Bike is running lean(I guess?) and my mechanic has given up

I have a 2012 Suzuki GS150 R. It has done ~25200kms which I bought second hand 3 months ago. The problem with it is that it backfires(popping sound) when i take the bike above ~5-6k rpm and suddenly close the throttle. Also the bike is over heating after like 10-15mins of ride. On the brighter side, mileage is great, I am getting around 50kmpl.
I know running the bike lean will damage the internals of my bike, so I took it to my trusted mechanic he has finally given up. The following were the list of things that he did.
1. Tried to tune the AFR screw and no matter how rich he made, the bike kept backfiring - As far as i know AFR screw tunes the pilot jet. So I guess the pilots are in good shape
2. Cleaned the carburetor.
3. Checked the spark plug and it was ash white - So, the bike is running lean.
4. Cleaned the air filter.
5. I tried pulling the choke and revved in neutral gear, and just like I guessed, no backfiring which is making me believe that it has something to do with the Air Fuel Ratio.

My mechanic says that everything is fine and the overheating is just because of the Shell Engine Oil that I am using but I really do not have a peace of mind. Also he said there may be some problems with the ignition coil.

I am taking my bike to a Suzuki ASC on monday. Just before that, I want to hear some inputs from my fellow members. What could possibly be wrong? Are there any ways to diagnose that I can do at home?

Bike: 2010 Suzuki GS150R
ODO: ~25200
Engine Oil: Changed 2 weeks ago, running Shell AX7 Semi Synthetic
Everything Else: Stock

Thanks in advance.

Re: Suzuki GS150R

Seats on our GS are quite comfortable. But for daily long commuting anybody uses seat cushions or anything?
Something like this? Any other recommendations or cheaper options?

Re: Suzuki GS150R

We have

1. additional seat cushion
2. ribbed, buttoned seat cover
3. wooden beads, like the they use in 4 wheelers

Personally, I feel all these beside increasing saddle height, they may seriously compromise rider's emergency responses/reflexes on our GS, esp those which are superficially fastened on top of actual cover.

Recently, came across "Anti Monkey-Butt" powder : Anti Monkey Butt Powder - Original Anti Monkey Butt Powder

Not available in India albeit expensive

how about Calamine + Prickly Heat Powder ?

PS: You can keep experimenting until you find a suitable solution.

Re: Suzuki GS150R

Yeah even i came across the butt powder recently. But not something i am looking for. I was hoping to get better cushion especially under the tail bone and thighs that touch the outer curve of the seat. Sitting for long periods causes pain/numbness respectively in the area i mentioned. And even more as my work wants me to sit infront of PC whole day. Something like this exactly takes care of what i mentioned.

Re: Bike is running lean(I guess?) and my mechanic has given up

Approved and merged!

Re: Bike is running lean(I guess?) and my mechanic has given up


Mechanics have got there own theories of describing the problem, and here comes another theory that engine oil is heating the engine Bakwaas, just get the carburetor internals checked and see there aren't any air leaks if there is any air leak then AFR will get lean, get a new plug and then get the carburetor tuned and see that whether the problem vansishes or persists.

Re: Bike is running lean(I guess?) and my mechanic has given up

I would go with what kusmakar says about the air leak. Please check the manifold and the replace any cracked rubber O rings in the carb. I have know of hig mileage two strokes that have similar problem and run perfectly fine after a replacement of engine oil seals - which was causing air leak from crank case and hence leaning out the mixture.

10,000km

Completed 10,000 km

Re: Bike is running lean(I guess?) and my mechanic has given up

Thank you mate! I took my bike to Suzuki ASC and the mechanic over there was an idiot. He says that's the way bikes have to be, misfiring and all. So I was skeptical and brought the bike home.
If its not much trouble, could you please let me know how to check for air leaks myself. No mechanic is ready to accept that there is an air leak.

Re: Bike is running lean(I guess?) and my mechanic has given up


Start the engine and let the bike idle, take a bottle with sprayer attached to it, fill up the bottle with water, now spray water at the intake manifold, place where the carburetor attaches to the rubber part which then attaches to the cylinder, spray at air filter joint to the carburetor and crank case joint, if there is any vaccum leak bike's idle will either increase of decrease.

Re: Bike is running lean(I guess?) and my mechanic has given up

^^^ @kusmaker nice idea there, what kind of sprayer is suggested here? I've one at home that's used in saloons; I bought it for pot-plants.

I'm no expert, just curious.

Does this SVC has a name & address? You didn't get the service done at SVC then.
How to identify if my motorcycle is misfiring? when it's backfiring?

Edit: found some nice pointers on misfiring

Motorcycle Repair: Misfiring Motorcycle, cylinder head gasket, fuel air mixture

you'll find GS150R's service manual(spanish) couple of pages back in this thread.

Re: Bike is running lean(I guess?) and my mechanic has given up

Thank you kusmaker! I will check this in the morning and let you know the results.

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Hey Spar, the SVC that I went to was Aryan Suzuki, Whitefield.
I am myself not sure on what backfiring and misfiring is, I am just quoting these mechanics.
Thank you for the link.

Re: Bike is running lean(I guess?) and my mechanic has given up



Saloon sprayer and the pot sprayer are same you can use any one of them.

Re: Bike is running lean(I guess?) and my mechanic has given up

Hi,
I opened the drain bolt in the bottom of the bike to drain out old oil.
Problem is, now the screw won't get tightened back.
It looks like the threads are spoilt, and sadly it spoilt on the engine side and not the screw side.

I tried opening the 3 outer screws, but i had only one spanner, the one that came with the bike.
Needless to say, spanner broke before the screw moved an inch.

Any idea how much it would cost to fix this thread and what will be changed ?
I'm planning to give it to service center tomorrow.

For now i kept a plastic cover in between and tightened the screw and poured the old oil back in so i can ride till service center tomorrow.

Re: Suzuki GS150R : Drain Plug - Thread Loss

Nothing to worry, get the Strainer-Plate changed, not sure about the name though. It's cheaper than the Bolt.
If interested, you can invest in proper tools
If threads on Bolt are intact, you can save a lot of money by just replacing that Plate:

Scary, be careful.