Scoubidou

My Feedback: (17)

I am gonna add some oil to be around 32:1 ratio, and keep the plug 'black' with all that oil

My engine is always difficult to start when cold for the first run. I flip the prop by hand 10 or 15 times without success but i soon as i use the electric starter, the engine start at the first try? Once hot, it start easy at the first or second flip. Does it mean i will always need my starter for the first run?

pe reivers

If the plug is too dark, your mixtures are set too rich. This is hardly influenced by the oil content.
First set your needles right. MVVS sets them quite rich to allow sure starts.
The low needle influences the full range, while the high needle is for the top half only.
That means, that the low needle must be adjusted first. Lean it out for max rpm, then open up 1/4 turn.
Then turn to the high needle, and find max rpm. Richen about 1/8 tyrn.
Now go back to the low needle, and check throttle response. Lean out, till response gets less, then richen up again to good response.
Finally readjust the high needle for max rpm with richest setting, maybe 50 rpm off peak.
Repeat the procedure as required to get it just right.
Now your plug insulator should show a deer brown color, or medium grey, depending on gas or oil brand. White indicates lean mixtures, black is too rich.
This is not changed by oil content, unless you enter the 1:10 range; Then the oil will darken the plug somewhat.

This works for me.
Important!! Set your standard idle throttle setting so that engine will keep running, and is switched off using the ignition.
Starting:
open the throttle to 1/3, then close the choke, and flip until the engine fires. (about 5 flips) The engine will stop again.
Close throttle to a few clicks open, open the choke slightly and start the engine. That should be in about 3 flips.
As the engine warms up, open the choke and check throttle response.

Alternative:
Choke the engine, ignition off, at 1/3 throttle, untill it is hissing wet.
Open the choke slightly, throttle few clicks open, turn on ignition, and flip.
Starting is on first or second flip.
Open the choke as the engine warms up.

Scoubidou

My Feedback: (17)

I am back to 32:1 ratio and burned 2 tanks of gas (12oz) today.

APC17x10=7400RPM
MA18x8=6900 and peak 7000RPM for 2 sec only.
temp:0 degreC

I hope this engine can swing my 18x8 prop at 7300RPM after 2 gallons or i'll be little bit disappointed. Maybe a Menz prop can help?? It sounds the MA 18x8 is too much prop without tune pipe. A 17x10 prop around 7500RPM would be better.

I removed all heavy springs on throttle and choke. I played with the idle adjustment and, PĂ© is right, the idle setting affect the top speed.
The engine is really tight and the high needle adjustment is very sensitive to get max RPM. I would say 1/32'' or 1/16'' of displacement can change by 200RPM the max speed.

Not able to start without electric starter today. After 15 flip, i used my starter. Maybe the cold temp has an impact on the MVVs like my glow engines? They are difficult to start during winter
Scou.

pe reivers

Daniel,

You either flood the engine, or are not getting enough gas in there for the first start. That is hard to tell from here.

If after about 5 flips the engine has not popped, kill the ignition, and remove the plug. If it is dry, then you know that no gas went up there. If it is too wet, the engine is flooded, and you need the starter to clear her lungs again.

I just LOVE gas engines ;-) Much like women, they need to be treated just right to achieve a friendly relationship.

pe reivers

around 7000 rpm is not bad for an in-cowl muffler and an 18x8 prop. Do not underestimate the thrust that such a large prop devellops.
Check in flight what suits you best.
See that more oil brings more rpm ?? <VBG> Engines just like to be slippery.

Scoubidou

My Feedback: (17)

I know what you mean, it takes time to understand what that engine needs to start. Patience is not really my strength and specially under 0 degree C!!

My problem is not giving not enough time to this hobby but my wife always blames me of giving all my time and cash in that hobby!!

