mvvs 2.5dfs/r sort of success
04-23-2014, 07:12 AM
#1
Senior Member
Thread Starter
Join Date: Nov 2003
Location: Bucks, UNITED KINGDOM
Posts: 165
Likes: 0
Received 0 Likes
on
0 Posts
mvvs 2.5dfs/r sort of success
Just had my MVVS 2.5 diesel sort of running.
Seemed to only want to start with tons of compression but once I'd had a few pops out of it at that compression I could slacken off the comp a bit - it would start but only run for about a minute - judging by the smoke it was well rich.
Lots of black exhaust residue.
It seemed very tight when I bought it new - I was chatting to someone at the Nats a few years back who had one and he said they're not easy to run in....
Still quite successful.
Annette
Seemed to only want to start with tons of compression but once I'd had a few pops out of it at that compression I could slacken off the comp a bit - it would start but only run for about a minute - judging by the smoke it was well rich.
Lots of black exhaust residue.
It seemed very tight when I bought it new - I was chatting to someone at the Nats a few years back who had one and he said they're not easy to run in....
Still quite successful.
Annette
04-24-2014, 03:46 PM
#4
Your fuel may be low on ether. If the oil in the exhaust is really black, you may be running it over compressed. Low ether fuel will need a lot of compression to stay running when cold. Your exhaust residue should range from a honey colour to light brown.
04-25-2014, 06:13 AM
#6
D1000 is good. If it is fresh, one would assume the ether has not gone off. In that case you may be running over compressed. I would get it running and once it is warmed up, I would back off on the "tommy bar" until the engine falters a bit and then lean it out until the engine runs smooth. If the engine is new, do not over prop it.
04-25-2014, 03:59 PM
#7
Join Date: Feb 2010
Location: Melbourne, AUSTRALIA
Posts: 68
Likes: 0
Received 0 Likes
on
0 Posts
My MVVS DFS/R runs a rather black exhaust most of the time, I think it might be normal for this engine as it shows no sign of distress or over compression.
Mine is running with throttle an tuned exhaust in a rather quick rc pattern plane.- very nice indeed.
Mine is running with throttle an tuned exhaust in a rather quick rc pattern plane.- very nice indeed.
04-26-2014, 03:05 AM
#9
Join Date: Feb 2010
Location: Melbourne, AUSTRALIA
Posts: 68
Likes: 0
Received 0 Likes
on
0 Posts
I'm running an APC 8x5.
it just gets on the pipe with a shallow dive then says on the pipe after that.
If I want to be on the pipe from launch it needs to be an 8x4 or 7x5, but I have found these a bit noisy and quick for relaxed flying.
Not sure of the rpm but I don't think the pipe works below 15,000.
it just gets on the pipe with a shallow dive then says on the pipe after that.
If I want to be on the pipe from launch it needs to be an 8x4 or 7x5, but I have found these a bit noisy and quick for relaxed flying.
Not sure of the rpm but I don't think the pipe works below 15,000.
04-29-2014, 04:48 PM
#10
Just rechecked mine today sitting in an old J 3 cub ( Nitroplanes??} span 50 inchs wt 48 oz 4 oz tank fitted with a wood zinger 9 x 5 8800-9000 idle about 3300 good transisition muffler stock MVVS 3225 conventional not tuned exhaust carried to back\
exits at rear KS alum tubing easy flyer no speed demon compression seems low but still a finger flip 10-15 after a choke martin
oh blue smoke of course oil out the stack dark honey color fuel davis ABC
exits at rear KS alum tubing easy flyer no speed demon compression seems low but still a finger flip 10-15 after a choke martin
oh blue smoke of course oil out the stack dark honey color fuel davis ABC
Last edited by AMB; 04-29-2014 at 04:53 PM.
08-08-2015, 08:43 PM
#11
Join Date: Jun 2014
Location: Hudson Valley. New York. USA
Posts: 283
Likes: 0
Received 2 Likes
on
2 Posts
I had heaps of trouble with an MVVS D7 today and came across this thread. In fact I took one of the comments and tried boosting the ether in the fuel but to no avail.
If anyone catches this update and has any advice, I'd appreciate hearing what you know.
This is supposed to be an easy-starting engine and I got Charlie Bupkus today after fiddling for four hours on it.
My arm feels like I pitched 9 innings today!
Here's a vid at the end of my efforts: https://www.youtube.com/watch?v=J0LBEtSOm1Q
Shows a bit of a bite but it never really catches.
If anyone catches this update and has any advice, I'd appreciate hearing what you know.
This is supposed to be an easy-starting engine and I got Charlie Bupkus today after fiddling for four hours on it.
My arm feels like I pitched 9 innings today!
