bigcam406

ran my Proboat Fastech nitro the last 2 nights,first night,ran good,went threw 3 tanks,and on the 3rd tank it died.finally got it in(thanks to a kayaker),found lots of water inside.outlet line was cracked at the fitting.fixed it.yesterday,i blew compressed air threw the outlet on the boat to see if it was leaking anywhere else.found that it was leaking around the cooling head.removed it,checked all the o rings,everything was where they were supposed to be.checked all lines and fittings.all good.took it out again last night,ran for approx. 3 minutes,then died.brought it in,hull full of water again.im stumped.i don't want to run it again,as the engine has already been exposed to water 2 nights in a row.threw some after run oil in cylinder and wd40 in the carb and spun it with the starter for approx. 40 seconds to get rid of the water that it ingested.anyone have any hints as to what would be causing it to leak so bad?i have another dynamite .15 marine,was thinking of swapping heads.any help would be appreciated,as the next week,weather is supposed to be perfect,and I want to put some running time on this boat before the fall.thanks.

amax

Check to make sure the Square Edge of the O-ring groove didn't Cut some of the O-ring off when they installed it. You can use a little RTV Silicone to insure it seals. But if it leaks a little it won't Kill the engine. You will learn How to deal with a Dunked Boat before long,,, It WILL Happen. You did the right thing to a point by using ARO and\or WD-40 for the initial flush but ALWAYS start the engine after flushing and allow it
to get to operating temp to insure All Moisture is evacuated from the Crankcase.

bigcam406

yes,im going to run the engine dry today to put some heat into it and get rid of the moisture.as far the amount of water,there was a lot in the hull.im thinking with all that is going on while it running caused it the water to flood the carb and stall it.the boat ran very well when it did run,and I wasn't really pushing it at all,still breaking it in with rich settings on the carb.when I took the head off,there was water in the cylinder,so it went through the carb.i'll keep you updated,as im going to try the silicone method you mentioned first.thanks for your help

bigcam406

replaced the head from my spare .15 Dynamite.shot some compressed air through the inlet off the rudder.leak is gone now.must of been the o-ring on the original head.thanks for everyones help.

bigcam406

took the boat out last night for the first time since I replaced the head.weather up here has been very hot and humid,and Lake Ontario was like glass(which doesn't happen too often).anyways,with the humidity around 90% and temps in the 30c range,this boat didn't want to start.went through 2 starter batteries,finally got it going.ran very well,water was exiting the outlet on the boat like its supposed to.was taking a vid with a Ipad,but unfortunately it didn't turn out too good as it was too dark by the time I got the boat going.i also found that there was still a small amount of water in the hull,but im assuming its from the stuffing tube.any tips on tuning for heat and humidity,as its going to last through the long weekend,and im going to be running the boat as much as possible while this hot spell lasts.

amax

You may still be a bit rich. Also if you're using ARO Properly you need to Flush the oil out First by Flooding the block (hold your finger over the carb and spin the engine) then remove the glow plug, Invert the boat, and spin the engine over until a majority of the Oil\Fuel blow out.
If you have the Fuel Mixture lean enough you should have a Head Temp at the glow plug around 180*F OR be able to only hold your finger on the head for about 3 seconds.
Make sure you have a Good HOT glow plug Igniter.
Try a Hotter Plug for the higher humidity.
Make sure you Prime the Carb by holding your finger over it and spinning the engine until fuel comes up the fuel line and reaches the carb (but don't flood it).
Have you removed any Head Shims Yet?

bigcam406

I flushed out all the ARO and WD40 before I went down there.took out the glow plug,used the starter and there was still a little in the motor .i installed a new plug(mc59),and filled it up.i left it a tad rich because its still relatively new and not fully broken in.for priming the carb,i just put my finger over the exhaust and watch the fuel line until the fuel reaches the carb.the glow plug driver was fully charged and I have never had any problems with it.i havnt removed any shims yet because im waiting to run a few more tanks through it.once I got it going,i let it warm up for a few minutes on shore.it idled fine,couple blips of the throttle showed me that it was still a tad rich,but that's what I wanted.threw it in the water and it ran flawless,for approx. 8 minutes varying the throttle,with a few full throttle spurts.i did notice that when I brought it back in,i touched the head and it was warm,but not hot.is there a hotter plug that I can use other than a mc59?i know once I start leaning it out more,it will run hotter,but in the meantime when breaking it in more,and should I remove a shim,as it has had 5 tanks run through it already.

amax

Until you get it Broke in it's going to be Hit and Miss with the Starting and Tunning. Sounds like your on the right track. Just keep working the needle Leaner bit by bit and it will start coming to life, especially when you get a head shim out.
What Fuel are you running?

bigcam406

i took it out yesterday,ran 1 shim.lake was rougher than usual.unfortunately,it got tossed upside down.after retreiving it,i drained all the water out,checked the motor,no water ingestion.fired right back up to my surprise.receiver now screwed,so i had to call it a day.fuel is Byron gen 2 20%.

amax

Which one do you have?

