Suzuki 2 Strokes

Hey all, I just bought my first GT 550 and I'm trying to get it on the road but there are some issues I was hoping I could get some help with. So I apologize for my lack of knowledge. Here's a photo



The bike used to start and when I took if for a long first ride, as it warmed up it started to sputter, smoke out of the left cylinder and when I got it home it barely stayed on and also sounded like it was starving for gas. I cleaned the carbs, used compressed air and carb cleaner, adjusted the float bowl heights etc. I also turned the pilot air screws as well according to the table in the Clymel book. Bike still doesn't start now. The bike has three pod filters and the battery is in good shape.

1. When I got the bike the vacuum line from the center carb had a black hose with a bolt in it and the connector from the petcock is just open...Not sure why this was done? Should I reconnect it? When the petcock is in the PRI position, there is a good steady flow of gas.

2. On the right side of the motor is a plastic filler for the transmission oil im assuming? When i look down there i don't see any oil. How can i check that the transmission and clutch oil are at a safe level? How do you drain and change those oils?

3. The most interesting issue im having is with the throttle cable that goes to the oil pump and to the carbs themselves. I tried adjusting the oil pump as stated in the book but as I pull the throttle back to get the dot on the carb body to the top of the slide, there is no slack left in the cable going to the oil pump and the adjuster nut is screwed in all the way. When the throttle is let go, this is the only time the lines on the oil pump line up. It seems like the cable is to short as the adjuster is screwed in all the way. Can this be adjusted? How can I properly adjust the throttle cables? It seems like there is no slack and the movement from idle to wide open throttle is very short.

I also included a video link to what it sounded like after the ride i took it on.
https://www.flickr.com/photos/131622719 ... 453895193/

Thanks for taking a look! Look forward to anyone's insight

Looks like your petcock was converted to manual operation.

A PO had done the conversion to one of my bikes.
As a result the three petcock positions were: on, reserve & off.

You should test the petcock to figure out which position is which & then remember to turn it to off when the bike is parked.

Slick looking ride. I like it!
Adjustment maxed out on the oil pump is a mystery. You can gain a little slack at the throttle grip, but not as much as you describe. The only thing I can imagine is the cable broke at one time and the proper length was compromised when the repair was made. If the marks on the pump are lined up at idle, you are definitely over oiling.. A new cable might be in order.
As far as the sputtering and losing power can be caused by a myriad of things. The most common is a blockage in the fuel cap vent. If the petcock is still correct then it will run out of fuel because the vacuum line has been removed. You need to drain the fuel and see what's up with the petcock. there are filters on it that can clog as well.
Three very important things on these old bikes. The first is the battery. It must be fully charged, or the bike will run like crap or won't run at all. There is no magneto so a fully charged battery is imperative. That alone can be the entire problem
You say yo adjusted the float level. If the bike was running fine, that normally isn't necessary. How did you go about it? If you fully inverted the carb, that is wrong. There is a spring on the float needle that must not be depressed when setting the float level. The tang on the float should be just touching the float needle, but not depressing it.
Never use compressed air on an assembled carburetor. This will collapse the floats. Collapsed or deformed floats should be replaced. It is impossible to accurately set the float level with deformed floats.
The third VERY important thing is never never use compressed air to clean the oil lines. There is a check valve on the end of all 6 lines. Compressed air will destroy these valves by over stressing the tiny springs in the valves. Use a pump oiler with solvent for cleaning the lines. Lung pressure is OK too
So, it is possible that your charging system is not working is not working. As you ride - especially with the lights on, the battery begins to deplete. As the available juice goes down, so does the motor. The charging system is easy to check with a voltmeter on the battery terminals.. At idle, you should see 12+. As the rpm's increase, the voltage should increase. At 3500 rpm's you should see nearly 14 volts. If the voltage doesn't change as the rpms increase, the charging system is faulty.
Was unable to see the video. All I got was the flickr page.

Hi and welcome.

As said above, the factory petcock is a vacuum type. It will flow fuel when set to 'PRI.' The line that was plugged with a bolt is the vacuum feed from the carb. If you've removed the bolt from the vac feed, it will be sucking air and making the fuel mixture way too lean. For the sake of getting the bike running again, I would plug the line and ensure that fuel flows on the 'PRI' setting. You can go back later and sort the petcock later.

Re the gearbox oil, just drain the old stuff and put fresh in there. See page 44 of the owner's manual, here: http://www.oldjapanesebikes.com/mraxl_G ... /index.php

Don't worry too much about which oil -- any mineral or semi-synthetic MOTORCYCLE oil for aircooled 4-stroke bikes will do, 10W40 grade is good.

Let us know how you get on.

There are 2 big plugs on the underside of the motor. One is angled and one is flush with the underside. Do not remove the angled plug. That is not the drain and parts will fall out. The plug that is flush (closest to the right) is the one you want.
If you look at the right side of the motor, there is an odd looking bolt just below the kick starter and a little to the right. Though rarely used, this is the oil level check' Bike must be on the center stand. Pour in oil till it begins to drip out of the bolt hole. That is FULL. Over filling will force the oil out of the breather (the pipe just behind the oil pump) and make a real mess. A tad low on oil is better than a tad high. I use Pennzoil 10W-40 in my transmissions. Lot's of others use regular gear oil, but I have never had any trouble with 10W-40

As coyote stated, there is a 10mm bolt with a phillip head in the center on the kick starter cover. When you remove it, oil should seep out if the crank oil is at the correct level. However, mine never seems to seep oil regardless of the oil level. May be due to the kick cover gasket blocking the hole. Regardless, all you have to do is shine a light in at the filler hole cavity. The very bottom of that cavity is the same exact height as the bolt on the cover. You want to barely see oil in the bottom of that filler hole cavity when the bike is level. On the center stand for example.

Could have just fouled the plug, or roached the piston on that side. I would pull the plug and check it out. Look in there with a flashlight and do a compression check if you have a gauge.

Video sounds like its running on 2 cylinders and bogging. Do you know the history of the bike? That may help.

You mentioned that it smoked on one side and got slower and now runs like it's firing on one or two cylinders.

That suggests that one crankcase was full of oil which has fouled that plug.

Remove all three SRIS valves to drain the crankcases, fit fresh plugs and try again.

Wow! thanks a lot everyone. I appreciate all the replies and am pumped to hopefully get a day off from work soon to try all these suggestions. I really appreciate all the help and direction. Will keep everyone posted.

tz375 wrote:You mentioned that it smoked on one side and got slower and now runs like it's firing on one or two cylinders.

That suggests that one crankcase was full of oil which has fouled that plug.

Remove all three SRIS valves to drain the crankcases, fit fresh plugs and try again.

Is there a step by step to draining the SRIS valves in one of the manuals online?

Possibly, but its easy access on the GT550. Right at the bottom of the front of the cases, you'll see three thin, black tubes, which are the SRIS lines. These are pushed onto a barb sticking forwards out of each of 3 SRIS valves screwed into the case. The SRIS lines may have a spring around them, often not. The SRIS line is held onto the SRIS valve barb with a steel spring band, likely now rusty. Prise that band off the barb and along the line a cm or so, then simply pull off the SRIS line. Then with a 12mm socket, unscrew and remove the SRIS valves. Stick some rag under the motor....unless you're very lucky, you might see quite a lot of two stroke oil perhaps mixed with fuel fall out. It gets in there because the check valves on the ends of the oil delivery lines from the pump often leak by, albeit slowly. Over months (or years!) of standing, I have seen the whole oil tank volume decant into the crankcases
Start a motor like this, and at best it will smoke for a week. At worst it can hydrolock and break something.
Once you have the crankcases drained, clean the SRIS valves with a little carb cleaner. They should allow you to blow with your mouth in one direction (out of the case) and not the other. Also, and maybe its just me, I like to blow up the SRIS lines towards the intake side (on the cylinder) to prove they are clear. Then put it back together and you're good to go, assuming plugs and carbs are clean, fuel is new, battery is good and ignition settings close enough. Oh, and on an old bike, best to assume plug caps and their junctions with coil wires are suspect until proven otherwise. I usually nip 3mm off the ends of the coil wires and refit the caps, then manually test I have a good spark at each plug before reinstalling.
Cheers,
Mike

My SRIS is blocked off, but this is where the valves are located. If the system has never been fooled with, it's likely that the lines are rock hard. The lines (simple tubing) are still available from Suzuki, however re-routing them is kind of a bear. Also if the valves have never been removed, there are tiny filter screens on the back side of the valves. These filters are EXTREMELY delicate, so if the screen filters are still there, treat them with great care. They are not available on planet earth. I'm not trying to scare you as the valves work fine sans filters. The valves are also still available from Suzuki, but they don't come with filters attached.
The whole idea of the SRIS system was to minimize huge clouds of smoke after extended periods of idleing i.e.sitting at long traffic lights. Other than that, the system really does nothing. Eliminating the SRIS is common practice but you must remember to block the system off at the intake as well as the crankcase. If the intakes are not blocked off, you will have huge air leaks on all three cylinders. Not cool unless you like pistons with holes



This is what the valve filters look like

Alright. So I did as you guys said above. Got the bike running, sounded pretty good. (Thanks!) And then my perfect day went to crapppp. the revs started to increase and smoke started coming from that left cylinder I mentioned above. So I quickly killed the bike and am not sure where to start. Gonna pull the spark plugs and assess the damage. If anyone has insight as to why that happened when the bike heated up please let me know.

As for the oil adjustment. I was able to take off a small jacket that fit into the cable to allow it to be longer and now the marks line up properly.

I also noticed that the SRIS lines from the crank case go to different cylinders. Is that meant to be that way? The barb on the left side crank goes to the right valve and the right side crank barb goes to the left valve

They should go to different cylinders.
Left base to centre inlet, centre base to right inlet, right base to left inlet.
This is so that the oil in each crankcase is pumped by the pressure of the piston descending (blowing out), into a different cylinder where the piston is ascending (sucking in). If you don't use SRIS, then the inlet spigots MUST be blanked off.