New to rotary valves, need some info

[corblund]

I'm new to the forum and rotary valves, please don't assume I'm some tard trying to be a winner with a mod. I just bought a '03 Summit with a mongoose built 720. It has rotary valves in it, I know the basics of what they're about but I would love some explanations from those who have good experience with them. I was considering going back to reeds seeings how I know reed motors well. The motor has Mongoose pistons (unsure of the ratio) its making about 160 pounds compression. Any and all info would be greatly appreciated.

 

[freekweet mods]

Not to familiar with a mongoose mod.Have heard of a 721 based off of a 670 with Sea Doo watercraft pistons. I can tell you that the rotary valved rotax engines were the best ever built PERIOD.

 

[vendetta]

if you want snappy throttle response you cannot get a better system. if it runs good leave it alone. and they are built really well

Rob

 

[Reeb]

670 Rotax with Wiseco slugs make it a 720. There have been a few conversions that came outta the Coast region. Slap the 700 and 800 Series III motors silly! Very hard runners!

 

[rat01]

720 rotary valve engine

I am going to assume that the basics include how the rotary valve works. I still have a 1996 mod sled with a Union Bay built 670. This motor pulled 140 hp on the dyno. I ran it hard and only put 1 set of pistons in it until 2008 when I replaced the crank and pistons as preventative maintenance. These engines were and are bullet proof. You would be hard pressed to get a series III engine with the kind of HP you have, unless you get a 2008-2009, or a modded engine. You will not have the exhaust comming loose, the reed cages delaminating, the bearing grease leaking out, or any other of the Series III problems. Run what you have and sleep well at night.