Topic: CB550 porting

[Pain]

I am going to do my own porting. I will post before and after, as well as progress pictures. Does anyone have recommendations or advice and can anyone give explanations/pictures of the following:

1) the pockets hondaman described
2) cross grooving

I am looking to increase performance to a high street racing level. I will be running CR29's, webcam A from dynoman (I have a brand new B that I won't be using - PM me), 605cc kit (or I may sell it and go with 650 pistons - opinions?).

I will be starting a build thread soon when my tank and seat finally arrive this week (~5 months late).

Thanks,

Pain

[turboguzzi]

do silicone castings of your ports, section them, the areas that need working on will become self explanatory and you will learn something in the process rather than blindly following someone's else advice and thoughts.

a win-win situation as they say

random example bellow, cant find the pics of my cb500 castings right now but i know they are in one thread or another...

http://www.cardomain.com/ride/765528/1964-amc-classic/page-7

[Ricky_Racer]

TG, any tips on the easiest/cheapest/most accurate way to do silicone port castings? Seems like one should use some mold release agent? Any difficulty in getting the silicone plug out after it sets up?  Thanks!  RR

 

[turboguzzi]

TG, any tips on the easiest/cheapest/most accurate way to do silicone port castings? Seems like one should use some mold release agent? Any difficulty in getting the silicone plug out after it sets up?  Thanks!  RR

 

not much in it. silicone costs a bit but is best, sort of self releasing, polyurethane rubber sticks more. all i do is spray a bit of chain lube into the port before pouring. after its dry, i insert a thin screwdriver and spray some wd40 with the tube into the gap to further release the rubber and make it "swim" inside the port. a lot of pushing from the combustion chamber side and it'll get out eventually. you do have to cut the casting on the center line between the valve guide and end of the port, otherwise the rubber will catch on the guide. see p2.jpg, a bit hard to explain but you'll understand when you do it.

i remember finding quite a few illustrated guides on the net on the process.

here are the ones i did of my current gpz750 build , graph represents the way the cross section area changes along the port



TG

[Rod]

TG I'm loving the chopstick scaling system you're employing there. Are they Japanese Imperial length or Eur-Asian Metric? 

[turboguzzi]

TG I'm loving the chopstick scaling system you're employing there. Are they Japanese Imperial length or Eur-Asian Metric? 

Italo-Argentinian

[Sam Green Racing]

nice one Yo. 

[Pain]

Thanks TG. For reference purposes, what brand silicone did you use?

Does anyone have information on the pockets hondaman described and can anyone make a statement about cross grooving?

I found a few older threads where people asked about the pockets with no clear answer.

The more I read into porting, the more complicated it becomes. I found information on mototuneusa.com telling me I should make my ports smaller. Any comment on mototuneusa (other than bigger ports doesn't necessarily mean better)?

[mlinder]

The mototune guy is talking about smaller ports on modern head designs.

He does it to keep intake velocity up. That's because modern designs are not very restrictive, unlike your 550 2 valve port design.

[Raef]

TG, very cool,

When you say silicone are you talking about from a tube "caulk" or do you have another source in a more liquid form?

 do you ever do a second mold after completion to double check consistency across the 4 cylinders?

Mark

[turboguzzi]

TG, very cool,

When you say silicone are you talking about from a tube "caulk" or do you have another source in a more liquid form?

 do you ever do a second mold after completion to double check consistency across the 4 cylinders?

Mark

No no, not tube caulk. It's double component casting silicone, resin + hardener you mix, i.e. 2K,

i use an italian brand that'll be irrelevant to the US, but google 2K silicone and im sure you'll find lots.

in the cb500/4 i did "before and after" castings. in the kawi, these are the "before", havent worked on the ports yet

the info in mototune is mostly about 4 valve designs, not 2 valve like ours, so apply at your own risk, at least in the 500/550 the ports are certainly NOT oversized.

TG

[Ricky_Racer]

Thanks for expanding on the concept, TG. This looks like fun!    RR

[BLUE71TURBO]

When you do a search for 2k silicone, make sure you google " 2K SILICONE-RUBBER "  That is the silicone you want.   

 Here, i did some searching for you fellow members and found this great site !   

               http://www.smooth-on.com/Silicone-Rubber-an/c2_1113_1136/index.html

   Just click on the blue " BUY ONLINE " button to get prices and different size buckets of the casting silicone.   

[Raef]

nice site,

thanks for the info guys, I have been wanting to cast some parts and I was thinking aluminum, I may try it in resin instead.

Mark

[Pain]

Thanks for the link Blue. My searching wasn't successful.

Pain