Porting and tuning?

New to this Hobby (sport) and new to this forum so please bare with me. I have been reading over this forum since I before I purchased the pocket bikes and I have found a mountain of usful information. Some of the information that I am interested in seems to be pieced through out the forum and putting these items together I still have some question. So I am going to list the questions and attach a graphic attachment in the hopes that I can get this information and get under way. Now the attachment is a Word document that I came up with so I am hoping that this works, if not I will try another way.

1. Cylinder porting and polishing: The intake and the exhaust ports are of a given size, I'm not sure of that size right now because I have not opened it up. How do you know how large to open them up? Is there a standard? Will this afect the reed cage by having more space around it?
2. When porting the intake and exhaust do you taper them (similar to a cone)? If so what direction should the cone face, I am assuming the small portion of the cone would face the piston on the intake side but I am unsure on the exhaust.
3. Tapered needle: I am not sure how to do this or what the intent truely is. When tapering do you simply knock the sharp edges of the radius at the point or are you removing material the length of the needle? Is there a spec that that you are shooting for at different points on the length of the needle?
4. If I do the porting work and tapering on the needle what would be the other Items that I would "need" to bring it all together. I am asking this in this fashion because the many of the items out there are bolt on items, will these be required to make the bike work. I would like to do this one step at a time and I would rather do the porting and what not first, check it out and ad the bolt ons from there.

Thank you.

For porting of the cylinder...

Look in the cag how-to's. I listed where you should port. If its still unclear, let me try to clear it up for you.

When you take off the head, there are two intake ports. There are two sides to the intake port...one side has a slight angle, the other side, there is no shaped angle to it. Thats the side you want to open up. Take your dremel, open it up about 2-3mm. Do that for the other intake port as well.

Unless you are putting on a FCS, you don't need to port the exhaust. Just clean it up using a sanding bit for the dremel. You can idex your piston on the exhaust side if you'd like, to let more exhaust gasses out faster, but you really don't need to.

For the tapered needle, keep a lookout on zero4's how to which should be up soon.

If you do decide to port the exhaust, yes you can taper it, but again, only port about 2-3mm on the sides, 2 mm up top, nothing on the bottom.

And for the ultimate performance adder while porting, add a boost port. Do a search. Rexracer posted his boost port. I don't know if he'll give you the exact dimensions though.

OR

Send your head to mike93eh. He does an awesome job on heads. I port heads as well, but too busy to do them at the moment.

Hmm...having trouble with this one. So you want to open up the side with no angle to it. What does "open up" mean? Simply widening it, or creating an angle and widening it, or simply creating an angle?

Also, you say to open up the un-angled side, then you say do the same to the other intake port. Is that just confusing wording or was there a reason why you indicated that "thats the side you want to open up?" Just trying to clarify. THanks for posting the info.

Actually the "how to" I will be posting soon will only be on rejetting the stock carb. But I'll answer your question here.

What makes the most difference when retapering the stock needle is exactly what you pressumed, smoothening out the sharp edge just above the point will increase your throttle response. If you want to go futher, taper it so it sort of ressembles a wooden toothpick. The more you knock off, the more fuel the needle will let in. Try and not to shorten the length of the needle though. Best way to do this is first remove the clip from the needle and chuck it in a drill. Make sure you chuck it past the notches otherwise you can break the needle at one of those notches when tapering. I use 220 grit wet sanding. After you get your desired taper, finish it off with some 600grit wet sanding. I prefer to use my own retapered needles over the triple tapered needle.

Inside the exhaust port, angle it slightly . Open up means taking a dremel and porting out the exhaust.

If you've opened up the head, you'll notice the two intake ports both have a slight angle to one of its sides. opposited of that angle is a flat part where it meets the cylinder. You can port that side up to 2-3mm.

If you don't understand what I'm saying, then don't attempt porting it. You'll easily have an ashtray when youre finished.

Gotcha. After re-reading your post it makes sense. For some reason I thought your reference to the unangled side was to an unangled intake port as compared to an angled one. Lol...I was wondering why one intake port would be angled and the other wouldn't

Anyway, that makes sense. So you simply widen the intake ports by 2-3mm each and you do so on the unangled side of each intake port. When you're done the unangled side is still unangled but simply further away from the angled side.

Correct. You want to keep that side untouched for one simple reason. Porting isn't always about opening things up. You want to keep the shape of the ports intact to promote good fuel flow and combustion. The velocity of the gasses decreases, which most likely will lower your low end power, but your top end should be good.

I don't know about anyone else reading this but my brian is on fire from all the different angles and un-angled stuff.....lol

Then porting isn't for you.

This is a good thread,id like to read somemore of the members take on porting.

Just finished mine

Nice picture, do you got one showing the boost port hieght? (tilted more toward you) How high did you go? What kind of angle is on the top? And could you let us know how it worked? Thanks

MY camera ran out of batteries when i was taking pics and this is the only good one i got . The boost port is about 1mm under the transfer port hieghts. angle at the top?

Does the top of the boost port direct the flow straight across the piston top (90 deg)? Or tapered to aim at the spark plug(30 deg)? Or shaped like the transfer ports(60 deg)?

Great thread!!!

I think it's time to bust out the dremel.

I'll have to buy a second CaG to race in stock class... heh heh

I found some batts,here are some crappy pics.I'd say its tappered in between the transferport tapers and pointing at the sparkplug. I am just messing around,I have never ported a 2stroke motor like this before,just 4 strokes.I'm waitin for my big bore so I decided to mess around with the stock cylinder and piston. My buddie did his already so I'm doin mine a little different than his to see if I can manipulate the power band a bit.

I bought two cags so I have one for stock class and one for open class . I can't wait till next season.

The reply I posted on this thread was supossed to bring alittle light humor to it, not to sound cocky but I went to a credible Auto/Diesel College and very well understand the workings of all sorts of motors for CAT to Briggs, but some of the people who read this stuff are ams or totally new to this, so without the pics and actually show what you are talking about, the use of the word angle 20 times in a two sentence reply can be confusing. Don't take this as a personal knock because I'm not here to make enemies but to learn things I don't know, to have fun doing it and to make friends with the same interests as I do. Thanx

Thanks for the effort and pics Outlaw50Please post your performance results.

Sure thing