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- New owner - One Cylinder Weak Spark -


KozyHeat

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if u got to throw a crank at it dude.. just go 4 mill... they sell cyinders here all the time for around 500 bucks sllready ported for 4 mill. ull never go back... i think u should keep it too...i played around stock motor for 2 years.im very heavy at 260lbs and need motor to push/pull me down the dunes.. i went with a 4mill... wishin i went with a 10 mill supercub or somehting of that nature.. u get tired of stock banshees qwick

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4mil you say? I would if I had pipes. There is a set of fmf's ? for $110 shipped in the buy/sell.

I will keep it stock - Honestly i haven't ridden many atv's so its all new to me - A twin 350 2-stroke is probably above my head a little bit. I want to squeeze out the most power on the stock cylinders because its out of the machine right now ready for a rebuild again. Everyone was impressed with my Banshee when it was running - Why not improve the stock cylinder characteristics and do it again except this time it will run all day.

 

Not going to sell it either. Definitely got to put it through its paces before I would feel comfortable selling it anyway. Glad it blew up on me and not after I sold it. Its really not a bad fix.

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what country do you live in??

 

and SEEE I TOLD YOU TO SPLIT THE WHOLE F'N MOTOR!

 

no way an 87-89 case with the OEM crank would survive a new top end.  even a piston to wall clearance debacle like you put back together....

 

yes weld the damn crankshaft...  if a shop will rebuild it with rods well go ahead and do it.  if the lower rod bearing exploded it probably trashed the big pin.  if it did you cannot replace that on a oem crank.  you either have to get new webbs OR buy a complete new crank assembly.  i'd suggest a NEW hot rods oem stroke crank.   you tried saving $$ and now you have a trashed motor with new trashed pistons in it...  ye ha

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what country do you live in??

 

and SEEE I TOLD YOU TO SPLIT THE WHOLE F'N MOTOR!

 

no way an 87-89 case with the OEM crank would survive a new top end.  even a piston to wall clearance debacle like you put back together....

 

yes weld the damn crankshaft...  if a shop will rebuild it with rods well go ahead and do it.  if the lower rod bearing exploded it probably trashed the big pin.  if it did you cannot replace that on a oem crank.  you either have to get new webbs OR buy a complete new crank assembly.  i'd suggest a NEW hot rods oem stroke crank.   you tried saving $$ and now you have a trashed motor with new trashed pistons in it...  ye ha

 

rebuild the motor. you can screw with all the external stuff all you want. its not going to run better.. yank it split it redo everything inside. then take the good motor, and fix everything on the outside. your comp is way to low..

 

You were totally right Camatv! My fault but I AM learning and having pleanty of fun. Vertically split cases are new to me and now that I realize they split within an hour I think I will do it more often. I only put new rings on the existing pistons but i was slightly mislead with re-ringing. I asked a shop about it and thought they knew how to measure correctly with a bore gauge and would take care of it.

 

I called up a shop and they said they can weld the pins but "typically in a stock application they shouldn't rotate so I don't think your going to need it."

 

Is the crank pin is part of the inner web then? No doubt my pin is bad on the one side then - The chunks of the washers and rollers are everywhere. I thought the kits came with new pins but that must be for the aftermarkets. E.g. a stock stroke Wiseco connecting rod kit would fit on a Stock Banshee crank but you don't use the pins in that application? it is supposed to be for an aftermarket wiseco stock crank?

 

I may need a left hand inner web :\

 

News to me! Thank you for trying to help me in November Cama. Don't give up on me!

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the oem cranks you have to buy new rebuildable style inner webb's.  to do an oem crank correctley takes some real skill.  you have to have them phased absolutely DEAD ON>  if its off by 2 degree's your timing will be all over the place  and the bike will have issues..  

 

back in the way back days you could buy IMS inner webbs and rebuild a stocker crank.  in all reality.  you can purchase  a NEW oemstyle hotrods crank for about 350ish?  probably less than the labor, rod kits, and rebuildable center sections you would need..  used to be the labor alone was in the 100-125ish range .. since i do my own cransk  i can usually redo a stocker for pretty reasonable.  plus  i can take a bunch of junk ones apart  and after specing a ton of parts get one together that meets OEM specs pretty well  usually with just using new lower bearings and thrust washers etc.  but this takes time and a lot of specialty tools  some of which i actually built myself..  if your motor has porting  or really anything over pipes.  it needs the crank welded..  