Here's a vid at the end of my efforts: https://www.youtube.com/watch?v=J0LBEtSOm1Q
Shows a bit of a bite but it never really catches.
08-09-2015, 12:49 AM
#12
It is hard to tell from just a short movie but to me it looked like is was over compressed. It fires but only rocks back and forth between two TDC points.
The large venturi can give a low suction but that would be something that you can check for with the engine running. In your rig the fuel level is well above the venturi and fuel will flow due to gravity alone. In fact that might also deliver too much fuel while trying to start the engine. I would suggest to not put any fuel in the tank at all until you learn how to start the engine. The easiest is to prime the side of the piston only, that should fire each time when the compression ratio is set right. Second option is to prime a little directly into the venturi that will give you a long enough run to get the hang of the starting and compression ratio. Once the engine starts easily and runs out the prime you can put fuel into the tank and tune the needle.
The large venturi can give a low suction but that would be something that you can check for with the engine running. In your rig the fuel level is well above the venturi and fuel will flow due to gravity alone. In fact that might also deliver too much fuel while trying to start the engine. I would suggest to not put any fuel in the tank at all until you learn how to start the engine. The easiest is to prime the side of the piston only, that should fire each time when the compression ratio is set right. Second option is to prime a little directly into the venturi that will give you a long enough run to get the hang of the starting and compression ratio. Once the engine starts easily and runs out the prime you can put fuel into the tank and tune the needle.
08-09-2015, 04:57 AM
#14
Join Date: Jun 2014
Location: Hudson Valley. New York. USA
Posts: 283
Likes: 0
Received 2 Likes
on
2 Posts
It is hard to tell from just a short movie but to me it looked like is was over compressed. It fires but only rocks back and forth between two TDC points.
The large venturi can give a low suction but that would be something that you can check for with the engine running. In your rig the fuel level is well above the venturi and fuel will flow due to gravity alone. In fact that might also deliver too much fuel while trying to start the engine. I would suggest to not put any fuel in the tank at all until you learn how to start the engine. The easiest is to prime the side of the piston only, that should fire each time when the compression ratio is set right. Second option is to prime a little directly into the venturi that will give you a long enough run to get the hang of the starting and compression ratio. Once the engine starts easily and runs out the prime you can put fuel into the tank and tune the needle.
The large venturi can give a low suction but that would be something that you can check for with the engine running. In your rig the fuel level is well above the venturi and fuel will flow due to gravity alone. In fact that might also deliver too much fuel while trying to start the engine. I would suggest to not put any fuel in the tank at all until you learn how to start the engine. The easiest is to prime the side of the piston only, that should fire each time when the compression ratio is set right. Second option is to prime a little directly into the venturi that will give you a long enough run to get the hang of the starting and compression ratio. Once the engine starts easily and runs out the prime you can put fuel into the tank and tune the needle.
I exhaustively tested this engine. I did the other thing you suggest numerous times - started from a closed NV, got it to purr a bit either thru priming through the exhaust port or the venturi or both, then gradually open the NV - to no avail. I pretty much exhausted pemutations. I added a screen at the end of the video that I am inserting here.
Don't know, first place to look is if anything is fishy with the NV when I get it out.
Cheers, Peter
08-09-2015, 05:02 AM
#15
Join Date: Jun 2014
Location: Hudson Valley. New York. USA
Posts: 283
Likes: 0
Received 2 Likes
on
2 Posts
I have run other engines in the last two weeks on this (fresh) Davis Diesel fuel, and I just tried boosting the ether content of the fuel a bit to see if that would have an effect..
There were notes online that some MVVS engines needed an unnatural deal of compression or higher ether - tried that with no positive outcome.
Cheers - Peter
08-09-2015, 09:05 AM
#16
As it does fire I think it is just a matter of finding the right settings. Is the engine new or used?
If it is a used engine you might want to check that the liner is in a correct position, I don't think there is any alignment pin and someone may well have put the cylinder the wrong way around.
On new engines I've found that a large plastic prop helps for the first starts. Not sure what you have on there now, but you can easily put on a plastic 9x4 or 9x5. Perhaps even a 10x4 just to get it running. A too large prop isn't any problem on diesels, they will just run cooler as the optimum compression setting is lower.
If it is a used engine you might want to check that the liner is in a correct position, I don't think there is any alignment pin and someone may well have put the cylinder the wrong way around.
On new engines I've found that a large plastic prop helps for the first starts. Not sure what you have on there now, but you can easily put on a plastic 9x4 or 9x5. Perhaps even a 10x4 just to get it running. A too large prop isn't any problem on diesels, they will just run cooler as the optimum compression setting is lower.
