1976 GT 550

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Paul Phillips
On the street
Posts: 13
Joined: Fri May 26, 2017 5:39 pm
Country: Canada
Suzuki 2-Strokes: GT 550, Gt 500, A 100, T 10

1976 GT 550

Post by Paul Phillips »

I saw a GT 550 run in an ad on line and bought it. Carbs have been in an ultrasonic cleaner, good ignition, lots of spark at the right time. New gas tank and fuel, new plugs. Engine cranks and wants to run, only on left cylinder. I think engine was possibly seized as cylinders are scored, but I have seen worse. I loosened exhaust in case pipes are plugged, no change. Compression is 125 to 130 on all 3. When it does try to run, a terrible smell of stale fuel is detected out exhaust. New plugs smell also of bad fuel. When it ran on line, it smoked a lot, even for a bike like this one. Crank seal on left side looks slightly damaged, but not that bad. If I didn't know better, it seems like it is trying to run on contaminated crankcase gas/oil. Guy who I got it from said it ran last fall and it was stored inside but not heated. It also seems to puff back out carbs, not very much vacuum while cranking. Any thoughts? I will reply with any answers to questions anyone would ask. Thanks for your help.

Paul.
GTandcbr
Yeah Man, the Interstate
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Suzuki 2-Strokes: suzuki gt 550j
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Re: 1976 GT 550

Post by GTandcbr »

Hi welcome to the forum. When the bike is cranked over pull the plugs are they wet? Is fuel getting through? It sounds to me like maybe the pilot jets are blocked it takes several attempts, even with ultrasonics to get those internal passages clear. Another common problem is in the float bowls. There is a brass tube sitting vertical. At the bottom is a non removable jet. This is the choke fuel feed. Sediment from the bowl can clog this. The tube also has minute holes at the top. This froths the fuel helping to vaporise it as its sucked along. Check your choke plungers are they lifting properly. These bikes like to be run regularly. The smoke from the exhaust is normal if it has just been started in the garage from time to time revved then switched off. Just needs a good run to blow out all the oil and water that probably collected in there.
Here is a copy of the carb manual to help you on your way.
http://www.3cyl.com/mraxl/gt/manuals/su ... /cover.htm" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
Those cylinder compression readings are okay and if the timing and spark are okay then i would suspect fuel delivery could be the problem.
You could try some easy start spray or similar into the carb intakes to see if it will start running.
98 carb Blackbird and GT550j
Paul Phillips
On the street
Posts: 13
Joined: Fri May 26, 2017 5:39 pm
Country: Canada
Suzuki 2-Strokes: GT 550, Gt 500, A 100, T 10

Re: 1976 GT 550

Post by Paul Phillips »

Thanks for the reply. I have tried starting fluid, still no fire, and the carbs have been apart several times now, but that doesn't mean they are clean right? The plugs do get wet, but not with fresh fuel. Strange thing though, it only fires on the left cylinder and I removed the head last night and there is what looks like a white, creamy oily substance on top of the piston and in the head. There is also no traces of normal black carbon in that cylinder like the other 2. I cleaned all the pistons and head reinstalled it and still will not run. All 3 cylinders are getting very good spark and I have gone through the timing proceedure and when I did a test start after the timing, the thing started right away, so I shut it back off to reinstall the tank so I could run it to fully warm it up, hasn't started since. Not running on at least the starting fluid has me baffled as you would think it would run for a second or two. Thanks so much for your input.

Paul.
GTandcbr
Yeah Man, the Interstate
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Country: WALES
Suzuki 2-Strokes: suzuki gt 550j
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Re: 1976 GT 550

Post by GTandcbr »

Hi. Is it just one piston that has this creamy substance on it? And if so which one? All the pistons and the head should have black carbon on them this is a given on a two stroke. When you clean this creamy substance does it reappear? Can you tell me how you setting the timing? As you know a big blue spark at the wrong point of the stroke is useless. What petrol are you using? It needs to be the highest octane and without ethanol if possible. Its important for it to be fresh too! What 2 stroke oil are you using? Sythetic,semi sythetic or mineral? Did you remove the oil tank and replace it with new oil because its integrity is not known it may be years old.
98 carb Blackbird and GT550j
Paul Phillips
On the street
Posts: 13
Joined: Fri May 26, 2017 5:39 pm
Country: Canada
Suzuki 2-Strokes: GT 550, Gt 500, A 100, T 10

Re: 1976 GT 550

Post by Paul Phillips »

Hello, it is only the left side cylinder that has the creamy goo on it. I have not removed the head to see if it reappeared yet but the plug looks like it might have. The fuel tank has been cleaned and re lined with excellent flow down to the carbs. I set the timing as per the Chilton manual bringing each cylinder to TDC and rotating the engine backwards 32mm so the points for that cylinder just start to open. The fuel I am using is 105 octane, yes 105, and it is fresh out of the pump as soon as yesterday. I am lucky that way as a friend of mine sells racing fuel. As for the timing, as I said before, after I timed it, I hit the starter and it fired right up, maybe I just got lucky I am not sure. Also, I just remembered something I should tell you about, the engine ran online with a Denso coil pack on it. It has very bad wiring on it, high tension and primary wires are bear in spots, but it ran. I bought the only coil pack I could find but it is what I believe a Kokusan coil. It has great spark, but after the no start I put it back on and still no start. Is it compatable with a Denso breaker assembly? Thanks again for all the help.
GTandcbr
Yeah Man, the Interstate
Posts: 590
Joined: Tue Mar 10, 2015 12:35 pm
Country: WALES
Suzuki 2-Strokes: suzuki gt 550j
Location: Wales

Re: 1976 GT 550

Post by GTandcbr »

