head porting and timing key

[Chet]

Fro those who have some time with he Sparks timing key, does this mod take away any top end power or over rev. and as for the riders who has had their head ported, was any combustion chamber mods done like raising compression,ect. does anyone have any pics of a Honda 400ex exhaust ports after it was ported. does a ported head make any noticeable gains in power with a stock cylinder and piston.

Chet

Originally posted by Chet
Fro those who have some time with he Sparks timing key, does this mod take away any top end power or over rev. and as for the riders who has had their head ported, was any combustion chamber mods done like raising compression,ect. does anyone have any pics of a Honda 400ex exhaust ports after it was ported. does a ported head make any noticeable gains in power with a stock cylinder and piston.

Chet

If anything I think the Sparks key added MORE top end then bottom end. Retarding the timing creates more low-end.

But im ok with that, i love top end power.

advancing the timing 6 degrees kind of creates an all around power gain. You deffinately dont loose bottom end it has much more snap mostly to the more instant throttle feel. It does give more mid and top end too. Anytime the rev limiter is increased usually they will advance the timing so it will keep pulling past where power usually drops off. I am really curious to see the 6 degree advance on a dyno just to see how much is gained and how the power curve changed

[Honda#4]

Here'ss my ported head pics

Intake

[Honda#4]

Exhaust

[leasureryan]

and you are not supposed to use the advance key with high compression....

[CSR400EX]

11:1 compression or lower works with the advance key. i built a 416 for a friend of mine with a 11:1 piston, timing key, stage 1 hotcam, ported head, yosh exhaust. i have to say it impressed me for a 400. it could probably keep up with a stock to mild 450 depending on the rider and conditions.

[sc400ex_rider]

sparks told me i could use the key with my 11 to 1 comp piston. to them high comp was 12.5 to 1.......... i have posted that on here several times. also if you have a question about a product it best to call the manufacturer.

[blankenship]

Originally posted by Honda#4
Here'ss my ported head pics

Intake


hey did you do this porting your self? is it even possible to port and polish your self

[Honda#4]

No i didnt do my porting I let a pro do that, porting isnt something i'd try on my own cuz it takes alot of know how to do something like that, best to leave it to a pro.

[dariusld]

Originally posted by Honda#4
No i didnt do my porting I let a pro do that, porting isnt something i'd try on my own cuz it takes alot of know how to do something like that, best to leave it to a pro.


Originally posted by blankenship
hey did you do this porting your self? is it even possible to port and polish your self

I did my own porting and I'm not an expert. I didn't do all the things the pros do but I have ran similiar modified bikes and easily pull away. I didn't go real deep into the ports and didn't go real big, but definitely opened up the ports.

The ports above look like mine, but the exhaust ports came out more polished than mine.

[dariusld]

Found an old thread.


Originally posted by dariusld
I did my own port and polish. When I took the engine apart to put in a new piston and cam,I figured what the hell. I thought if I don't go to wild, I won't hurt anything. First thing I did was to smooth out the casting flaws. On the intake and exhaust ports, there is a line going down the sides, I ground those down smoooth with the rest of the port. I was a little more aggressive with the exhaust ports than the intake. On both I tried to grind the spots that didn't give me a straight shot into the cylinder. I wanted a straight line in, as much as possiable.You want to match the port side with the exhaust manifold or intake manifold. If you go bigger than that, you will get a leak. On the exhaust side I just etched inside the exhaust gasket, took the old gaskets off and grinded down to those marks. They say you should go about an inch in. On the intake side I just started grinding down any humps in the port. Then I put the intake manifold on to see if it was a smooth transition, from manifold to the port. I did this a couple times before it was a smooth entry. The final steps was to polish the exhaust side. I didn't spend alot of time here. I didn't polish the intake at all. They say you shouldn't. I don't know if my port and polish made a differrence, positive or negative, but it was free. I love free. I'm not saying this is what you should do, I'm just telling you what I did. I don't think a port polish will help as much, if you don't have a cam.

[Honda#4]

Im sure you have the tools to do it from your last post you sound like you've done this a few times before, but for the average rider I dont quite think it's something you wanna just go out and do on your own. Usually I do alot of the stuff on my quad by myself but theres certain things i'd be more comfortable having a pro do, but thats just me.

My 2 bits worth

[brian76708]

yea porting is something that needs to be left up to the professionals you can make it worse by trying to do it yourself.

[drillteamleader]

Do you have any pics of that head with the valves out so people can see what is done in the valve seat area?

[Honda#4]

Unfortunetly I dont cuz I sent the whole head in, Sorry.