but with a cross-over tube on the bansee as mentioned earlier). There's a well known problem with them on the banshee - when they get wet (think slamming through a puddle), some have a severe run-away condition (mine did did it reliably
). You have to pull in the clutch and feather the throttle until the thing settles down or just kill it and wait for it to dry out in the worst situations. I tried everything to figure out what caused it and finally broke down and replaced them with Keihin PWK-28's. Haven't had the problem in the 2 yrs since and my throttle response is dramatically improved as well.
Last edited:
A couple of things to clear up!
Banshees use the same carbs as Blasters which operate a fuel enrichment system.
When you leak test you do not test anything before the carby boot, that's is possibly where it could be leaking.
The boot has been known to crack and leak under engine vibration.
Is is possible that the oil injection nipple is leaky.
Is the top of the carb snug and with a gasket fitted?
Even a leak between the carb and the air filter may cause runaway, even a loose filter, is has been known to happen.
Is the throttle cable tight or is there a little slack to allow handlebar excursions?
Banshees use the same carbs as Blasters which operate a fuel enrichment system.
When you leak test you do not test anything before the carby boot, that's is possibly where it could be leaking.
The boot has been known to crack and leak under engine vibration.
Is is possible that the oil injection nipple is leaky.
Is the top of the carb snug and with a gasket fitted?
Even a leak between the carb and the air filter may cause runaway, even a loose filter, is has been known to happen.
Is the throttle cable tight or is there a little slack to allow handlebar excursions?
if i pull the choke it slows down. im not sure on the jets sizes. i leak down tested from the intake boot. its not cracked or anything like that. i have not put my carb on my brothers blaster. needle clip not sure what that is? info pls? elevation im not sure im in Missouri and temp last few weeks been bout 70 when i was trying to get it goin. and it does this on COLD start up. i can go out and kick it right now one kick and it will fire and run away. no slack in my throttle cable. changed it when problem first happend figured throttle stickin cuz of throttle cable. yes there is a gasket in the top of carb. between carb and tors. its tight and not cross threaded. oil injection has been deleted.
Pulling the choke on and slowing down points to a lean mix, not enough fuel or too much air.
Check the pilot jet size, or set the idle correctly.
There should be a little slack in the throttle cable!
Is the oil injection nippe on the carby blocked off so that no air can enter?
Last edited:
This is on the carb and a lot of people don't know to cap it when doing the oil injection delete. In the diagram speedy posted the needle is #4 it has an adjustable clip on it.
What's the distance from the bottom of the slide to the bottom of the carb throat at idle?
Take your stator cover off and open your oil fill for the clutch side and do the leakdown test.
If your stator is sealed off very well, you may have a main seal leaking and it passes a leak down test.
If your clutch side's vent tube is blocked off or clogged, a main seal can be bad and it'll still pass a leakdown test. These aren't common concurrences, but they do happen.
Take your stator cover off and open your oil fill for the clutch side and do the leakdown test.
If your stator is sealed off very well, you may have a main seal leaking and it passes a leak down test.
If your clutch side's vent tube is blocked off or clogged, a main seal can be bad and it'll still pass a leakdown test. These aren't common concurrences, but they do happen.
