Banshee problem

[Toadz400]

Okay, all Yamaha bashers stay out of this thread...I just need help with this, badly.

Here's the situation: Got bigger carbs (PWK30mm's), got clamp-on filters and got it ported by a friend for cheap for my Banshee and had them installed. I got it running the weekend we had -40 wind chill and I had it running perfectly, just ripped my arms off to touch the throttle in any gear. The next weekend I brought it to the ice drags and it was probably about 10-15 degrees out and it ran absolutely horrible. It would run OK at 1/4 throttle but fall flat on it's face once you hit the main jets. So I figured it was just overly rich on the main jet so I put in the smallest size I have. Still falls flat on it's face, basically no better. I even ran no filters at all and it barely helped. I've raised and lowered the clip on the needle, nothing. I've made sure everything is clean inside the carb, still nothing. I checked the reeds the other night and both of them are in perfect shape still and my spark is great. I need help...I want to sell it, but I don't think I'm going to get far with it not running very well...

Here's the thread from BansheeHQ and so far no one has been able to help me over there, and once again...please, I don't need anyone saying anything about Yamaha sucking and blah blah blah. I own both a Honda and a Yamaha and I have been through my troubles with both of them...Thanks in advance for any help.

http://www.bansheehq.com/forums/index.php?showtopic=37789

[tigerdog]

two strokes can be really finicky with temp, thats why nwe spend so much time with jets on sleds . ten degrees can make a huge difference.
with port work you will gain flow on top end, but all the flow you gain on top is lost on low end.
btw are you sure you didnt go lean?
bigger ports mean the air and fue move slower because it is going through a bigger passage.
smaller passeges move air fasster from point a to point b resulting in better atomization of the fuel.
I would get in the carbs, and look for vacume leaks.

[Toadz400]

It wasn't a major porting, more of a clean up of the factory crap left over.

I'm sure I'm not lean because when I go higher it runs even worse. The plugs are also coming up rich, but I haven't been able to do a proper plug chop because I can't get up to speed! It falls flat on it's face and fouls out.

I hauled it on a trailer and had the petcock shut off, and before I ran it I put Stabil in the gas just in case there was any water in it, and my brother thought that maybe I could've put too much in there so I put in fresh gas and it still isn't running any better, maybe I just haven't run enough of the fresh gas through?

[tigerdog]

pull mthe carbs and check them, sounds like something is plugged up.

[Toadz400]

Originally posted by tigerdog
pull mthe carbs and check them, sounds like something is plugged up.

Carbs were already pulled several times, everything has been pulled out of it to be adjusted and I have cleaned everything possible...nothing is clogged.

Tomorrow I'll be able to do some more work on it and see if maybe I just ran too much Stabil in the gas, I'll probably have to make up a new batch of gas and throw out the stuff I have in it.

Anyone have any ideas???

[Toadz400]

Bump. Does anybody have any idea what could be wrong? Is no one answering me just because this is about a Yamaha quad and they are all just big piles of sh*t anyway, so why even help?

I didn't think no one would have any clue about what could be the problem with how it's running considering there are so many engine guru's on this site...well looks like I'll have to find another site to resort to:o .

[bradley300]

i would hep you if i could, you could compenste by adding more air like holes in the airbox etc. but you already gone as far as you can that way. is it a stock bore/stroke? i would sart from stock jetting and work your way up. it will take a while, but thats the oly thing i can think of

[Toadz400]

Originally posted by bradley300
i would hep you if i could, you could compenste by adding more air like holes in the airbox etc. but you already gone as far as you can that way. is it a stock bore/stroke? i would sart from stock jetting and work your way up. it will take a while, but thats the oly thing i can think of

I am running no airbox, not even filters right now and it's still rich. As for "stock jetting", these are aftermarket carbs and I am already several sizes under the recommended starting point. Yes it is stock bore/stroke.

[tigerdog]

so you have checked the carbs several times and are coninced they are right. how is the spark? could it be weak? or maybe the plugs are gapped incorrectly. only other things that come to mind right off.

[Toadz400]

Originally posted by tigerdog
so you have checked the carbs several times and are coninced they are right. how is the spark? could it be weak? or maybe the plugs are gapped incorrectly. only other things that come to mind right off.

Carbs are clean as hell, jetting can't get any leaner right now (I've gone down from a 175 to 150) and the spark is just fine. I even changed my coils and it's still the same, so it's nothing to do with that.

I can't believe I am only getting help from one or two people on this, usually I see tons of input in other threads...weird.

