Hi guys I'm just after your opinions

 

My fantic 305 runs really nice but it does have a noise from the top end. After speaking to people out and about they say this is noreal for fantic?

 

Iv put a video up of the noise my engine makes......

 

http://s1066.photobucket.com/user/tomburras/media/Mobile Uploads/2017-01/20170102_120521_zpsqamcpdrb.mp4.html

 

Does this sound normal to you guys?

 

Cheers! Tom. 

Smart phone videos always sound weird but all I can hear is piston slap. Not a big deal and as you have been told these Fantic's are prone to a noisy top end but still hold good compression. It's the skirt rattling so a new set of rings doesn't help. 

If you want to eliminate it you'll need a new piston and the cylinder re-plating that will cost about £300 all in. In case you don't know the cylinder isn't re-bored as it has a Nikasil coating that has to be professionally sorted.

 

Thank you I suspected that. Would you try and fit a piston kit first? Or woils it be likely the kakasil will be worn too?

 

Thank you fantic 240 motor!

There is an easy first step. Just take off the cylinder and head, get the bore are piston measured. Then you know where to start before spending any serious money.

Thank you. Can I remove the head with the engine in the frame? 

I'd say do it properly if at all. 

If the bike runs nice and the noise isn't too off putting then personally I'd leave it. I had my 307 cylinder re-plated and a new piston fitted as they were both very worn. It was then very quiet but now after a years use it has that familiar top end noise the same as my 309 that is original. 

If your piston looks like this it's time for a new one! I doubt it will. I bought my 307 as a dead project. It had been used as a field bike and run without an air filter and not enough 2 stroke oil.

Thank you I will have a look at it and update. Is it a difficult job pulling the head? Iv never done it myself my dad has done my bikes previously. 

Very interesting picture fantic 240 motor did yours need replating or was a piston kit enough to repair it? 

I had the cylinder re-plated along with a new piston. The cylinder walls didn't look as rough as the piston skirts. 

Taking the head and cylinder off isn't too technical. Nothing tricky just basic mechanical know how. If you are in any doubt about how to do it I'd get someone to help. 

I used http://www.langcourt.com/page27.html to re-plate my cylinder and http://www.fantictrials.co.uk/ supplied the new piston. 

 

Thank you. I'll whip it off soon and update. I seen a piston kit for sale on bob wrights, would it be worth fitting this to see if it quietens down?  

Personally I'd do both new piston and re-plating for a proper job.

 

Hi, Pistons are graded to the barrel, On top of the barrel will be a letter, usually A (smallest size) through to (H) largest size. Its imperative that you match the letter on the barrel to a corresponding letter on the piston. Only fit a new piston assembly, if the chrome bore is in perfect condition and as stated above same letters on barrel and piston. The 305 / 307 piston was a bad design,  and was Fantics solution to keep up with the direct crankcase reed valve engines of the period, I understand that the later pistons were somewhat stronger around the skirt, to stop the excessive piston slap, but i've had several pistons...can't really see any difference.

3 hours ago, fantic240motor said:

If your piston looks like this it's time for a new one! I doubt it will. I bought my 307 as a dead project. It had been used as a field bike and run without an air filter and not enough 2 stroke oil.

The piston in the photo is not necessarily scrap. It has just had a light nip up, there is hardly any wear on the skirt. Clean the nip up marks off with fine (800 to 1200) wet and dry, scraped out the ring grooves if the rings do not move freely and it should be OK.

Hi, Pistons are graded to the barrel, On top of the barrel will be a letter, usually A (smallest size) through to (H) largest size. Its imperative that you match the letter on the barrel to a corresponding letter on the piston. Only fit a new piston assembly, if the chrome bore is in perfect condition and as stated above same letters on barrel and piston. The 305 / 307 piston was a bad design,  and was Fantics solution to keep up with the direct crankcase reed valve engines of the period, I understand that the later pistons were somewhat stronger around the skirt, to stop the excessive piston slap, but i've had several pistons...can't really see any difference.