02-16-2009, 01:56 PM
ok so thought i'd dig this old one up and post here for like minded premix fanatix, glad it was still there on QT so its got some input from other members, mostly JJ, and was written from my own knowledge, so dont quote me or blame me for broken enjins, rods, etc etc 
enjoy........
ok so u got ur shee, ur pride n joy, got all ur new kit etc.
u hit the track, open her up and she pulls and screams like the beech(well under those popcorn pipes) she is, wanting u to hammer her more n more, the rush u get is exhilarating, the feel of it is like no other.......
sheer heaven........
........... then sum chop on another shee overtakes u like u looking for parking! u feign running out of juice and limp away, utterly distraught at wot jus happened....... how? why?
dont fret, its wot pretty much happens to any banshee owner at sum point in their life. u think ur ride is the meanest fastest shee out there and theres another shee jus waiting to pounce out the woodwork and show u differently, what does that leave u with?
i'm glad u asked........
pipes are of personal pref - FMF, Toomey, Pro Circuit, Bosson, etc
same goes for Air Filters - foam or fibre, lets not get started on k&n
Needles and Jetting - important cos u now flowing more air in and out the motor, coupled with a dyno and ur bound to be spot on to get most bang for buck out ur pipes n filter
Cylinder Porting - best left to the okes in the know, unfortunately prev experience has left me with the thought that there's more okes who think they know....... rule of thumb is that if the place cant tell u wot they doing and why they do it like that, then leave, rite there n then. mcdizzy and the 2stroke god himself eric gorr have awesome notes, calcs and formulae (sum too heavy for my brain tho) on how to do any porting from basic to extreme. jus go with the flow....... LOL
Milled Head - called skimming also, pretty much the most overlooked part of any 2stroke engine, coupled with different size combustion chamber domes makes for a lethal combo. get a guy who knows wot he's doing and u'll feel this mod in the seat of ur pants.
bigger isnt necessarily always better (i paid 20k to find that out) racing machines jus need refinement (juxtaposition.... racing.... refinement.... lol)
rather than modifying what was factory built, put ur trust in those lil jap okes who do actually know a thing or two or twelve about these awesome machines.
PART DEUX:
rite, this part will talk bout sum more bolt on mods as well as sum internal engine work: here goes
reed valves = these lil one way flappers operate at an amazing rate, varying from steel to fibre to carbon fibre. so many variables can make or break this mod (literally) - surface area size, resonance and stopper position cood make the reed flutter and break (fibre = ok, steel = OMG). mods to the reed cage to allow more flow have been seen, extreme cases of cutting out the centre ribs and using one huge piece to cover the gap are widely used in WFO throttle scenarios like drag racing. reed petal thickness and material can make for better rev response and improve bottom end acceleration. booysen came out with a two stage flapper that revolutionised the 80's (i think) and paved the way for vforce to make there pyramid shaped blocks increasing surface are without compromising petal integrity
coolheads - aftermarket heads that have more water channels to allow better cooling, some also come with interchangeabel domes for higher compression, nice bling for ur bike and some elimiate the need for head gaskets as it runs o-rings
personally the stock hed works jus fine once skimmed
sparkplugs!!! drat almost forgot!!! chuck the std BR8ES and replace with 9 heat range, they'll run cooler on the track, the 8's r used to burn the oil at low rpm if i'm not mistaken
degree keys - k first off i dunno lots bout this, but vito's sell a degree key and check out any sig mods of overseas shee owners and ur bound to find that in there. basically it shifts ur flywheel positioning forwardby a few degress, think its like 3 or 4, in turn advancing ur ignition timing of ur engine.....
i still need clarity on this, will find out more info promise
ignition plates - basically the plate the ignition coils sit on underneath the flywheel, its set with std holes on the shee, aftermarket ones make it possible to adjust in a circular motion to advance or retard ignition timing, does same job of degree key, only more flexible ito setting in increments
plates? who sed plates? aaaaah, clutch plates!!! with all this added power u gonna need stronger plates and springs, heck even a clutch basket! TUSK offers complete packages as far as i know and there's pretty much a plethora of makes and materials out there to suit ur need
more power = more speed, one of the things i'd reccomend changing on the shee is its front brakes, simple single pot calipers jus dont cut it lap after lap and fade away like the sun. the yfz 4 pot jobs fronts jus bolt on....... where's my mid year bonus..... :-)
the above is my own personal opinion and i in no way accept any harm done to u by doing any mods, be it arm yanking or massive induced smiles
JJ reply:
“Nice topic
There's always another shee faster than your own.
