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**HydBiker** · 04-03-2009, 10:23 PM

^^^
The bore kit is much better aligned as the bore, Piston and rings are made to a measurement with the right amount of clearances... you can not match that easily when you oversize the bore...

just go with the stock bore kit of RX100 or if you want it bigger, get that of the RX135... pls check with people if there's anything else that is different for the RX135 other than the bore kit.

**pk28.karthik** · 04-03-2009, 10:29 PM

yes with 135 bore kit clutch and crank also has to be taken care. 135 needs a bigger crank is what i have heard of.

with the 1.25 piston and bore drilled out and finished by a good worksmen will have no problems. the mileage will drop but will increase cc and power.

**HydBiker** · 04-03-2009, 10:35 PM

you did that very recently... and that didn't work so well!

**pk28.karthik** · 04-03-2009, 10:58 PM

the culprit was side oil tank. though functioning but on high revvs the oil was not passing. now since i have learnt the mistake wont even touch the side oil tank. pre mix is better.
coming to reboring, this time i am getting it done from a different guy. mech says with 1.25 piston the power will be equal to 110 cc. and estimation for this bore job on the whole is 1200 only. lets experiment what this will do to the bike and my pocket.
have already burnt my pocket so 1200 wont make much of harm.
if it goes well then the ego is back and so will the charm

**HydBiker** · 04-03-2009, 11:30 PM

oh! missed that point.

But, are you sure you can get a 1.25 size piston???

BTW, let us see some math here -

RX100 is a 98cc engine. Bore x Stroke = 50mm x 50mm = 98.1748 = 98.17 CC

with 1.25mm oversize piston it should be

Bore x Stroke = 51.25mm x 50mm = 103.1448 = 103.14 CC

Trying to prove nothing here. Just FYI that the calculation was wrong. To make it 110 CC by just over sizing the bore you need a 3mm oversize piston!

**pk28.karthik** · 04-04-2009, 10:53 AM

if i rebore and put 52mm piston kit?
120cc and bhp will be increased to nearly 15bhp.
port the exhaust to 6mm
change the sprocketing to rxz ones.
this is already putting a wild grin on my face. do you think i should go for this?
well i will go ahead and try. there is nothing wrong in experimenting right?

**HydBiker** · 04-04-2009, 01:14 PM

you are not entirely wrong there but your calculations are wrong... trust me, gaining power is not so easy!

FYI, the RXZ & RX135 come with a 132cc engine and the bore x stroke for them is 58mm x 50mm.

Yes, you can try it... but get the calculations right. Frankly, I am surprised that you haven't researched on these numbers before you want to try them... that too when you said you are out of money... I am not worried about the numbers and pride but I don't want you to be disappointed or heart broken once more.

With a 1.25 oversize piston you will gain a little more power than the stock setup but I wonder if that would be any noticeable... Yes, it is a 5CC raise but still... how much of that is getting on to the drive train and then onto the wheel? GO ahead and do this but don't get into the words of those mechanics who say it will become 110 CC.

A small tool for you - Engine Cubic Inch/CC Displacement Calculator

**pk28.karthik** · 04-04-2009, 03:15 PM

yeah i got the calculations wrong there for sure.
true there wont be a great outcome of power with this setup, but
a rx100 doing better numbers than the other 100s is a nice scene.
this setup wont be burning my pocket much. the mech has told me he will get this setup done for 1200 only. this amount is worth the experiment is what i feel.
even if this setup runs for a year its good. after that i will get the complete 135 setup from the base to head.

**HydBiker** · 04-04-2009, 04:11 PM

Originally posted by pk28.karthik View Post

a rx100 doing better numbers than the other 100s is a nice scene.

okay... so problem solved then

Please post the outcome once you get this done...

**pk28.karthik** · 04-04-2009, 04:28 PM

the bike will be oing in for the rebuild from tomorrow.
surely will update with the results.

**Shivanshu** · 04-04-2009, 04:45 PM

Originally posted by pk28.karthik View Post

the bike will be oing in for the rebuild from tomorrow.
surely will update with the results.

Karthik all the best man keep your fingers crossed and everything should go all fine...... so take caer and keep us posted....

**Velocity** · 04-04-2009, 06:14 PM

I had crossed the same situation few days back.. I had to re-bore it again just after 2000kms of last re-bore.

I have to thank Psycho (Pradeep) for his great advices & help in fixing my bike.

**nirvan** · 04-04-2009, 06:42 PM

Make absolutely sure the crankshaft was not damaged during the seize and its play is within limits.

If you are planning on keeping this bike, then I suggest you go with a new bore kit, stick with 100cc if your budget is low.

A conversion to 135 would entail:

* 135 bore kit (buy the 5-speed flavor) ~ Rs. 3500
* 135 5-speed head (or buy the 4 speed head if not available) ~ Rs. 1200
* 135 crankshaft ~ Rs. 1800

Always change the main bearings & all oil seals if taking the engine down.
Change the kick spring every time you open up the gear-case.

Change all the roller cages within the engine too.

A switch to 135 from 100cc would also involve jetting changes:

Jet sizes IIRC:
100cc: 115
135 5 speed: 135
135 4 speed: 165

**Sandeep_K_Ram** · 04-05-2009, 11:02 AM

Usually a 2 stoke is pretty simple to maintain as long as you do one basic thing right - Fuel-Oil ratio - get it right and she will just keep running. This is my personal observation - may not be entirely true in all cases.

Of course it makes sense for you to go for a 4stroke now - there are plenty of models out there which will suit your needs of a daily commuter... but just one hitch - I think, if you move over to 4strokes - somewhere down the line you might feel a tinge disappointed about dumping the 2s ...

**pk28.karthik** · 04-05-2009, 01:01 PM

guys no more plas of dumping her.
as a stop gap arrangement and experiment i am boring it out one more size and running the next size piston.
this build will run only for few months.

@ velocity
got to know about the issue from psycho , but good to know that your bike is doing good numbers now.

@sandeep_K_ram
no plans of dumping anymore. keeping this beauty for life.

@nirvan
thanks for the advice man, will take care of all those points when i sit with the mechanic

@all
will be updating more.

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