I am baffled. I have had my thundercat for almost 2 years. And I wouold like to think that I know it inside and out. I rebuilt the engine a few weeks ago and after a 9 month hiatus, got her back in the water. First couple of runs went great. Then, I went to start it. She started fine. Put the boat in the water and it sucked backward. I was shocked. I took a look at it. Started it again, put it back in the water and it did it again. ????

So I started it again and popped her back in the water and off she went. ????

Ran some fuel through, then ran my Miss Vegas. I went to start her again and noticed this time the exhaust was coming out of the the carb. (Shouldn't that be sucking air, I thought) I put it back in the water and it sucked backward. Did it again.

I restarted it and the same thing. I changed the prop and it still went backwards.

But it doesn't always happen. It seems the third time is always the charm. What it is going on here. I am absolutley baffled. Anu suggestions would greatly be appreciated.

what kind of starter ur using? if belt starter check the battery connection in right polarity and the direction of starter when starting it, either facing forward or backward coz it will give u different starter rotation...

I start with a Drill and the tiger drive. The drill is turning clockwise. I had been starting it the same way all day. It was the third or fourth run that it strated to reverse. Strangest thing that has ever happened to me in RC and I have absolutly no explanation other than there is so much back pressure at he exhaust that it is forcing out the carb. The boat engine stays running fine.

The engine might be kicking backwards when starting it. It's not uncommon for plane engines to do this.
Pull the plug out then crank it over ot see if it is turning the proper way.

If you are starting with the tiger drive the motor is kicking into reverse because the oneway bearing would not allow you to start the wrong way. When you rebuild the motor did you remove all the shims? Because most motors would kick into reverse when over compressed. What plug are you using? Some plugs have a longer reach which would increase the compresion. Use to keep my finger on the flywheel to check direction before throwing my boat into a race. If it's turning the wrong way you only have to touch the flywheel for it to kick back right way.

Thanks for the responses. I think it is over compressing. Should I add a couple shims to the head? I didn't realize that this could happen. It is only intermittent. Is there anything I can do to ensure that this doesn't keep happening and that it goes in the right direction every time?? It's really annoying. I didn't do any damage did I? It seems ok.

It shouldn't do any damage at all.

The best to overcome the compression on startup is to give the plug a 1/4 turn loose when starting. Once the motor runs tighten the plug and it should be fine. Otherwise ad a shim there should be a copper and a ali one. When you remove them it looks like one but is actually 2. Replace the ali one that is a 0.2mm shim. Should be fine. When the motor has a few hours running you can remove that and replace with the copper one which is 0.1mm. if it still kicks over re replace the 0.2mm.

Enjoy your motor. Watch the oil content in the fuel mix these motors like to spit its main bearing and destroy the motor.

make sure when your starting your motor ,the prop should be turnning counter clockwise.. Had that trouble with my CMB and TT motor.. I have to rever my electric starter con cables to spin counter clockwise..

and if your wondering what it is in inches the .2mm = .008" and the .1mm = .004"

Dan.

Again, thanks very much for the helpful replies. I think I am going to add a shim and sand down the shaft of my starter. I believe it is catching due to a tight fit. I am not going to hulk the glo plug down either and keep an eye on the carb to make sure it is sucking before tossing her in the water. It was only after the rebuild that this has happened. It is still so strange to me.

Did you change anything with the rebuild?

everything went back as i found it. i added a head shim and smoothed out the drill bit to keep it from catching. the problem was intermittent which is what really makes me wonder. i could see if it started in reverse every time, but this is on and off.

How much running have you got on the motor?

Be careful if using a electric drill on a tiger drive system, I learned the hard way, tore up 2 units in one weekend. If you hydrolock the drill will strip all the teeth off the gears! Trust me this happens. If you can switch to a belt, its a little more money for a belt and a starter system but it will save time and might even save a day on the water if you do not have a spare tiger drive unit in your pond box. If you use a belt system just leave the tiger drive system in place as it will not hurt anything.

Thanks for the tip. I set the chuck Clutch to keep it from forcing the tiger drive in case of fuel lock. Knock on wood, I have had the same tiger drive since day one (About a year) I have used the TD both packed with grease and fairly dry. To be honest, it is more reliable and less prone to slips without all the grease.

I took the boat out the other day and did not have many reverse starts. Maybe a couple. I still have a heck of a time with the pipe. I took it with me to Aeromarine (Hobby Stop) in Seaford and he told me to use a coke can and wrap the pipe using the aluminim as the coupler instead of the crappy silicone jobs I have been replacing. It looks a lot cleaner and heat resistant. I hope it holds. I just want to take her out and run her for 3 or 4 tanks without issues. I had a Warehouse Enforcer Man O War. It was a great boat but I like the smaller size of the TC 31 and the pep of nitro. I think i am going to put together a VS1 over the winter. My dad is all about the Miss Vegas and Lumar. I just don't like Hydros. They handle crappy and it is either full throttle or stop. Not for me. It's unfortunate because I have put more holes in the canopy than swiss cheese. I am trying to get rid of all that heat. It runs so good topless, but I like the canopy on. Even the designed over at Aeromarine said he should make me a better looking top. Any of you guys have anything cool as a lid?

http://www.rcuniverse.com/forum/m_4095782/tm.htm

Look in here lots of info. Including cooling the tune pipe.