I was thinking of doing some porting on my 96 300 Express. I have a friend that builds racing ATV motors for people who run nationals. He said that I can match my sleeve porting to my cast porting without hurting anything. I;m not sure if I heard him right. Does this make sence to anyone?

The reason I'm so concerned is that their is about a 1/8" I would have to cut all the way around my sleeve to make it match with my casting. This seems like a lot of timing changes for my motor and I really don't want to have to buy a new jug.

As far as beleiving my friend, I do. I just don't know if I heard him correctally. Or maybe I'm confusing some things around. My friend has only been doing this for a few years himself although his family has been into this stuff for many many years. I know that the one thing he's really getting known for is his work with the Blasters. My engine is basically the same(2 stroke, air cooled).

What do any of you think?

 

I origanally posted this 3 days ago and to my surprise no one responded. Anyway, I went back to my friend with my jug in my hand. He pointed out the stuff he suggested to do so I came home and started grinding.

While I was there at his place he showed me a Blaster jug he had just finished for someone. This jug was ported to be a trail riding/woods racer. He also had a stock Blaster jug there. I couldn't believe how much you cut out just for a mild port job. My stock jug was naturally bigger than a stock Blaster but, the ported Blaster jug was way bigger than mine. So, in reference, thats basically how much I've got to cut out of mine.

I've already started cutting on my exhaust port. I must say I am working really slow to help avoid any mistakes. I sure can't wait to get it back together. I se now why all the mods I made before didn't do much for me but I'm sure they will when I'm done with my port job. Not to mention that I'm going to have my head shaved done to help pick up some more compression. This should all turn out to be a good combination.

 

I would advise not raising the exhaust port much at all . Do you know how to chamfer port edges? I just hate to see you ruin your cylinder and will lend a little help so you can avoid disaster.

On the intake port DO NOT raise it like the blaster cylinder. If you do , the ring ends will poke into the intake and ruin it all.

Why don't we talk before you get to far into this? A cylinder is in the $400 range , I just hate to see you ruin one .

 

elroy,

I'd have to agree with Rick on this one. It does take PLENTY of experience to do a port job. You have to know where to take metal off of and where not to. Especially on Polaris machines. Sorry, Billy Joe Bubba and his die grinder just ain't gonna cut it this time.

Even if you do get it ported, then what? The 30mm carb you have on your 300 Express isn't going to flow any better. The pipe you have on it won't flow any better, either. You would have a motor that has the potential to flow very well (assuming that the rings don't get caught in the ports)but without a carb, pipe and clutch kit tuned to match the port job, it's a moot point.

 

Well, I finished up my exhaust port yesterday. Atleast as far as making the big cuts. I have to do the finishing touches today. I will end up about (.010) bigger top and bottom on my exhaust port but, a bit wider. I didn't really want to raise it even that much but I had to, to make it all clean up.

As for chamfering the port edges, No, I don't know exactally how to do it. I do know how they are supposed to look when its all done but, I'm not sure how I'm going to do this finishing touch yet.

My friend showed me exactally how to cut my exhaust port but he only said to open my intake port a little. He didn't say where or how to cut it. You have to understand though, that my friend makes a living building these motors for guys. He also knows how smart I am and that I'm a bigger perfectionist than he is. This all threatens him as far as telling me all his secrets. However we are good friends and he wouldn't let me mess anything up but, I know their are some things he wouldn't tell me because he knows I should be smart enough to figure them out myself. He will help me out as much as I need him to but, he won't hold my hand all the way through something.

As for the Pipe and Carb, I will be ordering a Pipe from Aaen. My friend has a stack of carbs that is almost as tall as me that are off stock machines that he has built for racing. I can ruit through there and have anything I want. Alot of them are off brand new wheelers. As for the clutching, I've already been doing that for a few years and right now I'm lacking the engine performance to make it any better.

I am interested in what any of you have to say about cutting my intake port. However, I'm not going to sit here for days and hope someone responds. I think I know what I'm going to do.(Whether it will be right or wrong, I can't be completally sure of until I'm done) Besides, knowone knows something until they learn it. And what better way to learn than to ask questions and just do it. I don't want to ruin a $400 piece but if I do, then I'll have to buy another one. And before I port it I'll ask more questions.

So, if anyone has any helpful suggestions, I'm all EARS. I don't mean to sound like I don't want any help but, I'm not going to sit around and wait for someone to help me. Believe me, I don't have anything else better to do anyway. I just get really bored sitting here all day, day after day, wishing that my wheeler would run a little better.

 

I have a price quote from Mickey Dunlap at 4 Stroke Tech, $250... That's for a 5-valve Grizz head. I couldn't bare the thought of f%$#@!g up my head!!! Elroy I hope it works out well for ya! Myself, I've used diegrinders alot where I work, I just don't have the knads to touch the head...

Tony

 

Well, I finished putting my motor together tonight and went for a small test flight before I had it all put together. All I can say is "WOW" what a difference. I still have to pull the head of again because I want to get a little more shaved off. I had it shaved once already put I was a little too concervative.

As for my little test flight, all I got to do was put it in a straight line and nail it. It accelerated like it was going staight down hill, of course this was after I got it to stop spinning. I then turned around and did it again. After I got back to where I started from, I cut the wheel hard to the right, punched it and nearly went out of control spinning and sliding from side to side. I decided to go back to shed. On my way past the kids, I punched it again as I came up over a little curb and the thing shoot straight up in the air scaring the poop out of me.

I can't wait till monday so I can get my head shaved down a little more. As for tomorrow, I will have to do a little more riding just because it gives me a woody.

My outcome from my first port job? So far, I have to say, a big success. I have to thank two people who actually helped me acomplish this, one is my good friend at Hetrick Racing and the other is a smart person who watches over us all on this board, Rick Ritter. I'll let you all know how it turns out after I get my head shaved more. Until then YEEHAA!

 

How much have you taken from the head already ?

How much compression do you have ?

How much clearance do you have between piston crown and head ?

What kind of gas do you use ?

Yea ,,,, I am nosey ..

 

<< How much have you taken from the head already ?

How much compression do you have ?

How much clearance do you have between piston crown and head ?

What kind of gas do you use ?

Yea ,,,, I am nosey .. >>




I've taken .040&quot; off the head, so far.

125# compression.

I have .070&quot; piston clearance.(Started out with .110&quot; clearance.)

I run only 93 octane.

I plan on taking another .020&quot;-.030&quot; off the head. I want to be in the 150#-160# compression area. I should have no problem running 93 octane in this compression area.

I must say, I have learned alot about porting. My first port job I feel was a success. However, their are a couple of things I will do differently next time.

 

I wouldn't get the clearance tighter than .050&quot; .
I am suprised the compression is so low after taking .040&quot; off already .