Dead GT380

I was doing work on my 75 Suzuki GT380 to repair a leaking petcok. Stuoid me left the valve on prime and it flooded the carbs. I got it ro run a bit, but then nothing. All of a sudden I lost all electrics. I checked my fuse and it is fine. What could it be?

Check the backside of the fuse box to see if it's melted.

Replace the glass fuse with a blade-style fuse?

It is a glass fuse. It is not visibly blown, but when I jump the connections I have electricity. Still won't start because of flooding.

Replace the fuse and kicked the heck out of the starter and it runs!!!

Now if I could get it to idle consistently. I just had the carbs cleaned and synched. The idle jet on the middle carb was partially clogged so it was unclogged. It was idling great for the past week, but afer my afternoon debacle it idles all ove rthe place. I had a nice idles at 1500 rpm to start. rode the bike two blocks and when I stopped it wanted to idle at 5000 rpm. I adjusted it down to 1500 and at the next stop sign it wanted to stall. I got it home and adjusted it to 1500 again. What gives?

Awesome!

I want to change the oil in the gearbox because the flooded engine may have contaminated the oil, but I cannot find a drain plug.

A GT380 is a ringding (two stroke) so flooding the engine won't contaminate the gearbox oil. If you still want to drain the gearbox and absolutely cannot find a drain plug, try this: look at the side case screws. If one of them has a copper washer, that's probably the gearbox drain. I had an old Yamaha WR200 drive me BONKERS looking till I saw that.

The most likely high idle culprits are vacuum leaks between the carbs and the engine and/or a sticky throttle cable. IIRC the 'Zook triples had a single cable which went into a three way adapter under the tank and then had a short cable from that to each carb. See if the short cables are misrouted or pinched.

You might also want to check the carb floats and their height. Sometimes on my rd the float sticks

if I hadn't started in awhile, and a slight tap on the side of the carb usually works.

In reply to Curmudgeon:

I agree with you about the oil, but I have read in several places that fuel could work its way into the gearbox. I will drain some oil and take a look. I looked at the carbs and they appear to be moving smoothly. I am thinking it might be a float issue.

Come to think of it, a float stuck closed could contribute to a high idle. Most ringdings will start idling high and erratically as the fuel level drops because they run leaner. I know of one guy who fried a motor that way; he continued to ride for a short distance with it running lean and damn if it didn't seize.

A two stroke's crankcase is completely sealed from the transmission. It has to be that way, otherwise the all important compression BELOW the piston can't force the fuel/air mix through the transfer ports to the combustion chamber. Sometimes the primary drive crank seal will go bad, that usually means the engine will suck oil from the transmission into the crankcase.

On the old bikes which used 80w90 in the transmission, you'd smell that sulfur funk in the exhaust and know there was a leaky primary seal. I also saw a tech article for later bikes which use regular motor oil in the transmission. You put that flourescent leak check dye in the transmission, then shine a black light at the exhaust with the engine running. If you saw yellow sparkles in the exhaust, there was a primary seal leak.

There is also a crank seal behind the magneto rotor, if it goes bad the engine will run lean because it's sucking air through the bad seal. That one is a bit harder to verify, sometimes if you squirt a little carb cleaner into the seal area with the engine running the idle will change, indicating a vacuum leak. But that's usually real hard to do because access is so difficult. The last bike I tried that on was a Hodaka which had points, every time I'd squirt a bit in there it would wet the points and kill the motor. I finally said screw it, split the cases and rebuilt the motor.

I just sent you a message Moparman.

In reply to Curmudgeon:

Found the problem. My petcock had another bad washer and would leak at different time. Thwasher had a crack all the way through one side. It would leak through the crack and then it wouldn't. Fixed the washer and now it is fixed. It idles nice and steady at 1300 rpm. The only problem I am having is that it has very poor throttle response now. Carbs were professionally cleaned and synched last week.

In reply to EvanB:

Saw and the answer is yes.

Carbs are definitely screwed. When you crack the throttle, the engine takes a crap, It bogs until you get above 4,000 RPM. Way down on power. I will have then gone over when I have it inspected.

Carbs are easy to sync if you have a manometer. And stick manometers are easy to build.

In your case, you'd need 3 tubes, not 4. I used motor oil in mine, ATF works well, even water works.

