PORTING, Does it really help or is it all BS???

[Silvermachine81]

Im going back to a stock GS1100 head (but I might fit 1mm oversize valves).
I cant afford to get it ported (Because I have to buy valves for it....) and am wondering if anyone here actually has proof that porting has done anything 'dramatic' to their dyno results.

I know that bigger valves will help as will slightly higher lift/longer duration cams but doesnt porting just give you more at redline and stuffs up your mids?

Ive seen plenty of guys with good horsepower and arm pulling torque without any porting done..........

[SqDancerLynn1]

IF it is a street bike their is not that much benefit, unless tou are doing pistons & cams. Not worth the money unless the valves need to be replaced anyway. Even then You loose on the low end to gain in the upper rpm range. The rest of the engine needs to be able to use the extra air flow It becomes an endless cycle

[Silvermachine81]

This will be its configeration......

Mikuni VM 36mm Roundslides, 348 webcams, 1134 wiseco kit, Star Racing Street Sidewinder pipe, Dyna pickup/dyna coils.

I just want a bit more up top (from the cams and 4'n'1) but keep those awesome mids that make the old GS1100 motor so much fun.

I dont need the top end squirt and no mids usually caused by head work.....

I think when you wander into most porting shops and say "I'd like you to tidy up the ports and make it flow a little better, It's only gonna be used on the road and it redlines at 9000 rpm so please dont go overboard.........."
They think you said "Please make my engine have 1 million horsepower and only have power between 10000 and 15000 rpm"

:roll:

[scotty]

This will be its configeration......

Mikuni VM 36mm Roundslides, 348 webcams, 1134 wiseco kit, Star Racing Street Sidewinder pipe, Dyna pickup/dyna coils.

I just want a bit more up top (from the cams and 4'n'1) but keep those awesome mids that make the old GS1100 motor so much fun.

I dont need the top end squirt and no mids usually caused by head work.....

I think when you wander into most porting shops and say "I'd like you to tidy up the ports and make it flow a little better, It's only gonna be used on the road and it redlines at 9000 rpm so please dont go overboard.........."
They think you said "Please make my engine have 1 million horsepower and only have power between 10000 and 15000 rpm"

:roll:

are you saying that with those mods, the portying didnt turn out the way you expected it???

[Silvermachine81]

Yep.

I just wanna keep the velocity up now.

I can remember one guy posting his dyno figures (From the same dyno) and he had really good power, I think it was like 130 RWHP.

He made 2 more drastic changes to the engine (one was porting, cant remember what the other one was) and he got about an extra 3 horse's IIRC??, Where you would have expected an extra 7-10%!!!!!!

The sums dont add up $$ wise or powerwise............

[scotty]

well once you are up there with horse power and mods, the gains get much smaller for each $$ you spend.
Maybe you need a set of smaller but more eficient carbs for what you want.

[Robert Corrie]

My 83 1100e is punched out to 1260 with a mild port job,Web g3 cams, coils, 33 mm smoothbores and a falicon supercrank. At 3 grand if I twist the throttle, all you see is a Blue Streak. It just wants "TO GO"!!

[lecroy]

Yes, anything to increase VE including porting will help.

[Silvermachine81]

well once you are up there with horse power and mods, the gains get much smaller for each $$ you spend.
Maybe you need a set of smaller but more eficient carbs for what you want.

I think the guy had RS carbs, stock head, cams, 1260 kit & pipe and had something like 130rwhp.
Then he went out to 1327 and got some porting done and got an extra 3 HP.
That just doesnt add up, something must have added power while the other one took some away....

I think just doing a tidy up would help but there are too many butchers out there or 'experts' who claim to know all.

I'm just saying good heads are becoming increasingly rare and you cant put the aluminium back again.....

[Silvermachine81]

My 83 1100e is punched out to 1260 with a mild port job,Web g3 cams, coils, 33 mm smoothbores and a falicon supercrank. At 3 grand if I twist the throttle, all you see is a Blue Streak. It just wants "TO GO"!!

My 36mm VM's are basically smoothbores (I think).
I used to have Flatslide RS 38's but they were just too big.

Everyone keeps telling me how awesome those 33's are for GS's but I cant find any, except on eBay for silly money........
Smart people must be holding on to them

[Hoomgar]

Everyone keeps telling me how awesome those 33's are for GS's but I cant find any, except on eBay for silly money........
Smart people must be holding on to them

There is a set for sale right here in the parts for sale section.
The seller is reputable. I just bought a set off him two months ago.

http://www.thegsresources.com/_forum/viewtopic.php?t=32652

[Anonymous]

OR

If you really want a lot of torque and about 200 HP go with a Turbo. I bought a used Mr. Turbo kit off of Dragbike.com for $1000 dollars, bolted it on a stock 83 1100ES and was kicking butt. It would lift the front tire with a roll on at over 80 MPH. 9.70's in the 1/4 mile. It was very fun to ride.

[Dink]

I agree that porting is not worth the money, unless you can do it yourself. I also think that oversize valves are a waste of time and truely excellent way to seperate you and your money You would be better served to be certain that jetting is " spot on" carb balance is perfect, that cam degreeing is set up to best effect. Have all those things "just so" and you will get best performance out of your GSX motor.
Dink

[Silvermachine81]

The oversize valve thing is because I have a brand new head still in the box (BWAHAHAHAHAHAHAHA!!!!) with no valves.
Ive got 8 x new intake valves but thought since I have to buy 8 x exhaust I might as well just up the to GS1150 sizes (GSX1135 to us Australasians ) as that bike had possibly the best and smoothest power curve of any bike ever.

I think they had that motor just about perfect so why not go to that size.
Aftermarket valves are quite cheap when compared to stock so it sorta makes sense doesnt it?

[Anonymous]

I know that bigger valves will help as will slightly higher lift/longer duration cams but doesnt porting just give you more at redline and stuffs up your mids?

Not necessarily, but porting is such a big area that it can be good or bad. What you are looking for is something like Motoman's high velocity porting:

http://mototuneusa.com/thanx.htm

Look at the high velocity porting articles for the idea. It will not trash your bottom end or midrange and you get a nice 5-8% gain everywhere. That is a good thing.

From the sound of it, what you need is a simple clean up job, which you can do yourself. Starting with the intake boots, make sure everything lines up with no sharp edges anywhere (this is akin to matching gaskets to the ports on a car motor). You want to clean out all of the little lips and edges that get there through production issues and impede flow. Then take a Dremel tool and a sanding drum and clean up the intake ports of all the casting flaws and the like. Do not remove the port walls, just the flash and junk left over from casting. If you are really ambitious, you could then bead blast the intake for a nice matte surface finish. Then STOP. That is enough. For the exhaust, you do the same except you leave a nice shiny finish on the port walls after the clean up. Again, remove no port material at all, just the casting junk and that is it. For your goals, you do not want bigger ports at all, just an optimized stock arrangement.

You would be better served to be certain that jetting is " spot on" carb balance is perfect, that cam degreeing is set up to best effect. Have all those things "just so" and you will get best performance out of your GSX motor.

Dink is right. You can gain quite a lot by making sure all the variables are as close as possible. You also want to be sure to degree your cams in to match the pipe and any intake mods. You will find a big improvement by balancing everything to work at the same RPM range. Having your intake come in at 4000rpm, the exhaust at 6500rpm and the cams at 7500rpm will not give you a satisfying motor.

Mark