Help with porting

[blaster7]

Hey guys my lil sis just got her first atv and yeah its a blaster,now she wants it ported but she has no cash so I've decided to do it for her,I've watched all of ken's vids and belive me I know what I'm doing when it comes to stuff like this all I need is a little help from you good guys hear on the blaster forums laughs,ok first of all it's a vitos 240 cylinder kit,and before you guys ask yes I have everything I need for this plus more ok now that that's outta the way hears my question,I know on the exhaust port it needs to be raised but what about the intake side? and if that go's up as well do I have to match it to the exhaust port mm for mm? also I was thinking 2mm on both but if someone changes my mind well it happens lol,also I'll get you guys some before and after pics as well,now it mite take a little time for me to get some pic's up so if you don't see pic's right away don't jump on me for it laughs and don't worry I'll get them up,well that's about it fellas hook me up,thanks for all your time.

 

[Surfrjag]

not much is to be done to the intake as raising them can cause the ring ends to catch. they meet just above the intake windows. you can narrow the bridge a little and knife edge the bridge along with removing some of the roof before the cylinder sleeve. most of the power comes from the exhaust port raising and widening unless you have the tools to clean up the transfer ports as well. good luck and be sure and post us some pics of what you come up with.

 

[1995blaster]

From what i read the more you raise the exhaust port and widen is the more topend and it really matters on the pipe if its a top end or bottom like fmf etc... im not an expert nor have done it but have TONS of time and patience and done some reserch but with reserch ill i can find is to knife edge and clean up casting flaws, exhaust ports i cant figure out anything really about triples which you already have or boysean ports.

 

[N8tsNastyBlasty]

before u start porting it read ,read, and read some more. not just here but everything you can about 2 strokes. try to decide what type of powerband your looking for and set the exhaust port timing accordingly. mac dizzy has a write up on a blaster build that may be of use. if you want to clean up the castings polish the exhaust its pretty straight forward. I go pretty wild when it comes to porting and it becomes like an ocd for weeks. you can look at my pics and get an idea of what i do but i dont want to give direct advice without tellin you im a self taught enthusiast.

 

[Larry's Shee]

Education is the key (read). Jennings, Bell, McDizzy. I:I Be aware as the exhaust is raised the powerband becomes narrower and peakier Not knowing your sister's experience/ability might not want to get to wild on the ex. Remember that it's more degrees of crank rotation than MM/IN raised, a little can be a lot ! Pay attention to symetry, (one side same as other). Transfers need to taper from bottom to top with no sudden changes in cross section.
Personally, I wouldn't narrow the intake bridge. Reliability vs output.
JMHO, your results may, and will vary. I:I

 

[blaster7]

hmmmm,well thats great to know,I won't touch the intake cylinder ports then,I'll stick with the exhaust port,im'a bring it up 2mm oh and I'm not worried about her she races a cr85r so I know she can drive,so I need to make this thing a monster for her,as for the transfer port I will taper them and smooth them out and guess I will just port alittle bit in the intake side but won't touch the cylinder port,if you guys could tell me what you guys port the exhaust to I would like to know,also I've been reading forever on this laughs and it gets old reading I want to do it now,like I think 2mm is kinda on the safe side I mean I've seen people say they go to 4mm on the exhaust,everything I've read doesn't really tell what mm is a good all around mm,on ken's videos he said stick to 1mm but I know he's just saying that for noobys I just want a bad azz all around port job without killing the bike,now it mite be an mx slash trail bike so I need a port to match,again thanks for all your help fellas.

 

[blaster7]

oh N8 I'm not worried if your self taught because if it worked for you it'll work for me I'm sure Ken wasn't just born a pro but then again you never know laughs,any info is better then none and especially if you've actully done it,thanks a bunch fellas.

 

[blasterfreek30]

i say go for it bro, we all gotta start somewhere....i cant be happier with the port work i did myself

 

[Larry's Shee]

Should be safe with 2mil. Be sure top of port isn't flat, taper it back towards side. In doing so you will actually make it a hair wider. Be sure to champher the port openings. Look around here to see what good or bad porting looks like.
While you're at it port your reed cage. Be sure to loctite screws.

 

[blaster7]

@blasterfreek30 I agree buddy,I just hope mine turns out as good as yours lol,oh and Larry's Shee what do you mean champher the ports can you explain it better bud.

 

[Luni]

Champhering is where it takes the sharp 90 degree edge off the port openings and smoothes it out. I think.

 

[nd jat]

Port openings need to be rounded or chamfered to allow the rings to pass the openings with out catching the edge. if not done ring life drops fast. In ken's vids he tells about it with good detail.

 

[blaster7]

kk will look over ken's vids better,thanks guys.

 

[Larry's Shee]

Basically the port is 90* to the cylinder. Can't remember the exact angle at the moment, but you angle grind the cyl 30* about 1/32-3/64ths of an inch. To para-phrase G. Jennings "it is to gently tuck the ring back into the ring groove" , in otherwords so you don't have a sharp edge for the ring to "snag" or catch on. Don't remember if O'Conner mentions it in his videos. Bevel might be another term for champher.

 

[blaster7]

oh do you mean how the top of the port in the middle is higher then the sides of the port? and that it has to remain that way,because I thought you ment that there's a burr left after the porting and it has to be removed,also guys I have another question for you how do I hone this thing? I know it's at 72mm if that helps,it still has hone marks in it it's so new lol,I just want to knock the glaze off can I just run some sand paper in there like let's say 800 grit? now before you ask yes I know how honing works laughs and yes I know you can't just go up and down in the cylinder lol,I know it has to have a cross hatch,again thanks for all the help guys.

 

[Larry's Shee]

Someone says Ken's vid explains bevel/champher. Think of it this way,(roughly) cylinder is vertical, 30*angle for 3/64, then port is horizontal. This little angle area goes all the way around port. It's most important on exhaust port because of it's size, tho transfers need to be done also. Actual intake port I just hit it with some emerycloth/sand paper just so it doesn't have a knife edge/burr.

 

[blaster7]

Well guys I'm getting there im'a try and get you guys some pic's today,it's really not all that bad yeah it can be a pain at times but all in all it's not to bad,and man as you start to get tords the end of each port it really shows the flaws of the vitos cylinder,and then when you look at the before and after pic's it's really amazing how doing alittle work can make such a difference ya know,I'm super pleased with it and I know when you guys see it your going to say yeah I mite do mine lol.

 

[blaster7]

This is the intake before porting.

 

[blaster7]

Intake after porting.

 

[blaster7]

Before porting exhaust.