Questions about porting

[Fre530d]

Hello guys

 

I am really interested in buying some ported cylinders.

 

Maybe gonna buy some unported cyl here and send them to the porting guy.

 

I want to have a 4mm setup.

 

Is it necessary to run bigger carbs with it, if yes , which size?

 

I drive mainly roads , what kind of porting is the best for me, drag or dune?

 

I want a reliable engine.

 

I was thinking of some RB porting or maybe Jeffs porting.

 

RB porting also sells 4 mm setups.

 

Or maybe it's the best to just buy a 4mm cub?

 

Since i drive mainly roads I better go that way?

 

I just don't know what to buy.

 

What is the difference in power between cub and 4mm setup with the same carbs?

 

THX for all the answers and sorry for all the quastions.

 

With regards,

 

Fred :beer:

[Bansh-eman]

are do youing drag racing on pavment? if so go cub... they are nice wot topend motors... keep in mind if you get stock jugs and port them then later on you want to add a 4mill your going to pay to report them again to makeup for the port timing differance...

[locogato11283]

I want to have a 4mm setup.

Is it necessary to run bigger carbs with it, if yes , which size?

a 4mm setup will work better with 33 - 39 mm carbs. stock will work but you are not gonna be gettin the full potential of the motor.

 

I drive mainly roads , what kind of porting is the best for me, drag or dune?

you could get by with either, but do you ride faster or slower most of the time? play riding sounds more to me like dune or woods port would be better.

 

I want a reliable engine.

I was thinking of some RB porting or maybe Jeffs porting.

RB porting also sells 4 mm setups.

i dont know shit about RB but i know jeff is good and also redline racing in oregon. i highly recommend both and have motors from both.

 

Or maybe it's the best to just buy a 4mm cub?

Since i drive mainly roads I better go that way?

you riding fast most of the time? if so cubs would be fine. however, if you ride trails and shit i would go with stock cylinders and the right porting for your riding.

 

I just don't know what to buy.

What is the difference in power between cub and 4mm setup with the same carbs?

a cub comes in any size and setup correctly will make more power than any stock cylinder setup of the same size.

 

THX for all the answers and sorry for all the quastions.

With regards,

Fred :beer:

no problem, thats what we are here for.

[Fre530d]

a 4mm setup will work better with 33 - 39 mm carbs. stock will work but you are not gonna be gettin the full potential of the motor.

you could get by with either, but do you ride faster or slower most of the time? play riding sounds more to me like dune or woods port would be better.

i dont know shit about RB but i know jeff is good and also redline racing in oregon. i highly recommend both and have motors from both.

you riding fast most of the time? if so cubs would be fine. however, if you ride trails and shit i would go with stock cylinders and the right porting for your riding.

a cub comes in any size and setup correctly will make more power than any stock cylinder setup of the same size.

no problem, thats what we are here for.

 

Now that's a nice answer :beer:

 

You just answered all my questions.

 

I ride fast practicly all the time because I drive on roads.

 

Maybe it's best to buy a cub setup with some 35PWK's?

 

How much power can I expect with a 4mm long rod crank setup?

 

RB porting told me about 75hp with race fuel on the rear wheels with a 4mm ported stock cyl?

 

But I have 20cc domes in a noss coolhead, trinity stage4 pipes and K&N pods.

 

What will the power delivery be with the following setups appr.?

 

Cub 4mm long rod w 35 PWK?

 

Stock cyl Dune ported to 4mm long rod w 35 PWK?

 

Cub stock stroke w 35 PWK?

 

Thx

 

Fred :beer:

[locogato11283]

I ride fast practicly all the time because I drive on roads.

cubs would prolly work for you then.

 

Maybe it's best to buy a cub setup with some 35PWK's?

cubs will run awesome with 33, 35 or 39mm pwk...take your pic.

 

How much power can I expect with a 4mm long rod crank setup?

RB porting told me about 75hp with race fuel on the rear wheels with a 4mm ported stock cyl?

thats about right for a good dune port. a drag port can get you more into the 80s. with the right pipes and carbs.

 

Cub 4mm long rod w 35 PWK?

roughly 85 to 95 hp depending on pipes and carbs.

 

Stock cyl Dune ported to 4mm long rod w 35 PWK?

id say right around 75

 

Cub stock stroke w 35 PWK?

75 to 80 im guessing?? depends on other things as well.

[Fre530d]

Thank you very much ! :beer:

[fredd2510]

All interesting options. Consider a couple more :

Use a pair of RZ350 cyl/ heads and their Powervalve setup. Not inexpensive, but not too pricey certainly less than a port job :-)

Consider that these engines ..can.. be made to generate an honest 80hp.. (Be assured that damned few other motors manage this trick, at least those using similar displacement... and .not internet hp either :-) ..without.. altering the OEM ports. .. yeah NO port job.

Why? basically cuz these come very well ported from the factory.. Mr Yama's engineers were not idiots :-)

Also the Power valves manage the exhaust timings so that it has useable power over a useable range 7, 000 to 10,500 rpms.. otherwise it would be only crazy power at 9500 and above.. as would ANY cylinder using similar portings.

To do this of course one needs well sorted Carburation, genuinely Good chambers, correct squish and carefull ignition setup.. not to mention a v well assembled engine.

Note: one can also buy programmable CDI units and Powervalve controllers for fair pricings for these motors.. Fergit foolish 4 degree advance keys.. when one can step the curves exactly where ineeded at 10 distinct points in the rev range.

Lots to learn before laying out yr hard borrowed $$ :-)

[Fre530d]

All interesting options. Consider a couple more :

Use a pair of RZ350 cyl/ heads and their Powervalve setup. Not inexpensive, but not too pricey certainly less than a port job :-)

Consider that these engines ..can.. be made to generate an honest 80hp.. (Be assured that damned few other motors manage this trick, at least those using similar displacement... and .not internet hp either :-) ..without.. altering the OEM ports. .. yeah NO port job.

Why? basically cuz these come very well ported from the factory.. Mr Yama's engineers were not idiots :-)

Also the Power valves manage the exhaust timings so that it has useable power over a useable range 7, 000 to 10,500 rpms.. otherwise it would be only crazy power at 9500 and above.. as would ANY cylinder using similar portings.

To do this of course one needs well sorted Carburation, genuinely Good chambers, correct squish and carefull ignition setup.. not to mention a v well assembled engine.

Note: one can also buy programmable CDI units and Powervalve controllers for fair pricings for these motors.. Fergit foolish 4 degree advance keys.. when one can step the curves exactly where ineeded at 10 distinct points in the rev range.

Lots to learn before laying out yr hard borrowed $$ :-)

 

Will the engine remain reliable?

 

Can you still get spare parts for the powervalve system?

 

Is it difficult to mount, adjust?

 

What do I all need :

 

Let's see

 

RD cyl

RD head

Carbs, what kind?

CDI from RD?

 

And more?

 

WFG

 

Fred

[locogato11283]

i personally wouldnt fuck with those rz/rd cylinders. id go with cubs before id bother with those things.

[Fre530d]

i personally wouldnt fuck with those rz/rd cylinders. id go with cubs before id bother with those things.

 

Thx Locogato

[Animalman294]

The cubs are going to be reliable with with routine maintainance, especially with the long-rod setup (less piston rod angle). Remember that their powerband is like a lightswitch on and off.......... :beer: