Ok, time to fix some leaks for good. Help!

General discussion about Street two-stroke Suzuki motorcycles.

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TRC
Around the block
Posts: 72
Joined: Thu May 05, 2016 11:52 pm
Country: USA
Suzuki 2-Strokes: GT550

Re: Ok, time to fix some leaks for good. Help!

Post by TRC »

Switched out the coils, no noticable difference in how it ran.

Now I'm seriously grasping at straws... Was searching some other forums about fouled plugs and came across this:

"This may sound stupid, but are your vacuum lines hooked up correctly? If you accidentally hook the one end of the vacuum line between the carbs to an overflow, you'll run lean on 1 cylinder and foul another."

My middle carb runs lean, left runs rich so I started looking at the lines. Fuel line between middle and left carb? Check. Overflow line between middle and left carb? Check. Vacuum line between middle and left carb? Hmm... Then I started looking for diagrams or photos showing how it should be to confirm and came up empty.

Here's what is there on my bike. A vacuum line connects from the petcock to the carb plate. From the carb plate there is a vacuum line to the center carb. The center carb is connected to the right carb with fuel, overflow (split in center with drip line), and vacuum. The center carb is connected to the left carb with just fuel and overflow (split in center with drip line) - no vacuum! Is that correct? I don't find anywhere on the left carb where a vacuum line could connect...it's plugged internally where it would. Seems weird...
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tz375
Moto GP
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Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Re: Ok, time to fix some leaks for good. Help!

Post by tz375 »

It does sound like a high fuel level. At this point, I would be tempted to stop checking float height and actually check fuel level. If your carbs have a float bowl drain screw, modify one to attach a short length of clear tube and see where the fuel level is on each carb. If they don't have a drain screw or main jet access screw, you may need a spare bowl to modify.

The next thing to do is to swap the choke plunger from left to say right carb and see if the black plug effect follows it. Those old plungers get hard and recess and don't seal well.

Of course this assumes all teh jets are new or like new and not old and poked through with bits of wire by a prior owner.
TRC
Around the block
Posts: 72
Joined: Thu May 05, 2016 11:52 pm
Country: USA
Suzuki 2-Strokes: GT550

Re: Ok, time to fix some leaks for good. Help!

Post by TRC »

Thanks. I replaced the needle jets (was an odd-ball no-name in one of them) and main jets (fixed surging issue) when I did a partial overhaul which also included setting float levels, cleaning channels, etc. Once the new injector line washers arrive the carbs have to come off anyway so I'm going to do a complete rebuild on the left one while I'm at it.

In the mean time, the bike is running well despite the left one eventually coating with carbon and it isn't the end of the world to carry a spare plug or two for when it finally fouls.

Again everyone, thanks for the help!
TRC
Around the block
Posts: 72
Joined: Thu May 05, 2016 11:52 pm
Country: USA
Suzuki 2-Strokes: GT550

Re: Ok, time to fix some leaks for good. Help!

Post by TRC »

One more update. I took a long ride early this morning prior to traffic taking over the streets and pulled the left plug after riding a good distance at 40-65 mph. The bike is running extremely well and the plug looked perfect. So the conclusion I've come to is this. I live in a major city and can't expect to ride it at 25 mph with a traffic light every block and have it be very happy. It's a cafe conversion bike that has been setup with Jemco expansion chambers, pods, etc - it simply needs to run faster than that. I've got my modern bike to commute on so I'm perfectly happy with my GT550 being my fun "toy bike" that I'm not going to be riding to work and sitting in insane traffic on. That's just not a realistic expectation for this motorcycle. No worries, I'm perfectly content terrorizing the streets at 7am on the weekends. :)

BTW, here's a video of the bike that the PO made: https://youtu.be/QmpAoAbTyOk" onclick="window.open(this.href);return false;

When I got it, it had all sorts of mechanical issues - needed a new clutch, one of the injector lines was broken and jerry-rigged together with a piece of tubing so the octopus had to be replaced :wth: , front brake caliper was in serious need of a rebuild, and so on. I'm happy to say she's come a long ways and again, thanks everyone on here for the guidance along the way. It's been really helpful. :up:
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