Irvine 39
03-07-2003, 11:50 AM
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Irvine 39
Irvine 39 Review By Peter Hawtin
I had never owned a fun fly model before, so after looking around for a suitable model, I saw a demonstration of the Weston Cougar at the BMFA South Midland Area rally. I decided that this was the model for me.
The next challenge.... what motor, do I use the Magnum? or go with the Irvine 36, ( I like to buy British where I can) the Irvine won.
I went off to the shop, cash in hand to get a shiny new Irvine 36...”have I seen the new 39 I am asked?” Now who am I to stand in the way of progress! I didn’t notice the price tag, or I just might of changed my mind!!
The one thing I always find interesting is opening a motor box for the first time. Even after working in the motor racing industry where boxes held engines made from exotic blends of mag-alloy, looking at a new model engine still gives me a kick (I know I need to get out more) The latest? range of red engines from Irvine does give a wonderful perception of quality, even before using the motor. I have now used several of the Irvine motors and the new 39 follows the family line.
Out of the box, the motor is very clean, this may sound like a strange comment to make, but I have looked at new motors and found small particles of swarf/metal around and even inside new motors. Always have a look down the intake, inside the exhaust and if you see any bits of metal then give the motor a good wash out with fuel before you start. The Irvine39 was well packed in its own plastic bag, very clean and nicely oiled.
The motor comes with a good quality silencer that uses an alloy spacer and baffle to keep the motor quiet. As usual the carb is packed in its own plastic bag allowing you to keep it clean until required on the model.
A small bag of tools are supplied designed to fit the exhaust and the carb pinch bolt, how many times have you had to dig in the bottom of your box to find an Allen key that (almost) fits.
The 39 fits in a 36-size engine mount; it weighs approximately the same as the old Irvine 36 including silencers. Some would ask why Irvine has produced this motor as it seams to conflict with other motors in their range ( the 39 is more powerful than the 40). It seams that it has been produced for the fun fly market, with the 36-size motor being the popular choice. Opening the motor up to 39 has given it the ability to turn bigger props with the same gusto as a piped 36.
The motor is a true triple ported two stroke as per 95% of current motors. Its ABC design should give many years of reliable fun. The motor was quite tight at the top of the stroke and "squeaked" as it went over TDC. I always ensure that there is sufficient oil in a motor before running it for the first time. I add a couple of drops of after run oil, but 3 in 1 works just as well.
The carb is secured with a clamp, tightened by turning a small Allen bolt with the supplied key. It is important that the clamp is aligned with the hole in the crankcase, before the carb is inserted. The carb has a small "o" ring that seals the carb onto the crankcase. It’s worth pushing the carb with your thumb as you tighten the clap to ensure a good seal.
The motor was installed in the Cougar using the mount that came with the kit. One thing to be aware of if fitting this motor in the cougar is that the exhaust is in a different alignment to the magnum motor Weston sells. This means that if you use the holes as drilled by Weston for the engine mount on the bulkhead, you will find the exhaust is not central under the model. This is an advantage as it helps to balance the model laterally.
Now came the bit I love!! Fuel pipes on Throttle connected, and out into the garden. (the wife had gone shopping) I set the main needle to 1 3/4 turns open, but left the idle screw as set by Irvine. I fitted a Taylor standard plug, primed the motor, I have found most Irvine’s like to be a little wetter than normal. The glow clip attached and two flips to start, it was so easy it shocked me!!
Running in is a personal thing, BUT VERY IMPORTANT. An ABC motor has to get up to running temperature as fast as possible, to bed the piston into the liner. If the motor does not reach running temperature fast there is a possibility of the bore getting glassed.
My method of running ABC motors in is to start the motor, with a rich setting. Once the motor starts open the throttle to full, and adjust the needle to full speed then open the needle a couple of clicks. Allow the motor to run at virtually full speed for 10 - 15 seconds then open the needle (still on full throttle). Wind the needle open until the motor is only just breaking into two stroke and leave it there for 15 seconds. I repeat this process of going from max RPM to very rich at15 second intervals for the first 3-4 mins, then stop the motor to let it cool. This process was done with three tanks of fuel, slowly lengthening the time the motor was left on max RPM. Then it was flown.
