[desideep]

Hey i also have a YAMAHA RX 100

It is a 93 model will be comleteing the 15th on the 1st November.

No Major mods done

A 100/90 Tubeless tyre at the rear
RDD Digital CDI
Alloy Wheels

[desideep]

Oh forgot to add... in some months this Boy is going to see A conversion to 135 5speed. and this also got a brand new MSR yamaha YZ Toe gear shifter it is one amazing thing that you can have on your RX... may get that for the RD aswell

[praJEEP]

Couple of pics of my bike.

[straight6]

Around 6-8 months back I had to put in a new piston(I think size 50 or 55). Immediately after it was put in there was this sound it made even at idle which made me think something was not right and the work done was not right.

When I asked the mechanic, he said that its new and when you ride it and carbon collects on the piston, it will go away. I thought maybe he's right. I didn't have any experience at this before as this bike belongs to a friend. As time went by(1200 kms), this sound was just like it was at the start, nothing had changed. Now, I was pretty sure I needed a second opinion. I showed the bike to a official Yamaha service station in Andheri and I was told that when it was 'bored', too much gap was left and there is now other way to cure this but put in a bigger(and last)size piston once again(70-75?).

At that time I decided to wait as I didn't want to spend money. Now, I've been offered a used block of a 4 speed 135 for 1000-1200 bucks which is still using the original piston. Do you think I should just go for that or should I put in that bigger piston?

I will not trust the previous mechanic to touch the engine anymore. I've been told by a friend to go to Tony in Malad as he's very good with 2 strokes.

[BIKeINSTEIN]

Originally Posted by straight6

Around 6-8 months back I had to put in a new piston(I think size 50 or 55). Immediately after it was put in there was this sound it made even at idle which made me think something was not right and the work done was not right.

When I asked the mechanic, he said that its new and when you ride it and carbon collects on the piston, it will go away. I thought maybe he's right. I didn't have any experience at this before as this bike belongs to a friend. As time went by(1200 kms), this sound was just like it was at the start, nothing had changed. Now, I was pretty sure I needed a second opinion. I showed the bike to a official Yamaha service station in Andheri and I was told that when it was 'bored', too much gap was left and there is now other way to cure this but put in a bigger(and last)size piston once again(70-75?).

At that time I decided to wait as I didn't want to spend money. Now, I've been offered a used block of a 4 speed 135 for 1000-1200 bucks which is still using the original piston. Do you think I should just go for that or should I put in that bigger piston?

I will not trust the previous mechanic to touch the engine anymore. I've been told by a friend to go to Tony in Malad as he's very good with 2 strokes.

Depends on the condition of the used block, piston and rings.

Another alternative is to get the old block re-sleeved to standard bore and buying a new Mahle piston+rings standard size kit.
Might work out to 1K or maybe less.
But then you need to run-in the new engine for atleast 1.5K kms. :P

I will check how much both the options cost usually.

[desideep]

dont get the resleaved thing... just get a new barrel it will cost you 2400 from yamaha includes all...

[straight6]

Originally Posted by desideep

dont get the resleaved thing... just get a new barrel it will cost you 2400 from yamaha includes all...

Where can I get it in Bombay?

[BIKeINSTEIN]

Ideally- it's recommended to buy the oem block+piston kit from a authorised Yamaha workshop/reseller.
If you have the money- you should only get oem stuff.

But if resleeved to standard bore using one of good quality and when done by a good turner(mech works), it works quite good for much too less.
A lot of riders/tuners with similar blocks, even ported, will maybe vouch for this.

The most important part is the rings+piston and Mahle was oem for the Indian RX-100 anyways.
In fact many pick up discarded fully oversized/seized blocks for cheap and get them resleeved and ported too and pair them with a new piston+rings kit.
A cheap way to keep trying stuff.

That's why it's very cheap to keep a RX going on- while a Shogun demands genuine stuff only which is also a rarity now- you may ask any good mechanic.

Why it still works good enough is coz Yam RX in India wasn't exactly very new/great tech and the oem stuff was also not very great in quality.
Except genuine RX135 pistons that are proper Al alloy and much lighter than the Mahle ones.
150 bucks for the piston rings that come with Mahle pistons for the RX and (was)1000/- for the TVS genuine 'made in Japan' rings for the TVS Suzuki Shogun.

