Just bought my 1st GT750 Need newbie TIPS

[Billiardking]

Hey guys just joined the forum and also just bought my first 76 gt750 complete bike been setting for ???? Years???? But in really good shape been stored indoors came with a fairing which I haven't seen any pics of in my google searches where fairing common on these bikes??
Also picked up two parts bikes a 75 and 76 complete but been sitting since mid 80,s

OK so the obvious I have to replace or clean or repair include

TANK
PIPES
Clean carbs
Flush and change coolant
Drain and change oil


A little about me
I'm a very capable machanic have rebuild cr250 2 strokes and several mini quad 90cc 2 strokes as well as 4 stroke Honda pusher motor


I've got good tank and pipes on parts bike
Already drained fluids

Question on carbs is
Can I just disassemble and clean like I have done many many times with dirt bike carbs
Or is there a kit required for these carbs

I checked compression and got 120-130 but old motor was spitin slime at me
Some of which was some kroil oil I squirted in cylinders
My question on cylinders is can I just get carbs cleaned up put good cleaned tank on and a battery
And get her fired up and just blow the years worth of sludge out of this motor
Or am I gonna need to pull top end and flush motor with diesel fuel ????

Last question on one of my parts bikes is a motor with only 14000 miles that is froze up
I pulled head and looks like center piston is rust welded to cylinder wall I cleaned and filled cylinder with kroil oil and am letting it set now
Does anyone have any tricks to getting one of these motors free after sitting for so long
Really hoping if I could get her free just boring top end and going with new pistons and rings and be able to use that motor


Thanks for your time and info

[Coyote]

I bought a 77 GT750 that had sat for 25 years in a chicken coop. It too had a stuck motor, but no rust. I tried all kinds of penetrating oil for weeks with zero success. Finally one night out of desperation, I got out my big framing hammer and a block of wood. I gave each piston a good whack with the wood on the crown. When I hit the third one, I saw it move slightly. I got in the kicker that I had been standing on for weeks. She spun right over. Worked for me, but like I said there was no rust. It was simply stuck in its old petrified oil.
The carbs are the same as any except for the diaphragm operated slides. Be very careful with those. Be sure there are no cracks or splits in them and are still pliable. The only other difference is the main jet and pilot jets are located in the float bowl, not in the carb body.
I also suggest that you remove the SRIS lines and valves from the crankcase and let them drain any old build up of oil and penetrating fluid. When you remove the valves, be very careful as the have a tiny filter screen on them that like to disintegrate. You can still buy new valves, but the screens are not available anywhere in the world. I don't have any screens on my GT550.
Some folks do away with the SRIS Just replace the valves with bolts. Find where they go on top (just ahead of the intake manifold) and cap them off. The hoses, valves and clips are still available from Suzuki.

[Billiardking]

Thanks for the info
I will give that motor a good Beating later
Next week and see if I can break her loose
Not sure what SRIS is but I will look it up

Thanks

[Cliff]

I've used a product called Evaporust in the past to free up stuck engines and other rusted up items. I had a chain saw that was left outside over the winter (don't know HOW that would happen??) and the chain/bar was rusted solid. Soaked it in Evaporust for a week, pulled the cord (what seemed like a million times!), started the engine and the chain was free! I also found a pair of rusted Vise Grips in the flower garden (ask my son how they got there!). Soaked them in Evaporust as well and they work as good as new, other than the rust pits that were left!
You can pull the carbs apart, BUT be very careful with the diaphrams on top!
Compression seems to be good on the motor but do a dry test as well.
The SRIS system recircles the unused oil from one crankcase to the next intake port. Remove the check valves from the bottom of each crankcase and drain out any oil/fuel/water or mouse crap that might be in there!
Fresh fuel, clean carbs, a good spark and you should be smoking!!

[kettle kid]

( 1 ) SOME DIESEL, LEFT IN THE BORE, A WEEK OR SO, AND HAVE A FEW BEERS...

( 2 ) Found this...

http://www.smokstak.com/forum/showthread.php?t=37566" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

[Billiardking]

Thanks again for the info
That's a interesting way to free up a seized
Piston may give it a try if PB soak doesn't work out

Thanks

[78whiteorbs]

Hey Billiard king- you wouldnt happen to have the parts that attach the oil pump linkage bar to the carbs on one of those parts bikes would you . It's the only thing holding me up on my build and I have been having trouble locating. Thanks, Brian

[Billiardking]

I do have a extra bar that connects oil pump to carb
I plan to premix I hate oil pumps so I can spar one

Send me a pm with our info
Thanks

[tz375]

GT750 motor is not designed to run on pre-mix and both the crank and crankcases need to be modified to run without a pump. I would strongly recommend that you reconsider that idea and stick with the pump.

