New guy with big bore questions

[Beer4Blood]

Hi all.....had a blaster for many years never thought of joining a forum despite the fact I'm on one with everything else I own. But now I'm here and I got questions. My blaster is currently .040" over. Needs re ringing and I was considering going bigger while at it. So can a stock block handle a 72'mm?

 

[tbrooks]

Not with the stock sleeve. There is no point in boring a stock sleeve larger for the power gain, because it is insignificant

 

[Beer4Blood]

Could you elaborate more please?

 

[tbrooks]

There's other guys here that will know more than me, but the stock sleeve can only be bored to 68.25, I believe. This would only give you around 10 more cc's and is not really worth it. I do believe you can have the stock sleeve removed and a larger sleeve pressed in, but you would prob just be better off getting a big bore cylinder. You can however add an aftermarket exhaust, some port work and a head mod and outrun otherwise stock big bore blasters

 

[jus_me]

^^^ like he said, No point in boring out a cyl to the max just because. Try and find a used maxed out cyl if you want to go the 72mm stock cylinder and sleeve route. You can find them very very cheap and sometimes almost free (maxed cyl). An after market 72 mm cylinder will have extra exhaust ports along with "Boyesen" ports ready to go. You can add "Boyesen" ports to the stock cylinder . There is a diy video and more threads about it if you want to go that way. As far as the xtra exhaust ports they have been done to a oem cylinder but can be tricky. Not recommended unless you have some real good experience. So best bet is to get yourself a 240 cylinder.. Vitos, Ct, or Airsal.. If you need re ringing you may want to measure the bore to see if it is in spec. Out of round and taper.

 

[79 bronco]

You will have to put a bigger 240 sleeve in your stock cylinder.

 

[Larry's Shee]

The cost of a BB sleeve in stock jug is about half the cost of a complete kit, and still doesn't have tripple ex, better transferes, or aux ports.

 

[Beer4Blood]

^^^ like he said, No point in boring out a cyl to the max just because. Try and find a used maxed out cyl if you want to go the 72mm stock cylinder and sleeve route. You can find them very very cheap and sometimes almost free (maxed cyl). An after market 72 mm cylinder will have extra exhaust ports along with "Boyesen" ports ready to go. You can add "Boyesen" ports to the stock cylinder . There is a diy video and more threads about it if you want to go that way. As far as the xtra exhaust ports they have been done to a oem cylinder but can be tricky. Not recommended unless you have some real good experience. So best bet is to get yourself a 240 cylinder.. Vitos, Ct, or Airsal.. If you need re ringing you may want to measure the bore to see if it is in spec. Out of round and taper.

So I'm not doubting you guys in any fashion. I'm taking in this information I just like to fully wrap my head around it. What is the difference in a stock sleeve and bb sleeve? Seems only one size sleeve would fit in a stock jug to me??? If that's the case then you could over bore the stock sleeve correct? I do understand you guys are saying it won't have the proper airflow to accommodate it's extra cc. Could someone point me to these adding ports diy? I'll probably just bore another .020 or .040 and re ring keep it cheap and simple and have me riding again quickly. I'd still like to see it....

 

[jus_me]

Stock sleeve is to thin. It maxes out just over 68mm. Stock steal sleeve "liner" isn't thick enough so it needs to be bored out past itself to install a new thicker sleeve. A re ring sounds fine if things are in spec and you get going quicker with minimal time and $$ involved This vis should help explain..

http://www.bing.com/videos/search?q...&mid=EE53C9B2795A08BD4AE2EE53C9B2795A08BD4AE2

 

[Beer4Blood]

Thanks! Guess a 240 sleeve will wait. Just tweak her out as best possible with what I got. Recommended mods?? I'm no stranger to porting. My kx will just be getting bbk before the blaster.

 

[jus_me]

I would start with an after market exhaust and a properly modified head. You can clean the ports up a bit from casting flaws and such and make things flow a little smother which will help all around. Could also remove air box lid if you don't go through water. Also know that any mods consisting of either airflow into the engine or exhaust flow out you will need to re jet your carb..

http://www.bing.com/videos/search?q...&mid=3F4A06C9BE74122D77CA3F4A06C9BE74122D77CA

 

[Beer4Blood]

Yep jetting is on the just for sure. Love tuning a carb. Had my ninja 600 screaming with just a little jetting action. Exhaust and high flow filter definitely. New reeds...and sprocket change, probably for top end? What you think? Anything else?

 

[jus_me]

The list goes on but it really depends on what you are looking for and your budget.

 

[Beer4Blood]

I want to keep up with the larger four strokes. As far as budget goes I'll be slowly trickling money into her piece by piece. Just not sure I can justify a$ 500 bbk atm.

 

[Beer4Blood]

So I'm trying to wrap my head around this boyesen port thing or boost port??

 

[Blaaster]

Every little helps!

 

[jus_me]

Here is a vid on someone doing one on it175, basically same cylinder as the Blaster. You cant go to big or you will go through the side wall. I would suggest to practice on a junk cylinder first.

 

[Larry's Shee]

Well, do this:

Haven't watched it in forever, you can widen/raise ex/ports a hair, a little is a lot in terms of degrees of crank rotation.

 

[Larry's Shee]

Also, other than what is in vid, search Gorden Jennings, H. Grahmn Bell, Blair, may be others, plus there are programs ($$) for porting. Also search Boysen ports, may, or may not be what you want. Can also do tripple ex ports, may, or may not be what you want/need/or can do.

 

[Beer4Blood]

Triple exhaust ports....where do I read on this. Just downloaded the two stroke tuners hand book