wide powerband diy porting

[Coupelx]

The intakes seem to be a matter of opinion on a reed valve engine. I went from smallish intakes and transfer tunnels to this and gained everywhere. It is also interesting to note that I then had to jet down from a 140 to a 132 on my 28pwks.

 

I've been told that most will like 186-188 for most all types of riding while keeping the blowdown stockish. I would first work on the width and shape to see if you can get what you are wanting.

 

I am all for a good discussion but all the parties need to bring something to the table. I don't know about the pistons as I've never done it that way. Its mentioned in some books though.

[Colby]

X

 

Those are some beautiful radiuses on the intakes of the transfers. Very nice. I also see you intakes are huge! I've read that big intakes tend to make a motor more lazy down low at? Thanx for the pics though. My plan was to go with a very mild port. Keeping my exhaust at 184 not to lose too much low power. What I've desided to do thanx to everyone that helped me is to put the motor together and see how she runs. If she is too peaky I am going to raise my transfers at 0.5 degree increments. I was also thinking to be more safe, maybe I should cut my pistons instead? I know this destroyes the whole compression and squish. Having said that, if I do get a better spread powerband by grinding my piston crown at the transfers positions, would the lower compression and messed up squish band cancell my gains out that the motor actually feels wors?

 

 

when i had my stock cyl. drag ported by HJR, i cut out quite a bit of my pistons, i know this makes them weaker, but i wanted to see if it would help, they almost match my intake ports.. actually KILLED my low end(even for a drag port) and seemed to help from the top of midrange-up... IMO

[registered user]

you wont be a superstar over night. you may never be a superstar. maybe you understand that, maybe you dont. but thats the way it is. i spent couple years reading books, examining different cylinders, picking up info across the web from anybody willing to talk. night classes at a college dont hurt either. its doubtful you even know the bare basics but youll learn in time. very few people in this industry know everything, hard to say whether they will admit it or not though. some can port like a mutha but cant weld to save their life. some can port and weld but dont have a clue how to make a correct pipe. i know of only one guy that i consider to have a good grasp on all aspects of these bikes. porting, cut a correct head, make a pipe, weld, machine a trench in the cases, and dyno the whole setup afterwards. he can do just about everything. ditch the tape measure and learn to understand the degree wheel is my advice

Edited August 27, 2012 by registered user

[trickedcarbine]

you wont be a superstar over night. you may never be a superstar. maybe you understand that, maybe you dont. but thats the way it is. i spent couple years reading books, examining different cylinders, picking up info across the web from anybody willing to talk. night classes at a college dont hurt either. its doubtful you even know the bare basics but youll learn in time. very few people in this industry know everything, hard to say whether they will admit it or not though. some can port like a mutha but cant weld to save their life. some can port and weld but dont have a clue how to make a correct pipe. i know of only one guy that i consider to have a good grasp on all aspects of these bikes. porting, cut a correct head, make a pipe, weld, machine a trench in the cases, and dyno the whole setup afterwards. he can do just about everything. ditch the tape measure and learn to understand the degree wheel is my advice

I keep getting the feeling you may be Mat shearer or someone else in the upper end of builders every time I see an anonymous post.

[So Cal Suspension]

I keep getting the feeling you may be Mat shearer or someone else in the upper end of builders every time I see an anonymous post.

lol, it's not Mat Shearer, but I think he's talking about Mat.

[camatv]

transfer 129-132/ exhaust from 192-196 intakes big but not so big they will crack. ( takes practice) intake timing also comes into play and so does shape of exhaust port, transfer aiming, and transfer tunnel porting, shaping, and internal texture's to achieve a decent midrange / lowend port . everything else has a huge part in this as well. domes are a huge factor in making a good midrange stump puller.. HUGE boost ports aimed the correct way and also pistons with proper window size and window aiming can help.

 

its not hard to make decent bottom to make a real tq monster ( over 50-55ft lbs) is difficult and will take every little advantage you can get.

