Jump to content

Left Cylinder Not firing


Recommended Posts

Hey Guys,

 

I want to run something by ya'll. I'm scratching my head on this one. I rebuilt a banshee engine for a friend of mine. I rebuilt it from the ground up. New crank, fresh cylinders with a fresh bore. New Reed petals (V-Force 2 cages). Everything assmembled as smooth as a baby's bottom.

 

When we fire her up, she sputters out of the left cylinder. So I was thinking... Okay... No problem... It's something small.

 

So... Compression tested... 150lbs both cylinders. Leak down tested... Passed. Spark... Both plugs spark nicely. Carbs... Calibrated, synched... In fact... Took them off, swapped out a pair of new carbs, recalibrated, resynched. Plugs... Fresh, new. Correctly gapped. Timing. Adjustable timing plate... Check! 0 degrees of advance. Stator pickup aligned with the flywheel? CHECK!

 

So what do I do? I pulled the head. THe right side is running normal. The left side... Mostly wet... Appears to be misfiring more than it's running. Enough so that it fouls the plug pretty quickly. Where does it misfire? All RPM ranges... Including Idle.

 

I'm scratching my head at this point. The liklihood of a CD unit going "bad is relatively low... And if it did... I don't think it would affect just one cylinder.

 

Yes, all the obvious things are elimited. TORS removed. Choke tubes correct between the carbs. Carb slides in correctly... Heck I swapped out to a pair of 28mm flatslides that I had in my shop just to try it, with the same results. The intake boots are new, not leaking. Standard crossover tube...

 

I just don't know what I'm missing. I've been building 2-stroke engines for 15 years, and banshee engines for over 10. I've never had this sort of thing happen, where I didn't find something as the root cause.

 

 

So, guys... I ask ya'll... Start throwing stuff out there... Anything you can think of... I've gotta get to the bottom of this before I go crazy.

 

BG

Link to comment
Share on other sites

  • Replies 41
  • Created
  • Last Reply

Top Posters In This Topic

holy shit, i had the same prob on my buddy's 03 (did the same rebuild damn near)spitting out the right side. id say check ur air/fuel mix screw. i think that was the prob or just do what we did and get the single carb, but it is a carb prob

Link to comment
Share on other sites

if it spitting gas, that carb is out of wack, and needs to be tinkered with. i put a 400 crank in my buddy's 03 (1st banshee i were worked on), had a the same prob, took it to the guy who did the 1st top end rebuild on it (this is highly recommended aorund harrisonville to rebuild banshees, he just hadnt put a crank in one, chris marteny[sp] if anyone knows him) messed with the carb and the 'shee ran like a striped ass ape. only prob was it burned up a tank of gas in about 3hr so he go the single carb. we thought it was elec. too but it was dumping too much gas and not letting it fire. id say wait til tomorrow and see what everyone else say. im jsut telling what i have seen

Link to comment
Share on other sites

Good Thoughts,

 

But swapped out an entirely new set of cages, same result.

 

Getting spark, both plugs.

 

Replaced spark plugs, several times. ;-)

 

BG

 

 

I had a similar problem, swap the reed cages from one cylinder to the other and see if the problem follows or put a different set on to check it out. Also buy a spark tester, they are only like 8 bucks. One other thing see if the top of the spark plug is unscrewing, had that happen to.

461720[/snapback]

Link to comment
Share on other sites

Have you tried looking inside the pipes? A buddy of mine had just rebuilt his shee and it had worked perfect in his driveway. Got to the dunes and was only running on the right side. Turns out he forgot to remove the paper towels that he had shoved into the exhaust ports to keep debris out. Right one was still in the expansion chamber, left one had made it up to the coupling and was lodged there.

 

 

Other than that, try swapping plug wires, then reeds, etc...

Link to comment
Share on other sites

Make sure there is a good ground on the stator with no paint etc. I have seen stators do that for sure. Tap the CDI or try and change it out with a known good unit.

Link to comment
Share on other sites

Like wall rat said swap the plug wires and see if your problem switches cylinders. If it does then it is electrical. Mine did the same thing would fire on both plugs when checked, but when ran would lay down on the right side. I changed my coil and flap brushed the frame where the coil bolted on and where the ground wire whent under the regulator. I think the grounding was my issue. Unlikely a coil goes bad.

Might even eliminate the key switch if you havent already. Just unplug it from the harness and run a jumper wire across the two on your harness plug.

Maybe check the gap between the pickup coil and the flywheel. should be between .015 and .020 i believe.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...