Daniel

ricfly52

I just checked into this thread and find it very informative and interesting. I have owned my MVVS 1.60 for a year now, and have been running it in a 25% Edge 540 that weighs in at 11-3/4 lbs dry. I am using a APC 17X8 prop. Its been awhile since I checked the rpm but I believe it to be around 8300 rpm. The Edge will hang on the prop but not pull up, so I don't hover down low[8D]. (I just hate pick up sticks, ya know what I mean Vern?) All in all, this has been a good engine for the plane it is in. I competed a bit this summer in basic Imac, and had a ball with it. It will do Imac sportsman fine but I doubt that it would do well above that. That is ok because I doubt I will ever get any better than that anyway. The biggest observation that I have had with this engine is it needs a good long break in. I ran about a half a gallon through it on the bench, here in my shop, and then stuck it in the Edge. I didn't get good performance until I had about three gallons through it. That gave me plenty of time to fiddle with the needles and kinda get them figured out. Don't be afraid to adjust your needle settings. If they get all dorked up(which I did ) just return to the original starting settings and begin again. It takes a bit of fiddling before you get good at setting it up. PE Reivers suggestions for tuning are right on, so check them out. This is a good engine and I have the older one. I bet the Red head is great.

Rick

Scoubidou

My Feedback: (17)

Hi Rick
What kind of muffler do you have to get 8300RPM with 17x8 prop?
Daniel

pe reivers

The engine revs too high when propped at 8300 rpm.
Around 7000 - 7500 is best, so for vertical acceleration try an 18x7-8. The engine then is tuned between max torque and max rpm, which allows for unwinding in the air.
Imac at masters level is possible with your combo and a mvvs tuned pipe, using an 16,5x12 Bolly wich will run at about 8200 rpm with a 9mm bore carb. (Some of the old 1.60 have the 7mm carb)

ricfly52

I have a Bisson pitts stlye muffler. I was wrong with the 8300 rpm. I checked it today and I am getting 7500 rpm. Sorry for the bad info. My engine does have the 7mm carby. I am going to drill it out to 8mm when I get a round tuit. As I said it runs pretty darn well as is. I have no complaints. I did take me a bit of hair pulling to get the needles set right, but I am sure that was my inexperience with gas engines. This is a good engine. Boy it sure takes a lot of flying to put a gallon of fuel throught it.

JAYNC

My Feedback: (7)

I have the bisson pitts muffler on my plane and it gets 8100 rpm on a master airscrew 17x8 scimitar prop. I am going to an 18x8 this weekend, I expect it to be around 7500. I have the redhead version and all I can say about it is that its tricky to start the first time but after its warm it starts good.

Scoubidou

My Feedback: (17)

Hi guys!
Do you use the electric starter or your fingers to start it from cold? How many prime do you use?

Jaync, you should follow PĂ©'s recommendations about the prop. That engine developps max HP in 7000 to 7500RPM range where 16x12, 17x10 and 18x8 prop will give more thrust than your 17x8 prop for less RPM!!

Thrust HP
17x8, 8100=15lbs. If you can really get that RPM, you will turn the 18x8 around 7400 or 7500...for 16lbs of thrust!!

My results after 1 gallon
16x12, 7400=10lbs of thrust
17x10, 7500=14lbs
18x8, 7000RPM=14.5lbs
Daniel

JAYNC

My Feedback: (7)

I also wrote that I am going to an 18x8 prop this weekend

pe reivers

If your engine has the 7mm carb, but has a graphite coated piston, drill out the carb to 9mm for best power.
I had more power with that engine than with the newer redheads and the carb with choke. That is, because the choke plate restricts the airflow. Also, the fuel jet protrudes in the venturi, which it does not in the drilled out carb.
The only difference is, that the main jet mut be opened an additional 1/2 turn, and say goodby to the extremely low fuel consumption you have at the moment. Everything comes at a price; Win some, loose some.

JimRoss

I hate to ask a question that may be obvious to so many people but just exactly how do you drill out a carb throat? If the intake venturi is rounded, does drilling it out cause any bad side effects?

JimRoss

Antique

My Feedback: (4)

Hey Jim, you use a drill
I put a larger carb on yours, picked up about 400 rpm....It's on the way back, you should get it next week.....Not as strong as the G26 on the same prop....

ricfly52

As far as drilling out the carb, that is the reason I have not got a round tuit! I know I can figure out how, because I have been a mechanic for 35 years! But I am just thinking it through with a bottle of Chivas. I'll get to it in time The drilling I mean.

