2 stroke help !!!!!!!!

[erectordale]

I'm frustrated with this thing (the 500) It runs but wants too rev really high after few seconds wants too die then all over again. I just replaced all the crankshaft seals the bottom end gasket is siliconed really well and carb boot is sealed and not cracked. I'm not sure the carb is set correctly as I have nothing too go from. the carb came off a running motor just needed a needle which i had wondering if this needle is possibly in correct and if this could cause this ????

[Bryan Raffa]

have you tryed a differnt carb? good reeds?

[MTS]

the carb you used wasnt off an oil-injected bike was it? could have a Open Port.....

[HondaHarry]

I may be stating the obvious on alot of stuff here, but figured i'll give my 0.02

Have you done a pressure test on the motor? plug the exhaust with a Rubber Freeze Plug, and build a plate with a shrader valve and pressure gauge that will bolt onto the intake flange. If everything is OK, it should hold 6psi for 6 minutes, if it drops, spray soapy water from a spray bottle all over the engine, look for bubbles, pull the oil fill cap and put your ear up to it and listen for air leaking (air can leak from the case halves into the transmission)
spray water on the case seam all the way around from the outside.

If all of that is ok, check your float height or even try that first (NOW i think of it)

Make sure the carb is getting fuel, check the tank vent make sure it is clear,
check the petcock for proper flow. Make sure you have plenty of fuel in the tank.

Also make sure that the slide is closing all the way. If the A/F screw makes no change in how the motor runs that is usually the problem. Disconnect the cable from the throttle or adjust it so you have plenty of slack in the cable.

Make sure the needle is not bent, you can even try lowering the clip one notch to richen it up.

Like I mentioned these are just suggestions, you may have done or know all of the above, but as hard as you have been working on that thing your brain could be fried (happens to me all the time) so I figured I would give you some feedback. :) HH (never even seen a Tiger in person, but love em anyways thus the avatar pic. hehe)

[erectordale]

this is off a can am a/c no oil injection I will try the pressure test and see if I can get the carb setting and double check them thanks for the tips guy's

[erectordale]

well I've done all but the pressure test as i don't have the gauge and such too do this test the a/f screw makes no differance the carb was disassembled and cleaned again today still acts the same will too much fuel cause this ??? just when I thought I had these fiqured out . I have 4 days till I leave for tf and want this running been 5 days so far and no improvement

[jonnyb]

that would really suck if you cant go to trike fest, hopefully you get it fixed, did you try another carb?

[erectordale]

I have 3 bing carbs for this but 1 was set for alky and 1 is incomplete the 1 I'm using was from a mx 500 canam supposedly ran

[Mosh]

dumb question here.is the choke flap moving around( if it has a flap) or is the choke sucking air?pull the air filter boot and block the carb opening with your hand.if it smooths out you are lean.another trick is lightly spray brake cleaner around air leak pionts while it is running.this might help find a leak. carb cleaner is a little more flammable that is why i use brake cleaner.and make sure the motor aint scalding hot.or you will have fire for sure.one more thing.you questioned the needle being correct.if that is not seating in the seat all the way at idle,fuel will seep up past there and cuase problems.

[erectordale]

I wish I had a 40 mm carb I would switch carbs. I truely think the carb is the issue I was extremely careful too make sure all sealing surfaces and seals are new and sealed so that leaves the Carb*&&^%#@%$&^&* pc of crap

[erectordale]

I know that compression is good as it broke a kicker today when it back fired

[Mosh]

back fired? that sounds like lean or timing problems.i have also seen carbs suck fuel past the seat and case of the carb.usually they smoke real bad and foul plugs and wont idle at all when that happens.good luck to you and you will find it.it is always a last minute battle sometimes.take a break and go back to it with a fresh outlook.

[erectordale]

I know this is a dumb question but a thought I have a 38mm flatside on the quadzilla this is 2 mm smaller think if I move this over too the tiger it would run as they are both 500cc

[erectordale]

dynamite please lol

[Mosh]

yes that should rule out carb problems.you can prolly run that carb if it will bolt up.i just would be weary about the topend jetting.give it a shot.dynamite is for having a good time.not trikes lol

[erectordale]

the 38 mm from the zilla acted the same I have a new crank coming tommorrow for this the one in there is ok just taking no chances as it was run with alky when i seal the bottom end what too use for sealant there is no gaskets in these rotax engines just seals

[TimSr]

It sounds to me like a simple problem of losing fuel flow. The fact that after it revs really high, and comes back down and starts over sounds like the floats are set really really low. You get a little gas in the bowl and the floats cut off, as it revs out of sight, the floats drop back down and allow justa little more gas in, they cut back off, it revs back up.....and the cycle continues. etc.
Also, there are the obvious gas flow suspects to check, open the petcock, and make sure it runs freely out the gas line.

