Hello All, I’m new to this site but have heard it’s a need to go site if you have a Pilot or Oddy. I would like to know what main jet I should run on a 85’ fl350. My buddy purchased it about 6 months ago from someone that did not know anything about it. He took it out and shortly after he blew a dime sized hole in the piston. He rebuilt the top end and this is what he found it has:

Engine has been ported
Piston is now 1 over
Water cooled head
32mm Keihin Carb
425 main jet, not sure what it had prior to the blowing the piston
DG pipe
K&N straight filter, which I’ll be changing to a Uni foam filter after reading blogs here

It runs fine here at home (just as it did for him before taking out) but I want to know what main jet I should use. We believe it blew due to the wrong jetting. I am purchasing it from him and I don’t want to drive 100 miles to ride it and the Engine blows again.
So is the 425 too big or too small? Or are other tweaks needed?

Thanks,
Will
I also want to put a gravity fuel tank straight to the carb. What are the pros & cons?

Hi welcome to the site. Your jet size is in conflict with your carb brand. The largest main jet you can get for a keihin carb is a 220. So is it a mikuni? Whats the compression at? Hole means detonation so it either had too much compression and low octain or it was super lean. 32 mm is stock double check the jet size and carb brand please. Also is it running a gravity tank with no fuel pump?

Thank you for the quick reply. Sorry for the delay I had to wait for my buddy to get me the info you requested. Yes it is a Mikuni and it is stamped with a 36 and has a 425 main jet now. It had a 320 when it blew so, I believe it blew due to the wrong jet size. At this time I don’t have a compression test tool but will get one soon if you still need me to get that for you. Fuel source comes from aftermarket top mounted tank to the fuel pump then to the “T” then to carb. I would like to go from top tank directly to carb. What do you recommend? Sorry for the previously wrong info about the carb. Thank you so much for you help

Also I live here in So Cal and ride in Ocotillo Wells, El Mirage and Gorman (Hungry Valley) for the most part.
Thank you

Give this a read when you get a chance http://www.pilotodyssey.com/BillGivensjetting.htm

A fuel pump is a must on the odysseys. If you have the right float valve you can eliminate the T for a mikuni carb. The 425 jet is a good starting point for the odyssey. Im here in socal also and we are heading to dumont this weekend.

Shoubadaba, thank you for your help, have a great weekend at Dumont and be safe.
Hoser, thank you for the link, I'll start working on that.