The motor and early flights were done on a 10x6 prop, and it really can sing on this prop! I have run the motor on several props but for fun fly, it likes a 10.5 x 5 Bolly or an 11 x 3 or 4 APC depending on what manoeuvres you are doing. I tried it with a 12 x 5 APC to see how well it could cope and it seamed very happy.
I have changed the plug to a warm model Technics, to help the motor pick up from lengthy (1-2 minuet) slow flying with the motor at just above idle, but that’s me being picky.
I did change the exhaust, to a Just engines throttle pipe. It gave the motor a little faster throttle response without the caminess of a full pipe. It definitely gave more power and switch like throttle response, but it took away the fine throttle control needed for prop hanging. I have now changed back to the standard exhaust and fine throttle control is easier. It has taken the crispness off the motor, and really the choice is yours. If you need a bit more power with instant pickup, go with the throttle pipe, if you want a “softer” motor keep the standard exhaust.
I started using Model Technics Irvine mix 10% nitro and 18% oil, as this gives a much cleaner bottom end. The motor has now done about 150 flights/ 30 hours of flying. I took the head off to look inside the barrel, and there is no apparent signs of wear and the piston is as clean as the day it first run.
The idle needle needed a little work to get it just right, I found it needed turning in about half a turn in all, but don't even start getting into the fine tuning until the motor has done a good 45 mins of running.
The motor starts first or second (backward) flick. My party piece with this motor is to prime the motor, (two flicks with finger on the carb, two flicks open carb...no glow clip!!) attach the clip and spin the motor backwards with the safety nut. It starts every time!!, the thing is most motors will do this if set up correctly.
One other thing, this motor is VERY quiet on the standard exhaust. OK at 15,000RPM on a small prop it is certainly singing, but at half throttle you cant hear it.
I would totally recommend this motor, and I know quality costs BUT!!! I must ask why the new 39 at £70 costs more than the old 36 at £60 and even more incredibly the (new ish) 40 at £60, I realise its probably a new crank case but its the same price as the 53!!
I had never owned a fun fly model before, so after looking around for a suitable model, I saw a demonstration of the Weston Cougar at the BMFA South Midland Area rally. I decided that this was the model for me.
The next challenge.... what motor, do I use the Magnum? or go with the Irvine 36, ( I like to buy British where I can) the Irvine won.
I went off to the shop, cash in hand to get a shiny new Irvine 36...”have I seen the new 39 I am asked?” Now who am I to stand in the way of progress! I didn’t notice the price tag, or I just might of changed my mind!!
The one thing I always find interesting is opening a motor box for the first time. Even after working in the motor racing industry where boxes held engines made from exotic blends of mag-alloy, looking at a new model engine still gives me a kick (I know I need to get out more) The latest? range of red engines from Irvine does give a wonderful perception of quality, even before using the motor. I have now used several of the Irvine motors and the new 39 follows the family line.
Out of the box, the motor is very clean, this may sound like a strange comment to make, but I have looked at new motors and found small particles of swarf/metal around and even inside new motors. Always have a look down the intake, inside the exhaust and if you see any bits of metal then give the motor a good wash out with fuel before you start. The Irvine39 was well packed in its own plastic bag, very clean and nicely oiled.
The motor comes with a good quality silencer that uses an alloy spacer and baffle to keep the motor quiet. As usual the carb is packed in its own plastic bag allowing you to keep it clean until required on the model.
A small bag of tools are supplied designed to fit the exhaust and the carb pinch bolt, how many times have you had to dig in the bottom of your box to find an Allen key that (almost) fits.
The 39 fits in a 36-size engine mount; it weighs approximately the same as the old Irvine 36 including silencers. Some would ask why Irvine has produced this motor as it seams to conflict with other motors in their range ( the 39 is more powerful than the 40). It seams that it has been produced for the fun fly market, with the 36-size motor being the popular choice. Opening the motor up to 39 has given it the ability to turn bigger props with the same gusto as a piped 36.
