1993 Suzuki DT 200 Flat spot

[nswell]

I have a Suzuki 1993 DT 200. The trouble arises between 1200 and 1800 RPM, after running for about 45 minutes the problem arises. The motor will bog and stall in the 1200 to 1800 rpm range. The motor will run fine at idle or above 2000 but if you accelerate slow or try to troll the motor boggs and stalls. The engine is hard to start after the stall and has to be choked again.<br /><br />I posted this topic earlier and some responses were the small jets on the carbs could be clogged and not letting fuel in. Also another writer posted that the magnets could have accumulated metal shavings created by the starter causing interference with the ignition. <br /><br />I have had the carbs rebuilt and adjusted the throttle position sensor (TPS) was also changed. Several mechanics through myself and the previous owner have trouble shot to dead ends. I thought the TPS would solve this problem since I have seen similar posts that were solved by changing the tps. But not this one!<br /><br />The problem is the boat runs fine for about 30-45 minutes so the problem is not evident at first. After this warmup period the problems seem to arise. <br /><br />My current mechanic is trying to get answers from the Suzuki rep which pointed him to the TPS. He mentioned boring out the jet holes to allow more fuel and mentioned several other reasons which seemed a little far fetched. Hopefully someone else has heard of this. Since I have spent like 1700 and the problem isn't going away.

 

[jim dozier]

Re: 1993 Suzuki DT 200 Flat spot

I do not know the answer to your problem. However, much of what you describe points to a lean condition coming off idle.<br />-The occurrence after the engine is warmed up.<br />-The need for a choke on a hot restart.<br />-The bogging on transition from idle to main jet.<br />However you have addressed the obvious with the carb rebuild and attention to the TPS.<br /><br />Several things can make an engine run too lean.<br />Too small an orifice or jet. This is usually the result of dirt or goo narrowing the orifice or jet but you might also have the wrong jets installed if this has always been a problem. Did this engine come from a previous owner at high altitude? The idle mixture screws may be set too lean. Most 2-strokes should have their idle mixture set a tad richer than optimum idle so that they will come off idle better. Some idle screws go clockwise some go counterclockwis for enrichment depending on whether they meter air or fuel, check your manual. The other cause can be an air leak which is leaning out the mixture. Check all hoses and connections in the fuel system AND the oil injection system and any recirculation hoses. This is easy to say and hard to do but at this point it probably needs to be done.

 

[nswell]

Re: 1993 Suzuki DT 200 Flat spot

Hey Thanks for the reply,<br />I tried to search all the fuel hoses and lines they all appear intact. The only thing I have found is that there is a small crack in one of the oil hoses. <br /><br />I have been speaking with the mechanic and searching this board. What I see from this board is that this problem has occurred before in different model year and HP Suzukis but there seems to be know solutions that has cured this.<br /><br />The mechanic has been speaking with Suzuki and says they are stumped. They would like us to get the motor hot and check the timing whenitas failing. <br /><br />The mechanic and myself think it is a fuel problem since the need for a choke after a hot restart. You can choke it through the section and make it work. The mechanic mentioned that these pilot jets should be the fatest offered though we did not pull the jets and verify that they are 92.5 like they should be we assume they have not been switched. I guess the next step will be checking these.<br /><br />Also the mechanic mentioned the switching of the top and bottom carburetors could have an effect on the performance but I don't know about that.<br /><br />Any help wouldbe appreciated thanks...

 

[jim dozier]

Re: 1993 Suzuki DT 200 Flat spot

You should replace the cracked oil hose. If 1 is cracked you should probably replace them all. Oil is the lifeblood of that engine. Kinda like saying my aorta has a small tear in it. It is possible, depending on where the crack is, that it may help the flat spot. If its between the pump and the intake manifold you could be sucking air in the crack causing a lean condition not to mention lack of lubrication. Its always something.

 

[garyN]

Re: 1993 Suzuki DT 200 Flat spot

Shawnow<br /><br />Have you checked the fuel pump on this? If it is mechanical you need to take it apart and look at the diaphram. I think your problem could be fine cracks in the pump diaphram.<br /><br />If you have checked that and it is OK then I am out of suggestions.<br /><br />Gary

 

[nswell]

Re: 1993 Suzuki DT 200 Flat spot

Thanks for the assistance guys. This problem is wearing me down. <br /><br />The fuel pump is ok and the jets are the right size (92.5). since the fuel system is virtually rebuilt I am running out of options. If anyone else has ever fixed the problem let me know.

 

[jafa]

Re: 1993 Suzuki DT 200 Flat spot

I'm not a mechanic , but 45mins sounds about the right length of time it would take to heat soak the entire block and sub components. Can you reproduce this in the drive or is it only under load when the engine gets hotter. <br />My guess now is the CDI/sensor/coil thermally failing, is there anyway you could run under load with the covers off keeping air flowing around the engine. If she runs for a hour with the cover off under load and fails within mins of the covers going back on it would point to a thermal issue. <br />Q for a real expert, with the covers on, once the coolant flow has stopped after the engine shuts down , does the air temperature around the block rise.

 

[rodbolt]

Re: 1993 Suzuki DT 200 Flat spot

hello<br /> by stateing it will easily restart but only with choke and you can choke it and get past the problem your running out of gas. if the cyl cant get fuel and air the motor dies. now we have to find where and why your losing it.have you tried constantly pumping the fuel primer while and just before it stalls ? and you may try opening up the intermediates a bit. most sensor failures on a suzuki will lock the timing at about 11*BTDC causing a fast idle and a loss of top speed. did you check the pumps or rebuild them ?<br />if you checked them how did you do it /

 

[nswell]

Re: 1993 Suzuki DT 200 Flat spot

Thanks guys<br />I am also leaning towrds a fuel problem. However, what would cause the stopage of fuel after 30-45 minutes and not right when I put in. <br /><br />I pulled out the jets for a visual and they seem clear. The jets are also riched up to try to keep it moist in there and not bog and stall. If the carbs are set to spec the problem gets even worse. I visually inspected the fuel pumps and the diaphrams looked fairly new. <br /><br />I sat and watched the motor today while running for like 15 minutes on the hose not under a load. The motor will run in this critical RPM range (1300-1800) out of the water. However, one thing I DID notice running on the hose is when the RPMs are at like 1300 to 1800 (the failure range) the RPMs will bounce slightly (maybe a variation of 50-75). <br />Are there any sensors that may cut off fuel flow?. I was reading up a little and most of the sensors seem to trigger reactions within the ignition system. <br /><br />Can a problem within the oil injection system cause this kind of trouble?

 

[jim dozier]

Re: 1993 Suzuki DT 200 Flat spot

I still think you are running lean in those rpms. Either not enough fuel or too much air. Restricted fuel orifices or air leaking into the system through a leaky hose, gasket, or connection somewhere. Try running the engine at the problem rpm under load for a few minutes at operating temp and then kill the engine without changing the throttle. Pull the plugs and examine them. Are they black, brown, or white?