340 to 440 conversion


Post Reply
2 YamaDoo
Posts: 5
Joined: Tue Feb 28, 2012 1:39 pm
Location: Ontario, Canada

340 to 440 conversion

Post by 2 YamaDoo »

Hi all, new to the site
I recently aquired a 76 trail twister with low compression on the pto side (95 lbs). A little scuffing on the piston sides and some flaking of the cylinder.
I'd like to know if the bottom half (cases and crank shaft) are the same for both the 340 and 440. I believe the stroke is the same. If so, are the electrics the same as well?
Mercury
Posts: 225
Joined: Mon Sep 30, 2002 1:39 am
Location: USA

Re: 340 to 440 conversion

Post by Mercury »

2 YamaDoo wrote:Hi all, new to the site
I recently aquired a 76 trail twister with low compression on the pto side (95 lbs). A little scuffing on the piston sides and some flaking of the cylinder.
I'd like to know if the bottom half (cases and crank shaft) are the same for both the 340 and 440. I believe the stroke is the same. If so, are the electrics the same as well?
All is the same except for carbs and cylinder and the cylinder internals.
2 YamaDoo
Posts: 5
Joined: Tue Feb 28, 2012 1:39 pm
Location: Ontario, Canada

Re: 340 to 440 conversion

Post by 2 YamaDoo »

Is it worth doing, or should I keep it original?
What top speed can I expect from a fresh 340?
Mercury
Posts: 225
Joined: Mon Sep 30, 2002 1:39 am
Location: USA

Re: 340 to 440 conversion

Post by Mercury »

2 YamaDoo wrote:Is it worth doing, or should I keep it original?
What top speed can I expect from a fresh 340?
Depending upon your weight it will be up to 15 mph slower and have less balls off the line.

340 parts might be easier to come by than 440 engine parts but could be more costly overall as you have to acquire new (smaller) carbs.
2 YamaDoo
Posts: 5
Joined: Tue Feb 28, 2012 1:39 pm
Location: Ontario, Canada

Re: 340 to 440 conversion

Post by 2 YamaDoo »

It's already a 340.
I think I can source cylinders, pistons and heads for a 440. Not sure about the carbs and intake though.
Mercury
Posts: 225
Joined: Mon Sep 30, 2002 1:39 am
Location: USA

Re: 340 to 440 conversion

Post by Mercury »

2 YamaDoo wrote:It's already a 340.
I think I can source cylinders, pistons and heads for a 440. Not sure about the carbs and intake though.
Sorry I confused myself...LOL.

I would keep it 340 you won't have to recalibrate the clutch either.
Post Reply