Query approved

cylinder rebore

sorry, this is not a reply but continuation of my query. The very reason i started this thread is, i had got a rebore work done very recently, abt a month ago (i.e., i increased my bore size to 58.5mm ) i had spent 1.25k on a new 2nd oversize ART piston. My mechanic suggested me to ride my bike slowly till i burnt about 8 litres of petrol. (my bike delivers 35 kms per litre of petrol n burning 8 litres means riding my bike slowly for 280 kms. ) i rode slowly for 300 kms to be on a safer side. After 300 odd kms, i opened the throttle n within a kilometer's stretch, rear wheel got locked accompanied by weird sound from the bore. (got ceased:-( ) damn!! I was literally on a verge of crying coz i had spent of mucha money n more importantly, ART pistons r not available for third oversize. :-( i just dont know wot could have caused the seizure coz i used to maintain oil quantity of 50ml per litre:-(
I just cant afford the same to happen again after this 3rd rebore at any cost!:-( i would be really grateful to u all if u could guide me, explaining all the points, so that my bore would never cease again atleast for 40k kms!:-) i want it to have a mirror finish from within, without a single scratch for more than 40k kms:-)

though 'm no expert but there could be 2 main reasons for this to happen:

1. the rebore job might be a shoddy work

2. 280 kms of running-in is low.. normal suggested run-in is around 1000 kms

3. not sure of this but 50 ml of oil in petrol... 'm not sure if it is right for run in. normally more amount of oil in petrol actually makes the bike run lean.. would this have effect on cylinder heating and seizure(!!!?)

next time make sure the rebore is done properly with exact clearances and make sure to run-in the new surface properly and open the throttle gradually there after.


anyways wait for the experts to put in their comments .. and all the best

Adding to what bhpistorqintorpm has told following are my Inputs;

1. The Run-in Procedure after the rebore is purely based on the tolerances set at the bore shop. Normally the factory keeps close to 40-50 microns clearance to my knowledge which requires 1000km Run-in. If your Mech has kept tighter tolerances then the Run-in period should be higher and not 300 kms as said.
2. The best way to avoid a seizure is to set high clearances which will give you slapping noise but never a seizure. As an example my Clearances are set at 30 Micron, the bike has clocked some 16oo kms and i know where the bike gets constipated & where it runs freely. It's just how well you know the bike.
3. Even if the Run-In is 300 kms as said, keeping 40-45 for 300 kms and WOT after that is asking for trouble always. One should be varying the rpm's & should gradually take the bike higher.
4. During Run-in the Oil required should be around 35-40 ml. Too much of Oil during that time also can cause glazing.
5. Are you Running on Autolube or Premix? If Autolube, failure of Oil Pump can also be a reason for Engine Seizure.

If you're gonna get another rebore, PM me, i'll give you contacts where you can get a nice job done in Mysore.

Hi Sunnyboi,

There are any things I see amiss in the running in procedure u have mentioned.

1. 300 kms is too short a distance for running in ... 1000 kms is required for brand new bikes coz the gearbox, crank and the rest of the parts need to mill correctly.

For only a new piston, around 500-600 kms should be fine.

2. While running in, the bike should be allowed to cool for approx 5-8 mins after each hour of running.

2. The Engine rpm must be varied, but should not exceed 3000 rpm. (rx135, without a tacho, is approx 40 kmph in TOP GEAR

3. Once 500 kms are done, u should not rip the engine .... infact, the running is should be a process of gradually loading the engine upto 3000-4000 rpm first and then going up by around 500 rpm per 100 kms.

0-500 -> ~ 3500 rpm
500-600 -> ~ 4000 rpm
600-700 -> ~ 4500 rpm
and so on ...

it should be done GRADUALLY.

4. Oil pump is better than premix.

If u intend to add oil to the petrol, do it as a contingency for oil pump failure ... NEVER as a replacement for the oil pump ....

At most add 10 ml / lit of oil in petrol if the oil-pump is functioning (It should be).

Also Mahale and Goetz are both manufactured by the

Escorts-Mahale-Goetz group... so u r safe there.

Next time be more careful ...

If u need a 4 speed block, I may be able to help.



RegaRDs

Alok

Bro, i have some queries 4 u. More slapping noise means more clearance, which inturn means more wear in less time. I want to enjoy a very smooth n creamy sound from my cyl block without the block getting seized. And i dont have an oil pump in my bike:-( so i have to mix oil with petrol.

Yes bro, i have to get a rebore work done shortly... I would be grateful if u could suggest me the best place to get this work done

Yes bro, i have to get a rebore work done shortly... I would be grateful if u could suggest me the best place to get this work done

More slapping doesn't have to be necessarily more wear & tear all the time. It all depends the way you Run-in & the oil the piston chamber gets to burn. Some crappy oil with high clearance sure will result in quick change to the next O/S. The process can be reversed also if good quality mineral oil for the Run-in is used say for ex. Motul motomix. Also it's not a four stroke to keep the engine sound muted as much as possible naturally, If it's a two stroke it has to scream mate.

@sixspeedtwin: thank u so much for ur vital info bro i'll keep all that in mind after my rebore:-) and as i dont have an oil pump, i have to mix oil with petrol n need to know the OPTIMUM quantity of oil to be added per litre of petrol during this run-in period

@sixspeedtwin: thank u so much for ur vital info bro i'll keep all that in mind after my rebore:-) and as i dont have an oil pump, i have to mix oil with petrol n need to know the OPTIMUM quantity of oil to be added per litre of petrol during this run-in period

@dual disc 200: oh ok bro.... The thing is, my friend has a 2004 model rx 135 (the one with sleek cat silencer and tank quickering some wot similar to rx100. ) i love to keep my ears near his cylinder block coz its so damn smooth. It gives out a sound like 'suiiiiin' (he hasnt bored it even once till now n the bike has clocked abt 65k kms. Still on the standard size piston!:O n if i keep no ear near my block, it gives out a sound like 'grrrrrr' which is so disappointing
Can a rebore job n a proper runin help me get the sound n the endurance(abt 65k + kms without a rebore ) my friend's bike has got?
N motul is full synthetic oil no bro? I use servo 2t which is available in indian oil bunks. Is this oil ok?

Yes, a good re-bore job with the right clearances coupled with a proper Run-In using good 2T oil at correct proportion can give you amazing results. The Motomix is a Mineral based oil that can give you excellent results during the bedding period. That's what I'm using & I'm in my Run-in now. Avoid going for Motul 510T or the 800T which is Semi Synth & Fully Synth Respectively. The oil that I use for the gear box is Mobil 15W 50 I guess, which I shall confirm if you need that.