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Another Porting Thread

  • Thread starter Thread starter Silvermachine81
  • Start date Start date
S

Silvermachine81

Guest
O.K, I bought an ex-drag race 1100 4V head thats previously run 8.80 for my 1134 (10.5 to 1) kitted Kat.
I'll be running web-cam 348's with 36mm Roundslide Carbs and a Star Racing Street Sidewinder pipe, but the bike is strictly for road use and perhaps the odd run down the strip.

Would a head thats been massively ported for drag use still maintain good street manners if the engine its straped to is in a low enough state of tune?
 
The porting would not bother it as much as large carbs and lumpy cams. For street use you really don't want to polish the ports. The small irregularities will keep a bit of turblulence in the airflow that will help keep the fuel vapor suspended. With polished ports (and the lower velocities of street riding), fuel will tend to drop out of suspension and puddle in the ports. You don't have much of a choice here, as it's already done, and you did mention "the engine its straped to is in a low enough state of tune".


.
 
No, They arent polished.
Just a, a little confused because some say larger ports ruin your velocity, But a GS1150 has more power everywhere & its ports & Valves are larger.

Guess I will just have to wait & see..............
 
On my 1100 I've got a Star ported head and Megacycle 355 lift cams with 38mm Radial slides and a Basanni header and my bike (after much tuning) runs like a bat out of hell. Also 1166 overbore. I still get 42 plus mpg. :cool:
 
RobGS850L said:
On my 1100 I've got a Star ported head and Megacycle 355 lift cams with 38mm Radial slides and a Basanni header and my bike (after much tuning) runs like a bat out of hell. Also 1166 overbore. I still get 42 plus mpg. :cool:
Click to expand...


I used to run a mildly ported head, 348's, 38mm RS's with the Star Exhaust.
It was running OK (good bottom and top end but BAD midrange) and I went on a trip with some friends who owned much more modern large capacity sportbikes.
I was the heaviest rider on by FAR the heaviest bike.
I kept up with them except through the tight windies & EVERY fuel stop I was putting in "at least" 20% less fuel than them!!!!!

I put it down to the useable low end powercurve and the ability to rapidly cover great distance's without having the rev the bejesus out of the GS engines.
 
I have noticed that after 4500 rpm it really starts to pull very hard. Great on the freeway but kinda' testy in tight situations where I forget to downshift to get in my powerband. :roll: Before I put in the new parts I'd just let the natural 1100 torque take over. I know now what it feels like to get the front tire at 12 o'clock at will. :shock: What a gas. :cool:
 
Also Rob, if you have round slide smoothbores they are probably 33 MM, not 36s. The 33s would help the bottom end & mid range by upping the vacuum signal with the smaller opening. Plus, if it has stock size valves it will help the port velocity on that small a bore size. If you want it to be a REAL animal, find an 1150 cylinder & make it a 1229! Ray.
 
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rapidray said:
Also Rob, if you have round slide smoothbores they are probably 33 MM, not 36s. The 33s would help the bottom end & mid range buy upping the vacuum signal with the smaller opening. Plus, if it has stock size valves it will help the port velocity on that small a bore size. If you want it to be a REAL animal, find an 1150 cylinder & make it a 1229! Ray.
Click to expand...

No these are 36mm Roundslides (not Smoothbores), I even swapped pics with an owner of some smoothbores and they are different.
I've only ever seen one other set?!?!
 
Silvermachine81 said:
No these are 36mm Roundslides (not Smoothbores), I even swapped pics with an owner of some smoothbores and they are different.
I've only ever seen one other set?!?!
Click to expand...
KOOL! I would like to see them but you live pretty far from me! LOL!!! Ray.
 
Silvermachine81 said:
No these are 36mm Roundslides (not Smoothbores), I even swapped pics with an owner of some smoothbores and they are different.
I've only ever seen one other set?!?!
Click to expand...

We used to make those carbs using 36mm dirt bike Mikunis. Bored them to 37 and reworked them to run on a four stroke. They used a 4 into 1 throttle cable arrangement. Is this what you have? It is no fun trying to keep them in snyc.

Jay
 
O.k, These VM's I talk of are supposedly the ones fitted stock to the New Zealand Homologation Special Wire Wheel Katanas GSX1100SXZ.
Now they are meant to be 33 VM's but mine measure 36mm (probably because im measuring them wrong as arent they not measured via the internal diameter of the spigot, but by the size of where the roundslide sits?!)
The SXZ was a very rare model made for NZ (20 only), for the Castrol 6 Hour race in 1982.
They have racing cams and clutch, Slide carbs, wire wheels, special big bore exhausts, better brake callipers and steel braided brake lines.

Heres a small pic of one below, It's not mine BTW.
 
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Help!!

Help!!

Actually, I could do with some help to Identify these VM carbs.

Spigot I.D is 36mm.
Carb throat is oval (as shown in pics above) and is 36mm high by 29mm wide.
They have "x488 10" stamped on the carb bodies.

The stamped marking is on the side facing the cylinder head and is written like...

x488
10

So are they 33mm or 36mm VM's?
 
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