qt50 exhaust porting

I want to grind out the exhaust port on my qt50. I have a spare cylinder to practice on so I don't screw up the one that's on the bike already. I have a Dremel but I just need to know the best bit to use so I don't damage it.

Re: qt50 exhaust porting

Jack Rutherford /

you're probably better off grinding down the exhaust side of the piston a couple mm. It's softer and easier to work. I think there are examples posted on this site for different bikes but same idea. If you screw up, a new piston is $20 or so. The softer metal will open up your choice of bits quite a bit as well.

Re: qt50 exhaust porting

i like the pinapple double cut burr off ebay. the cheepies r fine.

Re: qt50 exhaust porting

> Joe Mama Wrote:

> -------------------------------------------------------

> I want to grind out the exhaust port on my qt50. I have a spare cylinder

> to practice on so I don't screw up the one that's on the bike already. I

> have a Dremel but I just need to know the best bit to use so I don't

> damage it.

I never used a practice one... just draw the part you want to cut in sharpie marker and grind it slowly until the marker is gone. Then use sandpaper to chanfer the ports you cut.

Search porting on here lots of ideas and info.

Re: qt50 exhaust porting

I find that the double cut carbides tend to chip the cylinder plating more.

Power tools for everything but the last half millimeter then a little sanding discs and hand work.

Re: qt50 exhaust porting

Brandon Weiss (Detective brandon to you) /

> Sean Ruggles Wrote:

> -------------------------------------------------------

> I find that the double cut carbides tend to chip the cylinder plating

> more.

>

> Power tools for everything but the last half millimeter then a little

> sanding discs and hand work.

True, but i think a stock QT cylinder is cast iron. One of the reasons i love cast iron...no plating to worry about.

Re: qt50 exhaust porting

Jack Rutherford /

And here's your dinner:

All the bits you need and you can find them at ccspecialty

Follow his instructions and you should be fine. You can probably go 2mm easily when you raise the exhaust port on the qt. Or you can go 1mm and then run it and see and go more later.(edited)

Re: qt50 exhaust porting

thanks guys!! I got it done i'll post pics in a little while. I also soaked it in simple green sanded the shit out of the outside and painted the whole thing with high temperature paint good up to 2,000 degrees (I taped everything that shouldn't have been painted off) it looks really good I just need to clean it up and rub some 2 stroke oil so it wont get nasty again. its getting cold up here in Massachusetts so I'm probably going to take the old cylinder off and put the painted one on.

Re: qt50 exhaust porting

Jack Rutherford /

pics?

Re: qt50 exhaust porting

Here's the pic I think I could have done more but for my first time I think it looks ok. let me know if I can widen it further. I also sanded down the rough edges of all the ports.

IMG_E2664.JPG

Re: qt50 exhaust porting

Jack Rutherford /

what did you do to the port where it meets the cylinder chamber?

Re: qt50 exhaust porting

I took some really fine grit sandpaper and smoothed out the edges being careful not to damage the chamber. If I did it wrong let me know it’s an extra practice cylinder any input is appreciated

Re: qt50 exhaust porting

Jack Rutherford /

I'm just wondering if you raised the exhaust port at all. You can usually do so at least a couple mm without issue. You'll lose a little low end. You can also widen the exhaust port slightly without so much hit on low end. If you watched those Ken O'connor videos and followed them, you're right on track.

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