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PostPosted: Sun Jun 16, 2019 4:08 pm 
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On the street

Joined: Sun Sep 02, 2018 12:10 pm
Posts: 10
Location: Richmond, VA
Country: United States
Suzuki 2-Strokes: GT 750B
Hello everyone. My name is Todd in Richmond, VA. I have recently rebuilt my 75 GT 750 and cannot get it started.

Good spark, gas, compression and timing. I may have the wrong carbs. Mikuni TM 34

1st over bore and new OEM pistons. I have been reading the MIkuni set up guide and have the slides set at .040"
I have tried all sorts of sized starter jets and nothing. I also have some large pod (K&N) style air filters on it with expansion pipes.

Does anyone have any advice? Maybe just save up and get VM roundslides? I'm lost


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PostPosted: Wed Jun 19, 2019 11:49 am 
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Expert racer

Joined: Wed Jul 10, 2013 12:04 pm
Posts: 1070
Country: England, UK
Suzuki 2-Strokes: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S
First eliminate any ignition problems. e.g. Are all points in good condition and adjusted correctly? Are all 3 plugs in good condition? Have you accidentally connected the plug leads in the wrong order? Are all plug caps in good condition, well insulated and making good contact where they screw into the leads? Is the timing correctly set?
Then, and only then, you can check carbs accurately.
Have you checked the float height is correct on all 3 and that the float needle is sealing? Too much fuel will flood the engine.
If all 3 float needles are set correctly and are sealing, then try starting it using "Easy Start".
If it churns over on the starter without firing while using Easy Start, then you have too much fuel, so will need to reduce the fuel flow by changing jet size accordingly.
If the opposite occurs and it will only start on Easy Start spray, then you most likely have a lean mixture and need to put a richer jet in.
It can take a lot of trial and error to get the carb jets set up correctly, so don't be surprised if it takes a while.
Good luck


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PostPosted: Sun Apr 26, 2020 7:42 pm 
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On the street
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Joined: Sun Apr 26, 2020 6:00 pm
Posts: 17
Location: Ecuador
Country: Ecuador
Suzuki 2-Strokes: 1990 AX100
On well used carbs the needle jet (the hole the needle fits into) gets wallowed out and can cause too much gas entering the engine at idle. Sometimes you can take off the slide and the float bowl and look down into the carb to see if that hole looks oblong. If so then replace the needle jets.
Be aware that the slightest amount of trash can clog an idle jet. Strip the plastic off a bread twist tie and push it up into the idle jets.
Water in the fuel can make it really hard to start.
Last but not least take the bike to the top of a hill and push it down and then upshift into 2nd and let the clutch out. That higher engine speed causes a stronger spark and better fuel mixing so it is a good last ditch method.
If the engine has reed valves then make sure none of the reeds are broken off at the corner.
Spray water mixed with dish soap onto the ignition side crank seal. If it causes bubble then you are losing compression there due to the seal. It needs to be replaced. Replace the other side seal as well.


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PostPosted: Fri May 01, 2020 9:21 am 
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On the street

Joined: Sun Sep 02, 2018 12:10 pm
Posts: 10
Location: Richmond, VA
Country: United States
Suzuki 2-Strokes: GT 750B
I have had great success with the 34mm Mikuni Flatslides. Bike is using Newtronics ignition system and Dave Swarbrick expansion pipe set 3 separate pipes. Thank you to all that have helped me along.


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PostPosted: Sun May 03, 2020 11:38 am 
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Joined: Wed Jul 10, 2013 12:04 pm
Posts: 1070
Country: England, UK
Suzuki 2-Strokes: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S
After trying to start it, what do the plugs look like? Are they wet?
Is the bike backfiring from the exhausts during your attempts to start?


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PostPosted: Wed May 06, 2020 7:02 am 
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On the street

Joined: Sun Sep 02, 2018 12:10 pm
Posts: 10
Location: Richmond, VA
Country: United States
Suzuki 2-Strokes: GT 750B
I had a tough time figuring out why things were so oily. The spider (oil injector manifold) had some check valve issues. I was able to spray cleaner in the spider and use a very light vacuum pressure via hand pump to free the balls in one set i had. Trying to get the other cleaned up and not leaking as a back up now. Plugs are fine. Bike runs well. Nice power. Still havent had it on a major highway.


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PostPosted: Sat May 09, 2020 12:49 pm 
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Expert racer

Joined: Wed Jul 10, 2013 12:04 pm
Posts: 1070
Country: England, UK
Suzuki 2-Strokes: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S
Oh good. So you got it running then. :up: Great stuff. Hope you have many miles of joy with her.
The oil check valves can be replaced but it is a fiddly job and its very easy to damage the 40yr old plastic pipes. I replaced my check valves with new Kawasaki ones (broke one of the plastic pipes doing it :oops: and had to repair it using epoxy and a new piece of pipe). They are working fine so far, despite the opening pressure being different. Should you ever need to replace yours it is worth looking at previous posts on how to do it. I used a hair dryer to heat up the plastic, but it took me a while to realise you need to heat it up for a long time before you can pop/wiggle the valve out without damaging the pipe.


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