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/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> exhaust port dremel /cgi-bin/YaBB.pl?num=1510903196 Message started by mz250 on 11/16/17 at 23:19:56 |
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Title: exhaust port dremel Post by mz250 on 11/16/17 at 23:19:56 Can you Dremel the exhaust port out to fit the inside diameter of the header with the head still on the engine? If so how do you stop shaving getting into everything ? Cheers |
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Title: Re: exhaust port dremel Post by Dave on 11/17/17 at 02:22:18 Yes, it can be done. Rotate the engine to make sure the exhaust valves are closed. (You can do this by putting the transmission in gear, and pushing it forward until the engine comes to the compression stroke). Stuff paper towels or thin cloth pieces up the exhaust port to seal off the valve stem and guide area. It is best to use small pieces as they are easier to get lodged in the cavity. I lightly oil mine as it helps the paper/cloth stay lodged in the port. When done grinding......pull the paper/cloth out of the port. Don't blow compressed air up the port as it could blow pieces where you don't want them.....let the exhaust blow out anything that might be left after you pull out the rags. Don't remove the entire ring in the exhaust.....but you can make the hole a bit larger and round off the sharp edges. |
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Title: Re: exhaust port dremel Post by batman on 11/17/17 at 09:49:39 I believe someone used paper towel and a can of foam shaving cream in the same manor as Dave described. |
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Title: Re: exhaust port dremel Post by LANCER on 11/17/17 at 12:05:29 6B687D6468673D31090 wrote:
Aaaaaa........... |
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Title: Re: exhaust port dremel Post by SALB on 11/17/17 at 12:08:26 6F54594E5F53484E555D504F3C0 wrote:
A shop vac works great for getting a majority of the filings out. ;) |
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Title: Re: exhaust port dremel Post by Gary_in_NJ on 11/17/17 at 12:55:40 Anybody have a photo of what a perfect port should look like? |
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Title: Re: exhaust port dremel Post by verslagen1 on 11/17/17 at 13:15:42 sorry... that's NSFW |
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Title: Re: exhaust port dremel Post by LANCER on 11/17/17 at 16:04:36 3B31353F343D39306E686C5C0 wrote:
This port is not complete yet but the outer ring and the ridge behind it has been finished to a semi- level, more cleaning & polishing needs to be done. Notice the center wall behind the ridge has not been touched yet. The surfaces of the floor/walls/etc needs to be smoothed as you can see that there is a significant amount of irregularities in those surfaces. Also notice at the top of the outer ring that the surface is flattened slightly, giving the port a slight "D" shape. I typically flatten it more than shown here for a bit more of a pronounced D shape. The rounding of the sharp edges like the ridge line, and smoothing of the surface of the "inside" corners, following the flow of the gas, is typically more important than getting a shiny polished surface. There is only one surface that benefits from a real polishing and that is the inside corner immediately below the valve. That is important. Also, if possible, it is definitely beneficial if when having a valve job done that then machine shop have a tool that will "round" the surface immediately below the valve when the valve surfaces are ground. The average machine shop usually does not have these tools. http://https://s26.postimg.org/4b0pqxo61/DSCN0113.jpg |
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Title: Re: exhaust port dremel Post by Ruttly on 11/17/17 at 16:45:32 Lancer , What year it that head ? The casting on that web between valve pockets is horrible or maybe it's the pic. |
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Title: Re: exhaust port dremel Post by LANCER on 11/17/17 at 17:19:28 684F4E4E56433A0 wrote:
I don't know. The photo is dated Nov. '16 but I have no idea of year of the head. |
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Title: Re: exhaust port dremel Post by Ruttly on 11/17/17 at 19:00:02 I was wondering if the castings got worse or better over the years. My 96 had that ring but the rest wasn't too bad , I did the valve pockets from the seat all the way out it turned out nice. I know removing the ring takes away some low end torque but I was out to make a big bore that breathes for a wide powerband without using a larger cam. Well a tiny bit bigger I used the Webcam standard grind ,just a bit more lift & duration. Built my engine/bike as a daily rider that will last for years and handle my riding style. Porting singles is easy, it's when you start adding cylinders is when it really takes more time to make them all the same. |
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Title: Re: exhaust port dremel Post by batman on 11/18/17 at 01:27:50 Ruttly said," porting singles is easy" and he's right. but I think it may be better to say porting singles is easier. Lancer said attention is needed on the inside curve of the exhaust channel which is also true,(The gases wanting to hug the inside of the curve) but going craze grinding ,(removing to much material) can also ruin the head killing any chance of gaining hp and maybe even ending up with less. A well designed exhaust channel,(which we don't have) starts just behind the exhaust valve ,where the opening should be 85%-88% of the diameter of the valve and be only 6% larger at the exhaust header, as our exhaust passes the "shelf "the area just in front of the header pipe it becomes much larger and is why our motors have such low power . The pressure waves and gases ,when the valves first open can leave with speed as high as mach-1(the speed of sound) but as the exhaust stroke continues this drops and pressure increases ,this is where the size and shape of the channel becomes most important. A smaller channel, without a tight radius, may flow better because there is less drop in speed and less pressure (read back pressure)formed , and the reason to grind carefully. the size and contour of the channel represents 97% of it's worth ,polishing accounts for the other 3% so may not be worth the effort ,and may also remove to much material. this is one place where less(grinding) may be more(hp) . |
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Title: Re: exhaust port dremel Post by mz250 on 11/19/17 at 23:52:12 Thanks for the info I more question does anyone have a before and after photo ? Thanks |
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Title: Re: exhaust port dremel Post by Dave on 11/20/17 at 04:09:05 Most of this has already been discussed and photo'd. The "SEARCH" button can bring most of it back to the surface......if you use it. (Below is a link to the best one with photos.....there were a lot more that came up. You could also search "exhaust port) and get a lot more). http://suzukisavage.com/cgi-bin/YaBB.pl?num=1380686489/3#3 Here is a photo of an exhaust port that has been opened up a bit - but not crazy on the size or the polish.....it was a quick 20 minute job that will work fine on a bike with a stock car/cam/header. The size was opened up a bit....and the edges made rounder - you don't want to go too big on a stock engine.....and it doesn't make a lot of sense to have the hole get really big - then it tapers back down to the 1-1/4" header. http://i68.tinypic.com/24b9do6.jpg |
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