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:dunnoany ever tried to put a 600 head on a 750 bottom end
 

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Spunk Gargling Knob Gobbling Squid
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I am not positive but I believe that the main difference in a 600 and 750 are the heads. Might be wrong but I believe the bottom ends are the same. At least the engine parts I have looked up are the same.:dunno
 

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i am pretty sure your right about that mate i am 99% sure the casings are the same the 750 just has a differant crank barrels and pistons and head but my thinking behind the swap is that the 600 has a smaller combustion chamber therefore it will increase combustion by adding the 600 head giving a massive power hike i just wonder about the timing
 

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I'm pretty sure it won't work. Isn't the cylinder height/ head height different? I would also think the valves are smaller as well.
 

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I am pretty sure it will work. Not sure which cam chain to use to keep it in time, would have to use a platiguage or soldering wire to check piston to valve clearance, would recommend adjustable cam sprockets with press on retainers. If I remember right it does make a little more power. Would want to make sure your big end bearings were in good shape before you stress them any more.
 

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It is a direct swap.
The head has smaller porting and you will need to use the intake manifolds from the 750. You SHOULD match the port size on the head to the 750 manifolds.
The amount of POWER you make is not more then 3-4hp. BUT, the power curve is SOOO much more smooth across the RPM range.

John
 

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No problem with what you said john, but are you telling me that YOU wouldn't check piston clearance on assembly?

Also.... you would use the 600 cams? and the 600 cams have appropriate lift and timing? and the 600 cam gears have the same number of teeth with the same spacing....are the cam chains the same? So the crank/cam turn ratio is the same?
If I remember exhaust flange size and spacing is the same so that is no problem.
Yes I would certainly match intake manifold, port size as with any motor.
 

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The cams have the same timing. Many people have swapped the 750 cams into the 600 head for a little extra lift.

The cams are a direct swap, the deck height does not change with changing the head (I did confirm when I did the swap that the piston to valve clearance was in spec, tho I do not remember the number I turned out). Since the profiles on the head are the same when it comes to valve length, cam to deck height, and cam timing, there is really very little that would be out of spec with this swap.

I run the 750 cams in the 600 head to get the little extra lift.
The motor was stock other then a pipe and filter. We did a dyno run before the swap and the bike make a peak HP of 120. Had a HUGE dip in the 8K range.
After the swap, matching the ports to the intake, running a 600 head with 750 cams, the peak HP was 121 but the midrange was MUCH stronger (by near 4HP across the range) and the huge dip was all but gone.

I would not rush out and buy a 600 head for my bike, but if I needed to get a new head, I wouldnt mind having one from a 600... :)

John
 

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I used 600 head in 750 engine, it worked so good. I timed it like 600 (I used full 600 head) , it worked fast. After 1000km i opened the engine , result - without problems. I used the 99 and more octane fuel. for example Shell v-power. The only problem was the very big compression. That is the reason why I used the high octane fuel. When the engine was hot the starter cant start up the engine (it seemed like battery off) , that was the problem on petrol station . I took fuel , paid for it and needed to wait for about 2-5 minutes for take down the engine temperature. After it it started normally. I used the 750 head gasket. This modification produces + 12-15hp . But the problem I didnt think about its the combushion chamber in head. 600 have smaller of course :) and there is the problem with sharp edge. If somebody resolve this problem this engine gain about +17 or more hp.
 

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iv been really tempted by this for a long while now aswell

just wondering tho, say you do the thou swap could the same work with a 750 or 600 head on a 1000?
 

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Dyno addict!
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Bob Farnham did some motors in this vein some time ago, using a 600 bottom half, coupled to a 750 barrels/pistons/head etc. It resulted in a torquey motor of 700ish cc's. No real gains in raw horses, pretty much between a 600 and a 750 but very tractible.
What I'm not getting is where the alledged gains are coming from with the 600 head on a 750 motor though. If the 600 runs a smaller port, then that will move power lower in the revs, as GSXR-Freak says, and maybe pick 1 or 2hp up from a (much) higher compression ratio.
Ultimately, when tuning a head, you enlarge the ports, which allows better flow at higher rpm's. What you sacrifice is low speed (engine) performance. So moving to a head from a smaller engine will do the exact opposite of what the conventional tuning route leads us to. A head for a fast road motor will have smaller ports than a motor built for out and out race use, to keep the gas speeds up in the port, to aid low rpm power.
If 15hp is on the table for a 750 from a head swap, I'll take the Yoshi cams and flowed head off and throw a stock 600 head on and save myself all the hassle...................:scratch
 

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I have to disagree with any substantial gains, should only be 1-3 HP at most, and only in the midrange at the expense of upper rpm....
 

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Like I said guys, we didnt really see any large max power gain. What we DID see was a much better curve. I wish I had a scanner back then so I could have kept a copy of the printouts from before and after. The HP gain was nothing to speak up cause the dyno was not ran back to back on the same day or even the same dyno (same type of dyno just not the same shop). The big change was that the power curve was almost perfect with no other changes.
No more large drops in power in the mid range and this made the bike VERY nice to ride.

Anyhow, I wouldnt go buy a head just because, but if I had to replace a head, I wouldnt mind a 600 on my 750 motor.

John
 

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Dyno addict!
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John, have you ever experimented with crankcase porting? You touched on the subject on the breather thread, in that you looked at positive and negative crankcase pressures, but how about allowing the air to move around more freely?
Some motors have inter-cylinder holes at the bottom of the barrels, which I guess is for the self same reason, so am wondering if there's anything to be had in the SRAD motor. Even if it just allows the thing to spin up a little more freely.......
Daz.
 

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Bob Farnham did some motors in this vein some time ago, using a 600 bottom half, coupled to a 750 barrels/pistons/head etc. It resulted in a torquey motor of 700ish cc's. No real gains in raw horses, pretty much between a 600 and a 750 but very tractible.
What I'm not getting is where the alledged gains are coming from with the 600 head on a 750 motor though. If the 600 runs a smaller port, then that will move power lower in the revs, as GSXR-Freak says, and maybe pick 1 or 2hp up from a (much) higher compression ratio.
Ultimately, when tuning a head, you enlarge the ports, which allows better flow at higher rpm's. What you sacrifice is low speed (engine) performance. So moving to a head from a smaller engine will do the exact opposite of what the conventional tuning route leads us to. A head for a fast road motor will have smaller ports than a motor built for out and out race use, to keep the gas speeds up in the port, to aid low rpm power.
If 15hp is on the table for a 750 from a head swap, I'll take the Yoshi cams and flowed head off and throw a stock 600 head on and save myself all the hassle...................:scratch
Darren, just to help you out, I'll even pay for the shipping of those shitty Yosh cams and the useless flowed head to Australia, and dispose of them for you... LOL
Cheers, Ad
 

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I have not tried to do any porting on the cases. I try to keep the motor as close to OE parts as I can since I do not have the large amounts of funds to keep rebuilding as learn the hard way. lol

I do agree about the porting in the lower end, it COULD help things spin up a bit more quickly. But I would be more interested in a Polished crank with knife edging.

John
 
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