Non-starting 912 S
in General Tech Discussion
12 years ago
Hi Guys
My first post on the forum so please let me start by way of intro. I am in South Africa and fly a GT450 trike fitted with a 912S which I have had for 5 years during which it has done 600 hrs.
I am very pleased that my first post is not a plea for help but one to share my problem which I had which has been fixed.
During the last year the engine became harder and harder to start on the first start of the day to the point in recent months where it was impossible without the car jump-start and many kick backs.
I did a lot of research including this forum where I discovered that this is a fairly common problem with the older 912S motors fitted with the smaller starter motor and no soft start modules.
I found a lot of good advice here(Roger Lee in particular) and so I started the road to recovery.
First off a new battery - no change. I also use a battery optimiser.
I was concerned that all the time spent battling to start and the kick-backs had done some damage so I decided to take the gearbox off and send it in for an inspection. Report was that slipper clutch was very loose so it was all cleaned, tightened and a shim put in.
I made the trip to Oshkosh and picked up the Bullyhawke SSM and attended the Rotax 4 stroke maintenance talk.
Got back to SA armed with some new parts and info and did the following:
- Fitted gearbox and prob back on.
- Fitted the SSM
- Fitted a thicker second cable from the battery to the starter
- Did a full service including new plugs with reduced gap
Then the big test with one mag switch on only as the Bullyhawk only works on one mag. I hit the starter button. The engine turned over well, no kick back but did not start straight away. After a bitt of a struggle it did start but not the way anyone would be happy with and only after about 5 or 6 attempts. I was so depressed and was now convinced that it was all too late and my sprague cluch must be damaged and I would now be in for more cost.
I ordered a new high speed starter which is still on the way.
As my trike is nearly due for its annual inspection by an AP, I booked this with a local who is also a mate and asked him to check that my carbs were balanced properly at the same time. Another mate of mine had said that even out of balance carbs would still enable the engine to start.
The AP checked thr throttle cables and showed me how the one was much looser than the other and he corrected them. He then set the idle screw. I had read here this week that idle needs to be between 1700 and 1800 (Tks Roger) and mine has always been at about 1350.
Float levels were checked and found to be too high and adjusted.
Now he used his normal start procedure. Oil cap off and burb the motor by hand. Cap back on.
Mags off, choke on and a 5 sec crank.
Choke off, one mag on (with SSM), no throttle and he asked me to hit the starter button.
I pressed the button and the engine started instantly with the first revolution and purred like a kitten. I nearly kissed him:)
Now I am sure that the gearbox service, new battery, extra cable, SSM all made a difference but until the carbs were properly balanced it still struggled to start.
Just had to share and maybe give hope to someone else.
Safe flying
My first post on the forum so please let me start by way of intro. I am in South Africa and fly a GT450 trike fitted with a 912S which I have had for 5 years during which it has done 600 hrs.
I am very pleased that my first post is not a plea for help but one to share my problem which I had which has been fixed.
During the last year the engine became harder and harder to start on the first start of the day to the point in recent months where it was impossible without the car jump-start and many kick backs.
I did a lot of research including this forum where I discovered that this is a fairly common problem with the older 912S motors fitted with the smaller starter motor and no soft start modules.
I found a lot of good advice here(Roger Lee in particular) and so I started the road to recovery.
First off a new battery - no change. I also use a battery optimiser.
I was concerned that all the time spent battling to start and the kick-backs had done some damage so I decided to take the gearbox off and send it in for an inspection. Report was that slipper clutch was very loose so it was all cleaned, tightened and a shim put in.
I made the trip to Oshkosh and picked up the Bullyhawke SSM and attended the Rotax 4 stroke maintenance talk.
Got back to SA armed with some new parts and info and did the following:
- Fitted gearbox and prob back on.
- Fitted the SSM
- Fitted a thicker second cable from the battery to the starter
- Did a full service including new plugs with reduced gap
Then the big test with one mag switch on only as the Bullyhawk only works on one mag. I hit the starter button. The engine turned over well, no kick back but did not start straight away. After a bitt of a struggle it did start but not the way anyone would be happy with and only after about 5 or 6 attempts. I was so depressed and was now convinced that it was all too late and my sprague cluch must be damaged and I would now be in for more cost.
I ordered a new high speed starter which is still on the way.
As my trike is nearly due for its annual inspection by an AP, I booked this with a local who is also a mate and asked him to check that my carbs were balanced properly at the same time. Another mate of mine had said that even out of balance carbs would still enable the engine to start.
The AP checked thr throttle cables and showed me how the one was much looser than the other and he corrected them. He then set the idle screw. I had read here this week that idle needs to be between 1700 and 1800 (Tks Roger) and mine has always been at about 1350.
Float levels were checked and found to be too high and adjusted.
Now he used his normal start procedure. Oil cap off and burb the motor by hand. Cap back on.
Mags off, choke on and a 5 sec crank.
Choke off, one mag on (with SSM), no throttle and he asked me to hit the starter button.
I pressed the button and the engine started instantly with the first revolution and purred like a kitten. I nearly kissed him:)
Now I am sure that the gearbox service, new battery, extra cable, SSM all made a difference but until the carbs were properly balanced it still struggled to start.
Just had to share and maybe give hope to someone else.
Safe flying
