What kind of porting does this look like?

[dynofox]

What type of porting is going on here?

[Honda 250r 001]

cant tell much with out measurements, or more pics of the exhaust port.

take a simple tape measure and measure the distance from the roof of the exhaust port to the top of the cylinder.

[86 Quad R]

i've never seen the likes of that........ have you ran that cylinder? how'd it run?

[dynofox]

Originally posted by 86 Quad R
i've never seen the likes of that........ have you ran that cylinder? how'd it run?

Looking to possibly buy it but the current owner never used it and bought it already ported. It does look interesting though.

[Honda 250r 001]

Originally posted by dynofox
Looking to possibly buy it but the current owner never used it and bought it already ported. It does look interesting though.

i believe that port thats drilled on the intake is suppose to help something, but i cant remember. i think its top end. The cylinder looks like a mid-top port to me, if i had to guess.

[86 Quad R]

i gotcha..... if its priced right. it worth a shot to see what it's got. :D can ya post a pic down the throat of the exhaust?

[Honda 250r 001]

Originally posted by 86 Quad R
i gotcha..... if its priced right. it worth a shot to see what it's got. :D can ya post a pic down the throat of the exhaust?

yea fulltiltrider told me about this port that macdizzy puts in all his 250r cylinders. the macdizzy port, I think that may be it? Not sure but that cylinder has had some good work it looks like because the exhaust port doesnt look as boxy as a stocker.

how much does this guy want for this cylinder dynofox?

[dynofox]

Originally posted by 86 Quad R
i gotcha..... if its priced right. it worth a shot to see what it's got. :D can ya post a pic down the throat of the exhaust?

I just asked if he could send me some pics of the exhaust throat / port and do some measurements. My riding consists of woods, some of which is tight, wonder if this cylinder would make that type of riding miserable? Will let you know when I get more pics / measurements. :cool:

[86 Quad R]

hard to tell..... if its a high end port then yes you may nawt like it much. could get you hurt in the woods. :huh

[C-LEIGH RACING]

How do you spell the word, exspearamenting.

The holes Rick at Mac Dizzy drills into a cylinder, will be in the top of the reed chamber up through to the bottom of the rear transfer port to aid the boost port in scavaging.
Those holes you can see are drilled just about straight through so the flow would be under the piston.

It could be, who ever drilled those holes in it, knew to get more intake flow down into the crankcase you normaly open up the Boysene ports, but when you do that it takes a bunch of stringht out of the back of those old model cylinders & makes them prone to crack off the back of the cylinder.

Just drilling holes where those are located would add some flow to the crankcase without removing a lot of support.

I've seen those old model cylinders, set up with a lot of compression break off the whole reed chamber area from the high compression trying to blow the top end off the cases.
Neil

[All250R]

You're not going to be able to tell a whole lot about the port job until you spec the cylinder. There's a lot more to it than speculating about port shape and some interesting looking holes drilled in. I could be wrong because I don't have a port map, but he intake looks a bit bigger than stock. It may run like crazy, but could eat up pistons quicker than you're used to. But, again all we can do is speculate.

[dynofox]

The seller said from the roof of the exhaust port to the top of the cylinder is 1 7/8".

[machwon]

Based upon the 1-7/8 it doesnt have much if any porting at all. Pictures are hard to tell, but again doesn't look like any porting to speak of. Here's a pic of the other intake boost ports.

[machwon]

Here's a version I've done for several motors. I've seen no reliabilty issues due to adding these. They just take a lot of time and some guts when holding the tools to do these.

[All250R]

Originally posted by dynofox
The seller said from the roof of the exhaust port to the top of the cylinder is 1 7/8".
The stock barrel is about 1 11/16, or just over 1 5/8, and then if the barrel is decked it's going to be even shorter, so basically there's no way it's 1 7/8.

If you're getting a good deal on the jug, your best bet is to send it in to one of the builders on here you trust to have it spec's and the porting and build finished out. I doubt the ports are stock height, but if they are or close to it you've got a solid starter on where you can choose for rpm to deliver the power. Engines aren't just the porting. You want to go over intake, head and exhaust setup done to match as well. If I were you, if you buy it, send it to a builder to at least have it spec'd to make sure the custom work already done is finished - that alone shouldn't cost much, but if cleanup porting is required, that shouldn't be a lot extra either, but no matter what you want to have it spec'd before you spend the money on a piston and bore, gaskets and your time.