Porting basics

[tfaith08]

You have to also know when to chase an imperfection and when to leave or epoxy it.  If you're chasing one tiny dip in the casting or an accidental grind from the carbide, you should determine whether fixing it can jeopardize your entire surface. 

 

A guy (can't remember where I read it) was porting a 250R and his carbide grabbed and dug a rut right out to his cylinder.  He ended up going from his planned 188 duration to a 196ish duration and had to redo his transfers to match.  He lost out pretty badly, but he could have done a starting notch on both sides instead.  A starting notch is just a 3-5mm wide cutaway that can be up to another 10degrees higher than the rest of the exhaust port that is meant to aid starting.  Once you rev up, the effects of the notch aren't noticeable.  They're used to reduce kick-back from larger displacement engines and those with higher compression

 

That's one example of a fix it, leave it, or re-plan scenario.

[trickedcarbine]

tfaith thats great your trying to help but theres a few things you should realize and probly already have. besides the site sponsors theres probly on 2 maybe 3 guys that do their own work. everyone else has likely never touched a porting tool or know what happens in the cylinder and pipe during a running cycle. zillafag for example. sprinklerman and trickcarbine are a couple more that know only what theyve read on google. your efforts might be better spent on other forums but im sure you already realized that

I don't claim to be in to portwork. Never have. I've just called you on your bull shit which to this date you have never even validated. Till then you are just another fucking nobody like the rest of us. It's cute that you think of me though.

[sprinklerman]

I don't claim to be in to portwork. Never have. I've just called you on your bull shit which to this date you have never even validated. Till then you are just another fucking nobody like the rest of us. It's cute that you think of me though.

Yea. I'm still waiting on at least a picture of his work.. A running bike would be better.

But I'm not going to hold my breath.

 

Sent from a van down by the river

[sstaton1983]

There are people who claim they are builder/porters who come on hear trying to teach a sermon. Then their are those that just want to share and figure out new ideas to make a better running bike.... REGISTERED USER IS KEN OCONNOR. 

[sprinklerman]

... REGISTERED USER IS KEN OCONNOR.

I wonder if he was that "civic dude" too? Haha

 

Sent from a van down by the river

[trickedcarbine]

I'm all for people learning and researching and then putting it in to practice. On many occasions I've stated that I think it is good for people to try to do their own work, GRANTED, they are CAPABLE, COMPETENT, and PROPERLY EQUIPPED. It takes a certain type of fella to really dig in and willingly ruin a few cylinders to figure out what works and doesn't, then continue putting it in to practice through experimentation.

 

The problem is, more often then not, people on forums are in experienced and in way over their heads when it comes to this type of work. There is a reason there are so many hacked up craigslist bikes out there and these are the type of individuals doing it. There are always gonna be guys that in their own mind are sure they are improving things. Just remember this, if ten people are in a room and one says they are right and the other 9 say they're wrong, they are probably fucking wrong. Hence all the forums where one guy tries to "contribute" and then 30 guys point out what is wrong but the poster gets angry and defensive and it turns to a cluster fuck.

 

There is a lot to be said about doing your own work, and I commend anyone who tries. But it's important to know what your limits are.

[sprinklerman]

I'm all for people learning and researching and then putting it in to practice. On many occasions I've stated that I think it is good for people to try to do their own work, GRANTED, they are CAPABLE, COMPETENT, and PROPERLY EQUIPPED. It takes a certain type of fella to really dig in and willingly ruin a few cylinders to figure out what works and doesn't, then continue putting it in to practice through experimentation.

 

The problem is, more often then not, people on forums are in experienced and in way over their heads when it comes to this type of work. There is a reason there are so many hacked up craigslist bikes out there and these are the type of individuals doing it. There are always gonna be guys that in their own mind are sure they are improving things. Just remember this, if ten people are in a room and one says they are right and the other 9 say they're wrong, they are probably fucking wrong. Hence all the forums where one guy tries to "contribute" and then 30 guys point out what is wrong but the poster gets angry and defensive and it turns to a cluster fuck.

