SLORYDER Posted April 27, 2009 Report Share Posted April 27, 2009 I was wondering if anyone ever noticed any real gains from doing a cleanup port and widening the intake or exhaust ports any? Quote Link to comment Share on other sites More sharing options...
2003LimitedBanshee Posted April 27, 2009 Report Share Posted April 27, 2009 I was wondering if anyone ever noticed any real gains from doing a cleanup port and widening the intake or exhaust ports any? I've only just ported my first set of cylinders, change timings and all of that, so I am SO FAR from having a minimal understanding of the porting process, BUT... I would think you would see some gains from a "cleanup port". Even if you just worked over the intakes to improve the flow into the cylinder, it can't hurt anything. By knifing the divider and taking the step out of the roof of the intake, it has to help. As for widening the exhaust, I don't know. Again, coming back into flow, I don't know the flow capabilities of the stock exhaust port. In theory the risk of unnecessarily widening the exhaust port is that you will decrease the exhaust gas speed and potentially not empty the cylinder as effectively. Now, the stock cylinders might not be able to empty effectively enough through the stock width port. In that case it should help. There are a lot of people out there who have years of knowledge over me, and probably much better opinions/advice. Hopefully they chime in! Quote Link to comment Share on other sites More sharing options...
deckheight Posted April 28, 2009 Report Share Posted April 28, 2009 Yeah, it is worth it. Widening the exhaust will improve your upper mid-range, improve BMEP and slightly raise max rpm. Don't go wider than 42mm and you will be fine. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted April 28, 2009 Author Report Share Posted April 28, 2009 sweet I am also going to widen the intakes by narrowing the intake bridges significantly. Also thinking about opening up the port above the intake bridge.. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted April 28, 2009 Report Share Posted April 28, 2009 Playing with the intake ports wont get you much. The transfer and exhaust ports is where the power is at. Quote Link to comment Share on other sites More sharing options...
serius4play Posted April 28, 2009 Report Share Posted April 28, 2009 I know that after long periods of ridding a crap load of stuff sticks to the exost ports so if you tage em apart and clean em up and polish em down again then that hase to help. it seemed to with my dads 01 after he F@#$ed up the tranie and i had to compleatly take it apart and i noticed all the build up. i cleaned it out and carved the exost port a bit wider. idk how much but eatherway it helped it out. and yes iv been told widining gains mid 2 high power and a few more rpm and up gives you significant rpm gains. weather thats compleatly true or not idk. youl have to ask someone who isnt just experimenting with it and knos for sure how it works. (that is if they will tell you ) Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted April 28, 2009 Report Share Posted April 28, 2009 sweet I am also going to widen the intakes by narrowing the intake bridges significantly. Also thinking about opening up the port above the intake bridge.. how significantly narrow are you going to make the bridge? if you make it too narrow, that part of the cylinder, can bulge in towards the piston, and can cause the piston to stick. its more to worry about, on the exhaust side, if you had bridged exhaust ports, and you narrowed the bridge down. the exhaust side of the piston is the hottest, and the narrow bridge for sure would bulge into the piston. granted you are working on the intake side, i wouldn't worry as much, but the caution is still there. Quote Link to comment Share on other sites More sharing options...
sheerider1026 Posted April 28, 2009 Report Share Posted April 28, 2009 i have done a cleanup port on my trail bike.. i also widened my transfers and exhaust a little.. even with a 2 into 1 carb the bike runs very good for what it is.. there are a few guys on here that seen it run first hand.. not the fastest, but it was free power gained.. like said, be careful going to narrow with the intake bridge, not a lot of power gained in this area.. its all in the transfers and exhaust.. Quote Link to comment Share on other sites More sharing options...
flotek Posted April 29, 2009 Report Share Posted April 29, 2009 I was wondering if anyone ever noticed any real gains from doing a cleanup port and widening the intake or exhaust ports any? yes if done correctly it will be atleast noticable ,however its pretty archaic in stock form and porting has come along way since the late 60's/70's when the lc and rd twins came out ...the banshee needs alot more than a cleanup port if you want a wide strong powerband Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted April 29, 2009 Author Report Share Posted April 29, 2009 Yeah, it is worth it. Widening the exhaust will improve your upper mid-range, improve BMEP and slightly raise max rpm. Don't go wider than 42mm and you will be fine. 42mm as measured by a straight line from port edge to edge or along a curved radius? Quote Link to comment Share on other sites More sharing options...
2003LimitedBanshee Posted April 29, 2009 Report Share Posted April 29, 2009 42mm as measured by a straight line from port edge to edge or along a curved radius? Point A to Point B, do not measure along the radius, you will have a much larger number that way. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted April 29, 2009 Author Report Share Posted April 29, 2009 Point A to Point B, do not measure along the radius, you will have a much larger number that way. Thanks bro and can someone recommend the max I should raise the exhaust roof without touching the transfers? (2003 not sure if you were just being conservative) Thanks Quote Link to comment Share on other sites More sharing options...
deckheight Posted April 29, 2009 Report Share Posted April 29, 2009 (edited) Not quite that simple when you start raising the exhaust... Gonna need more info. What type power band do you want? What compression (octane fuel)? Rider weight? Tuned exhaust? Carbs? etc. In general, raising the exhaust will also raise and narrow the effective operating rpm range. Without increasing combustion chamber pressures you will lose some on the bottom and gain some on the top... Basically. This is all assuming your not talking about that 521 in your sig that I just noticed??? Thanks bro and can someone recommend the max I should raise the exhaust roof without touching the transfers? (2003 not sure if you were just being conservative) Thanks Edited April 29, 2009 by deckheight Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted April 29, 2009 Author Report Share Posted April 29, 2009 Not quite that simple when you start raising the exhaust... Gonna need more info. What type power band do you want? What compression (octane fuel)? Rider weight? Tuned exhaust? Carbs? etc. In general, raising the exhaust will also raise and narrow the effective operating rpm range. Without increasing combustion chamber pressures you will lose some on the bottom and gain some on the top... Basically. This is all assuming your not talking about that 521 in your sig that I just noticed??? no this is a set of stock cyls. Will probly mill the head some to run premium and the pipes will be pro circuit or pt hi rev.. Basically would just like to add some in top without completely killing the trailability. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted April 29, 2009 Report Share Posted April 29, 2009 no this is a set of stock cyls. Will probly mill the head some to run premium and the pipes will be pro circuit or pt hi rev.. Basically would just like to add some in top without completely killing the trailability. Pro circuits and pt high revs require two completely different types of exhaust duration. A lot of people work on the assumption that a trail pipe will kill the top end. I find it very much not noticeable when play riding. Obviously if you drag race someone with a decent mid-top setup they will out run you. I run a low-mid setup that is tuned extremely well, and when I play ride or even drag race it holds it own very well against most others setups that are quite the opposite. A perfect example of this stuff is guys who used to race in the mickey thompson series. They could take an mx tuned bike out to the dunes, and beat just about any other 250r up the hill racing. There is not really a way to gain top end without spending some money to keep the bottom end at least the same. Like switching to certain pipes, porting, and running a stroker crank. Once you start moving around exhaust durations, and switching to top end pipes, your lower power half is going to suffer. Do your homework, and make sure your motor owner knows that you can't trail ride a drag bike. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.