Suzuki DT75 2 stroke motor issues...

[cbadmin]

From: C-LionRay (Original Message) Sent: 12/29/2002 6:57 AM
O.K., time to break out the big guns and ask for a little guidence.
Background, River Trial prior to picking up my new to me boat.
The main motor ran rough. The mechanic and I checked the fuel water seperator to find old watery fuel. We drained the fuel tanks, added fresh gas and heat (or a similar product). Then we drained the carb bowls and ran the motor on the new gas. Then we changed out the spark plugs. The new plugs were not the same. The mechanic said there was a new number that cross refrenced. The plugs were gapped and reseated after they were run to temp. The boat ran MUCH better so I took it home. About two or three days later I launched the boat and went for a cruise to one of my favorite Sturgeon holes. Before I left the dock I pumped the fuel bulbs and ran the kicker and warmed up the main motor. Both motors had a good stream of water from the water port. I cruised 8 to 9 miles at various speeds without issue. I will fess up. I had left the kicker down for the first 5 miles or so. I wondered why I couldn't get up to 30 mph.... Raised the kicker and what do you know, 32 mph WOT. O.K. so a couple of miles later I noticed that the fenders were still out. o.k., I stowed them and carried on. It was starting to get late and I was moving right along when the main motor kind of stalled and the boat fell off plain to about 7 or 8 MPH. I cut the power and checked the prop. Nothing there so I fired it up and tried reving it up in nuetral, no problem. Put it back into gear and the same thing. I fired up the kicker and limped home. The easy steer made it easy....
At home I removed the fuel water seperator and dumped it into a glass jar. No transmission line, no water at all. Ichecked compression, 132 to 135 in all cylinders, that felt good. I'm thinking it may be the choke or the t-stat that controlls the choke. What do you think?
More to follow....


From: Mike Sent: 12/29/2002 9:36 AM
Ray -

That dealer you bought it from seems like an amicable fellow, have you called him yet? All I can do is feel for you. Larry the 2-stroke guy won't be home until Jan. 6, and that's too long to wait. Have you been back to the water to try the suggestions from the CB discussion? The disconnect on the end of the hose and the factory inline filter are easy changes, and a good idea to do anyway since you don't know their age. Checking the pickup tube inside the tank, and the strainer at the end of it, are good routine practices too. It is going to turn out to be something rather simple, but it can sure be frustrating until you find it.

Mike

From: C-LionRay Sent: 12/29/2002 10:02 AM
Thanks Mike, The 45 minute one way tow is the hardest part on me right now. It runs fine unless it is under loaad.
I just have to get it going before Wednesday. I've got fish to catch

From: stevej Sent: 12/31/2002 10:25 AM
Ray couple of suggestions
Any chance that your not opening a tank vent or have a clogged vent on the tank, If this a problem you would see the primer bulb getting sucked down as a vacume is created in the tank and at some point gas will stop flowing or the flow could be reduced to a trickle under load.
Also I expect there is a diaphragm style fuel pump on the motor it may have a problem. In either case I think the primer bulb would tell the story, if its empty when the motor quits I would think pump or vent problem.
My Yamaha has low oil and over temp sensors that could shut the motor down if triggered don't know about Suzuki.

I'm no expert but I have spent a lot of time around two strokes let me know if you need a hand.

steve

From: Fun Patrol Sent: 1/2/2003 9:16 AM
Here's a couple of things you can do to narrow down the source of the problem.

Remove the carb bowls and check for water and fuel. It may be that there is a drain and you don't even have to remove them. If there is nothing but air, you have a fuel delivery problem. If water and fuel, there is of course water in the fuel. If fuel only is present, pull the plugs and see if they are "wet", which will indicate if fuel is getting to the cylinders. If dry, the jets may be clogged. Blow them out. Otherwise, the fuel system is OK and you will need to check the ignition and timing as well as the reed valves.

Water in the fuel will usually present as a sputtering, or random miss. Depending on the amount of water, it may spit it out and continue running, run rough, or die completely. Running out of fuel will usually be a fairly smooth slowing then shut down.

The bulb will tell you a lot as mentioned by others in this thread. They are also a source of problems when they get old, with dirty/faulty valves, cracked bulb or compromised fittings. Wouldn't hurt to make sure the entire fuel line system is relatively new with no air leaks.

