OS FS 90 stange mixture settings
09-10-2007, 10:11 AM
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OS FS 90 stange mixture settings
Hello all,
I am helping a buddy tune an older OS 90 FS. The motor runs really well but the settings I had to use are really strange and I am trying to figure out what could be causing it. Basically the high end needle valve must be completely closed, full lean. And all adjustments are made with the low end screw. This is obviously not right, however, the motor responds to low end settings just as if I where adjusting the high end needle. With the current settings of full lean on the high end and the low end set where it is the top end is great, idle is great and throttle response is good. If I crack the high end needle The motor just floods out, my first assumption is a missing o ring on the needle valve, but this doesn't appear to be the case. Any Ideas?
Thanks
stan
I am helping a buddy tune an older OS 90 FS. The motor runs really well but the settings I had to use are really strange and I am trying to figure out what could be causing it. Basically the high end needle valve must be completely closed, full lean. And all adjustments are made with the low end screw. This is obviously not right, however, the motor responds to low end settings just as if I where adjusting the high end needle. With the current settings of full lean on the high end and the low end set where it is the top end is great, idle is great and throttle response is good. If I crack the high end needle The motor just floods out, my first assumption is a missing o ring on the needle valve, but this doesn't appear to be the case. Any Ideas?
Thanks
stan
09-10-2007, 10:31 AM
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RE: OS FS 90 stange mixture settings
hi,
i noticed the same thing on my fs90. the high needle setting must be half turn from full closed!! the manual says about 2-1/2 turns fron full closed but for new engines. i dont know if this must be the right setting but my engine runs fine! with 14x8 ma revs at 8860 max and i set the needle to 8450 max rpm(litle rich)
the idle is a bit rich . i didnt disasemble the carb to see if everything is ok.
achilles
i noticed the same thing on my fs90. the high needle setting must be half turn from full closed!! the manual says about 2-1/2 turns fron full closed but for new engines. i dont know if this must be the right setting but my engine runs fine! with 14x8 ma revs at 8860 max and i set the needle to 8450 max rpm(litle rich)
the idle is a bit rich . i didnt disasemble the carb to see if everything is ok.
achilles
09-10-2007, 11:06 AM
#4
RE: OS FS 90 stange mixture settings
Yep...I "inherited" a couple of FS-90's from my mentor's estate after he passed away. He had a habit of running long extensions on the NV's and they would vibrate like a tuning fork and wear the needle and seat. You could close the high speed NV all the way in, and it would still pass fuel...and that sounds like what's happening here.
You need a new needle and seat...
I'm not sure though if it's a seperate, replacable assy. or if you have to replace the carb body? (luckily for me, I found some useable, parts engines so...I scarfed the carb parts off them )
(Just out of curiosity, take a look at the tip of the high speed needle to see if there is a polished ring all the way around it? )
You need a new needle and seat...
I'm not sure though if it's a seperate, replacable assy. or if you have to replace the carb body? (luckily for me, I found some useable, parts engines so...I scarfed the carb parts off them )
(Just out of curiosity, take a look at the tip of the high speed needle to see if there is a polished ring all the way around it? )
) the .91 Surpass carb body is the same?
09-12-2007, 12:33 PM
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RE: OS FS 90 stange mixture settings
Hello; No the surpass carb is different and not interchangeable with the FS90 carb. I have 2 FS 90's and 2 surp 91's. I like the surps, but I think I perfer the easy going nature of the FS' on my Bingo on floats, and my 4 star 60. The surpass 91 is a fine engine, but more frantic and less able to tolerate big props.
09-12-2007, 01:35 PM
#7
RE: OS FS 90 stange mixture settings
d d is the needle and seat assembly swappable? When I "fixed" mine, all I did was use the carb off of a crashed .90 so I'm wondering if the Surpass assy. can be used on the .90?
Seems we had a similar thread here a while back, but I don't remember if it'll work or not?
Seems we had a similar thread here a while back, but I don't remember if it'll work or not?
09-14-2007, 09:07 AM
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RE: OS FS 90 stange mixture settings
Hey guys,
Sorry for the delay in getting back, crazy week. Thanks for the input. I will start looking for a replacement carb body.
stan
Sorry for the delay in getting back, crazy week. Thanks for the input. I will start looking for a replacement carb body.
stan
09-15-2007, 11:21 AM
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RE: OS FS 90 stange mixture settings
Hello; For parts for the "old FS90 try Noel Jensen at [email protected] He had the parts I needed to finish off one of my FS 90's that had shed it's rocker cover. Reasonable prices and prompt service.
Ps He doesn't like being called Neil
Ps He doesn't like being called Neil
10-15-2007, 09:32 PM
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RE: OS FS 90 stange mixture settings
Thanks everyone for the input. We got a new carb for the motor and everything works much better. THanks alot
stan
stan