A fully seized RX will cause total locking of the rear wheel- a seized Shogun locks like mad and then rolls on.
Let it cool and a seized shogun will still do 70-90kmph easily and get you to your destination while you will be very very "lucky" if you can get a fully heat-seized RX to start and get going.

I, on the other hand, have bought many blocks from auth. showrooms, run-in for 2.5-3K Kms and then experimented with them.
RX135 was new then and one didn't have used blocks available at CST road/kurla- and i was/am a firm believer of oem stuff- plus this resleeving thing wasn't exactly for performance buffs then- more common since past few years.
Also genuine parts for RX were in stock and easily available then.

[Sankar]

Straight6, which oversize piston are you using now? If the Yamaha mechs suggested that the bore can be saved by saying the .75 (3rd oversize) piston then you might want to give it a shot. Let me tell you that .75 is not the last oversize available for the Yamaha it is 1.0 (that is 59mm) piston.

And pistons upto 2mm oversize can be safely used in stock sleeve.

I suggest before you spend on a new bore kit try getting the bike rebored from a reputed reboring shop with a new .75 or a 1.0 oversize Escorts Mahle piston. Ask them to put skirt clearance of 30 microns which is safe for high speed usage with a proper running in of only 500km. Make sure the jetting is correct though.

[straight6]

Originally Posted by Sankar

Straight6, which oversize piston are you using now? If the Yamaha mechs suggested that the bore can be saved by saying the .75 (3rd oversize) piston then you might want to give it a shot. Let me tell you that .75 is not the last oversize available for the Yamaha it is 1.0 (that is 59mm) piston.

And pistons upto 2mm oversize can be safely used in stock sleeve.

I suggest before you spend on a new bore kit try getting the bike rebored from a reputed reboring shop with a new .75 or a 1.0 oversize Escorts Mahle piston. Ask them to put skirt clearance of 30 microns which is safe for high speed usage with a proper running in of only 500km. Make sure the jetting is correct though.

It cost me 2500 last time to get this screwed up job done. If I go for a new piston like you say I'm looking at the same amount. A new block will cost me 2400 as pointed out earlier. What do you think?

[bigron]

I ve got a 1994 RX 100.Bought it in 1996 i think.Black colour with white and red strips on the tank.Done roughly 80000kms.Stock condition.used it till very recently.Lovely bike and amazing power for a 100cc engine.will post pics soon.

[Sankar]

Originally Posted by straight6

It cost me 2500 last time to get this screwed up job done. If I go for a new piston like you say I'm looking at the same amount. A new block will cost me 2400 as pointed out earlier. What do you think?

2500 is too much for a reboring job!

Here's the price breakup:
1) A new piston would cost 1200 bucks if it's the OE imported Arts. (or) An Escorts Mahle piston would cost 500 bucks.
2) Reboring job would cost around150 bucks.
3) Labour charge would come very much under 300bucks for removing and refitting the cylinder head & bore.

So if you choose and Escorts piston the whole thing should fit well under 1k.

In your case it shouldn't have been 2500 unless you touched the bottom end also. Usually mechs do the crank resetting alongwith a rebore job and would give many reasons also. But it is NOT ALWAYS required.

The success of a rebore job lies almost entirely in the hands of the operator at the reboring shop. So find a shop with proper reboring equipment and with an experienced operator.

I think unless you could find a good machine shop to get the reboring done it's better to go for a new kit. Otherwise rebore.

[straight6]

The last time he even put in new connecting rods etc.

[Sankar]

Originally Posted by straight6

The last time he even put in new connecting rods etc.

Yep. So that explains the high cost incured last time. So probably this time it will cost you much lesser.

[chiragh_bir]

My 5 speed (Still working on it)

Details:
New Cylinder Kit
New Crank
New Bearings
New Clutch and Pressure plates + Springs and clutch basket
New Oils Seals
VM 26 Carb + Pipercross Filter (Will shift to UNI)
New orginal CDI
New Seat
Gladiator Disc Setup and Forks
New Alloys + New rear Zapper Q 100/90
New Chain Set

To be done :
Tuned Chamber
Clipons
Paint job
Mudguards at both the end
Fiber reeds
Autolite plugs
Versah Exhaust Gasket