Suzuki2Strokes.com

Sundial Moto Sports

Suzuki Two-Stroke Message Board
Suzuki2Strokes.com
It is currently Tue Sep 25, 2018 6:00 am

All times are UTC - 6 hours




Post new topic Reply to topic  [ 28 posts ]  Go to page Previous  1, 2
Author Message
PostPosted: Fri Jul 06, 2018 12:47 pm 
Offline
Around the block

Joined: Tue Jul 03, 2018 4:32 pm
Posts: 78
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.


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

Joined: Tue Nov 07, 2017 3:25 pm
Posts: 22
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


Top
 Profile  
 
PostPosted: Sat Jul 07, 2018 1:07 pm 
Offline
Around the block

Joined: Tue Jul 03, 2018 4:32 pm
Posts: 78
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.


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

Joined: Sat Sep 05, 2015 3:14 pm
Posts: 132
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


Top
 Profile  
 
PostPosted: Sun Jul 08, 2018 8:55 am 
Offline
Around the block

Joined: Tue Jul 03, 2018 4:32 pm
Posts: 78
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.


Top
 Profile  
 
PostPosted: Tue Aug 07, 2018 3:05 pm 
Offline
On the street

Joined: Tue Nov 07, 2017 3:25 pm
Posts: 22
Country: Portugal
Bikes owned: GP125, GT380
A quick update on my findings:
a) Drained the engine oil and checked for any contamination. None found and the oil capacity was about correct - a little less than the required amount.
b) The vacuum at the carb inlets is approximately the same for all cylinders. This was assessed using Karl Pa's advice of the hand over the carb inlets as I don't have a vacuum guage.
c) I stripped and checked that the spare oil pump to ensure that all was correct internally.

The bike starts easily on choke from cold (2nd kick), idles well and once warm will rev through the rev range all the way easily.
I took it out for a drive and the smoke is now non-existent once the motor is warm.

I am still having the problem where it will not rev beyond 4000 and after a short while seems to choke up and die. It will start up again straight after and run as before.
It may be my impression but when it started to choke a second time I pulled the choke and it seemed to stabilise (not want to cut out).

I have had the carbs off again and re-checked the jets, etc but all are clean and the settings OK. I have also removed the baffles but again all clean. I removed the 3 drain plugs at the crank and again nothing substantial came out.

I am at a loss at what the problem may be as in neutral will rev freely throughout the rev range but under load wont rev past 4000 and even below this is very sluggish and of course dies!
Any ideas as to what the cause may be and any recommendations to repairs this is greatly appreciated.

Many Thanks
Carlos


Top
 Profile  
 
PostPosted: Wed Aug 08, 2018 4:01 am 
Offline
On the main road

Joined: Sat Sep 05, 2015 3:14 pm
Posts: 132
Location: southeast pa
Country: us
Bikes owned: GT
CFS wrote:
It will start up again straight after and run as before.
It may be my impression but when it started to choke a second time I pulled the choke and it seemed to stabilise (not want to cut out)

Sounds like it could be a fuel starvation issue, remove plugs from bottom of carbs and you should have a good flow when gas is turned on.
Are the float height set right? what happens if you raise the fuel level in the carbs a little?

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


Top
 Profile  
 
PostPosted: Wed Aug 08, 2018 6:33 am 
Offline
To the on ramp

Joined: Tue Mar 10, 2015 12:35 pm
Posts: 411
Location: Wales
Country: WALES
Bikes owned: suzuki gt 550j
Are your jet needles in the correct position? Normally position 3. The main jet is responsible for supply of fuel alone 3/4 to Wide open throttle. If the needle clip is set too low it will allow too much fuel and cause the motor to bog down and even cut out I would check and try raising the clip to see if that works. Make sure to check the plugs to check it isn't too lean