The coil manufacturer is not a problem however when it comes to alternator,reg/rec points and condensers they cant be mixed and only work as a set. These bikes aren't highly tuned and i set it up using the marker plate and the crankcase mark. If you look through the little window on the points plate,turn the engine over by hand you can see 'L' 'C' 'R'. Just set the points which are attached directly to the plate(left) first so that the high spot opens when the indicator hits the crancase mark. Then secure the plate and adjust the other two the same way.By the way what year is the bike and is it a US model?
98 carb Blackbird and GT550j
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oldjapanesebikes
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Re: 1976 GT 550

Post by oldjapanesebikes »

A couple of thoughts:
  • - compression doesn't mean much on these - what does matter a lot is the state of the crankshaft seals
  • - any compression over about 85 psi is enough for it to run if the seals are good
  • - presumably you are sure the lower crankshaft area is not full of old fuel ? Pull the plugs and spin the engine over to blow out the bottom end, or pull the SRIS lines and use a suction pump to check
  • - if you cannot feel any suction on the intakes when the engine is spun over with the starter then most probably the seals are shot and it won't run regardless of the state of anything else (carbs, spark etc)
  • - to double check the state of the seals, you can do a leak down test - search this site for 'how to' info if in doubt
  • -another way of testing would be to fill each cylinder one at a time with diesel and check whether you have leakage into adjacent cylinders (some small leakage is fine - if it pours from one into the next the seal is shot)
Hope that helps ! 8)
Ian

If at first you don't succeed, just get a bigger hammer !
Paul Phillips
On the street
Posts: 13
Joined: Fri May 26, 2017 5:39 pm
Country: Canada
Suzuki 2-Strokes: GT 550, Gt 500, A 100, T 10

Re: 1976 GT 550

Post by Paul Phillips »

Hi guys, the year is 1976 and all I know about the bike is that it came out of Quebec, Canada about a year ago. I totally agree about the crank seals, as the bottom end smells terribly of stale fuel and when the bike turns over, the same smell comes out the exhaust, so you might be on to something here. I just removed the stator and the rotor, and checked the left hand seal. There is a deformation on the seal where it contacts the lower half of the crank, and I put some never seize paste all around the seal and I am pretty sure it looks like it might have sucked some in. Is that maybe where the creamy pastey stuff is from? Please forgive me guys, this is my first real problem I have had with one of these little engines, I build big block Chevies for competition and there is quite a difference! I also noticed before I reinstalled the exhaust pipes when I put new seals in there, the middle and right cylinder are scuffed up a lot more than the left cylinder. Thanks so much.
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joolstacho
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Re: 1976 GT 550

Post by joolstacho »

Who "re-lined" the tank, and what with? Possibly the liner chemical could be bad, contaminating the fuel, and getting in the carbs and crankcase.
A long shot but it's not unknown. It could account for the nasty smell too. I'd try flushing everything out with good fresh fuel, then rig up a test 'tin-can' fuel tank.
GTandcbr
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Re: 1976 GT 550

Post by GTandcbr »

Wow! There is a big difference in the engines! I'm sure with your experience you dont need me to say that if that seal is damaged there is only one answer....TBH age is never kind to these seals. If you intend keeping this bike i would split the cases and replace all of them.
98 carb Blackbird and GT550j
Paul Phillips
On the street
Posts: 13
Joined: Fri May 26, 2017 5:39 pm
Country: Canada
Suzuki 2-Strokes: GT 550, Gt 500, A 100, T 10

Re: 1976 GT 550

Post by Paul Phillips »

The tank liner is fine, and the bike still won't run with a test tank as well. I think I might split the case, do the seals and install new pistons, rings and do the bores also. If no one has a better idea, I think that is the route I will have to take here. I plan to keep the bike for quite some time, and if it works as good as my Titan, it will be a fun ride also.
GTandcbr
Yeah Man, the Interstate
Posts: 590
Joined: Tue Mar 10, 2015 12:35 pm
Country: WALES
Suzuki 2-Strokes: suzuki gt 550j
Location: Wales

Re: 1976 GT 550

Post by GTandcbr »

I agree with that course of action. IMHO thats the only way to be sure and its a great comfort to know you have new parts in there. I know I'm biased but these 550' s are an absolute hoot to ride and will compliment your Titan too! Let us know how you get on.
98 carb Blackbird and GT550j
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oldjapanesebikes
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Re: 1976 GT 550

Post by oldjapanesebikes »

Paul Phillips wrote: I think I might split the case, do the seals and install new pistons, rings and do the bores also. If no one has a better idea,
That is most probably the best idea. And where in Canada are you located ?

Just a heads up - parts for GT550 engines can be difficult to source. Con rods, some of the crankshaft bearings, some crankshaft and crankcase seals etc. are NLA from Suzuki. Just something to be aware of. 8)
Ian

If at first you don't succeed, just get a bigger hammer !
Paul Phillips
On the street
Posts: 13
Joined: Fri May 26, 2017 5:39 pm
Country: Canada
Suzuki 2-Strokes: GT 550, Gt 500, A 100, T 10

Re: 1976 GT 550

Post by Paul Phillips »

Splitting the case it is! I have seen some pistons and seals etc. for sale on ebay from Paul Miller in the U.S. I am from a little place called Port Perry, just east of that town on an Island. We are about 15 minutes north of the General Motors plant in Oshawa. Glad for all the input guys, you have been a great help. And yes, we do have big hammers here!

Paul.
Clifford
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Re: 1976 GT 550

Post by Clifford »

Too bad I didn't see your post earlier, rode up to smoke shack today!
The white crap sounds like water in the fuel/float bowls. Pull the carbs off and clean out the float bowls. The old girl won't run on water! Filled mine up at the Pioneer in Port once and she ran like crap.
Cliff!
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