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Not much for webs out there. Plus then I still need bearings + lab seal + labor.

 

Probably going to go with a new crank even though its the most expensive option but I will trust the components.

 

 

I answered my own question about the transfer porting.

 

 


 

 

This is what I call the lower transfer ports. You

want to match the port to the case and the gasket. Making them larger than the
case or the gasket at the bottom will not help you, it will cause unwanted
turbulence.

 

 

Found the answer to my question in the 

Banshee Porting DIY - thread pdf

page 16

 

https://workspaces.acrobat.com/?d=5eNaltKS9ZOTGrp0FI7cGA give it pleanty of time to load
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Oah yeah, first picture shows how I marked the cylinder but the marker went under the paper/bled through so I wiped it off and redid it.

 

Also I left room before the transfer was matched all the way so that I can sand / cut like crazy to get this more smooth.

 

Second and third photo is how I modded my file. Just a cheap set from Home Depot I got a long time ago. I need to cut the smooth tip off so its just one file.  I could see having a whole set of files would be nice. This one is a little rough.

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My pistons are going to be Namura ( cast ) 'high-compression' pistons. That term hurts to use... but anyway I had a stupid conservative squishband before. With these high-compression pistons are they going to sink more into the head giving me a nice squish less than ~.61mm? Do they move the piston pin or do they have a taller piston?

 

I am trying to determine gearing as well. I have long dirt roads.

 

Check it out.

Tire setup in the rear is 18 x 10 x 10

How silly would it be to run 16/38 gearing?  Would it be un-ridable and slow? 

 

I want top speed but that gearing sounds to be a little excessive and will not perform low end.

I do however like to go out and do some pulls though, so maybe its alright. I hope to take off at an aggressive pace and specifically faster than Yamaha Warrior.

 

geard.jpg

 

Other than that - Its going okay on the rebuild so far. Don't know about you guys but for me it takes time.

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T for top and b for bottom gap

 

You need the bottom ring gapped larger... 

 

Bore and pistons look really nice though - going to fix the ring end gap

 

finish Port matching the cases ( these new cylinders match really close)

Get my crank

new gaskets on the case and seals, crank bearings, seal it up well.

pressure and vac test it

^most important step

 

should be ready to rip yet again.

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I believe you all have seen many failures and I also found some broken skirts and pistons specifically with Namura. The stock pistons are cast, these are cheaper cast pistons from an island off of China's coast, Taiwan.

 

Maybe I'm doing it wrong but look at these numbers below... there is FAR to many people who just throw some pistons in their Banshee and don't even take the time to dress the piston rings...

 

Would it be fair to say that if I threw these in with

a) Too small of gaps

B) bottom ring gapped LESS than the top ring?

 

it would blow up? 

 

 

Glad you asked. I had that written down incorrectly on my photo because I am an idiot.

 

Are you measuring the ring gap in mm or inches? Take another toke and assess the situation.

 

I am measuring in Inches. I just forgot a ZERO.. or two

 

Right cylinder -  top ring .008" / .203mm - bottom .007" /  .178mm  | Manual recommended - 0.012 - 0.018in

Left cylinder - top ring  .009" / .2286mm - bottom .0075" / .1905mm | Manual recommended 0.012 - 0.018in

 

using the stats from the service manual

bansheegaps.jpg

 

or calculating it based on general guidelines

 

Bore - 64.69mm / 2.54685"

multiplied by a recommended .005" per inch it comes out to about .012" 

 

So my top rings are at .008" and .009" - That is smaller than .012" correct? I don't have that backwards do I?

I am going to get another set of feeler gauges.

 

Im running a stock cylinder setup, nothing aftermarket. A little more porting than I would have liked for my stock pipes. A pretty big exhaust and some eyebrows, and cleaned up the bump in the intake. Nothing done to the transfers.

 

Hopefully I am just wrong though and have messed up gauges / being an idiot.

 

On any bigger of a budget I would have gone with forged pistons, and a fresh bore on my cylinders. I couldn't do that this time. The pro-lites definitely held up to my crank wobbling around and spitting out needle bearings everywhere.

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