1985 Dt 65 2stroke

[Kenflan1]

Can you help?
I have a mid 1980s Dt 65 3 cylinders 2 stroke
The oil mixing system has been removed before I got the engine now direct mixing at tank
My problem is the engine appears to drop to safe mode after about 10 seconds at full throttle

I have carried out the following
Replaced fuel pump - but priming bulb goes soft - it's like petrol has to be hand pumped
Replaced carb. Gaskets
Blown out all the fuel lines
If I spray " easy start"at the carb. Area while the engine is struggling - it takes off at speed for a number of seconds ?? Why ?

I'm aware sensors from oil and heat units may need to be disconnected as these could be creating the safe mode --
Does anyone one know the correct process here and the colour coding of the wiring involved
Any help greatly appreciated
K

[Solarman]

K,
Your problem is most likely in carbs. It sounds like you may have improper adjustments, or blockages in air & fuel passages?

Did you rebuilt carbs ("new carb kits"), did you remove all the jets, and needle valve seats? Did you soak carbs in cleaner for a good couple hours? If yes on the above, did you use compressed air to blow through ALL of the holes and pas-sages for fuel AND air (very important step)? And, whenever needle valve seats are removed, floats have to be reset. Once all the above are done, then ALL the air mixture screws must be set identically by manual. Then the only other adjustment would be the idle stop screw, set at 700-800 rpms. Do not re-adjust mixture screws, this is what the factory sets them at to balance.

Now, it's very important for some motors (some older year models) that you do not mix up the jets between carbs. Some earlier motors had different jets installed in multiple carb motors to balance running.

Hopefully, this will help, and if you're still having some issues let us know.

Good luck, post back when able, to let us know how it's going.

[Kenflan1]

I have been told I might need new Cdi unit but want exhaust all other angles first
Before going to that expense
What do you think ?
Could the fault be in the CDI unit ?

[Kenflan1]

1985 Dt 65 2stroke

Hi solar man
Did the carbs
All seemed fine when opened
Floats etc all working fine
Refitted all and still had the same problem
Engine ran at full close speed etc but went into idle/ safe mode
After about 2.5 mins of running.

Seems like there is some sort of sensor sutting the engines down
( have tried to push the oil pressure switch on the side of CDI housing cover
Does not appear to effect anything)

Is there some thing we are missing here ?
Is there something we need to by pass
Can anyone help????
Ken

[Solarman]

I'm thinking still a fuel issue. If it is going to safe mode, because of a sensor reading, I think it would go within 12 seconds, as my motor did this every 12 seconds till I found a bad/ dirty connector, then it ran fine.

The bulb can get soft, but if pumping gets you running, or carb spray makes a difference, then fuel/ (maybe vacuum leak) is what it's pointing to.

What have you done to carbs and fuel pump?

Post back when able. Good luck.

[theshemdogg]

You have a clogged fuel filter, clogged fuel tank intake, or too small diameter fuel lines. Definitely a fuel starvation issue if starter fluid raises rpms when thats happening

shem