You mean the magnet side cover rt? man.. how can you? anyways.. i told you the sprocket cud be fake! good atleast one of your prob. got solved.
no need to dump the TM. what you can do is try another 135 stock carb with stock jets and see how the bike performs. This is the first thing you should do before u go to a mech. to try more experiments.

Bigger carb + stock intake = more fuel flow from the carb and lesser air intake, you need to match the AFR, if u cant ditch the TM and revert to stock carb.

Righto

But I should expect a drop in pickup & slight top end right?

Great idea; Sri - here I come

Araey boss, I tested even without air filter, if that's the case, then it should've behaved properly right? But it didn't. Then how come the TM28 was working fine all these years or atleast just before the build?

I guess some part is worn out or something like that; can you guess anything apart from airscrew or idle screw? Did you have a chance to watch the video Psycho?

I did watch that video,it didnt help, u are rising the throttle standstill you have to ride the bike simaltaneouslly shoot the vid, just cant comment anything further without seeing the things in person ..

why should you?its stock rt? 15/37?

The point is, at stand still, it doesn't stay at the same RPM & keep sputtering. Same case when riding too; after a certain RPM (don't have the meter) the sputtering increases & engine shuts off unless I start random throttling. Got the point?

Nope it was 16/34 & now its 15/34, though I've 37 & 39 with me . Let me know if I need to change the rear sprocks too; I wish to have a top speed than pickup.

Then you have to go for 16. although it wont matter that much with a 15.

by the way which air filter r u using generally in flat side carb air fillter is not necessary .If u go for air filter than u should try uni or something else,the sound of u r bike little harsh that's means it flutters, if u pulling in second gear or in final gear with steady throttle the sound is continuous not in stroke form .

But Aalop, I tried even without air filters & the engine stalls after reaching certain RPM, may be lack of fuel or air or both, not sure what's going inside!!!

I'm using stock airfilter; no matter which gear it is, idle or running, the engine begins to stall after reaching certain RPM.

tell me what is stock jet in flat side carb .i strongly suggest u, u have to check filter bcz these kind carb doesnt support stock filter

I'm running on 180 mains which is stock for TM28; 2 days ago I tried 165 mains which is stock for Rx. After changing to 165, all this issue started (check the video) main thing is the engine refuses to raise after certain RPM & beyond raising the throttle, the engine gasps for air or fuel & then dies.

So I thought 165 is wrong choice & replaced with 180, but to my surprise, the same issue happens with 180 which was not the case earlier.

What could've conked off?

you better try a stock carb asap. else you'd be beating arnd the bush. like psycho said, its difficult to trouble shoot online.

Boss, why are you using a TM28 for a stock 4-speed RX? If you are stockish kind of a guy then revert to stock settings. Just by plonking a TM28 on a stock barrel (which is hardly making 12BHP), you wont achieve anything. The very definition of stock is to be as per factory setting.

As Yamdoot has pointed out try for somebody else's OEM 4-speed carb & check it on your bike, i am 110% sure your problem will be solved. Try this stuff out & let us know of the results.

As for your TM28, if you are not able to get it right, then let the experts do the job for you. Don't tell me there any no good race mechanics in Chennai, i assume there are many in Coimbatore atleast.

Man i am sorry to say this, but you are really screwing big time with your bike. Even i had severe jetting issue with my VM26, but my guy has been into 2-Ts for the last 20Yrs, so he was sucessfull in tuning it as per my needs & now, no matter what i dont screw around with my bikes. Tune & Forget, thats how it should be.

I really don't want to start another argument here, but please stop screwing your bike. Revert to factory settings & i am sure you will have the desired result.

Peace.

Whew!!! Issue fixed finally today without taking ANY help of ANY mechanic. Had taken to a mech day before & sorry to say, he's the dumbest ass of the lot. He's never seen a TM28 ever in his life & over & above he comments saying this is a fantastic carb

Anyway, the backfiring or sputtering or whatever was there previously is still there. I cannot use the 165 mains because either the fuel or air is not mixing properly, but with 180 there're no such issues.; I need to plonk even bigger jet than 180 & hopefully that should resolve the problem.

Anyway, I'm not done with experimenting; will try more & post here. And yes, Yamdoot. do you wannt hear about the 15/34 sprockets? Just one word - its as good as empty vessel making much noise ; I'm sure its not going to cross 90 Kmph mark I guess; will try on Sunday morning & post an update here.

Anyone wants to know what the issue was? Its going to turn all your theories to dust for sure

Bigbore's stock RX on 15/34 crosses 110 on the speedo easily. Most of them do.