GT550 - is it under-powered for normal day-to-day riding?

[pearljam724]

Sounds like technical problems. When you own one of these bikes. It's very important to become familiar with what causes problems. All very simple things to learn. The number one thing that causes performance problems with these bikes per your quote " under-powered" is the battery. These bikes will not create peak power or run properly with anything less than a battery in very good condition. A lot of people will assume that their battery is good because the battery will start the bike, battery is fairly new or they only test it after charging it. None of this, means squat. You have to test the battery after its been charged and sitting for approximately 24 hrs, when key is turned on, while motor is cranking over and finally when the bike is revving roughly at 3k rpm with the lights on. Just because a battery will start the bike, doesn't mean it's any good. I pulled my hair out every day for a month trying to figure out why my bike refused to run right. Turned out, a battery I just bought a few weeks prior had a dead cell. My bike would start immediately with the bad battery, run fine, then several miles down the road. Leave me stranded because it was " under powered." Replaced battery with another new one and she roared to life. There are a couple mechanical faults that will cause the same symptom. But, without a doubt. The most common is the battery. That fact, will confuse a lot of people. They will often think their battery is good, when it's not. Timing and points are the second most common causing the same symptom. Very easy to address and fix. But, you have to educate yourself.

[GT750Battleship]

+1 on the battery & two strokes,I can feel when something is not "right" more often than not its to do with the condition of the battery !! Replaced lead acid battery a while back,now running a Mottobat,everything fine so far !

Cheers,
Roger

[tz375]

And what we haven't talked about is how much power can be extracted from a GT550 should one feel so inclined. With porting and decent pipes it should be possible to raise power considerably. what is "considerably"?

Stock and new they made around 32 stock new and fully run in and serviced closer to 37 at the rear wheel. That is not a lot, but it's enough to do about 100 MPH. With pipes and mild porting 45-50 should be easy to get to and 60-70 is not beyond reach.

So if you find you need more speed after it's running 100%, start to think in terms of bigger ports and decent pipes..

[Craig380]

And what we haven't talked about is how much power can be extracted from a GT550 should one feel so inclined. With porting and decent pipes it should be possible to raise power considerably. what is "considerably"?

Stock and new they made around 32 stock new and fully run in and serviced closer to 37 at the rear wheel. That is not a lot, but it's enough to do about 100 MPH. With pipes and mild porting 45-50 should be easy to get to and 60-70 is not beyond reach.

So if you find you need more speed after it's running 100%, start to think in terms of bigger ports and decent pipes..

The 'what's in a tune-up?' article from here is a great read: http://www.oldjapanesebikes.com/mraxl_G ... /index.php

It shows just how tolerant the stock motor is to timing etc being slightly out of whack.

[Vintageman]

On my 73 GT550 I raised my Ex port >1.5mm < 2mm. That is they are all now 38mm ex height where i believe it was ~40mm to start.

I went 1mm wider but, a mod I don't like due to ring snag.

I opened the intake passages first 1 inch or so after carb and lowered how far the oil injection tube sticks up.

I shaved my skirts 1.5mm or 2mm I forget.

I ran 0.035" off head then got nervous (ping?) and put back stock head. This year I plan to run 0.020" off head ala T350 gaskets.

Compression does make a big difference midrange hit.

I don't like to have to run high octane gas for i put a gallon at a time (fill when you can) and the pumps share the same hose with low octane

I run Bassani's 3 into 3 expansion chambers

The bike has a more power and my butt dyno did not notice any bottom end loss.

It's still a midrange hitting bike. My estimate I gained +400 rpm peak power point say 6900 vs 6500 and thus a 6900/6500 = >6% hp gain. The pipes themselves added as much alone.

So if it was rated 50 hp now 56-57 hp now using same rating

Well I wish I had moved peak to say 7500, but there is point its not the same bike

I love the bike.

It is unique in the pile or Harley’s and Rice rocket. It's raw. It runs the interstates no problem

It’s too heavy but, not like a GT750 or my CB900F.
I would like to make a cafe (drop e-start and put it on a diet)

It's amazingly smooth and has a great wide midrange power band. OK it's slow compared to a modern bike for sure.

But Its’ a triple 2 stroke!
https://www.youtube.com/watch?v=6V1zIYO1BYQ" onclick="window.open(this.href);return false;
https://www.youtube.com/watch?v=y0DvFBlWJ1U" onclick="window.open(this.href);return false;
https://www.youtube.com/watch?v=Tz0XsRbygig" onclick="window.open(this.href);return false;
https://www.youtube.com/watch?v=Okut7mxUX4o" onclick="window.open(this.href);return false;

You'll see everyone will check it out when you drive...
The very young will giggle at you or ask you to pull a wheellie (good luck with that)

[blurred]

The very young will giggle at you or ask you to pull a wheellie (good luck with that)

Well, at least now I have a goal.

As stated, appreciate the input guys. Getting close to attempting the first startup.