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MOKI RADIAL Care and Maintenence

Old 11-20-2021, 04:53 PM
  #4776  
marksp
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Just picked up a model with an early serial # 215 with top hat ignition that I’m planning on upgrading. Leaning towards CH-Ignitions CDI vs Rainbow-tronics based on 2S battery support, plug-n-play RPM telemetry to PowerBox Sparkswitch Pro, proven RCExl based electronics and easy to work with US support.

My questions for Rainbow users are -
1. Is there an electronic Rx controlled switch that works with 3S battery?
2. Has anyone sorted RPM telemetry? Manual states mandatory use of a “pull-up resistor”???

Thank you very much for your shared experience!

Last edited by marksp; 11-21-2021 at 10:29 AM.
Old 11-21-2021, 01:29 PM
  #4777  
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Originally Posted by marksp View Post
Just picked up a model with an early serial # 215 with top hat ignition that I’m planning on upgrading. Leaning towards CH-Ignitions CDI vs Rainbow-tronics based on 2S battery support, plug-n-play RPM telemetry to PowerBox Sparkswitch Pro, proven RCExl based electronics and easy to work with US support.

My questions for Rainbow users are -
1. Is there an electronic Rx controlled switch that works with 3S battery?
2. Has anyone sorted RPM telemetry? Manual states mandatory use of a “pull-up resistor”???

Thank you very much for your shared experience!
Hi, (saw you mentioned the PowerBox Sparkswitch Pro)
I would just give a warning on the "PowerBox Sparkswitch Pro" it is not safe!, I had one last year but sent it back to Powerbox, It cuts' of ignition, in short moments, it is not immune against the disturbances from the Moki ignition, Powerbox declined my complaints first (said it was badly installed), but I searched in their support forum and found at least 10 users complaining on ignition problems using PowerBox Sparkswitch Pro.
My theory is that there is a processor on the "dirty" side of the opto isolation managing the ignition telemetry and possibly also the ignition on/of transistor, I got suspicious after my telemetry data from the ignition side was korrupt, and the Moki stoppen now and then (luckily on ground at trial runs) then I watched the red "ifnition on" lead it is equipped with, and saw it was blinking each time the engine stumbled and sometime stopped!
May be they now have re-designet it, I told them it is not ready for market, since not all people are skilled in EMI disturbances and know how to make safe installations, ...who would take a risk with a stopped engine?
Old 11-23-2021, 08:03 AM
  #4778  
K Rohrbach
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Waiting arrival of my Moki 250 to go in Carf Corsair.
thank goodness for this thread as I’ve heard not much comes with the engine
being a turbine guy first I understand the importance of a perfect install and operational use of a high end power plant, of course a radial is a bit far from a turbine but knowledge is the key.
Old 11-23-2021, 08:25 AM
  #4779  
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Originally Posted by K Rohrbach View Post
Waiting arrival of my Moki 250 to go in Carf Corsair.
thank goodness for this thread as I’ve heard not much comes with the engine
being a turbine guy first I understand the importance of a perfect install and operational use of a high end power plant, of course a radial is a bit far from a turbine but knowledge is the key.
Welcome to the thread. You are going to love the Carf Corsair. I have one, its one of my favorite planes. Here is a build link to the Corsair you might want to check out if you haven't already....

CARF F4U-1 Corsair build thread
Old 11-29-2021, 01:20 AM
  #4780  
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Hello everyone,

i have noticed that Kolm engines propose a pressure tank system kit for the carburetor with a simple pet bottle. Has anyone tested this?
It's supposed to replace the electrical pump.
In previous messages i had the problem of my new S180 not starting and running only with a pressurized fuel tank. My engine is back at airworld waiting for feedback on the control.
https://ploberger-modelltechnik.at/e...ystem-kit?c=97

Comments are welcome.
Regards,
Lawrence

Last edited by tziger; 11-29-2021 at 07:17 AM.
Old 11-29-2021, 08:54 PM
  #4781  
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Default Rainbow-tronic ignition

Originally Posted by marksp View Post

My questions for Rainbow-tronic users are -
1. Is there an electronic Rx controlled switch that works with 3S battery?
2. Has anyone sorted RPM telemetry to PowerBox CORE? Manual states mandatory use of a “pull-up” resistor”???