Quote:
Milled Head - called skimming also, pretty much the most overlooked part of any 2stroke engine, coupled with different size combustion chamber domes makes for a lethal combo. get a guy who knows wot he's doing and u'll feel this mod in the seat of ur pants.
Definately one of the easiest and worthwhile mods on a banshee.
Especially for the high altitude oaks living in JHB or even Alberton. You can safely machine 0.75mm off the gasket sealing face of your cylinderhead and still run pump fuel.
Quote:
coolheads - aftermarket heads that have more water channels to allow better cooling, some also come with interchangeabel domes for higher compression, nie bling for ur bike and some elimiate the need for head gaskets as it runs o-rings
personally the stock hed works jus fine once skimmed
I have PD coolhead with 20cc and 21cc domes, eye candy only, not worth the price IMHO and no benefit in cooling. (My bike has a temp gauge). Go for a milled head to keep things stock looking.
Quote:
Needles and Jetting - important cos u now flowing more air in and out the motor, coupled with a dyno and ur bound to be spot on to get most bang for buck out ur pipes n filter
Sensitive issue, I don't see the need for a "jet kit".
The rewards for experimenting with different main jets and needles/positions on a banshee are huge.
My shee came stock with a handfull of useless small main jets as spare. When I bought the bike I immediately traded these for a pair of 300's, 310's and 320's at Perry Yamaha, a bit of research gave me the ballpark numbers for a shee with FMF's and K&N, no lid.
Now I only use the 310's and the 320's depending on altitude and weather. I like running a bit on the rich side of things for safety sake.
BTW, none of the dyno experts have ever been able to give me the correct A/F ratio for a banshee at full throttle...
Quote:
ignition plates - basically the plate the ignition coils sit on underneath the flywheel, its set with std holes on the shee, aftermarket ones make it possible to adjust in a circular motion to advance or retard ignition timing, does same job of degree key, only more flexible ito setting in increments
My shee has a PD adjustable stator plate set at +4, looks nice, but hidden beneath the cover. Should've done a bit more research before I bought it. The timing can easly be adjusted in 3 ways:
Degree key, shifting the relative position of the pick-up coil, or slotting the stock stator plate mounting holes (my personal favourate)
Degree keys have taken a bit of heat on some other forums, apparently some of these have sheared. The argument here (and I agree) is that the key only serves to index the flywheel to the crank, nothing else, what keeps the flywheel on the crank is the taper fit between the two. So obviously the keys that have sheared interfered with the fit between the two tapers resulting in a loose flywheel.
Maybe master Goigen can do a bit of research on lightened flywheels and their benefits/disadvantages.
Another good topic would be on the top ten most useless mods on a shee.
ok uncle JJ, seeing that u asked ever so nicely, i have spent countless unproductive work hours researching *
*this may or may not be true
Flywheels:
"A lightened flywheel allows the engine to rev quicker and harder, it will mean explosive holeshots. However this mod is not recommended for trail riders or "larger" riders (sorry Oz)." - pretty much means less unsprung weight to spin up, response is qwicker but will lag to rev up under heavy load.
think of 2 balls of different weight, u tie the light one to a string attached to a stick, and swing it round, see how qwik it spins up and how qwik it slows down.
now take the heavier one and do the same, feel how much more effort it takes to spin up, but once spinning maintains inertia
(my science teacher will be so proud of me now)
Clutch mod: lock-out/lock-up
"As the horsepower is increased, keeping the clutch assembly from slipping is a daunting task. There is a limit to the spring tension available and the forearm strength required to pull the clutch lever!!! A lock-out clutch assembly uses cam arms that can have weight adjusted for the amount of clamping pressure. The lock-out assembly uses centrifugal force to apply greater clamping pressure against the clutch pack as the RPM increases. More RPM, more clamp force = zero clutch slippage. Can be adjusted to work to shift under throttle but still apply many more times the clamping force against the clutch pack. Get the horsepower to the ground!" IMHO opinion its a nice to have/pretty to look at unless u running over 60ponies, it wood jus fascinate me all the time and i'd lose focus in a race, always checking the oil splash round and the clutch basket spinning up
Crankshaft:
not really a mod but prolly another item to go untouched wen modifying ur shee. have it recon'd new bearings, spacers and balanced n ur a for away for more hours of fun. another option is to have it trued n welded
Gear cutting:
yamaha do not build crappy gearboxes, and the only banshee box i have ever heard to fail was quadman's ballistic atv shee, then again a stock shee box used in motard racing conditions being hammered for almost 2 seasons (correct me if i'm wrong) at well over the 60hp mark never seeing a day under 7000rpm.....
str8 cut gears can handle more power transfer but also increase noise/whine, some like it sum dont.
boost bottle:
the jury is still undecided here, some claim it works some claim its shiny and other blame it for stuffing up the intake boots under vibration (which causes air leaks and lean conditions while running)
the theory sounds all fancy smanshy and yamaha have used it on two wheelers for years, mus b a reason why the jap mach's didnt chuck it on the shee
thinking of so many other things but gotta get back to work
JJ reply:
Nice analogy hehehe, now even I can understand it.
