first time portin...

Hello everyone, I am tryin to do some portin on my 372xp ...never have done it before...I have hogged out the intake and exhaust... I am not sure if I can grind more off to make the openings bigger fur better flow. I plan on polishin after hoggin it out more if needed. Also there is a little bur in the upper right...how would I smooth this out...and last of all...at the bottom of the jug...how much do I grind off here. I'm not lookin to make a hot rod...just trying to purk up my 372xp...thank you...hope the pictures help...

 

Modifying a saw for performance involves more than just indiscriminate grinding of the intake and exhaust ports...You need a plan mapped out before you start, material removal at the base is going to impact your timing and squish. Most people starting out experiment on Wild Things so they are out little money if something goes wrong.

 

Welcome to the Club! I know what I would have done to start, but that isn't going to help you know. I agree with Guido a blueprint would have been your best bet to start. I'm sure millermodsaws or mdavlee will be along shortly with some good wisdom to help ya out.

 

Thank you fur the in put...I know performance is more than just hoggin the intake and exshaust out. Can you clean and open them up and still get some positive results...right? Or not? So if I change the base it will change the timin? What if I just leave the base the same and clean it up lightly and polish it....would that help? Also...what about the bur on the wall...can I remove it? Or not...this is a spare jug so I won't be out no real money if I mess it up...I am a beginner at this and understand about the #s but I don't have the equipment to do that part...I barely had the tools to do this much...as always...thank you fur the comments and help...

 

Thank you fur your comment...

 

Thank you fur your comment....

 

Hey.... I was also wonderin if there is a different between 372xp blue coil and a black coil...thank you...

 

Why would you polish the base? And yes if you grind the base down it will change the timing as the ports are lower and open and close at different times. Also you dont have much room before the piston will slam into the top of the head so I reccomend not touching the base at all.

Increasing and polishing you will see a difference but worth your time I am not sure I am no expert.

The #s mean where in the rotation the intake opens and closes as well as the exhaust.

 

The Blue coil is a limited coil, black is unlimited. You'll want the black. As far as the porting goes. I'll help you out the best I can this evening when I get home and have my notes in front if me. As your grinding you need to pay very close attention to skirt widths, ring end location and it really helps to have a degree wheel. But that all said. I would not touch the base unless you have a lathe to cut it true. What was your factory squish? Be gentle with that jug as there not the easiest jug to find used. We will get ya there though!

 

Thank you fur the input... Sorry...I must have made a mistake... I know if you change the base... You change the timin...example...takin the head gasket out...brings the position up to improve compression but also changed the timin ...I am new at this part of saw building...I am talkin about cleaning up the ports at the bottom of the jug on both sides... Thank you fur the info on the coils...

 

It looks as though you have plenty of room to square up the corners of the lower intake without changing the timing. The other two marks on the intake look like they can be beveled out fairly easily.

 

Thank you fur your input and info...I don't have the equipment to find the degrees of opening and closing of the port...I would love to have the #s but what can I do with them with out the right tools...I do want to learn and thank you and every ones help...



PS...I not sure what the sqish is....

 

Your "squish" is the distance from the piston crown to the chamber surface at TDC

 

I think he is just saying he did not measure it and therefore does not know what it is?? Maybe I am wrong.

And to the OP yes you are correct removing the gasket lowers everything and reduced Houston to head clearance on TDC and increases compression from this reduced space.

 

Porting 101

Start by reading this!
Get an idea of what going down before we proceed!
All these boys will help you get this saw up and going maybe with even a little more gitty up! But ya gotta know what there talking about first!

 

Thank you fur your input... On the lower in take...is that at the bottom of the jug Thank you fur the info on the sqish too...I understand about the tdc...I just don't have the tools to find out what it is...

 

True that...and I am learnin...I have better luck with hands on or good picture...I don't read well and have a harder time comprehending what I am readin...uggggggggggggggg...true story...lol...thank you fur your help...

 

Yep.

You should be able to stick a piece of solder in through the spark plug hole and "squish" it with the piston at top dead center. Measure the thickness of the squished solder and there you go. You have just figured out how much space you have before the piston slams into the squish band at the top of the cylinder.

 

I was referring to the bottom of the intake port where your damage is.