Going ham! Advice?

[Guest]

Alright, I just bought myself a modified 1978 GS550E. To my benefit, the few chassis mods has turned the machine into a slightly more agile machine over stock. New rear shocks, re-spoked wheels, Bridgestone Battleax tires, new brakes and chain. Style is more streetfighter than café and I want to keep going in that direction.

I really intended this to be a project bike and as soon as a clear a space out to work on it I intend to do some upgrades and overhauls. With that in mind, I'm going to float around a few general questions for some topics I've never explored before.

Does anyone know of a successful front end swap on a 550E?

Fuel injection. Should I even consider?

A top-end swap or a larger motor is too generic, and 45 HP is simply not enough. These two valves are obviously over-engineered, but how well do these engines handle boost? (Yes, seriously.)

[Steve]

First of all,

You have some interesting questions, but you may not like some of the answers.

I will give you what I can.

Does anyone know of a successful front end swap on a 550E?

You might have to be a bit more specific. The 550E already came with dual disks, didn't it?

You looking for larger diameter? Upside down? What???

Fuel injection. Should I even consider?

Only if you are a masochist. Click HERE to see what another member has gone through to put fuel injection on his 1000. Be prepared to spend a while there, there are 354 posts in that thread.
If you click HERE, you will see the results of a search for "injection" in the thread titles only. That will show you what others have asked about the same topic. Happy reading.

A top-end swap or a larger motor is too generic, and 45 HP is simply not enough.

You must be shooting for the moon here, but you should at least know that your starting point is 49 ponies, not 45.
A 650 top end is a basic bolt-on that will raise that to just over 60 hp.

These two valves are obviously over-engineered, but how well do these engines handle boost? (Yes, seriously.)

Consider that Suzuki put a turbo on the 650 for a couple of years and ask that question again.
Of course, they did a few modifications, but the basic engine is pretty much the same. The compression ratio was lowered and a few other things were changed around, but it took the stock 62 hp up to 85, so they called it the XN85. You would have to find a turbo small enough to work with your little engine (the do exist, though) and it will take a bunch of project time to install it and get it right. In the end, you WILL have a unique bike, hopefully you will find it worthwhile.


And please explain "going ham".

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[nightfighter]

Haha. "Going ham" is merely and eye-catching phrase. I suppose I meant eventual all- out modification. I am completely new to the GS line and should be more specific.

"Front-end" meaning forks from another bike and the associated brakes (if any good) I've just dug around a bit and apparently some GS can accept GSX(R?) forks. Just looking for something that'll quicken up the steering a bit.

"Boost"
More like what are the weakest internal components? First to go?

The previous owner claimed around 40-45 HP. I am the fourth owner and apparently the first owner had it sitting for a while. I'll have to contact the second owner to get a full list of mods as all I'm aware of are the ones the third owner did.

The only reason I bring up FI other than some fun tinkering (I read that huge thread, his setup is almost Frankenstein-ish) is that FI might work better with a blow-through forced-induction setup. Forced induction sees negative and positive pressure at the manifold (correct?) which might be a problem with a fuel source that essentially requires suction.

[tkent02]

"Boost"
More like what are the weakest internal components? First to go?

On a 550? Nothing goes.

Pump it up until it does and then tell us.

[GSX1000E]

Making your little 550 into a 650 will get you close to 73 HP (not 60) and is well worth the effort... http://www.suzukicycles.org/GS-series/GS650.shtml
tkent is doing just that currently and perhaps you can find his thread in projects/rebuilds section.

[nightfighter]

Assuming I go the "no replacement for displacement" route over the "moar boost" route, shouldn't I do a 650 running 550 cams considering the GS550 had a more extreme cam profile? What would that do, like 80 something HP?

[nightfighter]

On a 550? Nothing goes.

Pump it up until it does and then tell us.

Ha, and waste a good engine. Not even the conrods or the crank?? Obviously the block is ridiculously overbuilt, I've seen it.

[tkent02]

Ha, and waste a good engine. Not even the conrods or the crank?? Obviously the block is ridiculously overbuilt, I've seen it.

Go for it.

[Steve]

Making your little 550 into a 650 will get you close to 73 HP (not 60) and is well worth the effort...

My bad, not sure what I was thinking of.

The stock 650 had about 73, as mentioned, and the 850 had a whopping 78.

I should know those two numbers, as those are two of the GSes we have in the stable. For only having 5 hp more, the extra 80 or so pounds really slows the 850 down. The 650 was actually the little pocket rocket of its day, with relatively light weight and plenty of power. However, most of them had shaft drive (a good thing, in my book) and a five-speed gearbox. With your lighter chain-drive and a six-speed (and a few fewer pounds), it would be even better.

Just in case you have not read up on turbo systems on bikes, most of them are a draw-through system. That puts a single carb on the intake side of the turbo, which then blows the mixture into a manifold that feeds all the cylinders. Very easy to set up, but if you get the mixture wrong, ... well, please post some pictures, they should be VERY interesting.

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[nightfighter]

Boost

Just in case you have not read up on turbo systems on bikes, most of them are a draw-through system. That puts a single carb on the intake side of the turbo, which then blows the mixture into a manifold that feeds all the cylinders. Very easy to set up, but if you get the mixture wrong, ...
.

I was thinking more along the lines of a centrifugal supercharger, just for the sake of throttle response and getting a linear power-band without doing a ton of tuning. Probably would do a draw-through for that setup. Course I would have to cut up the gearbox.

[JTGS850GL]

Fuel injection makes boosting much easier. No draw through issues and add programmability to the equation and you can have all kinds of fun. Lots of fabrication is in order but hay… Isn’t that what a project is all about?

A few years back I did a turbo charged, Haltech E6K programmable fuel injected Datsun 240Z that put down 384HP and 425 ft/lbs of torque during the dyno tuning session. Wicked car since it only weighed in at about 2350 lbs. A turbo or super charged 650 with programmable fuel injection would be a fun machine.

[Wraith]

I've played around with gs550 for years. Putting the gs650 top end on it helps a lot. Port the head, put some 400 bandit/gsxr400 carbs on (works well was looking at some gsxr750 watercooled carbs on but that needs some work).
Or remove the gs motor and put a gsxr/gsxf750 motor in there
GSXR front ends fit and the 600 Bandit rear end goes straight in, and either have the swing arm made into twin shock or monoshock the frame.