New Guy, New Project: GT550

[PHPaul]

As a separate issue and to calm my worried mind, can someone walk me through the test(s) to help determine the condition of the crankshaft seals?

[PHPaul]

IRT high idle: I went out and checked and the choke was on. Not sure how that happened. It does work in the opposite direction from the one on my Yamaha, I may have unconsciously returned it to the up (choke) position as up is "run" on the Yamaha.

Bit of a relief. More riding/testing today, sure hope that was the issue.

[PHPaul]

More investigation and problem (I think...) solved.

I neglected to tighten the jam nuts on the individual slide adjusters on the carb linkage arms. Outer two weren't too far off, but the middle one had vibrated all the way down and the slide didn't start coming off the stops until about half-throttle. Doh...

Adjusted all that and then got to looking at the throttle cable itself and due either to initial installation or the changes in the slide adjusters, it wasn't returning to idle on the pull side. Went through all that again and lubed the new cables just to be sure.

It now starts and returns to idle as it should.

I'll be chancing another test ride to see if the dropping cylinder is fixed, but given the middle slide problem, I strongly suspect it will be.

Thanks again for the tips!

[Alan H]

More investigation and problem (I think...) solved.

I neglected to tighten the jam nuts on the individual slide adjusters on the carb linkage arms. Outer two weren't too far off, but the middle one had vibrated all the way down and the slide didn't start coming off the stops until about half-throttle. Doh...

Adjusted all that and then got to looking at the throttle cable itself and due either to initial installation or the changes in the slide adjusters, it wasn't returning to idle on the pull side. Went through all that again and lubed the new cables just to be sure.

It now starts and returns to idle as it should.

I'll be chancing another test ride to see if the dropping cylinder is fixed, but given the middle slide problem, I strongly suspect it will be.

Thanks again for the tips!

Excellent news. That damn garage fairy at yours has been working overtime.

As a separate issue and to calm my worried mind, can someone walk me through the test(s) to help determine the condition of the crankshaft seals?

Does the bike start fairy easy?
Does it run fairly well?
Does it tick over when warm?
All plugs nice colour?
Gearbox oil level doesn't go down?

It's OK, leave it alone!!

[PHPaul]

Does the bike start fairy easy?
Does it run fairly well?
Does it tick over when warm?
All plugs nice colour?
Gearbox oil level doesn't go down?

Starts a little hard when it's stone cold, takes several attempts at full choke to get it to run without stalling, but warms up fairly quickly once all cylinders are firing. Starts instantly once warm.

Runs pretty darn good!

Ticks over reasonably well, I'll know more after another road test.

Plugs are maybe a BIT on the light side based on my limited knowledge. IIRC, a chocolate milk color is ideal, these are a bit on the gray side of that at the electrodes, but the base of the plug near the threads is darker.

Need to check the gearbox, but I have a known small leak around the shift shaft seal.

[Alan H]

Get the carbs set a tad richer and you're good I reckon.
my 550K takes a bit of starting cold, won't tick over until warm and rattles like a good 'un, but runs fine and pulls 8k in 4th and a bit less in top on standard gearing (last year in the Isle of Man) so I'm happy. It's 44 years old after all.
Normal running 70-75mph on a fast road is usually fine. the 550A might be a bit quicker - we shall see.

[pearljam724]

As a separate issue and to calm my worried mind, can someone walk me through the test(s) to help determine the condition of the crankshaft seals?

Paul, diagnosing crank seals is very easy. There are 3 methods to test or determine if the seals or a seal is shot. 1: the most effective and accurate method, but not necessary. Is a leak down test. 2: The easiest, reliable method is comparing plug readings of all 3 spark plugs. If your carbs are in good order. Compare the 3 plugs. If jetting is all the same. Jet sizes are rich enough for your intake and exhaust, no excessive cylinder wear, air adjustment screws and slides in synch. All 3 plug should have a very compareable reading. If a plug or 2 is very dry or lean, stays that way regardless of any carb adjustments you make. You have a bad crank seal pertaining to the same cylinder the plug consistently reads lean. 3: Seals will start to bypass air in early stages of them deteriating. That's when you'll start getting lean plug readings on a plug. When the seal or seals get beyond that condition the snorkel behind the oil pump will start puking crankcase oil from it at mid to high Rpms only. When this happens you'll notice crank oil dripping down the sides of the clutch cover. When this happens, you'll know it. No mistake about it. It's very important to read the plugs on a 2 stroke religiously. This can help avoid a possible piston seizure if you diagnose bad seals in the early stages. And have the seals replaced upon detecting the issue early enough. Instead of neglecting the issue, by continuing to ride it without knowing. Because someone would neglect to read the plugs often enough. People don't like to hear this. But, if the bike likely has original seals. They likely need changed. Rubber doesn't last for 40 years without the chances of cracking, swelling or ripping. If a plug is not reading too lean. Don't worry. Just continue to read them every few rides or so.