RACE 1600 Gen2 and RACE 2000 Gen2 are blended with 12% total lubrication while RACE 2500 Gen2 and RACE 3000 Gen2 are blended with an 11% total oil content. RACE 1600 Gen2 (16% nitro) and RACE 2500 Gen2 (25% nitro) are specifically designed for international competitions which limit the nitro percentages of 1/10 and 1/8 scale cars.

Go to your local auto parts store and get some Dielectric Grease and fill the next Rx Full of it then plug your wires in. It will save it next time.

bigcam406

fuel is Gen 2 2000 25% nitro,12% oil,that is what is on the label.is it wise to run it without a shim?

amax

That Oil content may be a bit Low for a Newbie especially for Break In (no Offense Meant) Most the Marine Fuels are 30% Nitro or Higher and 16% to 20%+ Oil.You might want to order some Klotz Super Techniplate and add it to your fuel.

Yes it is Good to remove at least 1 shim after break in to Lower the Squish Clearance around the outer edge of the piston. This does a couple things:
1: it increases the Compression Ratio = More Torque, Quicker Acceleration, Increases the Burn Rate of the Fuel, Advances Ignition Timing.
2: A Tighter Squish Band increases the Velocity the fuel around the Outer Edge of the Chamber is Forced into the Center of the Chamber= More Turbulence in the Chamber= Better Atomization and Emulsification of the Air\Fuel Mixture in the Chamber= Higher % of Fuel getting Burnt.
3: The Squish Band Also Keeps a little of the Fuel Mixture Unburnt around the Piston Edge to Lubricate the Piston\Cylinder contact area, When the Squish is Set Correctly it will prevent the Combustion Flame from reaching into that Tight "Squished" Area. Ideally on a .15ci to .18ci engine your Squish Clearance will be down to .004".

bigcam406

so,the basic physics of having a tight piston to chamber clearance apply to a small nitro motor as well.the reason why I mention this is because I have built quite a few small block Chevrolet's over the years for drag racing and performance use,and piston to head clearance(squish) is very vital in producing good power,especially when higher compression ratio's are being used.im going to run whats left of the fuel,as I still have approx. half of a gallon left,and with fall around the corner,theres no sense in going and buying another gallon,when it will be sitting all winter.as far as the additive you mentioned,how is it mixed,and is it widely available? also,will I have to adjust the mixture any different than running without it?im assuming running with it i'll have to run a tad leaner.thanks for all your tips BTW,you've been a great help.

amax

Yes the Basics are the same but with These 2 stroke engines you have the added need for Lubrication partially because it's a 2 stroke but also because we have No Rings. The unburnt oil completes the Piston to Cylinder Seal. The reason the shims are there is to Drop CR during Break IN.

KLOTZ is one of the leading Brands of oil for our applications, Not sure if it's readily available in Canada but I'm sure they will ship it there just Google KLOTZ Oil.

Yes you will need to re adjust the fuel mixture. You will have to adjust it every time you pull it off the shelf to run. Water Temp, Air Temp, Humidity, Barometric Pressure, Altitude, ALL Play a Critical Role in tuning a Nitro Engine. Think of it as your Hottest Drag Engine and how often do you Tweak It? If you do the math our Little engines run Close to the same HP to CI ratio as a Funny Car or Top Fuel Dragster.

bigcam406

im running 1 shim because im comparing it to a head gasket.i dont know how much cylinder pressure these little engines produce,so i dont want to take any chances with running without one.also,im not confident the head is machined perfectly to seal properly during the combustion process.do you have any thoughts on this?also,im aware that temp,humidity,barometric pressure,air density etc.have alot to do with tuning.i was just wondering if there was a quick fix for tuning with that additive involved.

amax

Sorry for the slow reply my comp has been down.

Tuning will be basically the same process, but will be a different setting. as far as the machining quality the Dynamites engines are pretty good. You can use valve grinding compound to Lap the head and sleeve together if you fell the need. You can use Gage Tape to check Clearance or a Dial Indicator or Depth Gage if you have access to such tools.
The most common area you need to seal is the sleeve to block fit, I put a Fine Bead of silicone under the lip of the sleeve when installing it.

bigcam406

no problem about the delay.i havnt run it since i flipped it.installed new receiver,have to swap servos.havnt had time(ball playoffs,work etc.),plus the weather hasnt been cooperating.this week is doable,so im aiming to run it sometime this week.im going to use some valve compound to lap the head and sleeve as you suggested.if it looks good,then i'll run it without a shim.i know it'll be performing better as we are in the middle of a nice stretch of weather with low humidity and cool temps(60-65 degrees) all week,so i better find time before its too late.thanks again for your tips as well.

amax

Just Don't Lap it To Much and make sure you Flush the engine out good after you lap the head to make sure there is NO Grit left inside, and check head\Squish clearance it should be .003" to .005"in. (approx. the thickness of a sheet of paper). If the engine is fully Broke In, With the Plug Out if it doesn't turn over with just a little resistance at TDC it's to tight. After removing the shim it will need a short break in also, about a tank or two with Short Spurts of full throttle at Max Temp.