1974 GT380 carb removel

[sdc1992]

Hello. I'm having trouble in figuring out how to remove the carbs on my 1974 GT380. Haven't found anything online that shows this process for my particular bike. Any help would be greatly appreciated.

[Craig380]

Hi and welcome. If it's a '74, all 3 carbs should be mounted together below a common plate.

The easiest way is this: remove fuel lines from petcock, the vac tap should not allow fuel to flow. Remove tank. Remove airbox by loosening clamps on carb mouths and the two bolts holding it to the frame. Waggle it out carefully.

Then loosen and remove the two 10mm bolts that hold the throttle cable adjuster plate to the carb mounting plate. When the adjuster plate is loose, you can remove the two cables from the pulley. No need to loosen or mess with the cable adjusters, just leave those as they are.

Then loosen the clips that hold the carb rubbers to the cylinder inlet stubs right off. Grab the left carb body in left hand, the right carb body on your right hand, and pull and waggle gently but firmly. The rubbers will pull off the stubs, just be patient.

Once the carbs are off, inspect the inlet rubbers really carefully. They do crack with time but easily can last a decade or so.

[sdc1992]

The bike has not ran since 1982. after re gaping the points and replacing the points I managed to get the bike to fire up for about 30 seconds before the nylon gear came apart. I replaced the gear and got the bike to run but only on the left cylinder. the center and right do not fire. I replaced the points and condensers yesterday also.

[Craig380]

New points have a protective coating on the point faces, which needs to be removed with a solvent like contact cleaner or carb cleaner ... I've had fun with brand-new points before

The carbs are likely to be full of crud, so pull them and give them a clean ...

[sdc1992]

Thanks for that bit of information on the points! and a huge thanks for filling me in on how to remove those carbs. here is another question. when setting the points I start with the points marked L for the left hand cylinder. I turn the engine with my hand pushing on the kick starter until the propeller blade marked L is in the small window. I line up the mark on the L propeller with the casting mark behind it and that's where I set the points open with a 0.014 gauge and lock them down and then repeat for the other two by setting the C and R marks on the propeller blade?

[ConnerVT]

Always set the point gap with the points fully open (at the highest point on the point cam). The marks (L/R/C) are for (roughly) setting the timing, which is where the points just begin to open.

[Craig380]

Not quite - the point gap is 14 thousands of an inch / 0.35mm, but that is at MAXIMUM point opening, on the highest part of the point cam. The so-called timing marks indicates when the points are only just starting to open. There's a big difference between these two.

Double-check you got everything lined up right when you installed the new nylon timing gear. Then set the point gaps at their widest opening for all 3 points. ONLY then use a timing buzzer, multimeter or similar to determine exactly when the points open.

To adjust the actual timing, if the L mark is to the RIGHT of the case mark when the buzzer / meter tells you the points are just opening, move the points backplate CLOCKWISE to advance the timing a little. If the L mark is to the LEFT of the case mark, move the points backplate COUNTERCLOCKWISE. You may also need to fiddle a little with the point gaps to get the timing in the right ballpark, especially if you're using aftermarket Daichi points.

Please note - even if you're well-practised at doing this, it can take a lot of fiddling and a bit of luck to get the point gaps and timing correct. Even tiny movements of the points baseplate can make a significant difference to the timing, so be prepared to spend some time going to and fro before you get it nailed. If you are not confident, or it's your first time doing it, it WILL take a long time, and you will use swear words you thought you have forgotten.

[sdc1992]

thanks guys! would have been nice if Suzuki had marked the points cam to show where the points were supposed to be opened at there widest..... I need glasses..

[tz375]

Fortunately, they are open for a long time. Rotate the engine to say the L mark where the points start to open and then keep rotating it until the points are fully open.

The points cam is not like a 4 stroke camshaft that lifts the valves , peaks and closes again. With points cam, the cam opens the points and then keeps them open for quite a while before they start to close.

[ConnerVT]

thanks guys! would have been nice if Suzuki had marked the points cam to show where the points were supposed to be opened at there widest..... I need glasses..

I put a little black mark on the side of the cam with a Sharpie magic marker, so I could more easily see where the high point is. And I sometimes need 3 pairs of glasses when I work on the bike.

[sdc1992]

Thanks a lot for all the great info your giving me on this. I've never really worked on a bike like this so its a big learning curve for me. I am hoping to get the carbs off this weekend and start the cleaning process. Question, Would you take the carbs apart from each other to rebuild? was thinking of getting a couple of gallons of carb cleaner so they could soak with the bowls off for a day or so. is that a good idea? Craig you mentioned the rubber intake boots lasting a decade. would it be a good idea to go ahead and start looking for new boots or wait and see what I've got after removing the carbs? There 42 years old now but the bike has less then 5000 on the odometer.

[Craig380]

Those inlet boots are almost certainly dead by now, so I would definitely replace them. I would pull the carbs first and remove the floatbowls to see what's in there - you might be lucky and they may not be full of varnish and treacle. In which case you might not need to disassemble them too far - a spray can of carb cleaner might do the trick.

I've had good results soaking carb bits with WD40 first for an hour or so, and THEN rinsing off with carb cleaner. Because WD40 is oilier, it helps dissolve dried-on crud better than carb cleaner alone.

Be careful with the carb jets, they are made of brass, so don't use anything metal in them or you'll oval them out. Those little plastic interdental brushes are great for cleaning the holes etc. Use your partner's or kids' brushes, however.

If you're unlucky, then you can break out the bigger guns.

[Rickybigblock]

On my 74 GT380 before I swapped out the rock solid boots I found it helpful to use a piece of wood to pry them loose. As long as you're going to clean them afterwards, it shouldn't matter if there's some wood debris left after.

[sdc1992]

Thanks guys! I will be digging into the carbs tomorrow. Wish me luck

[sdc1992]

ok. so today I rebuilt the carbs and got them back on the bike. thanks all for the help with getting them off. now there is a new problem though. I've lost my spark. I replaced the points and condensers last week and now I have no fire on any plug. I tested with a multi meter but the readings are all over the place. I gapped the points and plugs to specs to no avail. im thinking about putting my old points back on. at least I had fire on them.... any ideas?