[PHPaul]

pearljam, thanks for that explanation. I've copied it off and tucked it in my references for the bike.

[pearljam724]

You're welcome. If your interested in installing pod air filters. You'll need increased jet sizes or the bike will likely run too lean. You'll have to replace your broken arm on the carbs also or the one slide will not be in synch with others. They break as a result of people ratcheting them too tight. Epoxy doesn't work fixing them. Epoxy will hold to look at it, then it too breaks away under useage. They are available new, but expensive. $30 or so new.

[PHPaul]

You're welcome. If your interested in installing pod air filters. You'll need increased jet sizes or the bike will likely run too lean. You'll have to replace your broken arm on the carbs also or the one slide will not be in synch with others. They break as a result of people ratcheting them too tight. Epoxy doesn't work fixing them. Epoxy will hold to look at it, then it too breaks away under useage. They are available new, but expensive. $30 or so new.

Yup, replaced the two broken arms when I rebuilt the carbs.

Don't do pod filters, not trying to squeeze the last fraction of a HP out of a 40+ year old engine.

[PHPaul]

Had to run to the bank and seeing as we have just had our first Official 70° Day, I decided to take the bike. Suited up, got out to the garage and got to looking at the Suzuki. It's done, licensed and insured, but due to the temporary lack of a front fender (being built as I type...) it doesn't have an inspection sticker.

Decided to take a ride on the wild side and take the Suzuki anyway, being the scofflaw that I am.

Dang that little sucker is fun to ride. Much more nimble than the Yamaha, and cruised very comfortably at 70mph. The gearing on the Yam is such that it will loaf along all day at 55, doesn't mind the occasional blast up to 65 but much above that the vibration will put yer butt to sleep. The GT was turning about 6 grand in 5th and just whistling along. The only negative thing I'm finding is that it's quite "snatchy" at neutral throttle, 25-30mph in 3rd while dinking around town.

Suspension feels a little funny, I think I need to lighten the preload on the rear shocks and add a little to the forks. Getting a "clunk" when they unload over the crest of a hill so maybe a bit more oil as well. May need to snug up the steering head bearings a tad too.

All-in-all, I'm pleased. Between the "new toy" syndrome and it's pleasant cruising manners, I think the Suzuki will see the majority of road time this season. Plus it'll be way more of a head-turner, darn few 2 strokes of ANY vintage on the road around here.

[Alan H]

Excellent news.
On standard gearing 5000 revs on my 550K is 70mph, so 6000 will be about 84mph.
Lovely aren't they?
I would suggest you check tyre pressures first, then jack the rear suspension to highest, and check the correct fork oil amount. 20w50 is a shade more firm or if you carry a few extra pounds.........
I'm a bit surprised that a man of your integrity is so quick to break the law. I hope you are suitably ashamed of yourself.

The snatching on throttle roll off can usually be tamed by dropping the tickover a tad, and/or adjusting the air screws rich a small amount.
But it's a two stroke and they do it to some extent no matter what you do. Check correct chain tension and if it's slack, that can make overrun snatching worse.
Is it better if you 'just' open the throttle the tiniest amount?
Welcome to the world of two strokes.
Great aren't they?

[PHPaul]

Is it better if you 'just' open the throttle the tiniest amount?
Welcome to the world of two strokes.
Great aren't they?

Yup, it cleans right up as soon as you give it enough throttle so it's pulling instead of coasting.

Not my first two stroke, but my first in a VERY long time. Last one was an RD350 Yamaha circa 1973.

I'll try tweeking the mixture screws a tad and see if that helps, but as you say, it's the nature of the beast.

[pearljam724]

Awesome, Paul. As many would definitely agree. There's nothing like devoting all your time, money, etc. Then taking her out for the first ride.

[PHPaul]

Okay, it's officially "finished" (as much as any project bike ever is...)

Got the inspection sticker on it today and took my first legal ride. I'm happy, but I noticed that the master cylinder is weeping fluid from somewhere. Not the banjo bolt/brake line fitting, I suspect it's between the reservoir and the main casting, or possibly around the back side of the piston.

Easy fix, just ordered a new complete MC with a slightly larger (13mm) piston bore that will help the front brakes anyway. Comes with brake light switch wired and pigtailed, crush washers, banjo bolt, and lever. Bolt it on and bleed it.

Of course, one day when the budget can handle the strain, there's a bikini fairing and a set of spannies and...