Thank you very much for your shared experience!
Sorted solution to my questions above -

>> Rainbow-tronic offers Rx controlled 20v capable switch
>> Rainbow-tronic RPM Tach output supports Jeti MRPM (Hall) sensor. Smoke-EL Tele-Bridge converts Jeti-EX to PowerBus P2Bus for real-time CORE telemetry
Old 12-03-2021, 12:30 PM
  #4782  
Kelly Rohrbach
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[QUOTE=GeorgiaFlyer;12703867]Welcome to the thread. You are going to love the Carf Corsair. I have one, its one of my favorite planes. Here is a build link to the Corsair you might want to check out if you haven't already....

CARF F4U-1 Corsair build thread[/
QUOTE]
Got my Moki 250, what a beast of a looking motor.
I talked via email Hans at Moki about the electronics and he just said the current blue box is there design for their engine, others will work but why use another item that we did not design for our motors?
this is going in the Carf Corsair, some guys say baffle is a must other say no?? I may cut the cowl flaps open and make operational also will run a bit more oil than some, 38 to 1 , no more than 40 to 1 , oil is life and would think keep the engine a little cooler??
I have the laser heat gun and will do testing with baffle and cowl flaps and such to get a real life numbers and will share all my info,
Old 12-03-2021, 01:18 PM
  #4783  
RichardGee
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Baffling all radials is a MUST - Not optional, IF you want the engine to be reliable.
Extra oil and exit opening aren't enough to keep the engine running within its recommended temperature range.
Old 12-03-2021, 01:36 PM
  #4784  
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Kelly - sharing my personal experience with 2 Moki's. I have found the even when the Moki Radial is on the test stand, it will run hotter than when installed in a well baffled cowl. You can overheat the Moki if run too long on the ground.
Amsoil Dominator all the way. I have never run the engine with any mix richer than 45/1. Too much oil with rich needle settings and hot running temps can stick valves. The Moki is fed it's fuel from the carb through the center intake tube and directly into the crankcase. The main rod needle bearings are always lubed by fresh unburned fuel/oil mix. From the crankcase the fuel is distributed to the 5 intake tubes to feed the cylinders. Also, too rich of a mix will cause the lower #3 cylinder not to fire. We see this a lot when new owners are running in their engine. That is the reason the Moki recommends 50/1.
Old 12-13-2021, 01:50 PM
  #4785  
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Default Pulse pump

Hi, I would like to bring up the Moki “Pulse pump” topic for us who relies on it to drive the built in Walbro fuel pump. (using no electric pump or pressure system)

While doing my annual winter maintenance on my 180 Moki, I tested and disassembled the “Pulse pump” which have been running for 6h total.



It is important to know that it is working properly, so I think it is a good thing to test it’s performance regularly.

I took out all sparkplugs, disconnected the 3mm tube going to the carb and attached it to a 1Bar pressure gauge and run the prop shaft at slow rpm by a cordless drill machine on low gear.

And I could se it created pulses (+- 0,06 Bar up/down)

If you don’t have a gauge you could put the hose against you tongue, and feel a distinct air pulsating.



I disassembled the pulse pump to measure its cylinder-piston gap and clean out grease from top of piston. (so far no grease was visible in the hose)

The piston gap was, 0,05mm which should be ok, but there was a lot of grease on top of the piston, which is the weakness of this design, grease from cam area emerging up to top of piston, finally blocking the pulses to carb (this design could probably be improved by a better piston and sealing design)

I wish they had mentioned this cleaning, in the manual as a point of maintenance, ( se my image for amount of grease collected after only 6h)



While cleaning the pump house I discovered a small hole! bleeding out air and reducing the pulse strength!

I cannot figure out why this hole is there (maybe blead out grease?), are there anyone who know the purpose of this hole?

