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Gasgas txt 2018 125


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Standard cilinder head TXT200.
I think also piston equal to the former TXT 200, together with cilinder former TXT200 (in this case older TXT125 bored to right fit with piston).
(Older cilinders and pistons a little higher, combination cilinder and piston should be OK was delivered by my dealer)

Other parts:
- Wider smal end bearing of former TXT200
- Base packing combination resulting in squish of about 1,5mm, smaller more agressive and not fits my style (50+).
- Further made new flywheel weight, filling all available space behind cover, without adding cover spacer.
- Let the exhaust reducer in place (more docile?, did not check)
- 5mm longer bolts cilinder head.

More power at low rev's, hoped for less aggresive at high rev's.. not being the case.
These new 125 have new carters with minimal volume, higher volumetric efficiency.
I like it very much and will not return to 125.




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Yes it can be purchased through your local S3 dealer. S3 supply the complete kit for all TXT's (horizontal and vertical water pipe heads). We have done quite a few of them.

Basically it is a 250 piston with a smaller gudgeon pin and matching head and cylinder.


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  • 1 year later...
On 7/7/2019 at 8:24 AM, jha said:





Hello, my flywheel on my '17 TXT Pro is below. Could it be aftermarket? 

I have a friend with a '17 School 125 and it revs up SO much quicker than my bike and is a lot more fun to ride. I understand the stock flywheel is the same for both bikes. 

Can I just unbolt the three bolts and run no plate?!

Do I have to pull the flywheel out to get rid of the plate, or do just the 3 bolts hold it on? 


Edited by sammyd173
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