Barracuda Posted September 23, 2002 Report Share Posted September 23, 2002 guys/gals, I blew my banshee up and Im thinking about building a 420 stroker. What is involved in making this work. I know it will have a 7mm stroke on the crank, but how big will the cylinders need to be bored? I think it will use 67 mm pistons, is this correct? I know the case has to be worked for the rods, is there different levels of case porting, or is it pretty much all done to the max? Im looking at getting some 35 mm PWK's is this a good choice?My engine builder says it should still be duneable, which is important, what do you think? thanks for your input.. RoostKing... Quote Link to comment Share on other sites More sharing options...
100hp-shooter Posted September 24, 2002 Report Share Posted September 24, 2002 Barracuda, Well i have a 7mm stroker right now. My machine is a 398.6 cc. The cylinder is a stock cylinder .020 over. / with the 7mm stroke its a 398.6 calculated. To do the case port do not mill the case out to the max's. Since a 4mm Stroker crank is a direct drop in .. the only difference between a 4mm and a 7mm is 3mm. So you only need to mill 1.5mm's from the bottom of the case and the top of the case to clear the rods on the crank. As for the carbs yes a 35 PWK is a good carb ... i run 35 PWK's on my machine but we bored mine out to 38mm. I would ask your motor builder about the new PWM's though .. they are the cat's ass. Now if you mean your building a 420 big bore with a 7mm stroke your going to have around a 480cc + or - a few cc's .. since a 420 with a 10mm is a 499cc. Get that thing dynoed when you done and lets see the results... id be interested on how it sets up against mine if you going full drag that is. Hope it helps Shooter Quote Link to comment Share on other sites More sharing options...
Barracuda Posted September 24, 2002 Author Report Share Posted September 24, 2002 Shooter Thanks for the info. No its not a 420 big bore. I have been told that some of the other 420's that he has built dyno at around 70-73 hp, but I cant remember if that was on or off alcohol. Anyhow, i know this bike is going to have some power and im going to have to be careful and learn to ride it, but I cant wait! One more question, do you think this will be a good dune package? I dont want strictly a drag racer yet so it needs to be halfway able to dune. Anyhow i cant wait. Let loose with any other info you might have... RoostKing... Quote Link to comment Share on other sites More sharing options...
mosesduner Posted September 25, 2002 Report Share Posted September 25, 2002 I have 4mm stroker crank and used 67mm blaster style pistons and it calculated at 404. so with the 7mm crank you could be at 420cc. You'll need to decide how your gonna make up the 3.5mm longer stroke on the top. And you'll need a good port job to get the port timing correct. 35mm carbs are great i have 34s and they're fine. Hope it helps, al Quote Link to comment Share on other sites More sharing options...
Barracuda Posted September 26, 2002 Author Report Share Posted September 26, 2002 Thanks for the help guys. If you have any more comments, let me know! RoostKing... Quote Link to comment Share on other sites More sharing options...
DUNE-A-TIC Posted October 10, 2002 Report Share Posted October 10, 2002 It seems you allready have a builder in mind,who is it,if you don't mind me asking?Shooter pretty much covered anything I could add,though i'm no where near as knowledgable as he is.I'm in the middle of a 417 build-up,drag-port,34mm on alcohol..Though this not what your after,i'm curious,also,of the outcome of yours..Should be a killer,good luck!! Dune-A-Tic Quote Link to comment Share on other sites More sharing options...
Texas Outlaw Posted October 10, 2002 Report Share Posted October 10, 2002 Hey Dune, when do you expect to have it running? You and I should be some good close racing! Quote Link to comment Share on other sites More sharing options...
DUNE-A-TIC Posted October 10, 2002 Report Share Posted October 10, 2002 Told Charlie whenever is good for me.....I'm working on two bikes at the same time,that motor is going into the first chassis ready..... Dune-A-Tic Quote Link to comment Share on other sites More sharing options...
100hp-shooter Posted October 11, 2002 Report Share Posted October 11, 2002 Im re-working a new cylinder setup here in the shop for my machine later next week. Ill be putting a stock cylinder big bore with triples and crazy port timing to it. Its way outside the norm of running on a motor with CPI's but from what we have seen in the shop on the Dyno with these new pipes this cylinder setup on my 7mm should blow over 110hp. Well keep you all informed of the outcome. Were shooting for at least a minimum of 100hp on gas and 110hp + on Meth. Then maybee well throw some nitro at it to see if we can get it to the 120 mark. Wish you all the best of luck on your strokers and keep an eye on your rod play, crank bearings and air seals...all of these will either kill your motor or rob power. Later, Shooter Quote Link to comment Share on other sites More sharing options...
Barracuda Posted November 9, 2002 Author Report Share Posted November 9, 2002 Thanks for all the replies, I picked up my motor yesterday. Cant wait to get it going. I had Kenz Cycle tech in Mesa, AZ build this motor. Ive talked to a few of his customers and they seem to be happy with it. One guy wont ride his, says it scares him, its so fast. Bring it on! Ill let you know how it runs! RoostKing... Quote Link to comment Share on other sites More sharing options...
ollie Posted November 10, 2002 Report Share Posted November 10, 2002 shit, i was offered to rebuild my stock banshee engine to a 500cc ported stroker for 1200$ by one of the best 2 stroke engine tuners in the UK. but i guess there would be 100$ shipping on top of that Quote Link to comment Share on other sites More sharing options...
mcbike57 Posted November 17, 2002 Report Share Posted November 17, 2002 I know this is a year and more after the facts now. According to my bean counter with your figures you should have a 430 engine on your bansheeeeeee. I hope it worked out OK. Have fun. As to price: it may have been a little steep. Not major you understand. It also depends on the caliber of people involved too. Good people usually mean good work. That is worth a bit. Quote Link to comment Share on other sites More sharing options...
mcbike57 Posted November 17, 2002 Report Share Posted November 17, 2002 I thought the date on your post was 2001. Oh well. With that in mind my bean counter may not be countin' beans real good either. Still hope you got fun with that built motor. Quote Link to comment Share on other sites More sharing options...
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