pankajshirke

Make TVS Victor GLX
It has done 85000 kms in 6 years and now few weeks back,oil started getting consuming in the combustion chamber.When I race my bike harder at full throttle,I am able to see light smoke with somewhat bluish in color.
When bike's engine is cold during first start in morning,even after raising full throttle doesnt give smoke.Smoke comes only after the oil is hot say after running 15 kms and more.
After 2000 kms,almost 400 ml oil remains.
The mechanic told me that its time to change block piston and no need to change valves.
I searched in Pune and at no dealer TVS Victor GLX block piston is available.The time when it will be available is not known.
I searched for oversize pistons and found that they are only from SAM KRG.But many reboring people recommend Mahle because they are durable.
I looked for many threads and found many people on this site doing modifications like reboring 150 cc bike to 165 cc etc hence I am thinking for going for reboring by say 1 mm or 2 mm but oversize piston is available only till 0.5 mm.I have seen 2.5 mm oversize pistons also but only available for scooty pep and 1 mm pistons are available only for Pulsar 150
In Pune can I know from where can I get say 1.5/2 mm oversize pistons from pune and that too from Mahle.
Dimensions of TVS Victor GLX 125 are
Original Bore x Stroke 54.5 x 53.5

By a 1.5 mm oversize piston,bike becomes 131 cc and by 2 mm oversize it becomes around 135 cc
I have a good mechanical workshop person at Shivajinagar,Pune who assures of good fail free reboring job of whatsoever oversize piston you have.

Noor

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dream horse

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

NANOtechnology

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.

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pankajshirke

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

pankajshirke

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

pankajshirke

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

dream horse

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

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

dream horse

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....

NANOtechnology

@ 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.

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Expecting a lot from a fiero.