If anyone wants a cheap Banshee, here's one for ya'...I know no matter what I'm going to take a major loss on this:o :( .

[Toadz400]

Ha bump...anyone know what could be the problem? I'm starting to think maybe the stator or flywheel is damaged...has anyone had similar problems with their quad?

I need help on this I just can't let it sit forever.

I put the stock carbs and airbox back on and the problem is still there, except the backfiring is even worse...can see flames shooting out of the exhaust when I let off the gas.

[bradley300]

do you thnk mabe the carbs are too big? i know on a blaster national motor they use about a 32 mil carb, and thats a fully modded 200cc cylinder. heavy port work,milled head, reshaped combustion chamber and lots of compression. and you have a pretty stock 175 cc cylinder. i dont know much about banshee's, maybe those carbs are fine fr that quad, that could be all i can think of tho. it would als explain why it ran well when it was so cold, but when it warmed up, the carbs are just so incredibly rich that the motor wont run

[Yamahauler_04]

Couple of other things to check. Pull your flywheel off and make sure the key is OK. Sounds like the key could be bad.

Make sure that the intake manifold and boost bottle are sealed correctly. Idle the bike and spray ether on the intake manifold and boost bottle (just a little at a time). If the idle rises, you got a leak there.

I think you are way lean on the jets, but that's just me.

What are you running for fuel, oil, what ratio?

[zlam27]

im racking my brain trying to think of a culprit but its hard to diagnose without being there and being able to tinker with stuff. i had a banshee before my 400ex and they were really tricky to dial in.

back to basics...
fuel, air, spark

i dont know the effects of stabil in the fuel, but i doubt thats the issue.

make sure you are running the same fuel-oil mixture as before. changing this ratio will change your jetting.

check the air screws to make sure they are set appropriately.

sync the carbs. i dont know the exact effects of this, but its important with 2-carb machines.

i doubt its a problem with spark but just in case, check the spark and the plugs (sometimes the top piece comes off and it runs chopppy). change the plugs if you havent already to make sure they arent fouled.

move the clip on the jet needle up a few notches to lean out the midrange and also run some leaner jets - as a last resort.

thats all i can think of right now if you have already disassembled the carbs and cleaned them and everything in there looks good.

good luck, its usually somethin simple but takes forever to diagnose.

zach

[Toadz400]

I won't be able to check my flywheel for sometime, so I don't know if that's the problem or not. I don't have anyplace to work on it right now until spring when we get a shop put up (garage is full all the time).

Everything is sealed properly, even had new gaskets installed.

For fuel I am running 93 octane w/ Castor synthetic racing 2-stroke oil, 32:1 ratio.

I don't believe the carbs are too big, because I am having the same problem with the stock ones back on. Before I took the Banshee to the ice drags I had it running PERFECTLY, with the new carbs and porting done it ripped my arms off...but now it runs like sh*t.

I'm using the same gas as before when it ran great, the air screws should be set right...I played around with them and got them to where they should be. I don't believe you can sync these carbs, they aren't like the stock Mikuni carbs...but how would you sync them anyway? I know there are little windows on the Mikuni carbs, but the Keihins are pretty different.

I've already leaned it out as far as possible and it still runs rich - fouling out plugs and they are black and wet, I'm not understand this.

[Yamahauler_04]

To sync thise you take the airbox off and set the slides as close to even as possible. Tap the throttle and make sure that they open together.

Then go to your local VW shop and get a carb sync tool and use it to set the air screws to let in the same amount of air at idle.

If it ran good at the drags, and then ran like crap, I would drain the gas and put fresh gas in. Then if it still runs poorly, pull the head off and check the pistons.

Just because you used fresh gaskets, doesn't mean it sealed. Do a leak check anyway.

Almost sounds like a ring is letting go.

