Query approved.

Wont be a problem dude , dont worry
using 20w50 instead of 20w40 wont harm the engine..
and one more thing.. it is a 100cc bike , so it is not meant for very long rides.. it will definitely heat up..

No problem as such, just make sure to warm up the engine by idling for 1 min before moving after your bike has been standing for 5~6 hrs, rest is fine. But try to change to 20W40 before the winters otherwise you might face cold starting issues.
I own a discover 135 and currently using Motul 300V 15W50, and honestly I feel 20W50 is more suited to my bike's engine.

OT: Where is the oil filter located on a Discover 100? Mind sharing how to find it and replace the oil filter?
Your mileage is too low mate, even my bike delivers 46~48kmpl on constant 80 kmph ride on E.M.Bypass.

oh yes.. the mileage you quoted is much less than what you should get

but i guess it is a prob with all the discovers.. in the start , it gives very good mileage but as years pass , even if you have maintained it well , it will give low mileage

my dad's discover 125 (2006 model) used to give 56 kmpl few yrs ago..

now i calculated and it just gives 42 kmpl.. sad..

i dont think that there will be much harm....i am myself thinking of using 20-50grade oil in my pulsar 150....recomended 20-40 though.....reason-oil consumption but without any smoke...maybe power1 is the culprit or i am not getting the genuine one....
but at higher RPM you will find the oil too viscous to reach every corners of the engine...that may be only the concern i think so...

no it won't happen. Unless the bike is warmed up. And it may take little longer to warm up compared to 20w40.
Been using 20w50 (only in summers) no oil flow problem.
Have also used 20w50 in winters (min temp ~7'C) in a passion, had some cold starting issues and bike took pretty longer time/distance to warm up, nothing else.

so its a bit safe to use 20w50 during summer and then revert back to 20w40 during winter...

A thicker oil will not damage the internals(If the engine is warmed-up sufficiently in the mornings) but pickup and mileage decease for sure until you replace it with 20w40.

Why to waste it,use it for at least 1000kms and then drain then oil.

If you like to rip your bike.. you have got a better grade for it!!
Relax and enjoy the ride.. and the reduction in engine noise!

Ill effects if any .. Low mileage(2-4% less), Slightly reduced acceleration and Sluggishness at low engine rpms.

And yes, fully agree with what abhijit has said. Like for every engine oil, warm up the engine before ripping..

for me, 20w50 has worked wonderfully well in summers (as minimum temp is ~30'C and max can go upto 46-47'C) it has reduced (slight) oil burning issue seen with 20w40 in summers.
20w40 is just ok for winters nothing much. Sometimes gives cold starting issues (not problems). I mean 10w30 is much better for ~7'C application.
On an average, 20w40 is good for all year round.
And i must say, you should go through (atleast very first post of) 'Engine oil thread' pretty informative with engine oil weights/grades.

Sorry for late reply. The bike is running good. as it is a 100cc bike so i am not facing any drastic pick up loss ( may be a little but hav'nt noticed) and i rip it hard but after some time. at start i put it on idle for 20-30 sec and then ride it very nicely. dont' cross 40's till 1km. and after when i can feel the engine is warm then only i rip it.

My milege is damn low. and dont know why? after tuning , carb cleaning , using good engine oils , always check tyre pressure within 4-5 days. everything is accurate. the max milege i can get is 55. which is also low for this machine. One mech told me that the problem is with my clutch plates, but i have'nt changed that as i cant' notice any major problems with that but sometimes the clutch hesitates, like while stuck in traffic jam for some time when its time to relese the clutch but then the bike stalls with a jerk. and sometimes it slightly jerks while releasing the clutch. as i am driving for more than year so it can't be treated like its my hands synchronization with clutch and acceleration problem. else its ok.

One more thing is sometimes my bike does not takes gear, like when shifting to higher or lower gear it refuses, then i have to apply fore pressure to shift.

If these symptoms can help you to decide that if my clutch plates are gone then please notify me.

@Abhijit : DIscover100's oil filter is just in front of the rear break lever. i am attaching a picture which points its actual place.

No Worries

@reachsamik- That oil is not going to do any harm to your engine friend but check the user manual and switch to the specified oil grade. Following are some videos which will guide you with the ratings of the oil...no need to panic dear..

Choosing the Right Engine Oil - YouTube

Synthetic Oil Basics - YouTube

All about Oil - YouTube



For your tight gears there can be two issues- 1. The tighness of the clutch cable 2. The gears are not properly getting oiled

In the first case the mechanic can adjust it and the gear shifting will be smooth(happened to one of my friends) in the later case you can go for a FS oil(Motul is best I heard) which will make the gears smooth.

The average of your bike is very very low, my friend is getting 72 Kmpl from his discover 100 4G, you can ask your SVC to check the air fuel mixture and your engine idling(it should be near 1000 for 100cc I suppose not sure) also keep the tire pressure in check.

Hope it helps.

Re: No Worries

Dude you got awesome mileage. I have CT100B and it just done 5000 km and mileage is hardly 60-65. I have serviced it on time, engine oil was changed too (I was not there when they changed but you can see, it was black oil before I gave it for service) . I drive in range of 30-45. Still, low mileage, can't figure out why and its CT100B on which company promotes 99 km/l

Hey vicky1586, one of the videos guy talks about additives for engine oil. Do you use one of that for your motorcycle ?

Re: No Worries

Not needed on our motorcycles. It would cause more harm than (any) good.