Suzuki DT 3.5

[davidpaul]

Hello all, I have an old DT 3.5 (around 1980) and it has a problem which is driving me mad.

I've had the engine for about a year and it has never run right, although it will always start easy and run at low speed fairly well.

The problems start when you give her more than 1/3 throttle, instantly the rpm's pick up to near maximum and she will run well for 10 - 20 seconds and then the rpm starts to drop all the way down till she stops, she will restart easy enough.

She sounds as if she is running very rich when the rpms start to drop.

The engine has had -

New seals and lower main bearing
New impellor
New plug
New condenser
new float in the carb
The carb has also been cleaned and cleaned again and again
Points gap set (points are in very good order)
Timing set with a strobe light.
Fuel tank is clean as are the fuel lines, fuel pump is in good order

I've only used her twice as I have no confidence in her, although she always starts.

Please help save this engine from the scrap pile.

[boats.net]

If its running lean then applying a little choke will help it stay running, if running too rich then pinch fuel hose closed to carb and rpm's will increase for a second or two.

[davidpaul]

I've tried to apply various amounts of choke when the engine starts to die and it make's no difference.

I have taken the plug out after she had stopped and it's fairly dark in colour but it's completely dry, so she can't be stopping due to flooding.

When I pinch the fuel line the engine just stops, the rpm's don't rise.

I want to try another carb because it's the only thing I haven't swapped over from my other engine (also a dt3.5) the carb on that engine run's very rich on low speed.

As I can't find a sensibly priced carb for it I'm considering fitting a carb off of a Johnson 4hp two stroke, unless anyone one knows where I can get one.