[blue416ex]

ok hers my 2 cents on it i had a shee before my ex and i hated it just or this ereason i had the EXACT problem i just had the rebuild and a mild port job no bigger carbs thou exact problem fouled plugs spit fire out the exhaust when u let off it and backfires my problem was i used COMETIC gaskets they are CR@P go n order yourself a new set of OEM replacements why? because the OEM ones have metal in them and they crush and glue themselves once they get hot while the heads are off and your in there replace the rings they are cheap and a good maintenance thing whiule your already in there so go buy them next you will want to pull off the carb boots if you had to stretch the boots you may want to check them out for cracks and such pull on them and be absolutely sure there are NO CRACKS if they check out OK put some gasket glue around where the reeds bolt to the head this will prevent and present or future leaks next if you have a boost bottle scrap it and get the stock crossover tube boost bottles do nothing get the stock crossover tube for now and stickit in there and apply some gasket glue around the seal of it put on your carbs and make sure the CARB LINK TUBE is connected once mine fell out and would run but ran like ch!t do all this then see whats happening if its still all messed up put in a hotter plug and check out the degreekey if its damaged you need top buy a new one also throw some 89 octane gas in it itll make it easier to start DO NOT sprayt ether in it it screws up your piston/rings bad cuz it eats/ overpowers the oil almost like your running no oil so try this all and then post if the problem is gone


evan:macho

hope i was a help:D

[Toadz400]

I got the gaskets from a dealership, so I'm guessing that they are the OEM ones as they did cost me a lot.

I will have to try using gasket sealer like you said around all those areas, I am using the stock crossover tube as we had problems with the boost bottle after the rebuild.

I'm pretty sure the carb link tube is connected, I had to make one myself because I couldn't find it. I just found it so I will try putting the stock one on, maybe mine isn't working right, might've been too small to really work. I have looked at both the carbs before and they appear to be synced, I've opened them up and watched where they stop and start and it appears to be right on. I've got the air screws at the same too, I made sure to set both of them back to closed and go the same distance.

The rings might be the problem, I guess I could tear the head apart when we get the shop put up and do that...or else just rebuild it if it looks too ugly, I have a spare bore kit lying around.

I guess sometime I'll have to take off the flywheel cover and check it out...I'm really starting to think that's the problem, I should've checked it out the last time I had it apart.

It sucks because it didn't run good at the drags, ran awesome the week before...brought it to the drags and it crapped out on me when I got to the lake. I'm pretty sick of this because last year my Banshee stopped working on me at the same ice drags..but that was because an eletrical wire froze and snapped, but still...twice in a year it's done this to me at the ice drags.

[EPDP99]

just a suggestion try putting on stock carbs and see if anything changes.

[Toadz400]

Originally posted by EPDP99
just a suggestion try putting on stock carbs and see if anything changes.

I mentioned a few posts above that I have the stock carbs and airbox back on and the problem is still there.

[bradley300]

i hate to make you feel dumb, but i geuss we should ask the easy questions also, as small stuff often gets over looked. so, with that said, is it possible you have the choke on?

[j28d]

Hey, is your gear oil all still there? My Banshee ate a crank seal and ket fouling the plugs because it was sucking oil out of the tranny.

[Toadz400]

Originally posted by bradley300
i hate to make you feel dumb, but i geuss we should ask the easy questions also, as small stuff often gets over looked. so, with that said, is it possible you have the choke on?

Nope, choke is off after it "warms up".

Tranny oil - yep, tranny oil is still all there.

Any other ideas?? :confused:

[blue416ex]

try all tghe gasket sealer and def. check the intake boots sometime when you try and force in bigger carbs and have a boost bottle the weight/ pressure will crack them causing air leaks causing it to run lik poopoo lol

[mattonln]

It sounds to me like your running extremely lean because of the flames... sometimes when your jetted very very lean it acts like it is rich..... i think my buddy is running 280's or so in his shee which is ported and trued with pipes and direct mount.... try going way up on jets... WAY up.... I will ask him tomorrow when i see him and ask him what he thinks....

[Toadz400]

Originally posted by mattonln
It sounds to me like your running extremely lean because of the flames... sometimes when your jetted very very lean it acts like it is rich..... i think my buddy is running 280's or so in his shee which is ported and trued with pipes and direct mount.... try going way up on jets... WAY up.... I will ask him tomorrow when i see him and ask him what he thinks....

I have tried going way up and it just gets worse.

[Jay99400ex]

Here is one thing it might possibly be, slim but it's a chance.... theres a filter above your petcock inside the tank, i have seen them clog where it will get enough fuel till you get on it the run like crap, I hope this is your prob, it's a long shot but a chance.

[Toadz400]

Originally posted by Jay99400ex
Here is one thing it might possibly be, slim but it's a chance.... theres a filter above your petcock inside the tank, i have seen them clog where it will get enough fuel till you get on it the run like crap, I hope this is your prob, it's a long shot but a chance.

That has happened to me before, I haven't checked it yet though this time. I didn't think it would clog again when I've been using fresh fuel and it hasn't really been sitting for very long, but I think I should try and eliminate that from the variable list.