Okay i just rebuilt the top end on my 98 blaster and when i started it up it idles really really high and it wont go down. I had it bored to 67.00 with a 67.00 piston. i put all new gaskets. i even put new boysen reeds in. what could the problem be? and how can i fix it? thanks!!
HELP!! High idle after top end rebuild.
- Thread starter brsslam14
- Start date
Either your idle is set way too high (large flat head screw with knurled grip under the seat behind fuel tank)
your lean (got an air leak/ leak test it),
sometimes the wrong aircrew setting can keep it from idling back down well (turn the air screw, shifter side bottom back of carb, all the way in gently then back out to 1 and 1/2 turns)
I got a feeling if you rebuilt the top end you probably know where the idle and airs crews are and how they work.
Kinda narrows things down a bit, but I know I am forgetting something as well.
Did you make any other changes to the motor when you done the top end? Porting, different pipe, airbox lid, etc.
your lean (got an air leak/ leak test it),
sometimes the wrong aircrew setting can keep it from idling back down well (turn the air screw, shifter side bottom back of carb, all the way in gently then back out to 1 and 1/2 turns)
I got a feeling if you rebuilt the top end you probably know where the idle and airs crews are and how they work.
Kinda narrows things down a bit, but I know I am forgetting something as well.
Did you make any other changes to the motor when you done the top end? Porting, different pipe, airbox lid, etc.
Reed block and carb boot are places that leak badly if the screws are tightened up too much, they warp.
has it been leakdown tested ?
hi-temp copper rtv or yamabond used on intake gaskets ?
http://www.blasterforum.com/threads/how-to-perform-a-leak-down-test.44653/
http://www.blasterforum.com/threads/about-air-leaks-save-your-engine.55537/
http://www.blasterforum.com/threads/leakdown-testers.55015/
hi-temp copper rtv or yamabond used on intake gaskets ?
http://www.blasterforum.com/threads/how-to-perform-a-leak-down-test.44653/
http://www.blasterforum.com/threads/about-air-leaks-save-your-engine.55537/
http://www.blasterforum.com/threads/leakdown-testers.55015/
5.8 ft/lb for carb joint
Attachments
if you did not put the carb slide in wrong?
throttle cable is routed correctly
and or touch the carb during top end rebuild.
your getting free flowing gas?
then it should not be revving uncontrollably
ngk b8es spark plug gapped correctly
unless you have a massive airleak
throttle cable is routed correctly
and or touch the carb during top end rebuild.
your getting free flowing gas?
then it should not be revving uncontrollably
ngk b8es spark plug gapped correctly
unless you have a massive airleak
well some good news idles fine when i start it up with the choke on and even with the choke off it idles fine until i give it gas. Then it starts to idle high, and the more gas i give it the little bit higher the idle gets. i did mess with the idle screw a little bit could it be that?
Like Awk08 asked earlier, has it been leak down tested? Sounds like an air leak. My blaster is doing the same thing right now. Idles fine, and then as soon as I give it gas, just stays revved up for a little bit. Leak tested and found leaks all over the place.
Yeah, I wonder if choke is richening it up and helping hide the air leaks...
Last edited:
Edit: Sorry, I started writing this before your last post, but it's no kidding making sure you leak free, comes above oil change, fresh plug, mix ratio etc., an air leak will sneak up and bite you where it hurts.
I just been through that rodeo, had 1 minor and 1 substantial leak.
As far as taking a long time to idle down that can be caused by a lean airscrew setting. Try turning it in a quarter turn at a time. Wait about 20 seconds then Rev it a little and see if it idles down if it hangs for a little bit then idles down it is typically still lean on the airscrew, go in another quarter turn and try again. If the pilot/ airscrew is rich it usually idles down quickly then either starts 4 stroking (literally sounds like it's only firing every other rotation) or quits altogether. Once you get it where the idle acts right continue working turNing the airscrew 1/8 turn at a time checking for a good clean Rev when the throttle is pushed down quickly but smoothly.