I could not resist blocking the hole, by a O-ring in the groove, and run the engine with the cordless drill and the gauge attached, and could see that the pulse strength increased by 40-50%

To around +-0,1 Bar up/down

I will test this in the air next season if not anyone comes up with a good reason not to block this hole.



Engine driven by cordless drill at low gear with no sparkplugs


Old 12-13-2021, 08:07 PM
  #4786  
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Originally Posted by Robert-H View Post
Hi, I would like to bring up the Moki “Pulse pump” topic for us who relies on it to drive the built in Walbro fuel pump. (using no electric pump or pressure system)

While doing my annual winter maintenance on my 180 Moki, I tested and disassembled the “Pulse pump” which have been running for 6h total.



It is important to know that it is working properly, so I think it is a good thing to test it’s performance regularly.

I took out all sparkplugs, disconnected the 3mm tube going to the carb and attached it to a 1Bar pressure gauge and run the prop shaft at slow rpm by a cordless drill machine on low gear.

And I could se it created pulses (+- 0,06 Bar up/down)

If you don’t have a gauge you could put the hose against you tongue, and feel a distinct air pulsating.



I disassembled the pulse pump to measure its cylinder-piston gap and clean out grease from top of piston. (so far no grease was visible in the hose)

The piston gap was, 0,05mm which should be ok, but there was a lot of grease on top of the piston, which is the weakness of this design, grease from cam area emerging up to top of piston, finally blocking the pulses to carb (this design could probably be improved by a better piston and sealing design)

I wish they had mentioned this cleaning, in the manual as a point of maintenance, ( se my image for amount of grease collected after only 6h)



While cleaning the pump house I discovered a small hole! bleeding out air and reducing the pulse strength!

I cannot figure out why this hole is there (maybe blead out grease?), are there anyone who know the purpose of this hole?

I could not resist blocking the hole, by a O-ring in the groove, and run the engine with the cordless drill and the gauge attached, and could see that the pulse strength increased by 40-50%

To around +-0,1 Bar up/down

I will test this in the air next season if not anyone comes up with a good reason not to block this hole.



Engine driven by cordless drill at low gear with no sparkplugs

Thank you for these images Robert. Really turns the light on before the wrench turns. Thoughtful documentation.
Truly applicable on a "care and maintenance" forum. Good stuff!
Old 12-13-2021, 10:03 PM
  #4787  
Detlef Kunkel
 
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The little hole is for venting. It improves the function and avoids building up pressure in the gerarbox. Pressure would help grease to pass the piston.
Early engines did not feature this.
Do not change it.

PS it was high time to clean the pump!
Old 12-14-2021, 07:09 AM
  #4788  
Robert-H
 
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Originally Posted by Detlef Kunkel View Post
The little hole is for venting. It improves the function and avoids building up pressure in the gerarbox. Pressure would help grease to pass the piston.
Early engines did not feature this.
Do not change it.

PS it was high time to clean the pump!

So regarding the early engines without hole, What was the problem they wanted to solve by adding this hole? Because this hole makes 2 negative things, excess grease on top of piston and 40% less pulse efficiency. (this venting hole is placed above the piston head, at bottom dead center, so about half of the pulse goes to waste)

If the cam gearbox needs venting why not a separate venting arrangement.

PS yes I was glad I took it apart, I did not expected that much grease only after 6h runtime..
Old 12-14-2021, 10:02 AM
  #4789  
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Originally Posted by Robert-H View Post
So regarding the early engines without hole, What was the problem they wanted to solve by adding this hole? Because this hole makes 2 negative things, excess grease on top of piston and 40% less pulse efficiency. (this venting hole is placed above the piston head, at bottom dead center, so about half of the pulse goes to waste)

If the cam gearbox needs venting why not a separate venting arrangement.

