Notices
O.S. Engines Support Ask Bill Baxter your questions about O.S. Engines.

OS91fx question

Old 10-29-2005, 11:29 AM
  #1  
Runway
Senior Member
Thread Starter
 
Join Date: Mar 2003
Location: UK, UNITED KINGDOM
Posts: 173
Likes: 0
Received 0 Likes on 0 Posts
Default OS91fx question

Hi Bax
I've just bought a second hand OS 91fx two-stroke in excellent condition. However, I'm told there was a design change to the carb housing by OS some time ago to get around possible problems with overheating/bubbles in the fuel line.
How can I tell, please, whether I've got the older version or the newer one?

Thanks.
Old 10-30-2005, 02:37 AM
  #2  
Perminator
Member
 
Perminator's Avatar
 
Join Date: Jun 2002
Location: Västerås, SWEDEN
Posts: 43
Likes: 0
Received 0 Likes on 0 Posts
Default RE: OS91fx question

In the old version the whole remote needle valve assembly was a part of the rear cover. The new one has a brass arm which holds the remote needle valve assembly and there's a plastic housing for the needle too. In short, if you can remove the remote needle valve assembly without removing the rear cover, you've got the new one. If not, the parts are not very expensive and are easily obtained from Tower hobbies, for example.
Old 10-30-2005, 01:29 PM
  #3  
Perminator
Member
 
Perminator's Avatar
 
Join Date: Jun 2002
Location: Västerås, SWEDEN
Posts: 43
Likes: 0
Received 0 Likes on 0 Posts
Default RE: OS91fx question

On the old ones the rear needle valve assembly was a part of the rear cover plate. The new ones have a brass arm that is bolted on to the rear cover plate and the rear needle valve assembly is mainly in plastic. The brass and plastic are to reduce heat conduction and by that eliminate the bubbles in the fuel line.

So if the rear needle valve assembly is bolted onto the rear of the engine you're safe, otherwise you can just order the parts from Tower hobbies or something. Just look the .91 FX up and the parts will be listed at the bottom.
Old 10-30-2005, 02:15 PM
  #4  
Runway
Senior Member
Thread Starter
 
Join Date: Mar 2003
Location: UK, UNITED KINGDOM
Posts: 173
Likes: 0
Received 0 Likes on 0 Posts
Default RE: OS91fx question

Many thanks for that.
Old 10-31-2005, 12:16 PM
  #5  
Bax
My Feedback: (11)
 
Join Date: Apr 2002
Location: Monticello, IL
Posts: 19,483
Likes: 0
Received 3 Likes on 3 Posts
Default RE: OS91fx question

The newer version has a black plastic needle valve holder that's on a bracket that bolts to the rear cover.
Old 10-31-2005, 01:58 PM
  #6  
Runway
Senior Member
Thread Starter
 
Join Date: Mar 2003
Location: UK, UNITED KINGDOM
Posts: 173
Likes: 0
Received 0 Likes on 0 Posts
Default RE: OS91fx question

Many thanks for that, Bax

Runway

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.