OOps,I meant to say Hero MOTO corp.
Its Hard to forget Hero Honda.

Old bikes like Splendor , Passion , Karizma , on there owners manual last page HeroHonda 20W40 oil picture also present , but now it is replaced by 10W30 .

Can't say about smoke but seen some bikes having various problems but some are good .

Possible , thinner low viscous fluids have better detergency I think . The main cause is that the 10w30 HH oil starts to feel stale in 1000 kms and owners are therefore replacing it within 2000 kms max, whereas with 20w40 oils 3000kms is usual for people; remember that most people here don't count the time/miles for oil change , just changes when it feels bad . Quick oil changes = clean engine . The HH ASC itself told me not to dream even of the company recommended 6000kms drain period . I ran the HH10w30 for this winter , was very good during the season . Still have 2 bottles of the stuff left for next winter .

Cycle parts quality is same , Hero Moto had to do too much tinkering with the motor to conform to new stringent BS standards for urban areas . In July 2010 my bike's delivery was delayed for one month and the company sales manager told me this himself "all vehicles dispatch are stopped or recalled mid-way for BS update ." The main changes were done to cat-con exhaust (now very restrictive) , carburetor and valves . Better avoid this engine type now, was designed in the late 1960s when Soichiro Honda had never heard of emission norms .
I am also suspecting this on my July2010 splendor+ , mine is the first lot of BSIII+ compliant models with black (shielded) cat-con exhaust . Main symptoms are overheat on longer riding in some speed . The heat is about 30% less with 20w40 oil now, but still too hot when compared with other bikes I have had . I am checking all things one by one . Last thing to check are the valves and timing . Sibun did mention something wrong with new valve-sets . Faulty valves do cause engine overheat , no ? I have no exhaust smoke though ... hot exhaust port valve should cause smoke . Over restrictive hot-cat-con in exhaust doing some mischief at the exhaust port ?

Yeah , like all else .. I still love this tiddler .

Try swapping the exhaust assembly and carburetor with that of pollution model and see if there is considerable change.

@ALL

Has anyone tried Michelin 2.75-18 42P SIRAC STREET(Front wheel) ?

If those sweet sounding stainless steel exhausts of the original splendor is still available(?) and shall not cause other problem after fitting , I am looking to buy one new .

I think you will need a pollution model carb too.
BTW, I never knew that there was a pollution (old type) carb also until Sibun mentioned it in this thread earlier.

Pinaki ji better confirm with Sibun about my idea.

@All
Finally Solved the idling issue of my passion today

It was due to vacuum leak caused by the cracked air-suction valve pipe.
The pipe might have got hardened due to engine heat and eventually developed small cracks after so many years.
The leak was most noticeable at idle when less fuel is available which made the AFR very-very lean and that may be the reason why the RPM was not coming down soon after I left the throttle.
(Rpm used to come down slowly after I left the throttle)

How did I detect the leak ?
I used a butane gas candle and when I took it around the cracked pipe,RPM increased suddenly which indicated that there was a leak.
(Caution-There is Risk of fire if proper care is not taken)

What did I get to learn ?
Sometimes while diagnosing problems little and insignificant things get ignored and one has to take all the trouble .

whole assembly.

How much side-wise play is normal for the front sprocket ? Mine has quite a bit ...

Yah , there are differences in the earlier carburetors and current ones , they had to mod it several times through all these production years owing to pollution norms . That HH manager told me this too , while I was waiting for them to finish the BS-III update and send my bike down here . Used to meet or call him up daily to pester him then , poor fella .
It's a common problem with that rubber pipe connecting the carburetor to the air-box . It hardens with age and develops fine cracks . Recently I took it out fully and refit it to the air-box with rubber-glue , remember ? Replace it . I also told you so , that your mixture is lean . Yes , the tiny gremlins are the most troublesome pests .
You adopted the correct method to find leaks in the engines intake path , I usually check it by spraying the same carb-cleaner I used earlier . If the RPM changes on spraying the joints etc ... there is a leak . Hopefully you are not using a lighthed gas candle ?
Ok , you got me confused there when you said a "pair of" . Anyways I'll find out when I visit the ASC in the next week .

Its not the pipe you are referring,actually its the pipe which connects intake manifold to the air-suction valve.

LOL, Why would I use a lighted candle when I want the butane to make the AFR rich.

It is 100% normal for Front sprocket to have lateral play.
If you are facing chain jumping issues ,remove the sprocket and install it the other way.

Is it possible to purchase the old model from villages/tier 2 cities where BS III norms has not been implemented or does Hero Manufactures only BS III ?

To complete ten characters .

I got a that tube for just Rs.5/-from local spare parts shop,the length was more than enough so I replaced the petrol tube also.

Pinaki ji Thanks for suggesting 90w gear oil for oiling airfilter..the viscocity of this oil attracts dust more..I think filter will be wet for long periods

You are welcome Harish'jee .
Many people tend to employ more readily available engine oil for the purpose (HeroHonda ASC used their thin 10w30 to wet my bike's foam air-filter on first service). But engine oils are designed to clean the engine and flow well through the engines narrow oil paths . So they tend to flow off quickly and dry up on the foam . Of course if you get stuck in the middle of no-where with a clogged foam air-filter , you can use it .. it'll work perfectly well for a couple of weeks .
90 weight gear oil is not heavier(thicker or more viscous) than a 40 weight engine oil , they are about the same grade . This is possible because the SAE viscosity grading for engine oil and gear(transmission) oils are different . But gear oil does not flow off as easily as engine oils(they are designed to do so) . They also do not contain any viscosity modifier (single weight), detergents or dry up easily in use so it sticks very good , filters dust well good and keeps working for months .
This is why 90 weight gear oil is recommended by Honda and consequently by HeroHonda too , for wetting foam air-filter and lubrication of drive-chain etc , in all their owner's manuals . In my humble opinion , it works better than most purpose build products for both purposes and cost about a 1/100th too ( compared to special foam-filter oils and spray chain-lubes and chain waxes ) .

Pinakji ji ,,can we use a 140 grade gear oil for oiling foam..i asked this because in my garage we a have a lot of 140 w gear oil is available..which is used for my grandfathers lorry..

No , heavier grade oil like 140 gear/axle oil won't penetrate well or wet the foam thoroughly . It also has a potential to block the pores in the foam and prevent free air ingress . Remember that the oil traps the dust from air , while the foam merely acts as a carrier . So the oil that is well dispersed throughout the foam element and in small droplets is better for the purpose .
You can use the 140 gear oil for lubing drive chain , some feels it stays on longer than the 90 .