PS yes I was glad I took it apart, I did not expected that much grease only after 6h runtime..
A question.
Is the grease a product of the oil fuel mixture or an installed at the factory assembly lubricant intended to be regularly replaced in the maintenance schedule ?
Old 12-14-2021, 11:37 AM
  #4790  
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Originally Posted by Hyjinx View Post
A question.
Is the grease a product of the oil fuel mixture or an installed at the factory assembly lubricant intended to be regularly replaced in the maintenance schedule ?
Yes, the grease it is for the cam ring, in the area below the front cower, it is filled with grease.
It is probably also intended to lubricate this little puls generator piston

Airworld quote "We recommend that you have this grease replaced by us after a running time of about 50 hours (that is 300 flights of 10 minutes each)"
Old 12-14-2021, 01:12 PM
  #4791  
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Originally Posted by Robert-H View Post
Yes, the grease it is for the cam ring, in the area below the front cower, it is filled with grease.
It is probably also intended to lubricate this little puls generator piston

Airworld quote "We recommend that you have this grease replaced by us after a running time of about 50 hours (that is 300 flights of 10 minutes each)"
Hmm. Begs the question. Why not waste lube the assembly with mix oil and eject the used oil with a vent to atmosphere. Possibly eliminate the grease build up in the festo tube eventually blocking the pulse.
Old 12-15-2021, 12:52 AM
  #4792  
Detlef Kunkel
 
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Originally Posted by Robert-H View Post
Because this hole makes 2 negative things, excess grease on top of piston and 40% less pulse efficiency. (this venting hole is placed above the piston head, at bottom dead center, so about half of the pulse goes to waste)

..

Robert,
this conclusion of yours is not correct.
Old 12-15-2021, 12:59 AM
  #4793  
Detlef Kunkel
 
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Originally Posted by Hyjinx View Post
Hmm. Begs the question. Why not waste lube the assembly with mix oil and eject the used oil with a vent to atmosphere. Possibly eliminate the grease build up in the festo tube eventually blocking the pulse.


The impulse piston is not grease-tight, but even less oil-tight. It will affect the function of the impulse pump even earlier than with grease.

But in combination with an E-pump it is OK, because the impulse piston is superfluous.

I run my radial engines with very thick oil and e-pump.

I have had motors here that squealed when turned by hand because the cam drum and tappets were completely dry. Lots of metal chips and wear inside. Creepy. The grease was so stiff it didn't reach a single spot where it should have been. It was still there as a lump right where the Worker at Moki had put it.

Personally, I don't like the idea of lubrication with (stiff) grease in a closed gearbox.

Oil gets everywhere

Last edited by Detlef Kunkel; 12-15-2021 at 02:43 AM.
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Old 12-16-2021, 01:12 AM
  #4794  
Robert-H
 
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Originally Posted by Detlef Kunkel View Post
Robert,
this conclusion of yours is not correct.
Just want to explain my 3 statements above further, and still, to me it is not clear why they added this hole!

-The hole in the pulse pump cylinder is just above the pulse piston head at bottom dead center, the stroke is 4mm, the hole reduces the effective stroke to 3mm!

-The 40% pulse reduction is from a reduced pulse stroke, and it is measurement with a pressure gauge, it can clearly be seen the difference with and without hole! (motor is run by an power drill at about 200 rpm)



-And regarding the excess grease coming out on top of piston is based on two situations.

Firstly the hole; your statement that there was a overpressure in the cam area that needed to be vented out, which would lead to a flow of grease and air taking this path ..? (if there really is a overpressure in cam area it seems better to went it out elsewhere.)

And the secondly; The piston has a play and there is a pulsating negative/positive pressure in the pulse cylinder, ant that by itself would also pull up grease.

It would have been an quite easy thing to design a better piston-sealing arrangement than the existing, using modern sealing rings, why not make it right from the beginning! Then the Walbro built in pump would have worked perfectly at all time!

But in the end, its quite easy to unscrew the pulse cylinder now and then to remove the grease… if you know about the grease..

Still I wonder why Moki added that hole in the pulse cylinder, which problem did they want to solve?

PS I also like the idea with cam lubrication by oil, In my latest design of a 2 cyl boxer I put the camshaft in a sealed compartment half filled with oil, works well.
Old 12-16-2021, 08:26 AM
  #4795  
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Originally Posted by Robert-H View Post
Just want to explain my 3 statements above further, and still, to me it is not clear why they added this hole!

