gs1100 head porting at home.

[motocycle shawn]

any one have any info in head porting at home?
i want to port my own head but i know theres alot of math to it.
and how much would my gain's be .
i have a spare head i can do this on and all the tools to port and polish but not sure if i do it i will ever be able to tune the bike ,

any info would be great

[rapidray]

Shawn, the easiest way to learn is to have a SAMPLE to duplicate so you don't trash something learning. I just sent a 1000 8 valve head back to RCP that I did 1 port on so he could learn & do the rest. If you want, I will give you the same deal I did him. Send me the head you want done & I will do 1 port , intake & exhaust, along with the chamber for a hundred bucks + shipping back to you. I also did a valve job on his which really needs to be done before the porting as it is the guide for where to port to. The valve job on a 16 vave head is 225. Let me know if you're interested. Ray.

[posplayr]

So how do you balance the flow that way? Seems like you should do all the ports on the flow bench Ray.

My head from Terry, has significantly less bar buzz once balanced

[rapidray]

That would be up to him, now wouldn't it Jim? Ray.

[Nessism]

I ported my 1000 head using a rat tail file. Just kidding, it wasn't really porting but the file did a great job of knocking off the sharp transition between the machined valve seat area and the port on the short side radius. Quite honestly, I'd recommend against porting anything unless you have some knowledge. Smooth out the sharp edge on the short side radius, and smooth out any crappy casting flaws and call it a day.

[trippivot]

Do you want to flow 1 big bowling ball or 100 bb's down your port?

this is a real head porting question.

low lift flow improvements that increase intake velocity are what you want. just a bigger tunnel is not the answer!!

Just a good valve job can increase 5~8 C.F.M. on a gs 2 valve or 8~12 on a 16 valve

exhaust side has no power improvements after it flows over 60% of the intake flow number. don't touch the exhaust side.

grinding away at your head is risky business friends.

do not send your head to a no namer
do not ruin your own heads.
no one is going to match 3 ports to a demo.
most all ported heads make your bike slower

I have a real flow bench. I know. but it is up to you

PM me if you want info on pricing for porting. NHRA proven in div 5 div 2 div 3 IHRA and AMA pro star, legend cars, Dwarf cars, and 3/4 midgets -- Klemme Performance Motorcycles. look it up.

[nufnuf]

may like to read this.http://mototuneusa.com/homework.htm

[rapidray]

I run my flowbench on average about 10-15 hours a week. Lately a little less but as far as the GS heads I do, I am NOT going to send a PRO STOCK head out to someone to try to match 3 other ports to. The GS1000 head I sent to RCP he will have NO problem matching the 3 remaining ports to as most of the work is in the bowl area, blending the seats to the port. I did a port for him that will INCREASE low lift port velocity in his motor & increase airflow about 13 cfm. The bigger intake valves & back cutting the exhaust valves, along with the porting, actually brought the head up 19 cfm over stock. He will be able to get all the ports within 2-3 cfm of each other easily as he is not a YAHOO with a hogging bit. I think Shawn could do the same thing if he doesn't try to "improve" what I send him. Would it be better if these guys had flowbenches to be able to match all 4 ports airflow? Yes, but it's NOT a perfect world is it? They would also need the velocity probes I use more so than just measuring the airflow. Ray.

[rcp]

I'll provide a write-up and some photos as I get through porting the other cylinders on the head that Ray did for me. Tentatively I plan to start on the next week - but I've first got to finish pulling some GS1000G transmission and secondary-drive parts for jmlcolorado, and also finish cleaning up the jury-rigged repairs to crash damage from my first race round.

I think there's some principles to respect here:

- Horses for courses: street, drag, roadrace? Know what you're looking for beforehand. I'm my case I was looking for an engine with broad, rider-friendly power in midrange and top-end. This is probably appropriate for a street bike, which I believe your is Shawn, right?

- Saving money isn't worth it, IMO: I can't see where DIY porting makes sense if you're just looking for more power. More bang for buck from having a pro do it. It makes sense when you're looking to build skills and knowledge. I think Shawn, since you're asking, and the first questions aren't about money, that it may be worth it to you for the experience.

- Everybody starts somewhere: ignorant, inexperienced and equipment-less is where I was in February. I'm a bit better than that now.

- Do your research: porting is scary - you're taking a grinder to perfectly good parts and potentially ruining them. I think you want to have an idea what you're doing (again, know what you're looking for) before you tackle it. Porting seems to attract more disagreement than any other hot-rodding technique. I started with two books: "Superbike Preparation" by Jewel Hendriks (out of print, but available used through Amazon, and strangely, at my local library) and "Sportbike Performance Handbook" by Kevin Cameron. Both will give you an idea of what's involved, but the Hendriks is good for the hands-on process. Neither will tell you "do this to make a fast Suzuki GS". Be wary of car info - car intake seem to be manufactured to a much, much lower state of tune, and car stuff reports gains to be made by "hogging things out".

- It's your stuff: do what you want with it. It's a shame to ruin parts or make things worse, but old, commonly available bikes free you to try things you couldn't afford to do on rare or expensive ones.

That's all the advice I can currently provide - I should know more soon - hopefully before the family vacation that then leads into race round 2.

I've currently got no means, other than a kitchen sink sprayer, of measuring performance compared of one port to another. I may rig a manometer/shop-vac for measuring pressure, but I'll have no way of measuring CFM. Nearest flow-bench is a car guy an hour and a half away. If I keep at this, I may look at some of the DIY flow-bench equipment that's available. In the mean time, I'm not going to worry about it.

- Richard

PS. Ray's right, I'm "not a YAHOO with a hogging bit". I'm a hoser :-)

[49er]

may like to read this.http://mototuneusa.com/homework.htm

A very interesting concept,thinking outside the square? A valuable attribute, or crazy ill conceived notions?.

I used the same radical approach on my last Mazda rotary project ('89). Considerably smaller than stock primary/side ports combined with additional peripheral porting produced a very broad torque range, with generous top end performance. This triple swirl chamber design hadn't been tried before. A custom manifold allowed the staging of 2 side draft Dellorto carbs, which really enhanced this setup.



IMO, the earlier small port '79 GS850 heads produce better torque than the later heads with the larger CV carbs.

One thing that wasn't mentioned in Motorman's article was the effects of over carburation. That too, causes huge losses in port velocity/fuel atomisation on road machines, when mismatching has occurred.
CV styled carbs mask this tendency, while reputedly giving greater performance up top. Yeah, right!