_________________
98 carb Blackbird and GT550j


Top
 Profile  
 
PostPosted: Tue Aug 14, 2018 4:17 pm 
Offline
Around the block

Joined: Tue Jul 03, 2018 4:32 pm
Posts: 78
Country: Usa
Bikes owned: '74 GT250
Its so hard to diagnose a bike over text... i was thinking possibly ignition but it seems like a fuel problem especially since it seemed to help when you added choke. i dont recall if it was mentioned but check that fuel flows fast from the tank and make sure all jets are clear and the floats are adjusted correctly. Sometimes you can see through a jet but its restricted. Also make sure there aren't leaks around the intake between the carbs and cylinder the easiest way is spray a little starting fluid around them and if there is a change in rpm you have a leak. Checking the piston wash and spark plug color can tell you if its starving for gas there are pictures all over google if your not seasoned in reading plug color/piston wash.


Top
 Profile  
 
PostPosted: Sun Aug 19, 2018 4:03 am 
Offline
On the street

Joined: Tue Nov 07, 2017 3:25 pm
Posts: 22
Country: Portugal
Bikes owned: GP125, GT380
Firstly I would like to thank this forum and everyone who has helped me to get my toy rolling again.

A quick update:
I remove the carbs and the float bowls and noticed that the fuel level was incredibly low. The only one at a reasonable height was the left carb. I re-checked the float heights but these were correct so assumed the problem to be the needle valve. I checked the fuel flow from the tank to the carbs and this flows quickly and the needle is at position 3.
As I had 3 new carb kits for the 550 carbs I took the needle valve and seat (same size as for the 380) and installed these on the 380 carbs and re-set the float height.
I took it for a ride and it pulled through the whole of the rev range without any issues. It still spits a little black oil out of the 3 chambers and surely will still need finer adjustments, but for now I can enjoy it.

I have attached some images of the plugs taken after some WOT and normal riding (approx 20km) and one of my toy. The plugs shown are right plug on left, centre and left plug on right.
In my opinion the plugs seem to have the correct colour but will take all advice on board.

Once again many thanks to all.
Carlos


Attachments:
IMG_4389 (640x480).jpg
IMG_4389 (640x480).jpg [ 218.95 KiB | Viewed 300 times ]
IMG_4376 (640x480).jpg
IMG_4376 (640x480).jpg [ 159.33 KiB | Viewed 300 times ]
IMG_4372 (640x480).jpg
IMG_4372 (640x480).jpg [ 158.55 KiB | Viewed 300 times ]
Top
 Profile  
 
PostPosted: Sun Aug 19, 2018 10:52 am 
Offline
On the main road

Joined: Sat Sep 05, 2015 3:14 pm
Posts: 132
Location: southeast pa
Country: us
Bikes owned: GT
Glad to hear you are getting it worked out, nice looking "toy" you have there :up:

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


Top
 Profile  
 
PostPosted: Sun Aug 19, 2018 1:39 pm 
Offline
To the on ramp

Joined: Tue Mar 10, 2015 12:35 pm
Posts: 411
Location: Wales
Country: WALES
Bikes owned: suzuki gt 550j
Great news! Those plugs look fine to me. Just keep checking them from time to time to monitor what's going on. The bike should improve the more you ride it. These bikes like to be ridden

_________________
98 carb Blackbird and GT550j


Top
 Profile  
 
PostPosted: Sun Sep 23, 2018 10:11 am 
Offline
Around the block

Joined: Tue Jul 03, 2018 4:32 pm
Posts: 78
Country: Usa
Bikes owned: '74 GT250
Thats a nice looking bike! Looks like you got it tuned in quite nice. I'd just keep an eye on your transmission oil level to see if it drops. Riding a bike with weak crank seals can be a timebomb.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 28 posts ]  Go to page Previous  1, 2

All times are UTC - 6 hours


Who is online

Users browsing this forum: No registered users and 11 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Sundial Moto Sports forum © by Eric F. Kalamaja
Suzuki2Strokes.com