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2011 txt pro 300 to 250 cylinder


SRH
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Does anyone know what exactly would be required to downsize the 300 to a 250, looking at doing just this as despite trying to sell it to buy a 250 it doesnt seem to be happening right now unless I take a large hit on a px so figure I’d be better off in the long run doing this then I guess when I do come to sell it, it’s an added bonus to have both 250/300 setups 

Looking at the parts diagrams its the cylinder, piston, o rings, gasket that's different but i'm not sure about the head its the S3 head on mine and presume the head is the same but not the insert?

 

any help appreciated

Edited by SRH
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Cheers! There’s no weight on mine it’s all standard now with the exception of a 10t and a slow throttle, pricing up at around £320 for all parts required that’s all new parts and a recon cylinder a somewhat small price to pay I’d say, wondering if jetting will need adjusting? 

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Ive sourced a 250 complete cylinder, head and piston for a very good price, just looking on the parts diagrams and it also looks like the reed block and reeds are different any ideas?

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16 minutes ago, huski said:

Wait till you receive the cylinder and see if your reed block fits,bet they're the same

Yeah actually looking further into the diagrams for newer models it looks like the reed valve block is only different on the Raga/Keihin carb, rather than the Dellorto i'm running but yeah ill find out when i get the cylinder this week, thanks for the assistance guys ill update once its done.

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I can report back.... works a treat, for anyone looking to do this you need :

250 s3 standard head insert

250 cylinder 

250 piston and rings etc 

lower cylinder gasket, new inner and outer 250 head o rings, front Cush exhaust gasket and two front pipe to middlebox o rings.

i would also recommend you replace the little end bearing at the same time you may as well whilst your there. 

Verdict: 

power difference is amazing, it’s so much easier to handle and still plenty of power 

Costs: 

I was lucky and managed to pick up a second hand cylinder with head for £60 +£20 on gaskets sure the best £80 I’ve ever spent.

however if you need to or want to buy new you can do it for around £320 with a reconditioned cylinder.

hope this helps someone else in the future ?

 

any questions feel free to ask ?

 

thanks all for the assistance 

 

Rich 

 

 

 

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7 hours ago, nigel dabster said:

Ditch the slow throttle if you can, asap.

Yeah i rode it today and thought that may be the way forward now, take it most novice riders use the fast throttle?

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On 7/17/2019 at 1:51 PM, SRH said:

Yeah i rode it today and thought that may be the way forward now, take it most novice riders use the fast throttle?

I dunno i guess so by default. its a little bit like learning to drive in an auto it just means you take longer to get where you need to be and can learn bad habits.

As most will say its about throttle control.

You dont learn that so easy on a slow imho.

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