[Karthik.guru]

Hello folks! I've been touring on my 4V a bit lately and I keep finding myself hunting for a 6th gear constantly. I was wondering if a smaller rear sprocket would help. Has anyone here tried a smaller rear sprocket on the 4V to give it slightly longer legs on the highway?

[Grimlock]

Originally Posted by Karthik.guru

Hello folks! I've been touring on my 4V a bit lately and I keep finding myself hunting for a 6th gear constantly. I was wondering if a smaller rear sprocket would help. Has anyone here tried a smaller rear sprocket on the 4V to give it slightly longer legs on the highway?

I had tried the sprocket from the 2v, and would not recommend it. It is good for 85 kph, and anything above it really needs a lot of effort from the bike and rider.

[Karthik.guru]

Originally Posted by Grimlock

I had tried the sprocket from the 2v, and would not recommend it. It is good for 85 kph, and anything above it really needs a lot of effort from the bike and rider.

Thanks for responding!
AFAIK the 2v had a 38 teeth sprocket right? As opposed to the 45 of the 4V. Isn't that too much of a difference for such a small displacement motor to handle (not enough torque)? I was thinking more on the lines of a 40 or 42 teeth.

[Aragorn]

Originally Posted by Karthik.guru

Hello folks! I've been touring on my 4V a bit lately and I keep finding myself hunting for a 6th gear constantly. I was wondering if a smaller rear sprocket would help. Has anyone here tried a smaller rear sprocket on the 4V to give it slightly longer legs on the highway?

Hey there, Karthik.guru - here is one suggestion. Instead of modifying the rear sprocket, try modifying the front one. The stock 200 4V has a 13 / 45 front - front / rear sprockets. With this ratio, the engine sits at about 7000 RPM at 100 kmph.

It's not buzzy, but the engine feels 'busy'. Go one tooth up the front sprocket to 14 teeth. This reduces the final ratio by ~7.5%. Which will in-turn bring down the engine RPM to 6500 RPM at 100 kmph.

I took inspiration from this video:

https://www.youtube.com/watch?v=vCeP...NlIDIwMA%3D%3D

You can walk down to any Hero service outlet and order the part on this part number - 23801GF6000S.

Hope this helps!

[Karthik.guru]

Originally Posted by Aragorn

Hey there, Karthik.guru - here is one suggestion. Hope this helps!

Thank You! This was very helpful indeed!
I estimated (using one of those online calculators) that a 42T rear would give me about 7.5% increase in speed, which is pretty much what I wanted to go for. A 14T front seems like a neater solution. Did you need to add any links to the chain? Or was the stock 110 link chain enough for it?

[Aragorn]

Originally Posted by Karthik.guru

Thank You! This was very helpful indeed!
I estimated (using one of those online calculators) that a 42T rear would give me about 7.5% increase in speed, which is pretty much what I wanted to go for. A 14T front seems like a neater solution. Did you need to add any links to the chain? Or was the stock 110 link chain enough for it?

No additional links needed. The tension / slack can be managed with the chain tension bolt at the end of the swing-arm.

Side benefit of larger front sprocket: In theory, using a sprocket with more teeth reduces the curvature of the chain around the sprocket. So, technically it should also help increase chain life.

Cheers.

[Grimlock]

Originally Posted by Karthik.guru

Thanks for responding!
AFAIK the 2v had a 38 teeth sprocket right? As opposed to the 45 of the 4V. Isn't that too much of a difference for such a small displacement motor to handle (not enough torque)? I was thinking more on the lines of a 40 or 42 teeth.

Since the 4v had changes to the final drive, It was not very noticeable in the city nor did the bike struggle on trails or hills, overall, the revs dropped by 1k across the rev range. The goal was to stop hitting the 4k rpm band so often where some vibrations kicked in. The 38t sorted that bit out, made the bike really nice to ride around the city, but made it lag at high speeds.

Anyway, altering the front sprocket suggested in the above posts seems to be the more practical option here.

[Karthik.guru]

Originally Posted by Aragorn

You can walk down to any Hero service outlet and order the part on this part number - 23801GF6000S.

It didn't fit!

The drive shaft was too big for the sprocket. Are you sure you put this sprocket (re part number) on your bike? Because not only was the shaft diameter different, the sprocket itself, albeit 14T, was much smaller in overall diameter that the stock sprocket. Adding pictures for reference.

On a side note, if anyone needs a free sprocket, DM me!

[Aragorn]

Originally Posted by Karthik.guru

It didn't fit!

The drive shaft was too big for the sprocket. Are you sure you put this sprocket (re part number) on your bike? Because not only was the shaft diameter different, the sprocket itself, albeit 14T, was much smaller in overall diameter that the stock sprocket. Adding pictures for reference.

Sorry mate - I too ran into the same issue! I ordered the part without looking at the compatibility and I too have a spare sprocket now!

Next planned change is to source the rear sprocket from 200T 4V, which has 42 teeth. This will have the same effect as earlier mod (14 /45 vs 13 / 42). Have asked the local dealer to source it.

Also, plan to replace the chain with a rolon-brass chain during the process.

Will keep you posted.

[Karthik.guru]

Originally Posted by Aragorn

Sorry mate - I too ran into the same issue! I ordered the part without looking at the compatibility and I too have a spare sprocket now!

Next planned change is to source the rear sprocket from 200T 4V, which has 42 teeth. This will have the same effect as earlier mod (14 /45 vs 13 / 42). Have asked the local dealer to source it.

Also, plan to replace the chain with a rolon-brass chain during the process.

Will keep you posted.

Don't worry about it mate! I wonder if some other manufacturer has the magic 14T sprocket we need. There's no way to get PCD, shaft diameter, outer diameter figures for sprockets used in other bikes is there?

Also are you sure the 200T has 42 teeth? Because that was the first bike I looked at for a different rear sprocket and I kept seeing 38T everywhere.

[Aragorn]

Originally Posted by Karthik.guru

Don't worry about it mate! I wonder if some other manufacturer has the magic 14T sprocket we need. There's no way to get PCD, shaft diameter, outer diameter figures for sprockets used in other bikes is there?

Also are you sure the 200T has 42 teeth? Because that was the first bike I looked at for a different rear sprocket and I kept seeing 38T everywhere.

You are right - the earlier 200T had 38T.

I was a Hero service centre today. The 200T "4V" version was upgraded from 38T to 42T. I could see the spec on the e-catalogue.

Do try your local service centre once and let's tally notes.

Cheers!

[AMFSportster]

Originally Posted by Karthik.guru

It didn't fit!

Hi, did you manage to find a sprocket that works?

[AMFSportster]

Originally Posted by Karthik.guru

Don't worry about it mate! I wonder if some other manufacturer has the magic 14T sprocket we need. There's no way to get PCD, shaft diameter, outer diameter figures for sprockets used in other bikes is there?

Also are you sure the 200T has 42 teeth? Because that was the first bike I looked at for a different rear sprocket and I kept seeing 38T everywhere.

Looking for a 14T that fits :(