SRH

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

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

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.

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?

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?

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

the low compression insert was great but I just felt I didn’t have enough power in 1st again felt like riding with the choke on 

So I had a 10T lying around so I’ve fitted that and now sitting at 10/41, stock insert and slow throttle..I’ll see how I get on with this setup

Plug looks ok perhaps on the rich side if anything I was intending on riding Buttsfield quarry tonight but after going back to full power i decided it would be a good idea to test the bike out first to which i did......and had an off! wrecked my back and neck so now not attending tonight haha. Guess i either need to drop the gearing to a 9/10t and see if that's any better and if not rather than spending another £80 on a flywheel weight i guess ill just have to put the low compression insert back in and persevere with the what seems lack of power! Wish i had just bought a 250! i naively thought id manage it no problem and it was cheap for the year! all fails ill sell it ha Now to find an ice pack and a beer..........

Hello! Ive recently got back into trials after some years away and picked up a 2011 300 pro when i got the bike it was standard with the addition of a slow throttle the power delivery felt a bit too much for me so in an attempt to tame it down I fitted a low compression insert which seemed to work a treat however when doing a trial last week I felt it lacked power in 1st and I found myself using 2nd more almost felt as if the choke was on or something thinking it may be have been the insert I put the standard one back in and rode today and I’m back to square one with aggressive power any ideas or is this quite normal for a low compression to tame it down way to much i was thinking maybe I should try the low compression with a fast throttle instead of using 2nd for sections any advice much appreciated