Noob questions on big bore

[Biggt613]

Hi guys  noob here. Just picked up my first banshee a few weeks back. I vet race a rm250 and my son races 85’s soni am familiar with 2 strokes and love them but am not an engine builder. I can rebuild anything and have the tools to do so but this is new to me.

I have been looking around for a week or so on info for a big bore 69.5mm. I picked up a set of 69.5mm jugs which have obviously been sleeved. Research tells me 68 is as bug as you can go with stock overbores.  A trinity stage 4 head came with it with apparently 19cc domes which i believe means race gas. I keep c12 on hand fir the bikes anyway. Pistons also with it but used 69.42mmlook like wisecos but hard to tell. Supposedly had trinity porting but no markings on jugs identifying port job. It has been ported though and looks like a clean job. Would this be a 420cc kit? What else would i need to make this usable? 28mm carbs at least i would think. Adjustable stator to advance timing? It runs fine now but i like to plan ahead. Just want a reliable trail machine with the capability of some mx and ice racing up here in canada. Suspension and a arms etc i lnow what i need its the motor stuff i am trying to learn about. Seems to be stock stroke cylinders as well. I have read about short rod and long rods but Would prefer short so i dont have to change porting etc. Any help or links to read is really appreciated. Again just looking to the future. I like to plan and do things right even if it takes time. 

[gusto]

I personally wouldn’t put a dime into the engine. If it runs good run it until it breaks. Then upgrade.

that set up is from a time before CPI and Driveline cylinders and the domes and head are specific. 

[Biggt613]

9 hours ago, Biggt613 said:

Hi guys  noob here. Just picked up my first banshee a few weeks back. I vet race a rm250 and my son races 85’s soni am familiar with 2 strokes and love them but am not an engine builder. I can rebuild anything and have the tools to do so but this is new to me.

I have been looking around for a week or so on info for a big bore 69.5mm. I picked up a set of 69.5mm jugs which have obviously been sleeved. Research tells me 68 is as bug as you can go with stock overbores.  A trinity stage 4 head came with it with apparently 19cc domes which i believe means race gas. I keep c12 on hand fir the bikes anyway. Pistons also with it but used 69.42mmlook like wisecos but hard to tell. Supposedly had trinity porting but no markings on jugs identifying port job. It has been ported though and looks like a clean job. Would this be a 420cc kit? What else would i need to make this usable? 28mm carbs at least i would think. Adjustable stator to advance timing? It runs fine now but i like to plan ahead. Just want a reliable trail machine with the capability of some mx and ice racing up here in canada. Suspension and a arms etc i lnow what i need its the motor stuff i am trying to learn about. Seems to be stock stroke cylinders as well. I have read about short rod and long rods but Would prefer short so i dont have to change porting etc. Any help or links to read is really appreciated. Again just looking to the future. I like to plan and do things right even if it takes time. 

I agree. Everything is fine now but when it comes time for a top end i figure ill try it out. If i can get some guidance. Dont wanna ruin anything either. Guy i got it from said bike it came off had stock crank and timing he just replace the top end cause a ring stuck in a piston groove. No scoring on cylinders. I would post pics but it doesnt seem to wanna let me 

[gusto]

Use Tapatalk app to post pics.

So you bought this top end and it’s sitting on the shelf or it’s installed?

you could get away with the stock carbs I think.

800 gets you a driveline set up for fuel tire reference 

[rkooienga]

Hi, I am a new person to modifiing any quad or dirtbike, I love riding stock equipment, but my cylinder in my banshee was pretty beat up after my top end went out so I bought pistons and had my cylinders bored out to meet clearance with those pistons. The pistons are 64.95mm. My question is can I still run the stock pipes on the bike.