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421 cub ?


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Hey guys im buying a new shee tommorow with the 421 cub setup.. It has cpi inframes on it and i dont like how i cant see the polished jugs with these, i really dont like the pipes period. never rode them but by the look i can tell they will more then likely be removed, my ? is this... Is the flange on the cylinder bigger on the 68mm cubs? i would like to put some pt hi-revs on it if possible. Never dealt with a cub setup before only stock and ported stuff. Also, im wanting to rebuild the topend, from what ive seen you dont bore these. just re-ring and put new pistons in, re nikasil the cylinders when needed, anything i should be aware of when rebuilding? im not comfy with the fact he said they prolly have 30 hours on them, thats alot imo. :thanks:

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Whats the compression run on these? round 1200feet above sealevel... Im commited to this buy now damnit lol,i dont have any pics of it yet but ill be sure to add them to my sig when i get. Its a 98, plus 4 swinger, just repainted, 421, cpis,35mm keihins,pods, elka suspension, lockout clutch, haulers,mohawks, not sure what dirt tires, other odds n ins, dont like the plastic thats coming off asap, 4k

leaves plenty of room to improve :geek: old lady trippin on me cuz i got about a 2page list of stuff its getting in the near future tehe, but she aquired the 97 so she cant complain to much

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If you take off the CPIs on it and put Paul turners on it...please don't buy that bike.

 

BIG Step backwards...and you'd be wasting what that motor was designed to do.

 

Inframe Shearers will show off the cylinders more.

 

Or get out of frames and show the whole thing off.

 

What you're attempting to do is build fast car but put the equivalent of catalytic converters on there because you like the way they look.

 

CPIs and Shearer pipes run very well on cubs... PT pipes are trail type pipes for stock cylinder motors, not aftermarket cylinders with drag porting on them from the factory....

 

ALL of the cubs, stock to 14 mil have the small exhaust flange. If you want a 100HP duner like it says in your sig, going from CPI to PT pipes would be a BIG step backwards in that goal...and whomever is selling you the bike should tell you the same.

 

Check compression on it. Pull the head...see what size domes are on it. No need to rebuild due to time only. rebuild when the compression is low...nikasil cylinders and a properly maintained motor will last a long time.

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for inframe pipes, CPI's or Shearers are by far the best bet for Cubs.

 

I would certainly keep the CPI's....Shearers make a little more power on top, but the CPI's make the cube nice and rideable and still maintain some lowend and midrange power. Shearers will be all topend and harder to enjoy riding (unless your going to drag only).

 

30 hours is fine since cub cylinders are plated. You could change the rings but thats it, if it runs fine and has compression I doubt I would mess with it at all.

Edited by Justintoxicated
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lol confused, nah, i understand the flow of exhaust guys ;p just didnt think a 68mm bore is going to make a HUGE difference in the output of it, but ill take your word for it.. As for the cpi's ive read everything from here to china on them, i know they're performing pipes but they look like a 40oz bottle of beer on the side of the motor, UGLY, ill give them a try, but they are an eye sore imo.. I was looking for something that was all done up and had all the goodies but wheres the fun in that was my conclusion, im riding some other dudes bike, thats lame, build it, ride it, enjoy it and you've accomplished something, not buy it, ride it and have to tell the guy next to ya, umm ya i didnt do shit to it i bought it like this lol Thanks, preciate it fellers ill post some pics of it. IM NEW TO THE CUBS BARE WITH ME :thanks:

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lol confused, nah, i understand the flow of exhaust guys ;p just didnt think a 68mm bore is going to make a HUGE difference in the output of it, but ill take your word for it..

 

 

The larger 68 mm bore doesn't really have anything to do with the exhaust needs, its the drag port specs the cubs have. The cylinders you have are designed to make high HP at high RPM. Thats why everybody is telling you to stick with the CPI or shearer pipes.

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