I bought a 200 as I was to believe, but as I found out later it was a 125 with a 200(156) top end and piston. I had new piston and barrel re-chromed. It run fine for a few weeks and then stopped. On inspection the big end collapsed and damaged piston ring. cut  a long story short I purchased a second hand engine and run it as a 125. Problem now is I have a 200 carburettor(new) fitted. It runs fine but will it over fuel and do any damage to the engine? Can I re-jet PHBL25BS down to PHBL24BS?

Just monitor the colour the plug is and if too rich.drop the needle in the carb. It will do no harm if its a wee bit rich as long as it doesnt foul plugs

The plug looks fine and the bike runs sweet just wasn't sure if it was getting too much fuel. Just thought I might have to go down a size or two on the main jet.

Thanks for your response.

 

I have a 125 Pro (forward kick) with a PHBL25BS jetted for a 240. Like you I built a 125 and had a new carb from a different Fantic and wanted to try to save buying another. I reduced the main jet only and it runs nice surprisingly enough. I can't remember what main I went for but I'm happy to pull it out and get back with size. I'm sure it was a 92 (down from from 98) but as your 200 carb is jetted different from 240 I doubt it'd help. Idle screw is out two turns so haven't tried a smaller idle jet.

 

It doesn't four stroke or bog down and the plug has never fouled. It revs it's little hart out lugging me around and I've had some good rides on it hope you do the same. 

Mine has a 92 main in so should be ok then. It has a 48 slow/idle jet and a D33 needle. It was bought from Inmotion not long ago. The bike runs sweet and pulls 4th gear on steep hill climbs. I want to start using it in classic trials to give my beloved TLR a rest. I done a Welsh twinshock round last week on her and I hated putting her through that hell. It was brutal.

Anyway thanks for your help. I will let you know how I get on, hope to get out this week and give her a run out.

Regards,

Stuart

Find mine fine on trials with smallish hills and without too much mud. It won't pull third gear but has plenty to lug me up most stuff in first or second gear. I weigh about 13 stone so not an ideal jockey for a 125. 

 

Lots of people have commented how well it goes and love the ripping sound the exhaust makes. A great bike at the right event kind of sums it up. 

Took mine out for a test yesterday and it run great, first is no use at all, (too short) second is the gear I'd use in sections. It run sweet so I will run it as it is. Running 11 front 53 rear sprockets.