First and foremost: be very sure your points are properly gapped, the plugs are clean and properly gapped and there are no vacuum leaks between the carbs and the engine. if any of these are wrong the bike will never run right no matter what you do to the carbs. In fact, it wouldn't surprise me if you found your problem while checking these things.

Connect one tube to the intake of each carb, they should already have vacuum barbs for this purpose. start the engine and let it warm up, then you adjust the idle speed screws till the fluid level is even in all 3.

Once the idle is synced, open the throttle and watch the fluid level, all 3 should stay even. If one rises faster than the others, the cable for that carb is adjusted too tight. Run that carb's cable adjuster down a bit and try it again. If two rise faster than the other one, then run the adjuster for the 'slowpoke' up a little bit.

The idle mixture screws should be somewhere between 1 3/4 and 2 turns out from fully seated. If it stumbles a little, run them closer to the 2 turn setting.

If it's still 'flat' off the bottom, you need to pull and clean the pilot jets. If they are clear, then you need to go up a step.

Curmudgeon wrote: First and foremost: be very sure your points are properly gapped, the plugs are clean and properly gapped and there are no vacuum leaks between the carbs and the engine. if any of these are wrong the bike will never run right no matter what you do to the carbs. In fact, it wouldn't surprise me if you found your problem while checking these things

As I recall, Suzuki triples had three sets of ignition points.

Weird thing is that they were synched last week and have been acting up since it flooded. Plugs keep fouling (fuel). No leaks, pints and timing were all set last week. Only been running like this since it flooded (becuase I left the petcock on prime)

Are you still running the plugs that were in it when it flooded? If so, that's probably the source of your problem. If you can get to a glass beader, clean them and dry them thoroughly then try running it again. Or you can wire brush them but typically that's not as good a job. If cleaning them clears it up, buy some more plugs; it's been my experience that once fouled, plugs have a nasty habit of doing it again and again. Toyman ran into that with the Abomination.

Also, badly flooded two strokes will puddle fuel in the bottom of the crankcase. How to get rid of that? Get the engine thoroughly warmed up and ride the SNOT out of it, like wide open. Be sure to tell the nice officer why you were hooning.

In reply to Curmudgeon:

I cleaned the plugs until the were dry and tan. The carbs appear to be running rich. I rode the snot out of it in my development. I cannot take it outside until I get the new title. I wil then take to my local Suzuki shp. They are known to be very good with carb setups. Me, I am just an old Weber hack.

Todays spark plugs suck! 20 years ago the insulators were glazed at the factory to help keep out fuel from soaking in to the porcelin but now that most things run EFI the plug factorys have stop adding the extra costly step but note price of plugs has not droped.....

Change your plugs they can no longer be cleaned. Carry a spare set with cheap-o plug wrench with you at all times.

44

I've cleaned plugs and put them back in only to have the engine run as bad as it did before, the last time was on my last Hodaka. I bead blasted and then rinsed the plug with brake cleaner, stuck the plug on the head and kicked it over and the spark instead of jumping the gap ran down the side of the center insulator. New plug, it ran ran great. That squares with what 44 said abut the ceramic not being sealed any more.

Got the bike runniung better. It no longer sputters under 3000 rpm, but it doesn't accelerate eitherr. It just lugs. DK which is choke on and choke off as the orginal starter lever located on the handlebars was remived by a previous owner. The lever on the carbs is confusing. It seems to only run with the lever down, which looks like starter system on. It pulls pretty well between 3000 and 5500 and really well above 5500. I am new to this bike so I don't know how it is supposed to run.

The Mikunis on my XS have a lever on the left and a pull knob on the right. You push the lever down and pull the knob up to turn the choke 'on' (richen the mixture). Yeah, I know: nice and confusing. Piston port 2 strokes tend to not have much low end power, that bike doesn't have expansion chambers which doesn't help low end at all so what you are feeling may be perfectly normal. You may just have to get used to staying a gear lower and winding it higher than you'd expect. IIRC that engine did not use induction reed valves. If you can find them, reed valves are an enormous bottom and mid improvement.

Reed valve:

Greatly simplified reed valve operation:

Animation: http://www.2strokeengine.net/2strokeenginetuning/2strokeengineanimation.php

You might be able to adapt a reed cage from a 125 of some sort.

A company called GEM used to make alsorts of reed kits some just fit then got clamped in the intake hose.