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Jettng the Passion Stroker?


cjm02ram

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I am not saying the ports don't work. I am just wondering if those ports are the reason we have been having a hard time jetting the midrange. M aybe at a certain RPM, we get this situation and it can be jetted around. My PV motor masks it quite a bit, but I know others have had this issue.

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well im not surte that the backcountry spit -back theory has much of any merit considering cheetah cubs have hellacious boysen ports and would certainly cause alot of this spit back phenomena much moreso than jims added boysens ever would in his 12 port engines he does .

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Yep, from Patriot Racing. I don't want anyone to take this as a bash to Jim's motors, it's not that at all.

 

I was just wondering if the ports/spitback are what is causing us to have a hard time jetting the midrange on this thing?

 

Maybe it's the nature of the beast and something I'll just learn to live with. If so, fine, I couldn't be happier with my motor.

 

I just thought this may in some way tie into these motors and thought it was worth posting.

 

Anyone that want to learn way more than I can ever comprehend should check out that thread on PS about crank case pressure.

 

I figured enough of us have these motors on here to warrant this coming back from the grave.

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isnt back country dan wade?  if so, id give anything he says a bout a banshee some merit. 

 

not saying he's god, but damn close.

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yeah he knows a ton about 2 stroke engines ,no doubt ,does this mean hes never worng?i m jus t saying the cub boysens are easily twice the size of any boysen yo u could do to stock cylinders and theres really no problem with them so why would adding baby ones i nstock jugs create al l this reverse turbulence ,just my observation o n the subject

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I'm resurecting an old thread after reading some interesting, yet confusing to information about crank case volumes.

 

I know there were some issues getting these motors jetted right, the question to me is why?  Was it merely a jetting issues, was there something going on in the motor that we didn't account for?  There is a discussion on PS about crank case vloumes, that made something click.

 

Backcountry brought up something about Boyesen ports spitting back into the intake track that might have some merit to these motors.  For those of you that don't know, he is "one" of the most knowledgable builders of Banshee motors I have talked to.

 

Hopefully Jim can chime in here and at least dispell any ideas I have pertaining to this debate.

The above comment was liberated from PS.

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This was not just a rumor or bs. I told a few guys about this when this post first showed up and gee if you were wondering where I got the info from... yes it was from Dan Wade. We discussed the 12 port and potential fixes for some of the jetting issues. I showed him port maps with port numbers and pictures of all the ports. Reed spacers did help the couple guys with jims port work in my group. Take the advice for what it's worth :shootself:

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I for one, love the way my motor runs. I had issues with jetting, but I refuse to run anything bigger than a 32. I have mine pretty close and would probably have to get it on a dyno to dial it in anymore.

 

I didn't want this to turn into this, I just thought we could use the information to get these things to run the way they should. Oh well, BHQ definately has a knack of doing these kinds of things.

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The bike has all new seals and gaskets.  There was no other damage to the piston other than the melting of the center.  No exhaust port sise damage.

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Maybe one of the new seals gaskets, or your intake could have an air leak though?

 

Detonating would typicaly pit the head and piston prety bad, just burning a hole in it does not sound like it is detonating, especialy since it is just one side. Have you checked your compression?

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I dont ride it long enough for it to do major damage...I can tell when it detonates. You can tell when you are melting a piston and a plug. From my experience an airleak usually melts the exhaust port side of the piston.

 

Yes I have checked my compression. I am running 115 octane with 19cc domes. Its a brand new motor. Complete build by Jom. He checked all the seals again when he rebuilt it a second time. I've checked for airleaks on the manifold numerous times. It has to be electrical.

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set your dyna on curve 1 and see how it acts.

make sure your plate is at zero.

 

then you could try curve 2 and look at your plugs.

 

you sound like me, nmotion programmed my box but didnt tell me what curve i have or how much timing. i need to get it reviewed and see what they put on mine. i run curve 2.

 

who knows

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The "Boyesen" ports in jims 12 port are much larger than the typical added boyesen. He welds the outside of the cylinders up and cuts thru the original casting into the weld. I'm not saying they are larger than a set of cub boyesens, cause I don't really recall how large mine were...its been a while. But, I am saying that its worth a try to add some larger reed spacers.

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  But, I am saying that its worth a try to add some larger reed spacers.

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yeah worth a shot , iknow on the old 87 big reed box 500ccquadracers a reed spacer adds alot of additional power on a dyno because the boyseens o n that setup are huge and reed valve sits in preety far as it does on a banshee .sometimes an increase in cran k voulme is a good thing and helps direct the incoming charge into the transfers/boyseens better when the reeds are sat back into the valve some :bolt:

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