The motor is a true triple ported two stroke as per 95% of current motors. Its ABC design should give many years of reliable fun. The motor was quite tight at the top of the stroke and "squeaked" as it went over TDC. I always ensure that there is sufficient oil in a motor before running it for the first time. I add a couple of drops of after run oil, but 3 in 1 works just as well.
The carb is secured with a clamp, tightened by turning a small Allen bolt with the supplied key. It is important that the clamp is aligned with the hole in the crankcase, before the carb is inserted. The carb has a small "o" ring that seals the carb onto the crankcase. It’s worth pushing the carb with your thumb as you tighten the clap to ensure a good seal.
The motor was installed in the Cougar using the mount that came with the kit. One thing to be aware of if fitting this motor in the cougar is that the exhaust is in a different alignment to the magnum motor Weston sells. This means that if you use the holes as drilled by Weston for the engine mount on the bulkhead, you will find the exhaust is not central under the model. This is an advantage as it helps to balance the model laterally.
Now came the bit I love!! Fuel pipes on Throttle connected, and out into the garden. (the wife had gone shopping) I set the main needle to 1 3/4 turns open, but left the idle screw as set by Irvine. I fitted a Taylor standard plug, primed the motor, I have found most Irvine’s like to be a little wetter than normal. The glow clip attached and two flips to start, it was so easy it shocked me!!
Running in is a personal thing, BUT VERY IMPORTANT. An ABC motor has to get up to running temperature as fast as possible, to bed the piston into the liner. If the motor does not reach running temperature fast there is a possibility of the bore getting glassed.
My method of running ABC motors in is to start the motor, with a rich setting. Once the motor starts open the throttle to full, and adjust the needle to full speed then open the needle a couple of clicks. Allow the motor to run at virtually full speed for 10 - 15 seconds then open the needle (still on full throttle). Wind the needle open until the motor is only just breaking into two stroke and leave it there for 15 seconds. I repeat this process of going from max RPM to very rich at15 second intervals for the first 3-4 mins, then stop the motor to let it cool. This process was done with three tanks of fuel, slowly lengthening the time the motor was left on max RPM. Then it was flown.
The motor and early flights were done on a 10x6 prop, and it really can sing on this prop! I have run the motor on several props but for fun fly, it likes a 10.5 x 5 Bolly or an 11 x 3 or 4 APC depending on what manoeuvres you are doing. I tried it with a 12 x 5 APC to see how well it could cope and it seamed very happy.
I have changed the plug to a warm model Technics, to help the motor pick up from lengthy (1-2 minuet) slow flying with the motor at just above idle, but that’s me being picky.
I did change the exhaust, to a Just engines throttle pipe. It gave the motor a little faster throttle response without the caminess of a full pipe. It definitely gave more power and switch like throttle response, but it took away the fine throttle control needed for prop hanging. I have now changed back to the standard exhaust and fine throttle control is easier. It has taken the crispness off the motor, and really the choice is yours. If you need a bit more power with instant pickup, go with the throttle pipe, if you want a “softer” motor keep the standard exhaust.
I started using Model Technics Irvine mix 10% nitro and 18% oil, as this gives a much cleaner bottom end. The motor has now done about 150 flights/ 30 hours of flying. I took the head off to look inside the barrel, and there is no apparent signs of wear and the piston is as clean as the day it first run.
The idle needle needed a little work to get it just right, I found it needed turning in about half a turn in all, but don't even start getting into the fine tuning until the motor has done a good 45 mins of running.
The motor starts first or second (backward) flick. My party piece with this motor is to prime the motor, (two flicks with finger on the carb, two flicks open carb...no glow clip!!) attach the clip and spin the motor backwards with the safety nut. It starts every time!!, the thing is most motors will do this if set up correctly.
One other thing, this motor is VERY quiet on the standard exhaust. OK at 15,000RPM on a small prop it is certainly singing, but at half throttle you cant hear it.
I would totally recommend this motor, and I know quality costs BUT!!! I must ask why the new 39 at £70 costs more than the old 36 at £60 and even more incredibly the (new ish) 40 at £60, I realise its probably a new crank case but its the same price as the 53!!