I would like to add my take on this.
2-stroke twin, with cranks at 180Deg, fires every half turn of the crank.
4-stroke single, fires every 2 turns of the crank...
IMO the flywheel on the banshee is only there to provide the magnetism for the coils and to trigger the pick-up coil. There are even aftermarket ignitions available that don't use the flywheel at all...
I've ridden a well sorted banshee with a lightened flywheel and I could definately not feel any lag, it just revved nice and crisp.
This is a worthwhile and cheap mod that's easy to do on a lathe machine, you only need a flywheel puller (there's one in Torqueshop) and access to a lathe. Material can be removed from the OD of the flywheel on both sides of the pick-up triggers and on the face of the flywheel outside of the rivets for the magnets.
10 Points to abide to or not...
1) When setting up the f/w in the chuck of the lathe, check the run-out using the inside taper bore that meets with the end of the crank as a reference. Better still, replicate the taper end of the crank by machining a mandrel for the f/w to bolt onto the chuck.
This will prevent excessive run-out and vibration when the f/w is spinning on the crank.
2) Don't cut of the 2 triggers for the pick-up coil.
3) Don't use a jaw puller to remove the flywheel, use a flywheel puller like the one for sale in th QT shop.
4) Do not drop or hammer the f/w, the magnets can loose their magnetism.
5) Do not machine off too much from the outside diameter, if the material is too thin, the flywheel will break. There's plenty material available there, just don't get greedy.
6) Don't cut off the rivets.
7) Try to radius the transitions of all cuts to prevent stress raisers. IOW, don't leave 90Deg corners at the end of your cuts.
8) With the flywheel off, you might as well use the aerosol type spray coating to paint on the electric windings of the stator coils to improve the insulation, not expensive and can be bought from any electrical industrial supplier.
9) You might as well slot the holes for the stator plate as mentioned in the pervious chapters.
10) Don't blame me. (Flywheels are expensive)
enjoy........
ok so u got ur shee, ur pride n joy, got all ur new kit etc.
u hit the track, open her up and she pulls and screams like the beech(well under those popcorn pipes) she is, wanting u to hammer her more n more, the rush u get is exhilarating, the feel of it is like no other.......
sheer heaven........
........... then sum chop on another shee overtakes u like u looking for parking! u feign running out of juice and limp away, utterly distraught at wot jus happened....... how? why?
dont fret, its wot pretty much happens to any banshee owner at sum point in their life. u think ur ride is the meanest fastest shee out there and theres another shee jus waiting to pounce out the woodwork and show u differently, what does that leave u with?
i'm glad u asked........
pipes are of personal pref - FMF, Toomey, Pro Circuit, Bosson, etc
same goes for Air Filters - foam or fibre, lets not get started on k&n
Needles and Jetting - important cos u now flowing more air in and out the motor, coupled with a dyno and ur bound to be spot on to get most bang for buck out ur pipes n filter
Cylinder Porting - best left to the okes in the know, unfortunately prev experience has left me with the thought that there's more okes who think they know....... rule of thumb is that if the place cant tell u wot they doing and why they do it like that, then leave, rite there n then. mcdizzy and the 2stroke god himself eric gorr have awesome notes, calcs and formulae (sum too heavy for my brain tho) on how to do any porting from basic to extreme. jus go with the flow....... LOL
Milled Head - called skimming also, pretty much the most overlooked part of any 2stroke engine, coupled with different size combustion chamber domes makes for a lethal combo. get a guy who knows wot he's doing and u'll feel this mod in the seat of ur pants.
bigger isnt necessarily always better (i paid 20k to find that out) racing machines jus need refinement (juxtaposition.... racing.... refinement.... lol)
rather than modifying what was factory built, put ur trust in those lil jap okes who do actually know a thing or two or twelve about these awesome machines.
