1991 DT25 still bugging me.

This one starts easily, idles nicely on all three, bring the rpm up untill well past fast idle and it appears to go real real rich and chokes itself. I can get past that point by coming up quickly but it does the same in a few seconds at at say 1500.
Carbs have been cleaned and reset, floats etc. No leaking fuel so the needles are working. Rebuilt the fuel pump. Replaced the plugs with original type. Checked that the coil wires are making good connection. Replaced one coil as it was showing a slightly high primary resistance. Bulb stays firm. No difference if I pump the bulb. Checked the resistances of the stator coils and the gear counter coil. All good. The gapping looks good on the gear counter coil. Wiring is all good. Connectors are all good. Tried swapping the CD unit but no change. The oiling system has been disconnected but had the same problem before disconnect.
Just about had it with this one so any ideas would be very much appreciated.

Re: 1991 DT25 still bugging me.

Is the idle mixture adjustable on those carbs? If so, they may be misadjusted and you may have a link & sync issue. Two strokes go through a transition from idle to mid range and if the idle mixture screws are set too lean you get that stumble in the transition. Link & sync requires a service manual for your engine. That process is a series of adjustments that adjusts throttle pickup, idle speed, timing advance, linkage beween carbs, and is not just a one or two step process. Also have you verified that the pick up in the fuel tank is not obstructed thus starving the engine of fuel. Squeezing the primer bulb does not always help that situation if it can't suck fuel.

Re: 1991 DT25 still bugging me.

Thanks Silvertip. I do have manuals, in fact quite a library. They are of course invaluable. I have tried all kinds of settings on the idle jets but it doesn't clear the problem. Can get it to a point where I think I have it and back it comes. Have tried swapping the TPS but no change. I am running on a fuel tank and hose system that I use for testing regularly to eliminate that possible problem. Have tried the tank set up above the pump to help the pump if it is not working properly. No change. There is no link and sync on these Suzuki's. Everthing is done electronically.
Got me guessing.

Re: 1991 DT25 still bugging me.

James ... I must agree with Silvertip on this one, you need to link and sync the carbs, I took along time to get mine right .... they are not electronic .... see pic of mine ...... you sure you don't have any crank seal leaks?

Re: 1991 DT25 still bugging me.

Hi DJC. Ignition timing is taken care of by the electronics. The TPS and the gear tooth counter coil send signals to the chip to adjust the timing using RPM and Throttle position. The carb setting only requires that all carb butterflys fully close together. This sets the opening together condition.
Could have leaking seals but that would take a tear down to check. Anyway I have this motor in my shop now and will get into it when I have a chance.
Of course someone may have buggered the jets so I may just try replacing those.
My appreciation of this forum and your responses is boundless.
Many thanks to all.

Re: 1991 DT25 still bugging me.

well as you can see my motor is a full mod .... hahahaha nothing is standard on there ....

Re: 1991 DT25 still bugging me.

Ok Guys I think we have it. Used the carbs and jets from an 89 DT30. Now the DT25 runs ok. I reckon that someone buggered the jets on the DT25 carbs or they changed the carbs and they were not DT25 at all. They all look the same and the jet numbers looked right. Anyway thanks for you input and patience.