DarZeelon

OK, Asmund.

Then we'll have to find out what is so grossly out of adjustment.

asmund

yes that would be great. It can be as simple as I`ve been running it with to short a distance between the pipe and header. I`ll try to find out tomorrow as I now have increased the gap to 30mm. I just dug out my old rossi black tuned pipe to give it a try as well (just to see how high I can get it to run). But for 3-d applications that would not be the best as I recall, because the engine will go on and off the pipe as the trottle is beeing active used

asmund

well I just ran my 49 and it was no way I could get past 11200 on the 12-4. I tried every length within the silicone coupler with no luck at all.when I decreased the length the rpm dropped to about 9000. So much for this mount and fly minipipe[:'(].seems I have to use a much longer silicone coupler or some other tubing to try even more length. Am I the only one who has to go through all this to use 12-4 and 12.25 prop on this mvvs 49???

DarZeelon

Asmund,


Please check these:

Remove the header from the engine and look into the exhaust port;

a. Is the sleeve's exhaust port centered in the cylinder casing exhaust port (the top of the sleeve port is wider?
b. Is the sleeve's boost port center centered in the cylinder casing bypass?
c. Does your engine's 8 mm carburettor open fully, when the throttle arm is moved fully forward?

Please send photos and I will ask the moderators to move this thread into the MVVS support forum.

A particularly weak engine will give 100-200 RPM less then its stronger sibling; not 2,600 RPM less.
Problems with specific engines are solved within the support fora.

asmund

eureka!!!! I just had a long hard talk to my mvvs dealer, and he had found out that mvvs by mistake had put in a conrod from the 45 engine in the 49 engines, so compression is to low. that explains the tirst for nitro.he is going to send me a new set up and the right conrod then we`ll see if this engine can deliver the goods. I was at the point of returning the whole frustrating piece of ....metal, but now my faith is renewed.A little sloppy of mvvs to do this kind of mistake though, but it shows that also the best can fail.

Ernie Misner

You might need a whole new top end if it was already broken in with the piston not reaching full height in the cylinder.

Ernie

asmund

ernie, what do you mean by top end? . I`m getting new setup, as in sleeve, piston and conrod, so it should be ready for a new break in.

Ernie Misner

You will be all set up properly then Asmund. I just wanted to make sure you weren't getting a new con rod only. Keep us posted,

Ernie

asmund

Thanks,I will get back to this. will be 3-4 days before my parts arive,so by the weekend I guess I will have some better rpm readings to report

Ernie Misner

Now you can change it to rear exhaust if you want!

Ernie

asmund

well I got my new parts today and installed them. On inspection it appeared that not only the con rod was different but also the piston it self on my new set-up was higher/longer than the one I pulled from my engine.the new con rod was slimmer and longer too.So it will be most interesting to fire up the engine and run it in again to see if it will produse some power this time, if not I will return the whole thing and look for something else.

Gizmo-RCU

My Feedback: (27)

Send me the parts and I'll send you the Magnum. Seriously I am glad you are working thru it. Keep us posted.
Good Luck.

asmund

well it now tachs 13500 on the apc 12-4 and 13100 on the 12.25-3.75 and I expect these numbers to increase a couple of hundred rpm after a gallon or two. I have not tried different lenghts between the header and pipe yet. On the 12.25 it will go back to peak rpm from idle without adjusting the needle, but on the 12-4 I have to richen the needle then lean it out again to achieve peak rpm after idling, so this means I will have to increase the gap between pipe and header then?? I`m really looking forward to flying the engine this weekend

DarZeelon

Yes, Asmund.

Increase the length by 6 mm each time, until the response is immediate, or even hesitant, but does not require changing the fuel setting. Look carefully at the low-speed needle, to make sure it is not creeping out at full throttle.

It will improve if it hesitates. Try leaning the low-speed needle, a 'click' at a time.

rcpileit-RCU

Dar,

I have mixed a quart of fuel by adding 100ML of castor to FAI Omega to get the total oil content to 25%. I have run maybe 2 to 3 ounces of this through my .49 (my engine is one of the green head ones) with the best rich(??) 2 cycle rpms of 11,700 with an APC 11 x 6 prop. The silencer system I am stuck with is the 3250 muffled pipe and header with the pressure tap in the header. I have maybe 50 to 60mm air space between the header and the pipe at the present. The engine appears to me to be getting awful hot along with the exhaust system. I did notice that upon looking directly down upon the carb that the needles were not perpendicular to the shaft - hence I discovered the carb mounting nut was loose and tightened. The next run after this revelation, the pressure tap on the header pipe came loose. Upon inspection it appears it had been brazed in place? I am not sure. Could excessive heat have caused this to come loose? I am in the process of trying to repair with JB Weld.

Am I doing something major wrong here?


George

RcPileit

DarZeelon

George,


The #3250 tuned pipe is the wrong exhaust system for your engine.

It has too large a volume and is optimized to peak the engine round 11,000 RPM...


You want 13-14,000 RPM with the .40-.49 engines...


None of the headers MVVS supply with their .40-.49 exhausts have a pressure fitting!

The #3248, #3246, #3245 and #3245A silencers have the pressure fitting on the muffler itself, either as a bolt-in, or argon welded (#3248, #3246).
The larger .61-.91 exhausts, on the other hand, have the pressure nipple argon welded to the header...

Since you have the .61-.91 tuned pipe and the larger headers don't fit the smaller engines, you got some kind of a 'mish-mash' on your hands. I don't know who brazed/welded/glued that pressure fitting on your header, but it sure wasn't MVVS...

rcpileit-RCU

Good Morning Dar,

Again, I thank you for all your information. I think I now know why we no longer have a MVVS distributor in the USA! I received my engine as part of a kit (Morris The Knife) combo maybe 3 or 4 years ago offered by Morri_ Hobbie_. When I received the #3250 pipe I emailed and inquired if this was a mistake in shipping. I was told that it was a !QUOT!replacement!QUOT! to make up for being out of stock on the #3248, and that this was a !QUOT!great!QUOT! set-up for the Knife. Just from a mounting aspect, I knew better. I even tried to order a #3248 at a later date sometime in 2004 from their website. I got an order conformation notice via email and a follow-up notice that the item was on backorder - I have heard nothing from them since!![:@][:@][:@][:@][>:][>:][&o][&o][&o]

Okay, the rant is over!

I am in the process of letting the JB Weld cure for a day or so from my repair previously mentioned and I have fabricated a mousse can muffler. I will make a go of this or contact MVVS Canada and obtain the correct header and a #3248 pipe and try again.

Thanks again Dar!

I may be back with more questions later.

George

rcpileit-RCU

Thanks Dar,

I will have to see what my next plan of action is.


George