Water in the fuel can be a recurring problem. Of course your original water had to come from somewhere. And, obviously, the filter didn't catch it or it wouldn't be in the motor. The usual sources are contaminated fuel from the outside source, gas stations and fuel docks, (intermediate transfers from cans are especially suspect), and water entering your boat tank from an unprotected opening...such as the vent line. There was an article on the C-Dog site a while back regarding water entering the vent because of dragging a fender, but I know you would never do that. Oh, .........that's right! Hmmmm?

Once you have water in a tank, it's very hard to get every last drop out. I had an ATV with water in the tank and I removed and cleaned the tank, including flushing with alcohol several times and it still coughed up a few drops of water now and then. This was a single cylinder and it would often stop the machine. One drop of water could plug the main jet with an emulsion that required blowing it out. (WD-40 or such is a good field fix).

Good luck with it. Just think, Capt. Cook never had to worry about these things!

Roy

From: Mike Sent: 1/19/2003 8:09 PM
Ray -

Did you ever get this little annoyance figured out?

From: C-LionRay Sent: 1/20/2003 9:02 PM
Not yet, but this should be the week. No traveling, damn the honey do's, I'm working on my boat. It wasn't the vents.....

From: C-LionRay Sent: 1/24/2003 12:40 PM
O.K., I was getting real close. I had made up my mind to go ahead and rebuild the carbs, but I wanted to check the prop. I put the boat in gear with the safety clip pulled and no keys in the ignition and turned the prop. It turned one way but not the other. That seemed o.k. since the direction it was turning was forward but then I put the boat in reverse. I could turn the prop both ways but it seemed to be turning over the engine one way but not the other, odd.
I removed the lock pin, prop nut, washer and bushing stopper and... a piece of the prop shaft came off with the nut. I cleaned it up and it looks like it broke (Sheared) right through the hole for the cotter pin. About 5 threads back. There are enough threads to get the prop on but when I put it into reverse the prop will spin off .
Anybody think a machine shop can help me out here? Maybe build up a weld in the center so it dosen't mess up the shaft and bore a hole through it?
It's likely to mess up the balance which will wear the seals... ARGH!
My pockets are feeling pretty empty right about now. Looks like I'm gonna need a $200+++ shaft on top of what ever the problem is in the first place...
I sure wish I could just go get a nice new 4 stroke but I can't afford it.

I need to go fishing

From: C-LionRay Sent: 1/25/2003 12:02 AM
Anybody know where to get a deal on a 1993 Suzuki DT75 propeller shaft?
Should I steer away from used?

From: "Nancy H" Sent: 1/25/2003 11:03 AM
Ray,
A used shaft can be ok, but......The bearing and seal surfaces should be smooth and not pitted. The shaft should be checked to be sure its not bent!! Set the shaft on a pair of machinists v-blocks and rotate while checking runout with a dial indicator. Your shop manual should tell you the limit of run-out that is acceptable. When a prop hits a rock or log the impact can bend the shaft. A bent shaft can destroy the bearings in the lower unit by vibration. If you find a used shaft, consider why that shaft is for sale and is it damaged.
In adition to the cost of the shaft, consider the labor charge to teardown the lower unit and rebuild with new seals. I don't know about Suzuki, but special tools and knowledge may be required to correctly reassemble the gearcase. Check your shop manual for more info.
Larry

From: "Nancy H" Sent: 1/25/2003 11:22 AM
Ray,
If you have a scanner, can you scan the exploded view of the carb from your shop manual and post it or e-mail to me? I am not familiar with Suzuki parts, but if I could see a parts view of the carb I might be able to give you more advice.
When dealing with a fuel problem, remember that the fuel system starts at the tank vent, includes the tank, hoses, clamps, fuel filter(canister) and any filter on the powerhead, squeeze bulb, motor connector(are the o-rings in the connector ok?), and the hoses, clamps, fuel pump and carbs( the parts under the motor cover).
The fuel pump sucks the gas out of the tank so the fuel system is under vacuum until the pump and is then under pressure to the carbs. An air leak anywhere from tank to fuel pump can let air into the fuel lines and cause running problems at moderate to full throttle. There can be a leak that sucks air into the fuel lines without any gas leaking back out.
Hope this helps,
Larry

