Derbi Senda Wont Run When Hot?

For anyone who has tried most things and is still having overheating problems, up jetting is probably the solution, as the engine reaches top rpm for a little while, the gases can't escape fast enough so will overheat the cylinder and will defiantly size over time, up jetting will allow combustion to happen faster and push the hot gas out the exhaust at the right speed!

Try up jetting by 6-8%, "Thats just a reference" it may change depending on you're situation!

If you've added a tuned exhaust or bigger bore (cc) kit you defiantly need to up jet… but you should know this…….. right!

Portman
July 2014

adem.
I too have a senda same problem, when you say primary ignition coil you mean the one with the ht lead connected? If so there are 2 types listed for this bike of mine (2003) r 50 do you know if they both fit?

Keith
July 2012

so what do you do when a the oil is out??

ryan
March 2011

my derbi senda seems to like "eat" spark plugs..i put a new spark plug in and it runs fine but then 2 hours later it starts to splutter againn..but put another brand new plug in and it will be fine then later on it splutters againn..had new ht cap and lead also+70 kit? maybe over heating? any ideas ppl?

jake
October 2010

hi ive jist fited a new engine to my derbi senda - gilera smt it wont start there no spark ive put a new plug in i put a new cdi-coil on new ht cap and wire but it wont spark or its a very very weak spark it wont kick or bumpstart ive checked all the wires but there ok any idea would be very greatfull thnks

taylor
March 2010

lol ok ,the water going in the oil wont make the clutch slip if anything it will drag as the emulisfied oil is thicker then clean oil and if theres alot of water in it the derbis are prone to having the clutch plates stick together with rust if they stand for a while and can take some freeing off !
it sounds like its most certainly seizing up im afraid this could be due to the thermostat being stuck closed or oil starvation.the oil pump is on the right hand side of the engine just in front of the clutch there a small plastic panel there held on with 4mm hex headed allen bolts take this off and bleed the oil pump by undoing the small screw on the side and the top of the pump for a whioe antil the oil runs feely and there are no bubbles in it.then take the small pipe off the pump and start the bike and see if the oil comes out of the pump it will come out in small pulses and not fast look closeley for it.if its not working then put a new pump in or check the drive gear.if its working then its fine and the problem must be witht he cooling system ie the stuck thermostat.really do take it out they are a nightmare.unfortunatley the piston and maybe the barrel will have suffered from these seizures and they will need inspecting.the piston will be scored down the sides and the barrel may well look the same .pistons are cheap but the barrel is nickel plated on a derbi and they are not cheap even replating costs around £90.i use one of two companys for this langcourt or
poeton aptec.to see if the oil is mayo'd take the oil drain plug out on the bottom of the engine and see if its creamy or clear.good luck withn it these aregood bikes but they do have some small problems.get that thermostat out either way they are poop.

adam bike doctor
February 2010

Erm when it cuts out and you go to kick it over again, it feels like it has no compression the kick starts really easy to kick over, then theres nothing and when you bump it its really sluggish, how do i check all that oil is going all funny, see im a car mechanic but have no idea about 2 strokes and stuff, if the water was pushed in to the gear box wouldnt the clutch slip~?

Dan
February 2010

does the spark dissapear when it gets hot?if it does then the primary ignition coil is more than likley faulty,you need to see if its sparking after it has cut out.are you sure its not parially seizing up?does the ickstart feel stiff just after it has stopped?these sendas suffer from the thermostat sticking and then boil up and seize or blow the waterpump seals and push all the water into the gearbox and turn the oil to mayonaise (really called emulisfied oil)if i ever have a senda i always take the thermostat out and throw it in the bin they dont need one.its on the head next to the spark plug ,take the big water hose off the head and undo the big brass nut and under it there is the thermostat take it out and just put the pipe back on leave the brass nut off to it just restricts the water flow.trust me im a bike doctor :)

adam bike doctor
February 2010