 

gordon jennings etc never gave this info away for free they wrote BOOKS back then you had to go BUY them or subscribe to the magazines they wrote for, or take a COLLEGE class for the information.. not free. no internett freebee's in the 70's also there is one book i read that seemed to help the most with differnt powerbands and how to acheve them and its not very popular.. or even well known

 

there is nothing wrong with wanting to learn there is nothing wrong with wanting to build your own pipes there is nothing wrong with wanting to play with a motor, custom domes, learn to weld etc... yes the bigger shops and people with access to dyno's and lots of capital and time will almost every time produce a much better result than you can hope for. but hey. nothing wrong with trying. its very rewarding to acheive a build your happy with and proud of. just rember you didnt build it to impress the ding dongs on this site. build it for you. screw everyone else.

[registered user]

i see a couple problems right off the bat. no clear game plan of what or where to cut and doesnt have the proper tools. without a 90* tool you better put a fork in it because your done. and for the 3rd time figure out how to use a degree wheel. how to make a piston stop and find TDC. pretty simple things you need to know. gather some more info and aquire a few tools then dive in

[Coupelx]

I've been changing one or 2 things at a time to see how they change performance. I want to learn the relationship between everything. Takes alot longer but has payed off big. Careful research and planning my next changes has resulted in a bike that goes faster every time.

 

One thing that was repeated to me was everything in a 2 stroke is a compromise and you need to learn where to give up a little to gain alot.

[Wildcardracing]

I'm not going to give numbers or angles, but I'll throw in some advice.

1) Focus on velocity not volume

2) The smooth micropolished finish isn't going to yeild the best possible results

3) Lower blowdown periods will yeild stronger fronstide curves

4) DON'T flatten your transfer roofs

5) Staggered transfer arrangements will work well (develope a good loop charge)

6) Study your dome design, this can make or break a good port layout

 

-Brandon

[350skabarat]

i see a couple problems right off the bat. no clear game plan of what or where to cut and doesnt have the proper tools. without a 90* tool you better put a fork in it because your done. and for the 3rd time figure out how to use a degree wheel. how to make a piston stop and find TDC. pretty simple things you need to know. gather some more info and aquire a few tools then dive in

 

I have all the tools I need, I know how to use a degree wheel and I can find tdc with a dial gauge. Degree wheel is a primitive method imho. Trigonometry is way more accurate and faster. But I'm not gana lie, I did dive in abit too fast lol.

 

I've done nothing to the transfers yet besides clean small flaws. Taking it slow.

[sheerider11]

Yes. A pen and a 90* dremel tip. The only tools you need.

[350skabarat]

I'm not going to give numbers or angles, but I'll throw in some advice.

1) Focus on velocity not volume

2) The smooth micropolished finish isn't going to yeild the best possible results

3) Lower blowdown periods will yeild stronger fronstide curves

4) DON'T flatten your transfer roofs

5) Staggered transfer arrangements will work well (develope a good loop charge)

6) Study your dome design, this can make or break a good port layout

 

-Brandon

 

Thank you. Probably the best advice anybody has given me so far. I got advice from a very good builder, he said keep them low and wide. Which makes sense as alotof low end motors run low duration on exhaust. I did raise my exhaust to 184 and I've read and heard that I won't loose much bottom end at all. The only thing I'm worried about now is that my blow down is at 32 which is higher than stock. So I'm thinking that might kill abit of my bottom end but I'm ganna run it and then see how it is and make changes. I had an idea of lowering my blowdown by grinding piston crown abit to be safe so my transfers open earlier. If it spreads the powerband then I would work on transfers and get new pistons. But now as you say squish is pretty important? So is this idea of myn a bad idea?

[350skabarat]

Yes. A pen and a 90* dremel tip. The only tools you need.

 

Lol the pen is just there to give perspective on size man.

[sprinklerman]

Im all for DIY if you have the time. But you saying you having "all the tools you need" then posting a picture of a Dremel with a R/H attachment is FAAAR from correct. Several years ago (12-15) i tried doing the transfers on my banshee with that setup,,you'll see the error in using that as soon as you try it. I went straight away and bought a REAL r/h hand piece and motor and never looked back. You'll find that it spins waaay too fast and has zero torque. Thats a bad combo for doing detail work. Buy a good Foredom and R/H hand piece and THEN let the chips fly.

[Coupelx]

A degree wheel is far from primitive. Sit there with your calculator all you want, there's a reason several people have said to get a degree wheel. Read the damn books!