hibby

[img][/img] sorry trying to get picture posted.

PEERPSI

Why do you have the rudders tilted? The carb settings seem a little off to me. I would expect around 1 5/8 or greater on the L and around 1 on the high. This might explain why it seems to bog for you on glass surface. 8mm on the allen key sounds good, neutral or maybe 1 degree negative. Did WHH give you any guidance on the carb settins with the M5?

I found with my stock engine it performed great with the Zenoah factory settings of 1 5/8 and 1. With the CC promod I'm at 1 7/8 L and 15/16 H.

Are you measuring from the cylinder head on the pipe measurement? If so you may not be far enough out. See attached guidance from BH Hanson I believe.

hibby

I have the rudders tilted alittle to help lift the bow and it does help. I have the 644 carb not the 257 and there is 3 of us that are running the same carb but took the choke out and we all are close to the same on our needle settings. Back in april in the cooler weather we were running our high speed needles at 2-2 1/8 the m-5 couldn't get enough gas. I have tried leaning out the needles during the summer and it hasn't worked. Whh didn't give any carb settings with the m-5. Yes my 12 3/4 measurements are from the cylinder head to the center of pipe and I don't have much pipe to pull out or I will be past the 2nd o ring.

PEERPSI

I had the 644 on my stock Zenoah as well. The difference between the two is the absence of choke plate and air purge bulb on the 257 otherwise the same so needle settings should be similar. If you are too lean on the low your RPM's won't go high enough for the H setting to make much difference. 2 Strokes charge up the crank case with fuel as they run. If you are too low on the L needle that depletes and you find your engine bogging.

When I got the CC pro mod it had been set up in a rigger, much lighter boat. The settings were very near the stock settings. The first time I ran it would bog badly. Turned the needles out to CC's recommended settings of 2 and 1 and all was good.

Now an engine is esentially a heat pump. The heat of the expanding gases puts pressure on the piston causing a pumping motion. If you think about it in order to have more force you need to create more heat therefore you need more fuel. So a modified engine should at it's least need the same settings as a stock engine if not more. I'd expect the factory settings are a tad rich for preservation. My point being if 1 5/8 L is needed for a stock engine how can less work with a modded engine?

You're right about the pipe now that I think about it. The header pipe length was the limiting factor on mine as well. That said I was able to get 13 5/16" out of mine, just measured it. That gave me a top RPM of 16360 and speed of 49.25 MPH. If you use a pipe stop it just needs to be on the pipe with maybe and 1/8� to spare. The pipe stop will keep it from moving around and leaking.

Why do you want to lift the bow? That would lead to blow overs in my mind. Keep her flat and let the prop lift here up.

Dockman

Dropped my strut and went with a negative like PEERPSI runs and the boat jumps right up on the water and runs loose. Did not do any gps runs this weekend cause it's not my motor and only had it in for the weekend. Should have my new pipe and motor this week. I'am going to put my clutch back in the boat, it's just so much easier to deal with.

Dockman

I know a guy who claims to have run 52 - 54 mph with an m5 in a BJ55. He said he run the ferule flush with the bottom of the boat not sure what pipe he used.

Dockman

If I set my low needle out more then 1 1/8 turn if will not even stay running. My settings are 7/8 - 1 on L and 1 1/2 on H . (This with stock motor)

PEERPSI

I think that's way too lean on the low. Next time try the factory stock settings of 1 5/8 L and 1 H.

So the boat loosened up for you good stuff.

Dockman

That's not the factory setting.

Dockman

Here is a link for mt carb settings. Yes the boat loosened up nicely.
http://www.proboatmodels.com/ProdInf...ine_Manual.pdf

hibby

My boat wouldn't start if I had my L-1 5/8. 1 1/4 maybe.

PEERPSI

Those settings are for the 260PU which is an aircraft engine. See chart below.

PEERPSI

Those settings are for the 260PU which is an aircraft engine. See chart below.

dicko

Your starting point settings will depend on the carb you run, each type of carb has a different needle setting to start from. Here's a link to the baseline settings for each carb.

http://bonzisports.com/carbs.html

If you have swapped the carb out on your engine to a different type of carb, you will need to set the needles up for that specific carb, then fine tune to the engine/pipe/hull/prop/altitude you are running.

PEERPSI

My point is the carb settings after installing a mod cylinder intending to make more power can't possibly be less then stock. An engine will only make more power by burning more fuel, not less.

Also any carb setting chart I've seen always has the L higher then the H. If you look at the chart I posted they are about even for the lower rpm lighter load aircraft and then the L starts to go higher then the H as the load increases first marine engine and then helicopter being the highest.

Back in my sports car days when we built up for power the injectors were selected for the HP you were attempting to create. Always more flow for my power, never less.

Dockman

Neither will mine.

PEERPSI

Try adjusting your base idle open more, screw if you still use it or throttle trim if you've ditched the screw.

Dockman

Can't screw the idle screw in far enough without clutch so I use the gun and have it turned up to 50+ and then turn it back down alittle after take off. With the clutch I can use idle screw but no way will it start at 1 1/2 turns out and will not idle very well at 1 1/4 out. My runs at it's best 7/8 out but I try to run it at 1.