Scooterotica

Self built Imola engine, everything set or torqued to the correct settings and only the best parts used. Ignition set to 18 and the carb set slightly rich but something has gone very wrong here. I have been very lucky and only the piston is shot with no damage to the cylinder, cylinder head, reeds or crank. I have ordered a new piston and this time i'm going to take it to a pro to be rebuilt. Feel free to gloat, laugh, p**s take or offer your thoughts as to what went wrong.

I've holed two pistons in my imola same as yourself only fecked the piston. In the end the carb set up given by the dealer who sold me the kit was the problem. What is your carb set up? Also are you using the carb rubber that came with the imola kit?

Did you re torque after a few heat cycles ? could have dragged air in and leaned it off ?at least it going to be to expensive which is a massive positive

psychedelicropcircle wrote:I've holed two pistons in my imola same as yourself only fecked the piston. In the end the carb set up given by the dealer who sold me the kit was the problem. What is your carb set up? Also are you using the carb rubber that came with the imola kit?

Yeah same here, running on a 30mm VHSH Dellorto supplied ready jetted to suit my engine spec. I ditched the rubber inlet in favour of the metal one before i fitted the kit.

Andy Pickering wrote:Did you re torque after a few heat cycles ? could have dragged air in and leaned it off ?at least it going to be to expensive which is a massive positive

I did re torque the head after 50 odd miles and there was no signs of any air leaks when i removed the head yesterday. As you said not too expensive as blown engines go. I'm gonna take it to JB to rebuild, he done the tuning work and he knows what he's doing.

Thats a sickener m8. Its sometimes hard to tell with alloy set-ups but that looks either seriously under jetted or too much timing advance. Was it strobed at 18?
Maybe a grown-up could explain but there also seems to be a lean spot just where the needle is fully coming out of the atomiser. Its possible you could've been running at that point for a while without knowing it? Whatever it is, hope you get to the bottom of it. At least the barrel doesnt look too bad.

Andy Pickering wrote:Did you re torque after a few heat cycles ? could have dragged air in and leaned it off ?at least it NOTgoing to be to expensive which is a massive positive

fixed

:biggrin: doh

eden wrote:how did you set the timing?

I used a strobe gun that i purchased from Readspeed. It was spot on, i'm thinking either air leak or wrongly jetted carb. It's all a learning curve and with hindsight i should of let a pro build the engine.

are your casings welded to take those transfers and crank case feed?

Before anyone asks I had nothing to do with this

Hope ya get it sorted and it doesn't cost ya too much