08-09-2015, 02:05 PM
#17
Join Date: Jun 2014
Location: Hudson Valley. New York. USA
Posts: 283
Likes: 0
Received 2 Likes
on
2 Posts
Hi Mr Cox - This is a used engine, via a seller another RC site.
I will definitely check the liner.
The props is a Zinger 9-6 and I believe I have a larger prop.
I'll try those tests/changes and let you know the results - thanks for the help.
I will definitely check the liner.
The props is a Zinger 9-6 and I believe I have a larger prop.
I'll try those tests/changes and let you know the results - thanks for the help.
08-09-2015, 06:45 PM
#18
Join Date: Jun 2014
Location: Hudson Valley. New York. USA
Posts: 283
Likes: 0
Received 2 Likes
on
2 Posts
Update on MVVS 2.49 D7 Diesel
Update - I disassembled the engine tonight and the 6 head screws weren't even finger-tight. So, that's a big problem solved, I hope. Another question is whether the liner was inserted correctly. Pic below and if anybody has original paperwork for the engine with assembly diagram, that would be great.
Thanks! Poughkeepsie Pete
Thanks! Poughkeepsie Pete
08-09-2015, 08:45 PM
#19
My Feedback: (1)
Update - I disassembled the engine tonight and the 6 head screws weren't even finger-tight. So, that's a big problem solved, I hope. Another question is whether the liner was inserted correctly. Pic below and if anybody has original paperwork for the engine with assembly diagram, that would be great.
Thanks! Poughkeepsie Pete
Thanks! Poughkeepsie Pete
Also it's worth checking that the piston/rod is facing the right direction. Once again the exhaust deposits on the piston top will be the clue. Also check the rod "big end" for the recess to match the crankpin.
Last edited by qazimoto; 08-10-2015 at 11:23 PM.
08-09-2015, 09:13 PM
#21
Join Date: Jun 2014
Location: Hudson Valley. New York. USA
Posts: 283
Likes: 0
Received 2 Likes
on
2 Posts
Thank you all. Nice to get a definitive and easily solvable answer. I am looking forward to checking it out tomorrow - would do it now but I have neighbors, ha.
You're right about storing the engine with loose screws, that would work nicely. Should have checked when I was having all the problem. But now I know 4 hours worth of how not to run a diesel.
Well, I certainly learned a few things here, and will let you know how it goes.
Best,
Peter
You're right about storing the engine with loose screws, that would work nicely. Should have checked when I was having all the problem. But now I know 4 hours worth of how not to run a diesel.
Well, I certainly learned a few things here, and will let you know how it goes.
Best,
Peter
08-09-2015, 11:24 PM
#23
Join Date: Jun 2008
Location: Christchurch, NEW ZEALAND
Posts: 345
Likes: 0
Received 0 Likes
on
0 Posts
Hi Pete,
Thanks for for all your recent diesel videos, I could watch Diesel engines for hours (I know, sad right?).
You seem to have things pretty well sorted out and I'm sure you've now solved the MVVS's issues. I hope you don't mind a couple of suggestions though?
Firstly the position of your propellor. Diesels start best with a really snappy flick (it can almost look like a hit),known as the diesel flick. Most people tighten the prop so that one blade is at about the 2 O'clock position when the engine is just coming on to the compression stroke. This lets you get a really good flick as you bring your hand across the top. I might be wrong but it looks like you're prop is at about 12 and you end up pushing down rather than flicking across. It seems to work fine, so don't worry if this is easier for you, but you might get better results from flicking across.
Secondly, I noticed in one of your videos you left your fuel can open for a long time while you filled the syringe tank, emptied the tank, cleaned something out of the tank, then filled it again. You would have been better to fill then cap the can to reduce the ether loss (it evaporates really quickly) Even better would be to transfer enough fuel for a days flying to a plastic squeezy bottle with a cap and use that. That way you only have to uncap your can once. Plastic bottles are no good for long term storage but are OK for a flying or running session (some might disagree). Dr Diesel sells 'Valve Spout' bottles for this. These bottles are really good and probably worth the price if you are going to be doing a bit of Dieselling.
Hey, minor things and I only mention it because I only learned when I was told by someone else.
I'm looking forward to the video of your MVVS singing.
Dave H
Thanks for for all your recent diesel videos, I could watch Diesel engines for hours (I know, sad right?).
You seem to have things pretty well sorted out and I'm sure you've now solved the MVVS's issues. I hope you don't mind a couple of suggestions though?
Firstly the position of your propellor. Diesels start best with a really snappy flick (it can almost look like a hit),known as the diesel flick. Most people tighten the prop so that one blade is at about the 2 O'clock position when the engine is just coming on to the compression stroke. This lets you get a really good flick as you bring your hand across the top. I might be wrong but it looks like you're prop is at about 12 and you end up pushing down rather than flicking across. It seems to work fine, so don't worry if this is easier for you, but you might get better results from flicking across.
