[abhishek24x]

I own a 2005 model TVS Star City & its lying unused since 2-3 years. I'm now thinking of experimenting & swapping its 100cc engine with a Honda Unicorn's 150cc engine from the ATV I had made at my engg. colg as a project using a unicorn's engine & chassis. Since both bikes use engine as a stressed member & i think the swapping would be easy..is it possible??? Any ideas???

[abhinav.s]

I guess it should be possible if you consider all factors like handling, weight distribution etc.

The stock unicorn is around 140kgs IIRC and the Star City should not be more than a 115kgs. So you have to consider the weights of the engine and the way you will distribute the extra weight.

You also have to consider if the chassis can handle the extra power the engine makes since the Star City makes about 7-8Bhp while the Unicorn makes 13Bhp. So its almost double the power at crank.

All the best and do let us know if you go ahead with the swap!!

[ku69rd]

Originally Posted by abhishek24x

.is it possible??? Any ideas???

Mate,
What you gonna gain of it? understand if you are trying to build it to a purpose, here don't think it's gonna do a world of good. Can be done, but you might have to reinforce the chassis along the main tubes so that they get to handle the increased weight/speed/changed dynamics.

[Sutripta]

Originally Posted by abhishek24x

Since both bikes use engine as a stressed member & i think the swapping would be easy.

I would think it would be the other way around. Plonking an engine on a bed is easier than integrating it into a foreign chassis.

Regards
Sutripta

[SunnyBoi]

Illegal. 'nuff said.

[Rennjit]

Originally Posted by abhishek24x

... swapping its 100cc engine with a Honda Unicorn's 150cc engine

Yawn ..

... from the ATV I had made at my engg. colg as a project using a unicorn's engine & chassis. ...

Cool., can we have some details/ pics?

[KarthikK]

the RC book would then contain an invalid/obsolete engine number after the swap; and what happens when the bike is sent for insurance renewal inspection? Engine number mismatch again. Both your Registration Certificate and insurance policy become invalid with an engine swap

[abhishek24x]

Originally Posted by Rennjit

Yawn ..

Cool., can we have some details/ pics?

these are the initial pics that were lying with me in my laptop. The final model had a lot more changes like the whole front suspension was changed as well as the steering parameters. Mainly it was as 4x2, 150 cc ATV with real wheel drive. Final drive was via chain using my self designed chain-differential---the main USP. The differential was fabricated by mounting unicorn's rear sprocket on maruti 800's crown pinion(pic attached) I'll attach the final pics as well when i reach home..

Originally Posted by Sutripta

I would think it would be the other way around. Plonking an engine on a bed is easier than integrating it into a foreign chassis.

Regards
Sutripta

True.
But sir do you suggest my going in for that mod?? Atleast it'll feed my passion of automobile modification & will begin a new experiment for me to get busy with

Originally Posted by ku69rd

Mate,
What you gonna gain of it? understand if you are trying to build it to a purpose, here don't think it's gonna do a world of good. Can be done, but you might have to reinforce the chassis along the main tubes so that they get to handle the increased weight/speed/changed dynamics.

Changing the front forks is definitely on cards. Apart from it, is chassis reinforcement really needed?? People who go in for modifying their stock apache/karizma/r15 for track, do they also add something of this sort?? Please advice.

Originally Posted by KarthikK

the RC book would then contain an invalid/obsolete engine number after the swap; and what happens when the bike is sent for insurance renewal inspection? Engine number mismatch again. Both your Registration Certificate and insurance policy become invalid with an engine swap

For sure the old engine number will not be valid. Meanwhile i'll also check with the RTO regarding getting the new engine entered in the RC..


Note from Support: Posts merged.

[ku69rd]

Originally Posted by abhishek24x

Changing the front forks is definitely on cards. Apart from it, is chassis reinforcement really needed?? People who go in for modifying their stock apache/karizma/r15 for track, do they also add something of this sort?? Please advice.

Track means it might need a bit more technical insight please excuse me for that as am not technically qualified enough to make a statement. You might have to consider facts like the rigidity of chassis, balance with the new additional weights inputted into it. But for moto-cross you would definitively need to reinforce the chassis with additional metal. Cause have seen stock bikes suffering at the fork/steering stem due to the weight impacts.

Regarding the ATV, were you using Drum brakes?

[Sutripta]

Originally Posted by abhishek24x

....
True.
But sir do you suggest my going in for that mod?? Atleast it'll feed my passion of automobile modification & will begin a new experiment for me to get busy with
....

If you can afford it, thought it through, and have a fair idea of the consequences, by all means go for it.

I'm sure you have learned since building your ATV. Still, the pictures you have posted suggest that you have to do a lot more homework. Both design and workmanship.

Regards
Sutripta

[abhishek24x]

Originally Posted by ku69rd

Track means it might need a bit more technical insight please excuse me for that as am not technically qualified enough to make a statement. You might have to consider facts like the rigidity of chassis, balance with the new additional weights inputted into it. But for moto-cross you would definitively need to reinforce the chassis with additional metal. Cause have seen stock bikes suffering at the fork/steering stem due to the weight impacts.

Regarding the ATV, were you using Drum brakes?

no i used disc brakes on all four wheels..