 

There is a lot to be said about doing your own work, and I commend anyone who tries. But it's important to know what your limits are.

I agree with all of the above.

My issue comes in when people think they are saving money somehow by DIY. It simply isn't going to happen. Once you properly educate yourself and properly equip yourself ( no..not a dremel) you are waaaay past what a professionally ported cylinder from a reputable builder costs. Then you have sub-par results...unless you have several sets of cyls and a dyno to evaluate the results.

Btw: unless a builder has a dyno, or one at his disposal anytime he wants, IMHO, I hesitate to call him " reputable". Also.. If the builder doesn't at least test ride/race his own work from time to time, I hesitate to call him reputable....for the simple fact all he has to go by at that point is 2nd hand info ( customer feedback) which may or may not be accurate.

 

Sent from a van down by the river

[tfaith08]

If anyone is trying to save money by porting a cylinder by themselves, it's a waste of time.  However, if you have 4 machines and an extra cylinder or set of cylinders for each and already have a Dremel, you're potentially in a decent spot.  If you have some money, trash the Dremel and buy a porting setup. Now, I say Dremel because a lot of people have one sitting around or know someone that does.  I also think that a Dremel is a great tool to learn on because it is a limited piece of gear; you can't accomplish that much with it and it's hard to mess up with.  I was telling the guy that taught me that I wished that I had a ton of money to spend on a shop and the equipment to learn on, and he responded with, "If you had the money before the experience, you'd be stupid with it."  I agree 100%, which is why I think that most should start with a Dremel.  Hell, I prefer my Dremel when it's feasible to use it. 

 

For example, of those who do port their stuff, how many actually alter port widths and heights?  Of those, who can actually design them to their liking/needs?  Of all the people I've ever talked to, to include quite a few very experienced and intelligent mechanics, most have no clue what to start with.  When they do start "porting", they start with the bottoms of the transfers and maybe touch the exhaust up a bit if they have a long enough sanding bit or carbide and they leave it at that.  For that, a Dremel is fine. 

 

On the other hand, you have guys that actually have the potential to do a decent job.  If they start with a Dremel, they'll see the limitations and do what they can without over-stepping the capabilities of the grinder.  To narrow it down even further, you have a few that have the $600 for a professional grinder and bits, given that they have another cylinder to port in the future. 

 

I say all of that to say this: there is a very wide margin of people between those who port and those who don't have the money to do it themselves or pay a pro to do it.  You can't just shove everyone into one group or another.  What if a kid comes across an old LTR and uses his grandfathers Dremel set to try and learn on?  Is there anything wrong with that?  That's how the hell I got my start.  I'm all for free flow of information. 

 

In the end, you'll rarely beat a CC setup.  You have to have the CCs right angle grinder and a motor at a minimum.  No Dremel will ever beat a CC piece.  However, I'd love to see how a noob with a full fledged CC pro setup would compare to a pro with a Dremel. 

 

 

As for a dyno, they're a must if you're without someone to guide you.  I have occasional access to a dyno, but it's a sneak it in this day ordeal.  BUT, there again, most people don't have access to a dyno.  As mentioned in my post, beginners need to shoot for an adjustment to the current power curve rather than building something radical on the first go.  Once they achieve their goal, they should stop and call it good.  Placebo effect does start to kick in though. 

 

I also agree with the reputable builder thing.  A builder should always test their own work, albeit at a reasonable interval.  I've seen it and I've done it myself where numbers will creep over time.  For example, if I open my piston ports up on my Banshee to "X" by "Y" and then do someone elses, then another, then another, and so on, the surrounding area of the piston ports will have differed, even though the "X" and "Y" are the same.  I have a set of Banshee cylinders that have 2 different porting configurations on them.  One is for trail and one is for drag.  My widths and heights are all upstairs as well as written down, but those curves from all those cylinders will blend together after a while.  If I come across a guy who's open to me trying something new on his cylinders, I'll do it to his bike.  If it works, I'll add it to the 2 that I have sitting. 