Secondly, I noticed in one of your videos you left your fuel can open for a long time while you filled the syringe tank, emptied the tank, cleaned something out of the tank, then filled it again. You would have been better to fill then cap the can to reduce the ether loss (it evaporates really quickly) Even better would be to transfer enough fuel for a days flying to a plastic squeezy bottle with a cap and use that. That way you only have to uncap your can once. Plastic bottles are no good for long term storage but are OK for a flying or running session (some might disagree). Dr Diesel sells 'Valve Spout' bottles for this. These bottles are really good and probably worth the price if you are going to be doing a bit of Dieselling.
Hey, minor things and I only mention it because I only learned when I was told by someone else.
I'm looking forward to the video of your MVVS singing.
Dave H
08-10-2015, 03:05 AM
#24
Join Date: Jun 2014
Location: Hudson Valley. New York. USA
Posts: 283
Likes: 0
Received 2 Likes
on
2 Posts
Cheers!
Hi Pete,
Thanks for for all your recent diesel videos, I could watch Diesel engines for hours (I know, sad right?).
You seem to have things pretty well sorted out and I'm sure you've now solved the MVVS's issues. I hope you don't mind a couple of suggestions though?
Firstly the position of your propellor. Diesels start best with a really snappy flick (it can almost look like a hit),known as the diesel flick. Most people tighten the prop so that one blade is at about the 2 O'clock position when the engine is just coming on to the compression stroke. This lets you get a really good flick as you bring your hand across the top. I might be wrong but it looks like you're prop is at about 12 and you end up pushing down rather than flicking across. It seems to work fine, so don't worry if this is easier for you, but you might get better results from flicking across.
Secondly, I noticed in one of your videos you left your fuel can open for a long time while you filled the syringe tank, emptied the tank, cleaned something out of the tank, then filled it again. You would have been better to fill then cap the can to reduce the ether loss (it evaporates really quickly) Even better would be to transfer enough fuel for a days flying to a plastic squeezy bottle with a cap and use that. That way you only have to uncap your can once. Plastic bottles are no good for long term storage but are OK for a flying or running session (some might disagree). Dr Diesel sells 'Valve Spout' bottles for this. These bottles are really good and probably worth the price if you are going to be doing a bit of Dieselling.
Hey, minor things and I only mention it because I only learned when I was told by someone else.
I'm looking forward to the video of your MVVS singing.
Dave H
Thanks for for all your recent diesel videos, I could watch Diesel engines for hours (I know, sad right?).
You seem to have things pretty well sorted out and I'm sure you've now solved the MVVS's issues. I hope you don't mind a couple of suggestions though?
Firstly the position of your propellor. Diesels start best with a really snappy flick (it can almost look like a hit),known as the diesel flick. Most people tighten the prop so that one blade is at about the 2 O'clock position when the engine is just coming on to the compression stroke. This lets you get a really good flick as you bring your hand across the top. I might be wrong but it looks like you're prop is at about 12 and you end up pushing down rather than flicking across. It seems to work fine, so don't worry if this is easier for you, but you might get better results from flicking across.
Secondly, I noticed in one of your videos you left your fuel can open for a long time while you filled the syringe tank, emptied the tank, cleaned something out of the tank, then filled it again. You would have been better to fill then cap the can to reduce the ether loss (it evaporates really quickly) Even better would be to transfer enough fuel for a days flying to a plastic squeezy bottle with a cap and use that. That way you only have to uncap your can once. Plastic bottles are no good for long term storage but are OK for a flying or running session (some might disagree). Dr Diesel sells 'Valve Spout' bottles for this. These bottles are really good and probably worth the price if you are going to be doing a bit of Dieselling.
Hey, minor things and I only mention it because I only learned when I was told by someone else.
I'm looking forward to the video of your MVVS singing.
Dave H
I have to get one of those Valvespout bottles on order with Dr Diesel over here - Eric Clutton. He imports them and I see them in a lot of videos. I now understand how volatile the ether is in the fuel from what you say - you have to really protect it. I have the raw model diesel ingredients sitting here so I can boost the fuel I have left in that first can of Davis Diesel I am running.
You are correct about the placement of my prop - I was shooting for a down swing which I can now correct. TDC was about 11'is o'clock. All the while I was flicking the prop I was wondering what beating a frail plane would have been taking if I were trying this while it was installed in a plane rather than a test stand. I could see the landing gear squashing under the effort of starting the engine - ha.
I'm glad you watched my videos - I want to get on to showing the engines in actual airplanes actually flying! Maybe showing my early efforts will be helpful to other newbies, too.
Thanks for the share, very much appreciated.
