GT750 won't idle on left cylinder.

[Striker1423]

The head is gonna have to come back off. I'm getting water from center and right pipes. A bit rpm the left pipe as well. But the white smoke hasn't stopped.

[Striker1423]

Is it possible for the o-rings on the bottom of the block to leak? I have to drain the coolant and pull the head again, but I'm curious if it could be pulling coolant from under the barrels.

[teazer]

Is it possible?  Anything is possible.  maybe an O ring is undersized or split or is out of place, but that's really unusual. If they are aftermarket O rings I guess that's possible.

That could cause a leak into the bottom end and that would be on the serious end of the undesirable scale.   

[teazer]

Would you believe me if I said no? 

First thing I'm checking now though. It didn't leak before the rebuild so I figured I'd get lucky.

.  Yeah.  Right....

Do a leakdown test and see if you can detect where the leak is coming from before you tear it down. The head is easy to check. Pull the head, clean off any gasket mess left and place it on a dead flat surface.  I use a granite surface plate but a decent old thick mirror works well too. Put a thin smear of bearing blue on the head and press it down on the flat surface. Lift it and see the imprint on the plate.  Anywhere it didn't sit flat will be obvious.
   

[Striker1423]

Will do. I admit I was being lazy but that's because my time is short in the garage lately. So is summer...

Oh well, should have checked and that's that. 

[Striker1423]

She runs well! Not the biggest issue I thought it was. Pipe just collected a lot of shit. Just needs the anti-surge jets. I already have them, just need to tap the holes and install. Put 45 miles on it with no real issues.

[Evans Ward]

^ Excellent!    Yes, the anti-surge jets will smooth out any issues just past tickover. Richard's site (Pink Possum) has some great info and instructions on all things about GT750 carburation.

[m in sc]

for those that dont speak buffalo, whats an anti surge jet?

[Striker1423]

The GT750 is known for off-throttle and low-throttle surging. Sounds like engine gallop. Causes erratic stops a bit too if you engine brake as the motor loads and unloads.

Excerpt from here: http://pinkpossum.com/GT750/carb/BS40carbs.htm

Surging on large capacity two strokes is a common design problem. With the BS40 carbs, Suzuki had hoped that surging would not be a problem, but unfortunately many bikes still surged at low throttle openings.

The fix was described in a Suzuki Service Bulletin and is quite simple.  The passageway in front of the pilot air jet is tapped to take a screw in Mikuni air jet - the same type as all VM series carbs. Part number is BS30/97. The new air jet is either 0.8mm or 0.9mm depending upon model and effectively changes the fuel slope across the pilot jet. Order from SUDCO or your local Mikuni supplier.

At idle, there is no change in fueling, so it works just the same as before the modification. At higher revs on a closed throttle, it richens the mixture enough to eliminate that lean surge condition. The way it works is  that on overrun or at a steady at say 3,000 on a closed throttle, the motor creates a relatively strong vacuum which on a stock motor, pulls in too much air via the air jet and it creates a lean surge.

By restricting the air jet slightly it causes the mixture to become slightly richer under those conditions. At idle, the vacuum in the carb is much lower, so the change does not really affect idle or slow running.

[Striker1423]

First attempt before installing the surge jets is to increase the fuel screws rich by a quarter turn. Idles even better now, will report back after I ride it again. I can safely report the bike does the ton. Gotta bed the rings somehow.

[m in sc]

sweet! 

[Striker1423]

Idle still hangs at around 2k on occasional stops. Comes down and stays if I just barely let off the clutch for a second at a stop. Maybe the carb sync is off.