Jump to content

Top End Porting


biodave27

Recommended Posts

The only way to tell what kind of porting you have is to see a port map or know the port durations. Measure the distance from the top of the cylinder to the exhaust port top. Give me this number in MM. Do this for the transfers and the boost port as well. With this info you can tell what the builder was shooting for. You can't tell just by looking into the intake port which has nothing to do with the port timing.

Link to comment
Share on other sites

looks like someone opened up those intakes a ton. between the size of those intake ports, the 34mm carbs, and with the exhaust duration being unknown, they all decrease bottom end power. do as ssd said and measure from the top of the ports to the top of the cylinder. these #'s should help determine what kinda port job you have after the durations are calculated. give us the #'s, and we'll get the duration for you.

Link to comment
Share on other sites

You will need to pull the head off the machine to measure things. The motor is easier to work with if it's on a bench but removing the pipes and gas tank and any other items in the way can work for you. You need to measure the inside of the cylinders. All port roofs should be chamfered a little but you can still get a "close" enough number to get an idea about whats going on.

Link to comment
Share on other sites

Yes, I have seen that same cut a bunch, looks like Rudy Kurtz drag port, and if you have no bottom end its because transfers are to high like most so called " drag port" engines are. Paaathetticc. Trade them cylinders off for some stockers and have them properly cut for what your doing, some sucker will want them maybe on ebay. Oh, and by the way brainy one that thinks that changing the intake windows will not change things....hmmm.....eeeeeeehhhh wrong. Inreasing port windows lowers velocity and increases volume....hmmm, doesnt this hurt your bottom... I think so. Come on fellas, dont give the guys advise if you dont know your butt from a hole in the ground......The only people that get anything from your advise is people like me that giggle at your comments. Look kiddo, call a reputable builder and have them guide you in the right direction and dont take the advise from something you read on the net. Most of these guys are just telling you things they have found themselves somewhere else on another website. I learned the lessen the hardway, and now Im fast :D

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...