The clever way that Suzuki engineers designed it to be different and to make sure the pump system is effective, unfortunately has to re-engineered to run on pre-mix

[78whiteorbs]

I just found that out from a local guy as well- Have to run pump!
Found out I did have the arm though and there was just a plastic ball and a adjustment nut and a lock nut that secore the whole thing to the carb. Thout is was missing but I actually had it just over looked it !


thanks for the offer though man I do appreciate it . Could use a decent master cylinder though if you have one ..... mine is NASTY!

[Billiardking]

Dammit so I have to run a pump
I'm just tring to get her started right now and I have some full synthetic motul 800 premixed at 32:1
With 91 gas in the tank now
The oil tank is not on bike at alla dn I plugged rubber line
I've only started bike on starter fluid and seemed to fire right up with no problem
I've put carbs on and now can't get motor to fire and I'm not getting gas plugs just smell like rotten oil/gas and they are new plugs

I'm assuming my cleaning and cheap carb kit from the E Bay did not work
Am I damaging motor by just tring to get her started
Does the pump oil enteral motor components ???
I changed oil and put 2200 cc rotella T 15w-40 back in per side case info
I run this oil in my quads with wet clutch so figured it would be ok

How can I tell if pump is pumping ???? Pull a line and turn motor over ?????
I did pull SRIS valves and cleaned and replaced them mainly to drain any crud from lower crank case

Can I just hook the bar back up to carb and install tank is that all that's evolved with pump system ???
What oil you guys run ???
All my 2 stroke stuff is dirt bikes and quads
I've ran full synthetic for years in them can I use same stuff in this motor ????


Thanks as always for the info

[Billiardking]

Another question about tank petcock
Is there a off position ???
Mine says Res,On and Pri
Anyway to turn things off ???

Tank and petcock from a 76 and I just rebuilt petcock

Thanks

[Coyote]

There are 6 lines. 3 feed the intakes providing a pre-mix of sorts. The other 3 lines feed the bearings on the crank shaft. This makes the pump essential. If you run pre-mix with no oil pump. the crank bearings will receive no oil and fry in short order. You really can't tell much by just turning the motor over. The pumps move the oil very slowly so it's hard to tell.. What most do is prime the lines with one color oil and put a different color oil in the tank. Then you need to run the motor for 15-20 minutes to see if the oil in the lines start to change color. Also, the 3 lines that feed intakes move more oil than the 3 lines that feed the bearings, so 3 lines will change color faster than the other 3. It won't hurt anything to run the premix you have in the fuel tank now, but hook the oiling system back up first.
Synthetic oils were a pipe dream when these machines were built. You would do better running a semi synthetic oil. There are plenty on the market. Iron Butt Alan put 150,000 miles on his Buffalo using nothing but Suzuki CCI oil. That should be available from your local Suzuki dealer.
The petcock is vacuum operated and if you don't have the vacuum line hooked up, you won't get fuel to the carbs. Both run and res (reserve) are the off positions There is a little o-ring on a plunger on the diaphragm side of the petcock that shuts the fuel off when there is no vacuum. If you pull the line off in the run or reserve position and fuel runs, that little o-ring is bad. They tend to get hard and brittle with age. Most petcock rebuild kits include this o-ring. The Pri (prime) position is for filling the carbs after they have been off for service or the bike has sat for a while.
So how it works is, flip it on prime and wait about a minute. Then choose run or reserve. The bike starts, the petcock has vacuum and the diaphragm pulls the o-ring off its seat and allows fuel to flow. Be careful not to cut or rip the diaphragm when you service that side of the petcock. I usually work my way around with a dull pen knife. Replace the o-ring and check the o-ring seat. If it's dirty ar cruded up, roughly shape a pencil eraser to the tapered seat. Put a little fine lapping compound on the eraser and spin it back and forth with the palms of your hands.
Optionally, you can go with a standard on, off, reserve petcock. Parts n More has one for $30 and a 44mm adapter plate for $7. If you go that route, remember to cap off the vacuum spigot on the center carb. You will have a massive air leak if you don't.

[Billiardking]

Thanks Chris for the info
I got oil system back in and some oil flowing
Still got to pull carbs and recheck everything there
I've rebuild / cleaned many carbs but never these CV
Style maybe I missed something

Question on setting float height do you set float height with jet open or closed
I set it with the jet closed basically with carbs upside down

Thanks as always

[Coyote]

If the springs are depressing when you invert the carbs, set the carbs at an angle were the float tang is just touching the needle spring but not depressing it. I guess that's what you meant by opened or closed. If it is, then the answer is open.