Saito 125 big problem!!!!
06-24-2008 | 07:15 PM
#26
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From: Cincinnati,
OH
RE: Saito 125 big problem!!!!
The screw you thought was damaged, might not have been. Take a look at this carb screw kit for the Saito 125:
http://www.horizonhobby.com/Products...odID=SAI125A90
The screw on the far right shows the smooth part of the bolt, without threads.
Edited to add - The BOLT on the far right, not including the set screw!
http://www.horizonhobby.com/Products...odID=SAI125A90
The screw on the far right shows the smooth part of the bolt, without threads.
Edited to add - The BOLT on the far right, not including the set screw!
06-25-2008 | 12:58 PM
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From: Nottingham, UNITED KINGDOM
RE: Saito 125 big problem!!!!
thanks for the info chaps, I know I would not have as much top end speed with a 3 blade prop , but would the engine run hotter and use more fuel with the slight increase in load or would the third blade help the cooling effect, I ask this because Iv never used one before and like the idea that scale looks are enhanced with 3 blades.
06-29-2008 | 11:02 AM
#29
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From: Istead RiseKent, UNITED KINGDOM
RE: Saito 125 big problem!!!!
ORIGINAL: Pawel Rzedzicki
Hello!!!
I have a Saito 125, its has about 6 liters of fuel thru it. Previously it was in funtana s90 and now in Somenzini Yak 54 69". Its side mounted. During last flights i noticed it dies during idle. If i leaned lsn more it died rapidly, if i richened it died after 10-20 seconds. I was a little confused but once i noticed the throttle barrel has too big about 2 mm axial play (i dont know if this is a correct word- it moved in the carb along the lsn) I removed the little screw which end sits in the groove on the barrel. It apperaed it was too short and its end didnt get into groove deep enough. Because of it the end of the little screw had worn causing the barrel play. I found a similar screw, grinded its end to fit the groove and installed in the carb. I took the plane to a field, started engine, warmed it up and finally got stable perfect idle.
And thats the end of good news. Now i have a huge and first time in my life problem. When i tune the high speed needle with WOT i must turn off the HSN about 4 full turns!!!!!!!! I wouldnt care but it causes dramaticly rich midrange, almost deadly rich.
The only idea coming to my mind is: with defected throttle barrel leading screw i had to turn in the lsn too much to get pretty stable idle and now the needle comes into the sprayer too deep. If you have any other ideas please help me and give me some advices.
My LSN in turned 3 full turns in from flush with the throttle lever. How are yours?
Hello!!!
I have a Saito 125, its has about 6 liters of fuel thru it. Previously it was in funtana s90 and now in Somenzini Yak 54 69". Its side mounted. During last flights i noticed it dies during idle. If i leaned lsn more it died rapidly, if i richened it died after 10-20 seconds. I was a little confused but once i noticed the throttle barrel has too big about 2 mm axial play (i dont know if this is a correct word- it moved in the carb along the lsn) I removed the little screw which end sits in the groove on the barrel. It apperaed it was too short and its end didnt get into groove deep enough. Because of it the end of the little screw had worn causing the barrel play. I found a similar screw, grinded its end to fit the groove and installed in the carb. I took the plane to a field, started engine, warmed it up and finally got stable perfect idle.
And thats the end of good news. Now i have a huge and first time in my life problem. When i tune the high speed needle with WOT i must turn off the HSN about 4 full turns!!!!!!!! I wouldnt care but it causes dramaticly rich midrange, almost deadly rich.
The only idea coming to my mind is: with defected throttle barrel leading screw i had to turn in the lsn too much to get pretty stable idle and now the needle comes into the sprayer too deep. If you have any other ideas please help me and give me some advices.
My LSN in turned 3 full turns in from flush with the throttle lever. How are yours?
When I took it out of storage I noticed over 1mm of end play on the carb needle barrel. I removed the screw and the pictures show what I found - both sides had been worn flat! I turned a 3mm cap screw down at the end to fit closely and it now runs perfectly!
Richard
07-31-2008 | 08:26 PM
#30
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From: , TX
RE: Saito 125 big problem!!!!
Sorry to revive a slightly old thread, but I have run into this same "worn out" carb barrel screw problem as well. I check them on every Saito I get, new and used. My most recent 1.25 (used with "only 1 gal" through it) had big flats on this little screw tip and the carb barrel had at least 1mm play easy. This is NOT correct. The barrel should have the least amount of play as possible, otherwise the engine will be able to change it's tune at any time in mid-flight.
If 1/2 turn on the LSN makes a big difference, imagine the needle moving 1mm _directly_ in and out with the barrel slop. Yes the barrel is also opening up a little more air at the same time, but not anywhere close to the mixture ramp that the LSN taper is designed for (thus the spiraled "ramp" on the barrel to start with).
A quick fix is to shim the bolt head so that it stops at a different angel, and play with torquing it down just right to remove as much slop as possible.
-Colin
If 1/2 turn on the LSN makes a big difference, imagine the needle moving 1mm _directly_ in and out with the barrel slop. Yes the barrel is also opening up a little more air at the same time, but not anywhere close to the mixture ramp that the LSN taper is designed for (thus the spiraled "ramp" on the barrel to start with).
A quick fix is to shim the bolt head so that it stops at a different angel, and play with torquing it down just right to remove as much slop as possible.
-Colin
