Derbi Senda Drd 125 Sm not starting

[Michael666]

Hi guys, I have a problem with my derbi senda drd 125 sm. I bought the bike, it used to run very smooth no problems at all, apart from the part that the guy gave me a new speedometer which when I install doesn’t work, texted the guy never replied ( dumb me that I didn’t check it next to him ) apart from 3 icons on the Speedo anything else didn’t show up. I needed the bike to travel to my workplace so I installed a Speedometer on my phone so I could travel. Recently the bike has been cutting itself out while riding. Unfortunately I had to leave then the bike for 2 weeks as I had to go Poland, then I had self isolation for another 2 weeks. After that I tried running the bike and even the start button didn’t work ( before it used to ) only way I can start it is by running with it on a second gear and adding throttle. But of course it’s not nice and I feel like it can damage the bike even more. Things I have noticed overall before the current situation : The bike would just die from time to time, Speedo not working, bike shaking while riding, after hitting the starter button I had to add throttle from time to time so it wouldn’t die. 
 

I am sure the battery is 100% alright, even got a new one from my mechanic who’s away till February. He has checked it etc 

 

It’s my first bike ever I am a total noobie, please explain everything as smooth as you can, cheers guys !

[Mississippi Bullfrog]

A lot of none starting issues say the battery is fine, and then after checking everything else it turns out the battery is at low charge.

 

The issue with the Speedo may be related but it's hard to know without knowing what's wrong with the Speedo.

 

If it was running before being laid up for a few weeks I'd start by making sure the battery is fully charged. The fact that it seems to start on a bump start suggests that's the most likely problem.

 

Give it an overnight trickle charge then try it.

[WD-40]

I think that's the manual for your bike https://www.dealerinfo.net/newsitems/DERBE/DERBE_19627_Wmanualsenda1254t2005y.pdf

 

Based on that manual I think your bike is DC CDI so it needs a charged battery to have spark so I agree with @Mississippi Bullfrog the place to start is charge your battery or jump start it off another battery. The battery is very small capacity, only 6Ah so it wouldn't take long to discharge it. When the bike is running check the voltage across the battery. It should be around 13V.

 

The speedo is mechanical. Page 135. You could disconnect the cable from the back of the dash and spin the front wheel, check if the cable turns when you spin the wheel. If it doesn't the cable could be broken or the gear in the front wheel could be broken. The only thing on the dash that's electrical is the neutral light, indicators light, main beam light and the tachometer. Check if they are all working after you charge your battery. The speedo is mechanical not electrical.

 

All that is based on that manual. If it's the wrong manual for your bike ignore what I said.