-The hole in the pulse pump cylinder is just above the pulse piston head at bottom dead center, the stroke is 4mm, the hole reduces the effective stroke to 3mm!

-The 40% pulse reduction is from a reduced pulse stroke, and it is measurement with a pressure gauge, it can clearly be seen the difference with and without hole! (motor is run by an power drill at about 200 rpm)



-And regarding the excess grease coming out on top of piston is based on two situations.

Firstly the hole; your statement that there was a overpressure in the cam area that needed to be vented out, which would lead to a flow of grease and air taking this path ..? (if there really is a overpressure in cam area it seems better to went it out elsewhere.)

And the secondly; The piston has a play and there is a pulsating negative/positive pressure in the pulse cylinder, ant that by itself would also pull up grease.

It would have been an quite easy thing to design a better piston-sealing arrangement than the existing, using modern sealing rings, why not make it right from the beginning! Then the Walbro built in pump would have worked perfectly at all time!

But in the end, its quite easy to unscrew the pulse cylinder now and then to remove the grease… if you know about the grease..

Still I wonder why Moki added that hole in the pulse cylinder, which problem did they want to solve?

PS I also like the idea with cam lubrication by oil, In my latest design of a 2 cyl boxer I put the camshaft in a sealed compartment half filled with oil, works well.
---------

it is also about the absolute pressure in the pulse line. Without a vent hole acting in the direction of the pulse line, pressure or vacuum can build up. One of the butterfly valves then works worse and worse until it no longer opens.

PS from 4 to 3 mm is minus 25%, not minus 40.
Better to have 75% working instead of 100% in a more critical situation.

This evolution of Moki makes absolutely sense in everydays use..
Old 12-16-2021, 10:28 AM
  #4796  
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Originally Posted by Robert-H View Post
Just want to explain my 3 statements above further, and still, to me it is not clear why they added this hole!

-The hole in the pulse pump cylinder is just above the pulse piston head at bottom dead center, the stroke is 4mm, the hole reduces the effective stroke to 3mm!

-The 40% pulse reduction is from a reduced pulse stroke, and it is measurement with a pressure gauge, it can clearly be seen the difference with and without hole! (motor is run by an power drill at about 200 rpm)



-And regarding the excess grease coming out on top of piston is based on two situations.

Firstly the hole; your statement that there was a overpressure in the cam area that needed to be vented out, which would lead to a flow of grease and air taking this path ..? (if there really is a overpressure in cam area it seems better to went it out elsewhere.)

And the secondly; The piston has a play and there is a pulsating negative/positive pressure in the pulse cylinder, ant that by itself would also pull up grease.

It would have been an quite easy thing to design a better piston-sealing arrangement than the existing, using modern sealing rings, why not make it right from the beginning! Then the Walbro built in pump would have worked perfectly at all time!

But in the end, its quite easy to unscrew the pulse cylinder now and then to remove the grease… if you know about the grease..

Still I wonder why Moki added that hole in the pulse cylinder, which problem did they want to solve?

PS I also like the idea with cam lubrication by oil, In my latest design of a 2 cyl boxer I put the camshaft in a sealed compartment half filled with oil, works well.
Hi Robert,

I know that the existence of the hole is to avoid a hydraulic lock in case the small cylinder becomes completely filled with grease. I would not block the hole. There is an explanation earlier in the thread from Stuart Mckay.
In case of an hydraulic lock there will be a carnage in the cam area.

BR,
Lawrence
Old 12-16-2021, 02:39 PM
  #4797  
Robert-H
 
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Originally Posted by Detlef Kunkel View Post
---------

it is also about the absolute pressure in the pulse line. Without a vent hole acting in the direction of the pulse line, pressure or vacuum can build up. One of the butterfly valves then works worse and worse until it no longer opens.

PS from 4 to 3 mm is minus 25%, not minus 40.
Better to have 75% working instead of 100% in a more critical situation.

This evolution of Moki makes absolutely sense in everydays use..