[erectordale]

the fuel from the tank is not obstructed in any way not even a petcock on it it really flows and will let a pint thru in a few seconds the float is where it was set Iwill try too set this as there is no books on the 500 canam for guideance on this bing carb the 400 used near the same carb and i will try too set too that I really think its carb as well but who knows eventually i will find it

[BigGreenMachine]

dynamite please lol

LOL Take your time, you'll get it. Moshman has some great advice.

[Unclediezel]

Unless you carried that carb home on a feather pillow and took "Kitty" steps, it can easily get jarred out of whack ---even if it ran fine 10 minutes ago. ---take the bowl off and make sure the jets are clean and the float is set right.... It sounds like youre way too lean......Also----Carefully try running it with the fuel cap off...If the vents are plugged on the tank---or the carb--Fuel wont flow, and your bowl wont fill to capacity.

[erectordale]

I will call Bing tommorrow and have them send me a complete rebuild kit and the proper jets for this engine. these are the same as a canam 500 so they should have the starting point. I will have additional jets higher and lower sent as well so I can dial it in. was going too just buy a new carb too make sure that it was 100% but at 393.00 i will rebuild mine

[MTS]

The bing carbs are notorious For having Leakage Issuese with the rubber O-ring/seal in the choke assembly, causing it to be pretty much imposible to jet...

[erectordale]

well that could be a issue as it acts like a air leak

[BigGreenMachine]

Time to ebay a 40 mil Keihin or Mikuni, whatever your preference.

[erectordale]

the choke is leaking air and all the jets are the wrong size some larger some smaller all new ordered will be here by 10:00 am tommorrow I searched for hrs anhrs last night too get the correct jetting info woo hoo !! this should fix the puslating

[Mosh]

the 38 mm from the zilla acted the same I have a new crank coming tommorrow for this the one in there is ok just taking no chances as it was run with alky when i seal the bottom end what too use for sealant there is no gaskets in these rotax engines just seals yama bond for aluminum cases.it is available at any bike shop for like 11 bucks.the choke seals were sucking air? i thought that might be the case. seen that happen on banshees some times.

[jason 32]

yes !! it could be ive fixed some crazy *Edited**Edited**Edited**Edited*!! let me tell ya
but it sounds like a air leak are your floats in right ??? fuel pluged up??
pilot jet clogged??
main jet loose?
see if needle is in 2nd clip
air screw/ nomore than 2 and a half turns out from all the way seated(closed)

[erectordale]

OK I recieved the carb parts today just finished re-roofing the house now off too the barn for a carb rebuild will post as soon as I know Dale

[MTS]

Make sure your Seat for the needle float is in the carb TIGHT....cover the hole in the seat with your finger and blow though the fuel inlet to the carb to check for air-tight seal....

[erectordale]

all new and works well I had this started now no pulsing just races must have a air leave in the cases I will have this out and re assembled once again yamabond this time. think the sealant I used is not holding too the vaccum

[erectordale]

I have a tube of yamabond here and will be reinstalling in the morning Thanks John

[erectordale]

This thing is KIck my _ _ _ I have the motor all reassembled and installed broke the coil fixed and reinstalled have great spark, have fuel, and just getting intermitent back fires I tried retarding the timing but still nothing advancing still nothing. I must be missing something here. I don't have much kick left in my leg any input would be helpful (even gave it a shot of ether against my better judgement but tried anyway just got a backfire)

[slothminx]

You sure the coil you repaired isnt earthing out to the frame?! I had this when the coil on my Z went bad, intermittant backfires. I mounted the coil so that the body was away from the frame and it started right up.

The body of the coil had a tiny crack in it and the soark was jumping right out.

This pic is pre tearing the Z down.

http://img436.imageshack.us/img436/2089/dsc071562nx.jpg

[erectordale]

I checked that and it's not arcing at all has to be grounded good too have spark

[slothminx]

Have you got a spare coil you can rig up to try?

When the plug was out checking for a spark it had a good blue spark, only when the plug was in did it arc.

[erectordale]

this is the only coil I have thats why I repaired it the sprk is good and blue I truely think that its something other than spark but I've been wrong before ( kicking this mule over has got me wore out )

[slothminx]

How long have you been trying to start it? It might be completely flooded out now, I took almost half a cup of fuel out when mine went bad. That could be preventing her starting.

[erectordale]

over a hr no its not flooded the plug seems too be dry

[erectordale]

this ran but raced before i resealed the cases and added another new piston it raced so hard it fried the first piston bad also replaced main bearings and head gasket