 

Is Registered User really KOR?

[registered user]

not KOC. just a nobody that prefers to work on my own shit

 

 

[registered user]

Aiming the transfers toward the back of the cylinder (opposite from exhaust port) should keep the fuel from dumping out the exhaust. Something i think about is crank case volume and how it effects crank case pressure.. I came across a set of cases that  had alot of material removed around the crank area and wondered how much that effected the pressure to move fuel and air up the transfers..

 

JUST THINKING OUT LOUD....

if you were going to increase the volume it seems like it would be best to do it up high. perhaps in the tunnels themselves or near by. in 1 transfer cycle not all the case mixture will make it to the cylinder. the tunels can only pass X amount in a very brief time. so to me it doesnt make sense to put extra volume far away, like down in the case bottom, where it has basically no chance of reaching the cylinder on that particular cycle.

[tfaith08]

I'd thought about where you could add the extra volume as well.  However, I'll never chase that idea because I don't have the resources.  I know Passion Racing has some stuff like this conjured up and used on bikes, but you'll never squeeze any info out of those guys.  I do agree that along the bottoms of the transfers would be a good idea, but you have to worry about structural integrity as well.  However, around the crank wouldn't be too bad because the piston's downward travel would force the charge out of the way, potentially creating a bit of momentum in the direction of the transfers.  Again, I haven't put much thought into this.

 

I have seen a few hot saws that have the factory ports epoxied over and huge transfers cut out in them that are made out of epoxy.  Maybe that would be a consideration for a way to add structural integrity back to the removed area. 

 

Actually, I'm thinking about scavenging now and think that the extra diameters and tapers of the throat and first megaphone sections would contribute greatly to this.  I just got through reading a thread where a guy wanted to know if a Banshee pipe would work on a Blaster.  I like reading stuff like that because you'll occasionally have a guy post up some scientific reason as to why it won't work.  Now, I'm thinking that a pipe designed for extra cc would pull more of that mixture and work well with the extra volume.  I'm sure that the reverse megaphone would have a big part in this as well, but pipe design eludes me.  I think it also plays a slight part in getting the reeds back open when the transfers uncover (or slightly thereafter). 

 

In the end, if we have the same volume in the cylinder at 90 +/- degrees BTDC, it doesn't matter if we lost some out of the exhaust port to make sure that the exhaust gasses were purged more effectively.  BUT, that's where the reverse megaphone comes in.  Maybe a throat and megaphone designed for 40cc more and a reverse megaphone that can only handle 20 extra cc would do well here.  Yeah, we'd lose some AFM, but we'd have more in the cylinder and when shooting for maximum performance, who cares about fuel economy?

[trickedcarbine]

not KOC. just a nobody that prefers to work on my own shit

Finally. That's all you had to do.

 

 

[trickedcarbine]

if you were going to increase the volume it seems like it would be best to do it up high. perhaps in the tunnels themselves or near by. in 1 transfer cycle not all the case mixture will make it to the cylinder. the tunels can only pass X amount in a very brief time. so to me it doesnt make sense to put extra volume far away, like down in the case bottom, where it has basically no chance of reaching the cylinder on that particular cycle.

There are ways to aid the case to transfer flow of fuel but there aren't many folks doing much with it. Most motors rarely have the proper case work if any. I'm not just talking about gasket matching the cyls and upper case half either. I tried to make a thread on it a while back but it's worth mentioning here I guess.

[Pasi S.]

Why most people say, that you can´t use a Dremel to port your cylinders? I have a cheap Chinese copy of Dremel(with a "wire") and in my opinion it works just fine.

I use Snap-On 90 for transfers.

[sprinklerman]

Once you use a foredom you'll see why. Haha . Just being able to use a foot pedal and have a lower rpm to grind at makes them vastly superior.

Also a 90° handle with a reversible motor makes the transfer work much easier.

 

Sent from a van down by the river