PART DEUX:
rite, this part will talk bout sum more bolt on mods as well as sum internal engine work: here goes
reed valves = these lil one way flappers operate at an amazing rate, varying from steel to fibre to carbon fibre. so many variables can make or break this mod (literally) - surface area size, resonance and stopper position cood make the reed flutter and break (fibre = ok, steel = OMG). mods to the reed cage to allow more flow have been seen, extreme cases of cutting out the centre ribs and using one huge piece to cover the gap are widely used in WFO throttle scenarios like drag racing. reed petal thickness and material can make for better rev response and improve bottom end acceleration. booysen came out with a two stage flapper that revolutionised the 80's (i think) and paved the way for vforce to make there pyramid shaped blocks increasing surface are without compromising petal integrity
coolheads - aftermarket heads that have more water channels to allow better cooling, some also come with interchangeabel domes for higher compression, nice bling for ur bike and some elimiate the need for head gaskets as it runs o-rings
personally the stock hed works jus fine once skimmed
sparkplugs!!! drat almost forgot!!! chuck the std BR8ES and replace with 9 heat range, they'll run cooler on the track, the 8's r used to burn the oil at low rpm if i'm not mistaken
degree keys - k first off i dunno lots bout this, but vito's sell a degree key and check out any sig mods of overseas shee owners and ur bound to find that in there. basically it shifts ur flywheel positioning forwardby a few degress, think its like 3 or 4, in turn advancing ur ignition timing of ur engine.....
i still need clarity on this, will find out more info promise
ignition plates - basically the plate the ignition coils sit on underneath the flywheel, its set with std holes on the shee, aftermarket ones make it possible to adjust in a circular motion to advance or retard ignition timing, does same job of degree key, only more flexible ito setting in increments
plates? who sed plates? aaaaah, clutch plates!!! with all this added power u gonna need stronger plates and springs, heck even a clutch basket! TUSK offers complete packages as far as i know and there's pretty much a plethora of makes and materials out there to suit ur need
more power = more speed, one of the things i'd reccomend changing on the shee is its front brakes, simple single pot calipers jus dont cut it lap after lap and fade away like the sun. the yfz 4 pot jobs fronts jus bolt on....... where's my mid year bonus..... :-)
the above is my own personal opinion and i in no way accept any harm done to u by doing any mods, be it arm yanking or massive induced smiles
JJ reply:
“Nice topic
There's always another shee faster than your own.
Quote:
Milled Head - called skimming also, pretty much the most overlooked part of any 2stroke engine, coupled with different size combustion chamber domes makes for a lethal combo. get a guy who knows wot he's doing and u'll feel this mod in the seat of ur pants.
Definately one of the easiest and worthwhile mods on a banshee.
Especially for the high altitude oaks living in JHB or even Alberton. You can safely machine 0.75mm off the gasket sealing face of your cylinderhead and still run pump fuel.
Quote:
coolheads - aftermarket heads that have more water channels to allow better cooling, some also come with interchangeabel domes for higher compression, nie bling for ur bike and some elimiate the need for head gaskets as it runs o-rings
personally the stock hed works jus fine once skimmed
I have PD coolhead with 20cc and 21cc domes, eye candy only, not worth the price IMHO and no benefit in cooling. (My bike has a temp gauge). Go for a milled head to keep things stock looking.
Quote:
Needles and Jetting - important cos u now flowing more air in and out the motor, coupled with a dyno and ur bound to be spot on to get most bang for buck out ur pipes n filter
Sensitive issue, I don't see the need for a "jet kit".
The rewards for experimenting with different main jets and needles/positions on a banshee are huge.
My shee came stock with a handfull of useless small main jets as spare. When I bought the bike I immediately traded these for a pair of 300's, 310's and 320's at Perry Yamaha, a bit of research gave me the ballpark numbers for a shee with FMF's and K&N, no lid.
Now I only use the 310's and the 320's depending on altitude and weather. I like running a bit on the rich side of things for safety sake.
BTW, none of the dyno experts have ever been able to give me the correct A/F ratio for a banshee at full throttle...
Quote:
ignition plates - basically the plate the ignition coils sit on underneath the flywheel, its set with std holes on the shee, aftermarket ones make it possible to adjust in a circular motion to advance or retard ignition timing, does same job of degree key, only more flexible ito setting in increments
My shee has a PD adjustable stator plate set at +4, looks nice, but hidden beneath the cover. Should've done a bit more research before I bought it. The timing can easly be adjusted in 3 ways:
Degree key, shifting the relative position of the pick-up coil, or slotting the stock stator plate mounting holes (my personal favourate)
Degree keys have taken a bit of heat on some other forums, apparently some of these have sheared. The argument here (and I agree) is that the key only serves to index the flywheel to the crank, nothing else, what keeps the flywheel on the crank is the taper fit between the two. So obviously the keys that have sheared interfered with the fit between the two tapers resulting in a loose flywheel.
