Troubleshooting DT300I no-start

[CROSSBOLT]

This will be an exercise to see what works and what does not, step by step, in solving a problem common to any gas engine powered machine but particularly my DT300i. I will try to lay this out in a logical matter, posting results of each test until WE find and correct the cause.

History: 2013 DT300i, new old stock, purchased May 2016 to replace one stolen and totaled. 6200 miles, last oil filter change 6116 miles. Original battery may have been new in 2016. Absolutely no starting problems from first sight, hot, cold, any temperature. Gas cap vented, WOLO horn installed on separate fuse directly from battery. Sucessful ride last week. Washed this last Saturday.

Symptoms: Either brake lever + start switch spins starter with normal noises. Usually starts during second revolution signified by starter sound of slowing during compression. Spins 4-5 revolutions with no tendency to fire. Side stand and run-stop switch cycled with same result.

First action: Put on charger to bring battery back after abnormal, unsuccessful start.
2nd: Prove side stand switch. Side stand up- all lights on panel show, tach and speedo cycle, fuel pump heard.
           Side stand down- all lights except CELP, no fuel pump sound. PASS.
3rd: Prove run-stop switch. Run- same as side stand up.
            Stop- same as side stand down. PASS.
4th: Find battery voltage, no load, ignition on engine not running and engine running.
        Kymco analyzer can only get the last two above. I show two meters, the green one is medium priced and the black is one of those 15-17 dollar cheapo that read the same as the green. Both agree with the Kymco tool. The bike started normally three times! The only conclusion I can draw is that God did prevent me from riding that day.

24 April
5th: Find starting voltage. Hooked up Kymco analyzer before start. Would have done pictures if three hands were originally issued! First start was reluctant spinning 4 revolutions before firing. Showed 9.1 volts on analyzer which I think is too low. What do you think?

           

[Stig / Major Tom]

Not enough miles to be a hard start due to valves....or is it?

My 2nd thought is 2013 battery (could even be a 2012). If it is a 2016 - How big is it? CCA?
It seems to me that, while EFI is great, it also likes a very healthy battery.

Stig

[CROSSBOLT]

Me, too! Tomorrow!

[ophelia]

Valves were a little tight on my first Downtown the year after purchase. Luckily, adjustments are easy with the screw-type adjusters. No fussing with shims. Seat bucket out, valve cover out of the way, make sure valves are fully closed. Pair of small open wrenches and trusty flat feeler gauges. Adjust away! 0.12 mm intake and exhaust.

[de dee]

Sounds like my problem ,  pull the spark plug check the spark,    Reg. and stator check next,. 

[CROSSBOLT]

Have had some home-type issues with higher priority (grass, mower repair, etc.) over this project. Will be back on it shortly.

[CROSSBOLT]

Check latest message mod for update. You think 9.1 volts while cranking is too low?

[Viper254]

I don't think 9.1V is cause for concern

[CROSSBOLT]

The internet tends to disagree, Viper. Depending who, the concensus is 9.6 volts minimum for GM, 10-11 volts for all others. As far as we are concerned, it is the voltage below which the ignition fails or the ECU fails to function. I DID get a new idea from the search, however. That is to test the voltage drop in the fat wires that power the starter, including the ground wire and the start relay. This is done by paralleling the voltmeter with each leg to be tested. The concensus on permissible drop is .5 volts or less. There is ABSOLUTELY NOTHING in the service manual about this.

[Viper254]

Shows what I know!

Hopefully you can get it sorted.

[CROSSBOLT]

Not at all, Viper! All either of us know at this point is what we have read either in a book or on the Internet and possibly someone's opinion. I certainly have never had the idea of measuring voltage drop in a section of heavy cable. I think it can be done without removing anything but the seat and met-in tub. We will see....

[Viper254]

The internet tends to disagree, Viper. Depending who, the concensus is 9.6 volts minimum for GM, 10-11 volts for all others. As far as we are concerned, it is the voltage below which the ignition fails or the ECU fails to function. I DID get a new idea from the search, however. That is to test the voltage drop in the fat wires that power the starter, including the ground wire and the start relay. This is done by paralleling the voltmeter with each leg to be tested. The concensus on permissible drop is .5 volts or less. There is ABSOLUTELY NOTHING in the service manual about this.

Would this not be same as voltage drop across the battery? If the solenoid (and later starter) are fed quite directly from the battery on the fat cables.

[CROSSBOLT]

Yes. This checking voltage drop on cables will reveal where is most of the drop. For instance, the battery will be at fault if the individual cable drops are less than.5 volts. I am guessing at that last number. Ideally, there should be zero drop on each cable. That would leave 12v at the starter if there were no battery internal resistance. More on this later. I gotta read some more....

[CROSSBOLT]

My eyes are falling out! I have scoured the internet to arrive at some conclusions. First, there is a concensus that motorcycles in general should show no lower than 9.5 to 10.5 volts during starting. Second, 12.3 volts no-load is regarded as 50% capacity. Lastly, I am guilty of over complicating this problem! So, in a few minutes, I will be ordering a new battery for the scoot. I will do a start voltage test with the new battery and post the results.

[Stig / Major Tom]

My eyes are falling out! I have scoured the internet to arrive at some conclusions. First, there is a concensus that motorcycles in general should show no lower than 9.5 to 10.5 volts during starting. Second, 12.3 volts no-load is regarded as 50% capacity. Lastly, I am guilty of over complicating this problem! So, in a few minutes, I will be ordering a new battery for the scoot. I will do a start voltage test with the new battery and post the results.

Gotta love this guy!

Stig