Query Approved and Moved

to my knowledge there is no bore size over 1...........

if find difficult to get the the bore piston of victor go in for the jive or star city which as the same bore stroke..............

star city has 2 type of engines 109~110 & 100cc...so get the 110cc bore piston block..............

i hope this should sort out....

if ur in for some mod u can try the 3valve setup of jive but get things checked as jive is a auto clutch engine & is there ny relation with valve setup...if not u can go ahead & have fun biking....cheers

Hello Pankaj.
I am running 5.5mm bore over stock on my TVS Fiero F2.
i actually installed rtr's bore kit as the block structure as well as the stoke length is the same.

However if you can source any piston which falls exactly on TDC without popping out even a 0.1mm extra, then the work can be done very easily.
If it is popping out slightly then the piston head can be shaved, if its below the TDC, then you'll have a loss in compression.

There are Fiero's running Karizma's as well as P220's piston.

I know a pulsar running some car's piston too.

So basically just find a piston with the bore size of your choice (54.5 + ~1 to ~3) and plonk it on the con rod.
All you'll need is to match the bore to the new piston, if you want to go beyond 3mm you'll need a new sleeve, and also some head work.

A knowledgeable lathe guy might know all this.

Just for information, TVS Fiero has a bore of 57mm. So you might be able to use that piston.

Reboring

Thanks NanoTechnology
You say that Fiero's bore is 57 mm but its stroke length is 57.8 mm whereas GLX has stroke of 53.5 mm hence it is too much greater than the TDC.
Also I asked in Pune for oversize pistons but was unable to find out.
I am getting 1 mm oversize from SAM but the person who rebores doesnt recommends SAM.He says that for good reboring job,Mahle pistons are good.

I also met one guy in pune who prepares bikes for racing(especially Yamaha bikes) saying that he can put an Apache RTR block piston on my bike but it is on experimental basis and doesnt guarantee whether this will work.Cost for this will be around 10,000
And nowadays Glx original block pistons are out of stock.They are not available in pune from 3 months and it is not known when they will be in stock.TVS service center suggested me to do reboring of max 0.5mm due to this

Here are few bore x stroke ratios for some bikes which I have found out
Apache RTR 62 x 52.9(its bore is 7.5 mm extra and stroke is o.6 mm less)
HH CBZ classic 63.5 x 49.5 157 cc
HH Ambition 58.5 x 49 5 mm 135 cc
Pulsar non-dtsi 57 x 56.4mm 143.3 cc
Yamaha RD 350 64 x 54 mm per cylinder
LML Graptor 61 x 51.6 mm (but model stopped many years back)
The only bike which has a 53.5 mm stroke is a 998 superbike from Yamaha having 77 x 53.5 mm per cylinder but 23 mm boring is impossible


I see that only Apache's stroke comes near to GLX when it comes to the size of stroke(52.9 whereas GLX stroke is 53.5 so 0.6 mm less)

few questions
Will the reborer do 7.5 mm boring because I seen that these people doesnt do bores more than 1 mm oversize(Maybe it will be different with sleeving)
Secondly the stroke is 0.6 mm less than the TDC hence loss in compression.Will this compression loss be significant?

Total cost of sleeving is 850 rupees and reboring is 150 rupees per 0.5 mm


Thanks and Regards
Pankaj

Rebore


Actually my bike is 125 cc Victor GLX hence 110 cc pistons of star city/jive wont do.
Even I saw Flame's block piston but it wont fit to my bike because GLX block is wide and short whereas Flame's block is elongated and little bit narrow than GLX.Though both GLX and flame has the same piston of 54.5 x 53.5

Dear Nanotechnology
From where did you get 5.5 mm oversize bore?
For me 2 or 3 mm also will do but I am not getting it.Max 1 mm oversize is available
By the way how is your bike doing after 5.5 mm boring.I hope your fiero is now 165 to 170 cc.Does it give problem like oil consumption?
Also how is the performance for long rides on highways
Could you also tell me about these points

Thanks and Regards
Pankaj

sorry i overlooked it...............

then u can try the flame bore which as the same bore & stroke dim.....

i think u have converted ur 150 to 180cc hence the extra 5.5mm bore....

the sleeve thickness of a cylinder will not be more than 1.5mm (to my knowledge) hence the boring has a limit of 1.0 (which is the bigger piston available for a oem bore) so there is no chance of putting a 5.5mm in a 4 stroke single cyl that to in india until u do a big mod as joel used to do....

@ pankaj

Why are you soo worried about the stroke ?
the stroke length is determined by your con-rod's length.
The piston's bore is important here.

see, if you go for a bore of say 6-7mm, its possible with a new sleeve.

as i told earlier, i know of fieros running karizma's as well as p220's piston, a pulsar running an esteem's piston.
The stroke length isn't determined with the piston, but the con-rod.
now the only possibility of the piston coming above or below the TDC (ignoring the piston's length) is the attachment pin to the piston's head difference.

if you attach any piston on your bike, your stroke will remain the same, because the con-rod will travel the same, isn't it ?

as far as the loss in compression of 0.5mm is considered, well its not significant at all if the bore is over 3mm if you keep your cylinder head stock.

do 1 thing, check if the distance between the pin to the piston's head of different pistons.
If its exactly the same as yours, then just match the bore to the new piston (with or without the new sleeve as per as the lathe guy's suggestion) and you'll be able the use it.

Its no rocket science as far as i know.

I would request our knowledgeable senior member PSR to give his word here and comment if i am wrong at any place.

My bike is 180cc and is performing amazingly, its as reliable as stock with some head work.
I am running stock valves, stock cam, but slightly bigger ports and a bigger carb.

Engine feels very torquey.

I think it will run completely fine on Himalaya rides too.

@ dream horse

With a new sleeve, you can do an oversize of 7-8mm too.
In some bikes even more.

Replies in bold

Rebore

Thanks PSR and Nanotechnology for throwing some light on bores

So for example
My bike's bore x stroke is 54.5 x 53.5 mm
hence if I do sleeving and put a HH Ambition piston having stroke length of 49.5 mm then also it will do if I dont change my Crankshaft and my engine stroke will be same 53.5 only right?
And also Pulsar 150 has say 57 mm stroke for example but if its piston skirt and the position of my piston pin matches,then also it will not create problem and also the piston will not hit the crank on downward stroke

So at present if I do sleeving and rebore for Apache RTR piston having 52.9 mm stroke will also do if it matches all the parameters suggested by PSR?

Regards
Pankaj

The stroke is determined by the crankshaft and the bore size by the piston diameter...If there is no space for accepting a larger size piston then you can't overbore the bore to suit it....Normally every bore can safely overbored by 1mm in dia from stock and it is the 4th oversize....some bore can go up as much as 4 to 5 mm, depending on the bore wall thickness and safety of crank and other parts.....

Thanks for your inputs PSR sir..
as usual delivering your best.

rtr's piston will be 62.5mm, its almost 8mm overbore, so that's a bit too much.
I suggest you to go for fiero's piston, as i don't think it will hit the crank on its way down.
it will give you a 2.5mm overbore, so i assume you might not even need a new sleeve.

secondly, if you are going for any piston with a smaller stroke, it will definitely not be a problem to hit the crank.
even ambition's piston might do, what is its bore size ??

@ psr

the pic you've posted is too small.
Secondly i reckon anand is running karizma's piston which has a stroke of 10mm more than the fiero's, if that's a fit, i assume all others might.

Anand is running a Karizma piston of 65.5mm.dia......Again the piston does not decide the stroke length...if the total height and piston pin to crown height match there will be no issues.