Better Results with my MV

f41stryker · Jun 21, 2009

After rasising the strut to the near recommended height I did notice increased performance out of my MV. Still figuring out what to do as far as fuel goes, I used O'donnell 30% nitro yesterday but its still a car formula gas, not boat specific...so I need to get that situation rectified.

Okay-here is the million dollar question- Why does my MV's speed seem to vary sooooo much when I have it at full throttle? I'll throw it out there and it gets on plane, I start applying throttle more and more and the boat picks up speed and then suddenly it will slow down. Is this a tuned pipe issue? I have the stock engine/stock pipe in there right now with the stock exhaust coupler. The material seems fairly thin, last time I inspected it I didn't notice any holes but to me, it seems like the engine will get on the pipe and run good and then drop off and then pick up and then drop off. I DID remove the head shim and I'm using an OS #8 glow plug. I wish I had a digital video camera so I could film my boat and get advice on it!

I must say that I really enjoyed running the boat yesterday. It actually showed some performance and was pretty fun to run. I was actually keeping up and possibly faster than my brother's formula fasttech. Unfortunately the pond we run at has a lot of trees around it and there is quite a bit of debris in the water and not to mention turtles, so there was a tendency for leaf litter to get hung up on the rudder/strut.

byron westman · Jun 21, 2009

If it's bogging out at full throttle it might be to lean . richen it up a 1/8 turn or so .

Bill Gibson · Jun 21, 2009

Yep! It sounds like it might be just a tick lean...if its really hot where you are at, that can make things a little more sensitive.......make sure that your prop is nice and sharp, and balanced...that also can make a BIG difference in performance!

f41stryker · Jun 21, 2009

I'll double check all those things, I'm anxious to get some better fuel boat specific fuel because I think that would help out a lot, I think O'D fuel only has about 12% oil if that in it...

Bill Gibson · Jun 21, 2009

f41stryker said:
I'll double check all those things, I'm anxious to get some better fuel boat specific fuel because I think that would help out a lot, I think O'D fuel only has about 12% oil if that in it...

You will be glad when you can go to better fuel...40% or better nitro will give your boat some kick! Also a good reason to cut out the area you mentioned on your other post..The harder you make these little engines work, the hotter they get and the more cooling they need!

camaroboy383 · Jun 21, 2009

Did you call john?? Tellin ya, give him a call and he will set you up lovely.he will mix it to what your using it for.

For sure sounds like your lean.fatten it and see if its doin the same thing.

Or hate to say it but ive seen that happen when you get a high rpm bearing wobble. The bearing will start to bind when it vibrates. Typically you can see signs of this on the crank. The fit on the bearing i.d isnt very tight to the crank, it will be shiny where the inner race rides on the crank.this is the sign to watch for, shiny spot = bearing siezure at high rpm. Which for sure will do what you explained and for sure will lead to a broken rod or crank.

Alden