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DT40C hard to start, and loud pop on firing

AndyB2019

New member
Hi All,

I just went out to test my gears after changing the impeller, and the engine was a pain to start, it took ages!

It's electric start, and has always been a bit of a pain to start, but this time, I got a loud pop, and it died. Then after a while more of trying, I got another loud pop and it started running. This is the first time it's made these popping noises.

After warming up, I stopped it, and then it restarted fine.

Did I do something silly?

My routine is:

Pump the primer bulb until firm.
Choke open.
Fast idle lever 3/4 up.
Turn engine over.
When it eventually starts, after a number of tries, close choke and ease back on fast idle as it warms up.

Any tips on easier starting, and any idea what the loud pop was? Flooded maybe?

The engine is a 1984, and new to me last year.

Cheers,
Andy
 
What do you mean by " choke open " when trying to start it ?-----What position is the choke flapper in when you say " open " ?
 
By pop I assume you mean the lean sneeze that suzuki's are known for? Ideally your motor should start immediately, if not it is time for a proper carb clean. Your starting method is correct, but it should not be hard to start. if the carbs is set up correctly and clean it will fire right up. I will suggest a decent carb clean and then reset your fuel/air setting.
 
Thanks for the reply! It was a loud bang, like a car backfiring. Can I clean the carbs without dismantling? I'm not the most mechanically minded.
 
Ideally dismantling would be no 1. Alternatively you can just reset your air/fuel mix for now (1 & 1/2 turns outwards from soft stop) and then run fuel system cleaner in your fuel. you can then lightly adjust the air/fuel mix if it doesn't run perfect, but do this on muffs first.
 
It idles nicely, a bit high though, or do you have it on fast idle?

When you remove your air box, above the throat of the carb you will see an adjustment screw, that is the air screw, I think this model also have another adjustment on the right hand side of the carb, I'm a bit rusty with this model though.
 
That's just how it idles. The idle screw is all the way out; if it turn it in, the idle speed rises!

I just changed the spark plugs, as they were on my list to do. They weren't badly fouled, but they weren't gapped right! I put in new plugs gapped at 0.8mm, and she started much better.

Though now I've noticed some exhaust fumes that seem to be coming from under the front of the cowling! Normal?!

Cheers!
 
You can adjust the cable coming from your control to lower the idle. It is normal for exhaust fumes to come out the middle port on the leg upper where the water sputter out yes. Try and reset your cable from your control box, then adjust your idling, then fiddle with the air/fuel mixture.
 
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