Any how all that doesn't matter because if you got air leak(s) the you will be chasing your tail, I about wore my airscrew out adjusting back and forth a half turn either way, trying to make it perfect every ride. I finally ended up masking the leaks with a big fat main jet and set it so it run somewhere between a little rich and really rich, left it there and began getting ready to rebuild.
When you first started it it would run so rich that if you floored it it would just sputter, then once it warmed up pretty good it would lean back out to about right.
It lasted a while with a DG pipe, sensible riding, taking it easy if it were hard to start, 24:1 mix with good ethanol free 93 octane, watching the cylinder and head Temps closely.
All this to prevent detonation.
And this was on a basically stock setup.
Take it from someone who learned the hard way and LEAK TEST IT.
I finally leak tested before tearing apart a locked up motor, and sure enough, all the difficulty jetting, constantly worried about overheating and detonation, and alot of distraction that might have kept me from catching the piston before either failed.
Later Ride Smart
Deebee
I just been through that rodeo, had 1 minor and 1 substantial leak.
As far as taking a long time to idle down that can be caused by a lean airscrew setting. Try turning it in a quarter turn at a time. Wait about 20 seconds then Rev it a little and see if it idles down if it hangs for a little bit then idles down it is typically still lean on the airscrew, go in another quarter turn and try again. If the pilot/ airscrew is rich it usually idles down quickly then either starts 4 stroking (literally sounds like it's only firing every other rotation) or quits altogether. Once you get it where the idle acts right continue working turNing the airscrew 1/8 turn at a time checking for a good clean Rev when the throttle is pushed down quickly but smoothly.
Any how all that doesn't matter because if you got air leak(s) the you will be chasing your tail, I about wore my airscrew out adjusting back and forth a half turn either way, trying to make it perfect every ride. I finally ended up masking the leaks with a big fat main jet and set it so it run somewhere between a little rich and really rich, left it there and began getting ready to rebuild.
When you first started it it would run so rich that if you floored it it would just sputter, then once it warmed up pretty good it would lean back out to about right.
It lasted a while with a DG pipe, sensible riding, taking it easy if it were hard to start, 24:1 mix with good ethanol free 93 octane, watching the cylinder and head Temps closely.
All this to prevent detonation.
And this was on a basically stock setup.
Take it from someone who learned the hard way and LEAK TEST IT.
I finally leak tested before tearing apart a locked up motor, and sure enough, all the difficulty jetting, constantly worried about overheating and detonation, and alot of distraction that might have kept me from catching the piston before either failed.
Later Ride Smart
Deebee
Last edited:
Message Awk08, I just picked one up from him. Very good quality.
The thing about doing it with ether or carb cleaner is that when idling or revving freely, it really doesn't pull much if anything through the leak ( depends on where it is and how bad).
SInce many leaks wont show up at all unless your on the throttle and under load, and since the motor has to be off, to check the left main seal. The ether trick doesn't really work
The right main seal is even harder to expose but burning trans oil, fuel oil mix I the trans oil, as well as loss of trans oil all tend to expose a leaky right main seal.
I will never again own a two stroke, without having a way to leak test it. an exhaust plug, and some way to put pressure on the motor to at least expose a major leak should really come in your factory tool kit.....but then they couldn't sale as many parts and rebuild kits. Lol
SInce many leaks wont show up at all unless your on the throttle and under load, and since the motor has to be off, to check the left main seal. The ether trick doesn't really work
The right main seal is even harder to expose but burning trans oil, fuel oil mix I the trans oil, as well as loss of trans oil all tend to expose a leaky right main seal.
I will never again own a two stroke, without having a way to leak test it. an exhaust plug, and some way to put pressure on the motor to at least expose a major leak should really come in your factory tool kit.....but then they couldn't sale as many parts and rebuild kits. Lol