From: C-LionRay Sent: 1/25/2003 11:09 PM
Depresion is setting in. I don't think I have the funds to get this all taken care of right now. I was leary about the vibration that I felt but being so close to realizing my dream of owning an Sea worthy vessel I had to go for it. I don't have any regrets and frankly I am lucky to have found this problem in the driveway rather than loosing the prop on the water. I've got a boat that talks to me and I listen.
At this point I think it would be best to take the boat in to the dealer and let them look it over and give me their opinion.
What do you all think?
I'm pretty confident that I can complete the carb rebuild and clean out the fuel system but if there are issues with the lower unit there are too many "Special tools" to deal with.
I hope I don't have to wait long enough to buy another motor. I'd rather not put more than a thousand dollars into this 2 stroke as I plan to repower with a 4 stroke in 5 to 7 years.
I found a 97 on Ebay (mine is a 93) but I'm not sure if the parts interchange. If they do I'd fork out money for the parts motor cause it has a hole in a piston. The lower unit and the electronics are all good.
I guess I could still put around on the kicker

From: C-LionRay Sent: 1/26/2003 9:01 AM
Larry, you have e-mail

From: "Nancy H" Sent: 1/26/2003 10:46 AM
Ray,
I got the scans you sent. It looks like the carbs are not too hard to work on. You should obtain 3 carb kits first. The kits should have the gaskets, o-rings, needle & seat, and a new float.
Remove the top carb to start. Turn it over and remove the float bowl. Now look to see how the float is held on. There is probably a pivot pin which slides out. Before removing the float measure the float height as shown in the shop manual. Write down the measurement. Remove the pin and float and needle. Inspect the needle and seat.
Now you need to check the air adjustment needle. DO NOT JUST REMOVE IT!!! Mark the position of one end of the slot with a marker and carefully screw in the needle counting the turns until it seats. Write down the number of turns it takes to seat the needle. It may be 1 or 1 &1/4 or 1 & 1/2 or whatever. You want to be able to reset the needle to the original setting.
For the next part, WEAR SAFETY GLASSES!! Now remove the air needle. At this point, you can remove the main jet. Use a screwdriver that fits the slot in the jet snugly. Jets are brass and easy to damage. NEVER CLEAN OUT A JET WITH A METAL TOOL!! Now spray carb cleaner(using the small straw on the carb spray can) through the jet, through all openings and passage ways in the carb. The point of this is to verify that all jets and passages are clear and clean. If you find gunk anywhere, remove it carefully. If you have compressed air, you can blow through all openings and passages to clear them.
When the carb is clean, replace any o-rings or gaskets, install the jet, install a new float & needle, set the float height, reassemble the carb and float bowl. Install the air needle and set to the original setting.
Do the same with the other two carbs. Only work on one carb at a time!!
Now what have we accomplished? If you found gunk in a jet or poassage, or if the float level setting was way off in one or more carbs, or if a needle was way off of the factory settings, this may have fixed the problem. If every thing was clean and set properly, the carbs may not be the problem. After putting it all back together. pump up the squeeze bulb and start the motor. ( Don't forget to run it in water. DO NOT START DRY!!)
After a test run on land on the flusher or in a large bucket , launch the boat and see how the motor runs. Adjusting the air needles affects the idle and off idle. Adjust the needles a little at a time (1/8 of a turn at a time) and wait 10 -15 seconds for the motor to react. This is the part that need some experience. Mayby ask the dealer about the adjustment.
Remember that a two stroke need to be in the water(not on a flusher) to tune the carbs. The backpressure of the motor leg being in the water affects the carb tuning. You cannot tune carbs on a flusher.
If all this is too complicated, or you don't think you have the skills or tools, Take it to the dealer!!
I would get an estimate from the dealer before starting. You have to buy the carb kits either way, and the dealer would be responsible for the outcome.
I hope this helps, its hard to work on a motor over the computer!!
Larry

From: Chuck S Sent: 1/26/2003 12:15 PM
Somebody needs to put this into an archive or FAQ!

-- Chuck


From: C-LionRay Sent: 1/26/2003 9:30 PM
Thanks Larry, I may need to find out about the shaft first. I am suspecting that I may have lower end damage beyond the sheared propeller shaft.
What would you recomend?
How can I check for damage beyond the prop shaft?

Dave, This is a great place for the info, we just need to keep a backup. I'll take care of this one should anything happen I'll send it where it needs to go. Isn't this a great community?

From: "Nancy H" Sent: 1/26/2003 10:36 PM
Ray,
If you drain the lower unit oil, you can inspect the oil for metal fillings or chips, and note the color and condition of the oil. If water comes out then the seals or drain/fill plugs are leaking. If the oil is thick like a chocolate shake, there has been water in the oil for a while.
Any other inspection requires dissasembly. If you intent to replace the shaft, the shop can take it apart, note damage and give you an estimate.

Larry

From: C-LionRay Sent: 1/27/2003 6:50 AM
Larry, Thanks again. I'll do it and get back to you here.