Strm Trpr

Did you try taking your filter off to see if it clears up? Also, when you start your bike cold, do you use your choke? And, is the tube that connects the choke of the left carb to the right carb installed?

check compression? Is the "back-fire" noise when you're getting on it going thru the gears, or on decel? And have you properly done a plug chop?

Here's a Clymers Manual. http://www.farmandsandtoys.com/partdetail.asp?partid=172 Just like said above, the reed cages are between the cylinders and the carb intake boots. Before you go tearing into it, you can remove the left carb and let it hang over the frame. Shine a flashlight in thru the intake boot and look at the reed pedals. Chances are the left cylinder reed pedal(s) are broken. If the reed cages are stock, then you can get a set of these and be on your way cheap. http://www.ebay.com/itm/Boyesen-Power-Reeds-YAMAHA-YFZ350-BANSHEE-1987-2006-REED-/400570100168 Since you have a 4mil stroker and these are good for some pretty decent horsepower gains over the V-Force 3's, you might want to give these a shot. They're not as cheap as just swapping out the reed pedals on stock cages, but you'll feel the difference over stock, guaranteed... http://www.ebay.com/itm/BRAND-NEW-V-FORCE-4-REED-VALVE-SYSTEM-BANSHEE-87-06-/121159970663?pt=Motorcycles_Parts_Accessories&hash=item1c35b26f67&vxp=mtr

Try swapping ignition wires from cyl to cyl and see if the popping moves from right to left. Check the air gap of the pick up coil on the stator. It should be .019".

That guy looks baked...

What octane fuel? What oil and mixing ratio? And what elevation?

Have you checked your reed pedals for damage? What do your plugs look like? What mods do you have? Is your exhaust sealed throughout? Have you done a plug chop?

You can do a 421 Serval or a 421 Cub. A 421 Cub is a ported Serval. My choices would be a 421 Serval Dune Ported with Shearer InFrames by Redline, FAST or HJR. Redline is in OK at the BHQ ride as is probably FAST. ^^^ You'll have to wait months to get your motor back, but word around the campfire is they are worth the wait. Kevin at HJR is home and turns around motors is two weeks or less, guaranteed... Wildcard is another option.

More specs and pics of the condition of the pro-taper bars please? Are the 1-1/8"?

So you plugged off both exhaust flanges and one intake boot and pressurized the other intake boot and your leakdown results were good? If so, then I'd start looking into cleaning the carbs and jets really good and also make sure your floats are set correctly. What carbs and jets are you currently running? And make sure fuel flow is not obstructed in any way.

Good call on the gas tank dowels.

What oil and mixing ratio are you using? Remember, less oil means more fuel to burn... What needles are you running? I'd move the clip to the middle just to be safe. You are trying to dial in your top end... Do a plug chop!

You still have the stock carbs? Got Pics?

2013 texting acronyms page 4 http://www.abbreviations.com/acronyms/SMS/4 This is one is great... FMLTWIA

I know your post is about 3 wks old, but since then Redline Racing built a stk cyl 4mil dune port running stk carbs, cpi inframes vf2's on race gas and put down 83hp and 44ft*lbs of torque.http://bansheehq.com/forums/index.php?showtopic=169881

Stock banshee gearing is 14/41.

I highly recommend both of these tools. I have one of these to tune my idle. http://www.ebay.com/itm/New-Hour-meter-Tachometer-2-4-Stroke-Small-Engine-Spark-For-Motorcycle-Boat-Bike-/181189333163?pt=LH_DefaultDomain_0&hash=item2a2fb9d0ab And, I haz one of these to synchronize my carbs at idle and at 5500rpms. http://www.farmandsandtoys.com/partdetail.asp?partid=59

What mods do you have? People run the FAST clutch and springs in 421cc 4mil strokers all day long. I have one in my 87, but it's still stock. This winter it will be getting a 4mil stroker dune port stock cylinder treatment. That same clutch has about 1 HR of ride time on it and it will go in the new motor.

Agreed! Ahhh, that's some serious heat build-up then.

So, crankcase pressure is leaking into the transmission and over pressurizing the trans and consequentally blowing the front sprocket seal out?

Man, that's a whole lotta paddle right there! Wish I had the power to turn those! Bump for a killer deal!

RMATV sells OEM parts now, and they have it in stock.

The alignment of the arrows is for the pancake bearing set screw, not the cable adjustment at the perch. When aligning the arrows, the clutch cable end shouldn't even be in the lever, per spec.

Wait, is this a joke? How can you have over 1000 posts and not know how to jet a stock motor? Do you have idle screws and is your idle in spec between 1400-1500 rpms? The off idle hesitation is your air screws, and possibly carbs not in sync.

Start your own thread and/or search.