Problem with FS91SII
05-24-2011 | 06:50 PM
#26
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From: Mumbai, INDIA
RE: Problem with FS91SII
Well, I ran the engine yesterday with the 10% nitro fuel. Ran it behind my appartment, so ran if for less than a minute so as to not irk the neighbours or attract a crowd.
I have no idea where the LSN was, I just took it out and ran it. Initially it did the same thing- it cut at idle before I could get around to stand across to give full power. Second time, it started struggled and then actually ran backward sending exhaust out (I think) through the carb which surprised me, it ran only for a couple of seconds. Third time I kept the driver on till I was able to get around to stand across. Then I went to full power and adjusted the HSN fairly and then came back to idle. This time I idled for 20-25 seconds and it didnt cut, which I think is fairly ok as it wouldnt last more than 10 seconds before.
Thats about all I wanted to and can do without going to the field. Remaining adjustments can be done on-field. I will check the LSN again, I think it is at 3 turns out, left there during the Sunday's trial-and-error. I will set it to 2.5 before I go and will also use the plain castor on field (though I will carry the nitro fuel as well)
One surprising thing is the way it sounded when outside- like a motorcycle engine. In fact, it sounded different than even the very same engine when it was on another airplane. I am quite surprised that it requires nitro. I would like to have one can of fuel for both my 2c & 4c engines, so I need to drop my nitro content. Do you think 4-5% is enough?
By the way, this was with the same same "old worn out" plugs. Guess they were not really worn-out
Ameyam
I have no idea where the LSN was, I just took it out and ran it. Initially it did the same thing- it cut at idle before I could get around to stand across to give full power. Second time, it started struggled and then actually ran backward sending exhaust out (I think) through the carb which surprised me, it ran only for a couple of seconds. Third time I kept the driver on till I was able to get around to stand across. Then I went to full power and adjusted the HSN fairly and then came back to idle. This time I idled for 20-25 seconds and it didnt cut, which I think is fairly ok as it wouldnt last more than 10 seconds before.
Thats about all I wanted to and can do without going to the field. Remaining adjustments can be done on-field. I will check the LSN again, I think it is at 3 turns out, left there during the Sunday's trial-and-error. I will set it to 2.5 before I go and will also use the plain castor on field (though I will carry the nitro fuel as well)
One surprising thing is the way it sounded when outside- like a motorcycle engine. In fact, it sounded different than even the very same engine when it was on another airplane. I am quite surprised that it requires nitro. I would like to have one can of fuel for both my 2c & 4c engines, so I need to drop my nitro content. Do you think 4-5% is enough?
By the way, this was with the same same "old worn out" plugs. Guess they were not really worn-out
Ameyam
05-24-2011 | 07:00 PM
#27
Senior Member
RE: Problem with FS91SII
Try removing the headshims under the cylinder head to increase the compression ratio, it may help with general performance with lower nitro.
It is "normal" for four stroke engines to require some nitro, specially for idle.
My thunder Tiger 75 4 stroke didn´t like 0% nitro fuel at all...couldn´t get more than 8300rpm...with 10% nitro it goes to 10640 rpm.
Bigger engines tend to work better with lower nitro than smaller ones though...
It is "normal" for four stroke engines to require some nitro, specially for idle.
My thunder Tiger 75 4 stroke didn´t like 0% nitro fuel at all...couldn´t get more than 8300rpm...with 10% nitro it goes to 10640 rpm.
Bigger engines tend to work better with lower nitro than smaller ones though...
