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PostPosted: Fri Jul 06, 2018 12:47 pm 
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On the street

Joined: Tue Jul 03, 2018 4:32 pm
Posts: 32
Country: Usa
Bikes owned: '74 GT250
So if its not the crank seals have you checked the SRIS? (Suzuki Recycle Injection System) It recycles leftover 2 cycle oil by routing it the the transfer ports and thereby burning it off in the combustion. Simply put the oil in the crankcase of each cylinder is routed to the transfer port of another cylinder. I think the center cylinder's excess goes to the right cylinder's(clutch side) trnsfer port, the right cylinder's excess goes to the left cylinder's port and the left cylinder's excess goes to the center cylinder's port. Its a pretty cool system but if there are pinched/plugged hoses then it could possibly be causing or adding to your problem.
I would recommend getting a manual as I can explain it in more detail but the manual would do a much better job than me I'm sure as I'm great at seeing the system in my head but explaining it on a message board is difficult for me.
I hope this makes sense and helps you.


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PostPosted: Sat Jul 07, 2018 11:25 am 
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On the street

Joined: Tue Nov 07, 2017 3:25 pm
Posts: 20
Country: Portugal
Bikes owned: GP125, GT380
Hi Indy 650,
I have a Clymer manual and a manual downloaded from this forum but I don't think my motor has the SRIS system. I believe this was on the earlier models only - or am I wrong?
My motor is from 75 and only has the crank drain bolts at the bottom of the motor. I have a spare damaged 76 motor which is identical.
I have the feed from the oil reservoir to the oil pump which is mounted on the oil distribution system 'octopus' which then connects 6 lines to the cylinders with banjos (2 per cylinder). These lines have check valves at the motor end of each and I have tested these and they are perfect - no leaks. I used the approach of hanging the 'octopus' filled with oil as mentioned within this forum.
The crank seals were in good condition when the motor was opened and checked but I am not ruling these not to be the problem. As a crank rebuild is pretty expensive (and beyond my means at the moment) I will try everything else first.
The oil is new and didn't have any contamination when last checked but I will drain it and re-check. There are no leaks on or around any part of the motor or floor so the hence the assumption that the seals are ok (the bike is parked on the side stand for long periods).
I have re-cleaned and set the carbs, cleaned the exhausts and new insulation in the baffles and have another oil pump to try which will happen during my summer leave.

Any further advice is welcome and appreciated.

Thanks


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PostPosted: Sat Jul 07, 2018 1:07 pm 
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On the street

Joined: Tue Jul 03, 2018 4:32 pm
Posts: 32
Country: Usa
Bikes owned: '74 GT250
ya if you just have drains then it must not have SRIS. Im not sure the exact years that did and didnt come with it. i guess you will have to see what the other oil pump does and go from there. Hopefully that solves the problem.


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PostPosted: Sat Jul 07, 2018 4:36 pm 
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On the main road

Joined: Sat Sep 05, 2015 3:14 pm
Posts: 104
Location: southeast pa
Country: us
Bikes owned: GT
CFS wrote:
The crank seals were in good condition when the motor was opened and checked but I am not ruling these not to be the problem. As a crank rebuild is pretty expensive (and beyond my means at the moment) I will try everything else first.

Some suzuki twins have main bearings oiled by the transmission oil, bad crank seals suck this oil into the cylinder and burns it, when it does this it lowers the transmission oil level.
If I am not mistaken the GT380 mains are oiled by 2 stroke oil. so the only cylinder that can pull transmission oil is the right cylinder, at the seal behind the primary gear. You say all 3 pipes are smoking and spitting oil, as long as the cases were sealed good when put together, I would look at something that affects all 3 cylinders, like the oil pump.
You can check crank seals, by pulling carbs and hold your hand over carb boot checking suction on each cylinder as you kick over, they should be about the same. I rigged up a vacuum gauge to hold against carb boot when checking mine.

_________________
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe


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PostPosted: Sun Jul 08, 2018 8:55 am 
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On the street

Joined: Tue Jul 03, 2018 4:32 pm
Posts: 32
Country: Usa
Bikes owned: '74 GT250
Your correct the 380 doesn't lube the crank bearings with the transmission oil but I have had a few bikes that sat for a long time and all the seals were cracked and leaking so the tranny oil leaked in the clutch side cylinder and burned in all 3. This isn't very likely but I thought I'd mention it as I have seen it before. I'm curious to see if the different oil pump fixes the issue. Its hard to try diagnosing a bike on the internet.


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