JimRoss

Ralph,
What kind of magic did you do with the ignition? I guess I'll see it when it gets here but I'm curious as all get out.
Oh, BTW, thanks for the expertise on drilling out the carb. I woulda never thunk of that.

Just got my hands on three more gas engines today. One Weedie and two Homies. $5.00 each.
Only thing wrong with them was they leaked gas. Awwwwwww!

JimRoss

Antique

My Feedback: (4)

No magic, The sensor I sent you had two wires crossed..Made a temporary sensor mount, timed it a 28 BTDC, it runs fine....I kept my larger carb..Try the one from your G26, it will work..
Re drilling out carbs....Some carbs have a brass fuel nozzle protruding into the venturi..You don't want to drill into it...There was an article a few years ago when Ryobi engines first became known...One of the things was drilling out the carbs, there were two types, one with the brass nozzle and the other without..The nozzle can be pressed out to drill the venturi, than pressed back in..It's easy to get aluminim chips in the small holes in the bore, so clean out the holes after drilling...Super Tech carb cleaner from Wal Mart is the only kind that still works, $.87 for a big can....
The difference between the small stock carb and a WA 125 was about 400 rpm.....
Going from a 3/8 to a 1/2 to a 716 carb on a G26 made less than 200 rpm difference..Maybe the engineers know what they're doing ?

pe reivers

Unlike the new carbs, the 7mm carbs as fitted to the MVVS have no brass main jet, but a small bore right to the gas supply. For that reason they can easily be drilled out with a sharp drill.
The drill tip should be ground for drilling brass (negative cut angle). That way the drill will not grab. The drill must not be any old one, but have sound and sharp spiral edges.

pe reivers

Daniel,

did you measure the thrust yourself, or use ThrustHP?

My realistic and not so optimistic calculation spreadsheet calculates 13.1 lbs with 18x8 at 7000 rpm.
With the mvvs pipe you will get about 7600 rpm on 18x8 Menz-S, and 8200 on 18x8 APC-N, and that calculates to 16.5lbs (15lbs on APC-N). This is in agreement with fish scale field measurements, engine hot.
A giant leap forward for a few ounces extra weight (pipe + header is 11 ounces)

Scoubidou

My Feedback: (17)

Hi PĂ©
Unfortunately, my engine stand did not have wheels to measure real thrust! My thrust calculations came from the optimist ThrustHP software. I uninstalled the engine stand to put my engine on my plane. Next test session will be in spring 2004.

Does it mean the APC 18x8-N turn 8% more RPM than Menz? If it's the case, i would have 7500RPM with my Bisson muffler. Does it make sens? [X(]
Cheers
Daniel

Charley

My Feedback: (2)

Pe,

I have an older 1.6, not broken in yet. Is it worth the $$ to convert it to the graphited piston and drill out the carb in order to take better advantage of the tuned pipe?

How much for the pipe/header and piston shipped to 78028?

Thanks,

CR

PlaneKrazee

My Feedback: (14)

Why doesn't MVVS sell them with a larger carb if there is that much performance gain? Too much performance for the design? Do you void the warranty if you make these changes?

This engine needs larger cooling fins semilar to the SM30. The new piston, in my opinion, is to prevent melt down when it gets too hot.

Charley

My Feedback: (2)

Warranty? This is my hobby, not my business. ;^)

They sell them with the larger carb and graphited piston now. MIne is older and doesn't have those things, hence my question.

I flew this engine, fully cowled, in a 120 size H9 CAP 232 with a Bisson Pitts muffler. Didn't have any overheating problems. It just wasn't enough power for the rather heavy CAP.

I came by a 1/4 Lanier Xtra 300L that's a lot lighter than the CAP was. More wing too. Thought I might try the the 1.6 in it w/tuned exhaust.

Just wondered if it was worth it to get the graphited piston.

CR