Maybe master Goigen can do a bit of research on lightened flywheels and their benefits/disadvantages.
Another good topic would be on the top ten most useless mods on a shee.
ok uncle JJ, seeing that u asked ever so nicely, i have spent countless unproductive work hours researching *
*this may or may not be true
Flywheels:
"A lightened flywheel allows the engine to rev quicker and harder, it will mean explosive holeshots. However this mod is not recommended for trail riders or "larger" riders (sorry Oz)." - pretty much means less unsprung weight to spin up, response is qwicker but will lag to rev up under heavy load.
think of 2 balls of different weight, u tie the light one to a string attached to a stick, and swing it round, see how qwik it spins up and how qwik it slows down.
now take the heavier one and do the same, feel how much more effort it takes to spin up, but once spinning maintains inertia
(my science teacher will be so proud of me now)
Clutch mod: lock-out/lock-up
"As the horsepower is increased, keeping the clutch assembly from slipping is a daunting task. There is a limit to the spring tension available and the forearm strength required to pull the clutch lever!!! A lock-out clutch assembly uses cam arms that can have weight adjusted for the amount of clamping pressure. The lock-out assembly uses centrifugal force to apply greater clamping pressure against the clutch pack as the RPM increases. More RPM, more clamp force = zero clutch slippage. Can be adjusted to work to shift under throttle but still apply many more times the clamping force against the clutch pack. Get the horsepower to the ground!" IMHO opinion its a nice to have/pretty to look at unless u running over 60ponies, it wood jus fascinate me all the time and i'd lose focus in a race, always checking the oil splash round and the clutch basket spinning up
Crankshaft:
not really a mod but prolly another item to go untouched wen modifying ur shee. have it recon'd new bearings, spacers and balanced n ur a for away for more hours of fun. another option is to have it trued n welded
Gear cutting:
yamaha do not build crappy gearboxes, and the only banshee box i have ever heard to fail was quadman's ballistic atv shee, then again a stock shee box used in motard racing conditions being hammered for almost 2 seasons (correct me if i'm wrong) at well over the 60hp mark never seeing a day under 7000rpm.....
str8 cut gears can handle more power transfer but also increase noise/whine, some like it sum dont.
boost bottle:
the jury is still undecided here, some claim it works some claim its shiny and other blame it for stuffing up the intake boots under vibration (which causes air leaks and lean conditions while running)
the theory sounds all fancy smanshy and yamaha have used it on two wheelers for years, mus b a reason why the jap mach's didnt chuck it on the shee
thinking of so many other things but gotta get back to work
JJ reply:
Nice analogy hehehe, now even I can understand it.
I would like to add my take on this.
2-stroke twin, with cranks at 180Deg, fires every half turn of the crank.
4-stroke single, fires every 2 turns of the crank...
IMO the flywheel on the banshee is only there to provide the magnetism for the coils and to trigger the pick-up coil. There are even aftermarket ignitions available that don't use the flywheel at all...
I've ridden a well sorted banshee with a lightened flywheel and I could definately not feel any lag, it just revved nice and crisp.
This is a worthwhile and cheap mod that's easy to do on a lathe machine, you only need a flywheel puller (there's one in Torqueshop) and access to a lathe. Material can be removed from the OD of the flywheel on both sides of the pick-up triggers and on the face of the flywheel outside of the rivets for the magnets.
10 Points to abide to or not...
1) When setting up the f/w in the chuck of the lathe, check the run-out using the inside taper bore that meets with the end of the crank as a reference. Better still, replicate the taper end of the crank by machining a mandrel for the f/w to bolt onto the chuck.
This will prevent excessive run-out and vibration when the f/w is spinning on the crank.
2) Don't cut of the 2 triggers for the pick-up coil.
3) Don't use a jaw puller to remove the flywheel, use a flywheel puller like the one for sale in th QT shop.
4) Do not drop or hammer the f/w, the magnets can loose their magnetism.
5) Do not machine off too much from the outside diameter, if the material is too thin, the flywheel will break. There's plenty material available there, just don't get greedy.
6) Don't cut off the rivets.
7) Try to radius the transitions of all cuts to prevent stress raisers. IOW, don't leave 90Deg corners at the end of your cuts.
8) With the flywheel off, you might as well use the aerosol type spray coating to paint on the electric windings of the stator coils to improve the insulation, not expensive and can be bought from any electrical industrial supplier.
9) You might as well slot the holes for the stator plate as mentioned in the pervious chapters.
10) Don't blame me. (Flywheels are expensive)