No you are wrong, the pulse pressure never reaches the butterfly valves, it stays in a separate diaphragm chamber

Also the 3 and 4mm 25% is from caliper measurement and the 40% is from pressure gauge measurement, I don't know why they don't correlate, but the sinus function is involved here.. crank movement..

Last edited by Robert-H; 12-17-2021 at 04:48 AM. Reason: After close investigation of the carb.
Old 12-16-2021, 02:48 PM
  #4798  
Robert-H
 
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Originally Posted by tziger View Post
Hi Robert,

I know that the existence of the hole is to avoid a hydraulic lock in case the small cylinder becomes completely filled with grease. I would not block the hole. There is an explanation earlier in the thread from Stuart Mckay.
In case of an hydraulic lock there will be a carnage in the cam area.

BR,
Lawrence
Ok, actually once I saw a small pile of grease in the area where the hole are, but at that time I really newer understood where it came from, I'll search for Stuarts thread.
Still, this hole to me appears like a quick dirty fix, instead of designing a proper piston and sealing, that don't leak anything from below and if there are a overpressure in the came area vent it out elsewhere.
Old 12-16-2021, 10:40 PM
  #4799  
Detlef Kunkel
 
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Originally Posted by tziger View Post
Hi Robert,

I know that the existence of the hole is to avoid a hydraulic lock in case the small cylinder becomes completely filled with grease. I would not block the hole. There is an explanation earlier in the thread from Stuart Mckay.
In case of an hydraulic lock there will be a carnage in the cam area.

BR,
Lawrence


A hydraulic lock in a cylinder that is constantly open at the head ( leading to the hose to the carb?)

This is not a four stroke cylinder where the valves are closed any second rev.


anything that passes the piston is fed to the carb, I do not see a locking chance there. The diaphragm in the carb would suffer, but it is soft and not solid enough to cause the piston unit a damage.

This system works like it is. I do not say well.

In my eyes it works at the mimimum limit and that is no good, but it works if you keep a constant eye on it and check and / or clean it every few flights

the given space is limited and does not allow much to increase the capacity mechanically and significantly. We will not discuss that away.

I stopped thinking about the pulse pump long ago. If you see what Mr Walbro was facing when he createt the internally fuel feeding layout, he had the massive pulse of a 2-Stroke crankcase at hand.

Such a small ( or a bit bigger) pulse piston is miles apart from that and will always be.


Luckily, there is a pretty easy alternative; the use of an electric pump.

It is so easy to get rid of this dangerous issue, hard for me to understand why so many people have a problem with that. The prefer to operate expensive engines at the lean limit.

Many comparable engines are supplied with an e-pump today when they leave the factory, or al least the manufacturer recommends the use.

Nevertheless, this topic keeps on filling forum discussions. Immortal little favorite.



BTW with my phoenix 4-cyl engine, I was thinking to equip it with a mechanical fuel pump, attatched to the engine like a generator in a car.

The engine uses a 3-stage oil pump, and a fourth pump unit could have been for fuel. Some extra fuel proof shaft sealings were all it had needed. Not very complicated.

The total effort - including a pressure regulator - compared to the e-pump that can be placed wherever you like- stopped this idea.

I have never have regretted this.

The red circles show the 3-stage oil pump and the E-pump.

Works flawless for 9 years now. Even somebody who has no idea about engines can set the carb easily, because it is absolutely clear where the perfect setting point is.
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Last edited by Detlef Kunkel; 12-16-2021 at 10:54 PM.
Old 12-20-2021, 12:23 AM
  #4800  
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Hi,
I have just ordered my electric pump. My engine is new and i had troubles even to start it after 3 hours of running in. I sent it back to Airworld and the explanation was that they found grease in the carb. They also changed the membranes. Without playing the expert, i had the carb open just before i sent it back and i did not find any grease in it.
I was not feeling comfortable wit the explanation so i ordered a pump.
When i asked them several times if i need one, they do not stop you from buying but they say it's just an improvement and the engine runs perfectly without it.

Best regards,
Lawrence

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