Porting help

[Waternut]

I just got the Race Logic porting templates for my 750sx. RL only sells sxi and sxr templates and judging by what's written on the template ("750/800"), I'm guessing they are the same anyway. I actually have a couple questions...

First, the bottom template for the cylinder looks like it wants me to completely remove that bottom section. Do you agree?

Second, since this is an sxi template, it accounts for the higher exhaust port timing when the instructions say to line up the template with the top of the cylinder. I have no desire to raise the port timing since I only do freestyle. If I line up the template with the top of the port instead of the top of the cylinder, it looks as though I would only widen and slightly reshape the bottom. 1mm would come off the bottom center of the port if I did this. Should I lower it or try to keep that bottom line intact?

Sorry I tried to take pictures of the exhaust port but they were either too dark or too bright to really see what's going on.

 

[SUPERTUNE]

Yes, Cut all of the bottom away like the template.
On the bottom of EX. port, put the cylinder on with pistons and a stock base gasket, rotate crank so the piston goes all the way to BDC then look and see if the bottom of ex. port is above the piston top, if so grind the bottom of port to match if needed...
Don't raise the exhaust roof, just widen port.

 

[Waternut]

Makes sense...thanks

One more question. Supposedly the templates are specifically designed for a stock bore. If I'm 1mm over already, should I just use the template "as is" or make the cut slightly larger or smaller?

 

[c_legaspi]

please take step by step of your port job if you can. it will be nice to see your port work and the results after you get it back together and ride.

your report or the power you gain may influence me into trying the RL template.

 

[dirtyoz]

Thats pretty cool, I have been casually looking for porting templates for 701's. I would love to give her a try. I second the step by step idea. Lets see some pics.

Oz

 

[Matt_E]

Makes sense...thanks

One more question. Supposedly the templates are specifically designed for a stock bore. If I'm 1mm over already, should I just use the template "as is" or make the cut slightly larger or smaller?

As you go up in bore size, the ports need to get bigger.
1mm isn't much, but maybe go slightly bigger than the template.

 

[Waternut]

I'm trying to develop a write up as I go...

One more question. I know generally not to raise the port, but should I raise the sides of the port up to the upper limit where it is now?

 

[Matt_E]

I wouldn't.
That would create a pretty flat port roof, which isn't friendly to ring life.

 

[Cross]

I wouldn't.
That would create a pretty flat port roof, which isn't friendly to ring life.

But its good for power. There is always a trade off.

 

[Matt_E]

True, very true.

At this point though, I am more concerned about longevity.

 

[Waternut]

Here is a pretty bad picture of where I am now. The yellow is the remaining section of what the template would have me cut. I'm thinking of grinding the sides a little but not to the edge of the yellow. I am definately concerned with reliability but the port is pretty flat on the bottom but not even close at the top. I've already cut the bottom half of the port as that's a given but the top is where I'm having doubts.

 

[SUPERTUNE]

Go for it! Just follow the template line and don't raise port like you said, keep a big corner radius at the top corners and about 1mm port chamfer when done at the top and just around to the side.

 

[c_legaspi]

im a little confused about this port thing. i thought you didnt want to raise the exhaust port but is the section marked in yellow for grinding raising the exhaust port.

did you say that the bottom of that exhaust port has been grounded already?

did you align the template with the top of the cylinder or did you just match up the template exhaust hole with the top of the exhuast port?

 

[Waternut]

Well I believe the 701 templates are more accurate as the 701 engine are more consistent. I just lined up the template with the port as best I could and went from there.

I didn't actually "raise" the port as far as the maximum limit. The raising that I did is kind of a gray area between raising and widening. The yellow paint that you see is actually what I was hesitant to grind. Everything else had already been removed.

 

[c_legaspi]

okay thanks. looking good. cant wait for your test ride results.

 

[Waternut]

Just wanted to update what there is to update...

Since the pistons I have are Wiseco's and I didn't realize it, I ordered regular rings initially which turns out will not work with Wiseco pistons. So I desperately tried calling everyone I could think of to get the rings in by Friday Sept. 12th.

On Thursday the 11th I had given up and decided to order the rings from a place in Michigan figuring they'd easily get here by the following Friday since it only takes 2-3 days to ship something to me....Boy was I wrong! I ordered from www.N2products.com who claim they ship parts within 24-48 hours. Well here it is the 24th and still no rings. I've called them countless times and left 2 messages. I've also contacted them via email twice as well and haven't gotten a single reply to any of my inquiries. Mistake or no mistake...if you can't respond to a simple question, your business sucks!

The end of the season is quickly approaching and I'm sitting around with an engine in pieces. Mother @#$*&@#($&@#

 

[grasshopper]

very interesting.... any updates?

 

[Waternut]

Yep. The porting worked out pretty well. See the link in my sig for the full write up and results.