1983 VF750F interceptor engine problems

scuba14c · 01-27-2007, 2:38 PM

I bought the engine off a 1983 VF750 that someone was parting out, but I have some problems. When I bought it the seller said that coolant leaked into the crankcase. I have narowed it down to a head gasket or cracked case, but that isn't the current problem.
I tried to get the engine to turn over and start, but I don't know how to hook it up. I have the kill and start switch, but the ignition assembly was not included. I think it is the two wires next to the kill switch. Also, the battery connects to the positive wire that is clearly marked. The negative is not marked. I assumed it was the wire going under the crankcase cover and connecting to the side of the starter motor. Is that correct? I also used a voltmeter to test some of the connectors coming off the harness, and they are live. Does anyone have a clear diagram they could put up so I could see what needs to be connected to start the engine?

Thanks

GONE14S · 01-27-2007, 3:58 PM

Before you try and start it ,just turn it over and do a comp. test. This will help you with the head gasket problem. Just take a set of jump cables hook up the ground side to the motor and hit the hot wire on the starter ,it will turn over if there is nothing stoping in. Of course you jumping it from good batt. This will let you do a leak down test and comp. test.
If there is something broke in the motor this would the best way to find out....if the motor started and there was something wrong you could do more damage than it had before.

Kurt

scuba14c · 01-27-2007, 7:10 PM

I thought about that. Where is the positive terminal for the starter motor? How would I know if the gasket is bad? Would I hear something?

GONE14S · 01-27-2007, 10:05 PM

There is a thick black wire running to the front of the motor coming from the Battery relay down the right side of the motor. It goes to the starter just above the oil filter.
Pull all the plugs before you turn the motor over. If the is water in one of the clyn. it will shoot out the plug hole when you turn the motor over.
After you do that just do a comp. check on all clyn. They should be around 175-180 on each clyn. If the is 0 between two clyn. then the head gasket is blown between the two. If the is more than a 30 psi between any of the clyn. than you might have a valve or ring problem.

Kurt

scuba14c · 01-28-2007, 1:25 PM

I tried to turn the starter motor over by connecting it directly. It sounded like the motor turned over, but the pistons didn't move. I did a quick test and there wasn't any oil in it, should I dump some in to see if that helps, or is the engine seized?

GONE14S · 01-28-2007, 9:36 PM

Pull the stator cover off. There's a bolt right in the middle of the rotor. Put a socket and wratch on it. Turn the motor if you can. If not turn it the other way. If the motor only goes so far one way and than the other you may have a broken rod.

Kurt

scuba14c · 01-28-2007, 10:08 PM

Where is the stator cover? Is it the aluminum housing over the alternator?

GONE14S · 01-28-2007, 11:20 PM

The cover on the left side of the motor. Sort of big and round, just in front on the shifter lever.

scuba14c · 01-29-2007, 7:08 PM

Ok, I pulled the cover off and the engine turned over manually very well. Then I direct connected the starter again but it wouldn't turn over. I took the right side cover off and looked at it when the motor was engaged. the starter motor was spinningthe worng way. I reversed the polarity and it turned over with the starter perfectly. Is it supposed to be hooked up this way (circled in pictures)? Am I not connecting something, or connecting it wrong?

The files are to large to attach. I will edit with a link soon.

Edit: There should be 4 pictures with red circles around the connections and a breif explanation.

Engine pictures from motorcycles photos on webshots

GONE14S · 01-29-2007, 9:52 PM

The starter clutch will spin freeliy in one direction.it's supposed to.
It should turn the motor over in the other direction. If the starter motor spins by it's self with the starter clutch gear than you are spining the starter motor the wrong way. Rev. it and it works. You just had it hooked up wrong.
Just a question: Do you have any body that might have some mech. exp. on bikes that can help you out a bit??

Kurt

scuba14c · 01-29-2007, 10:17 PM

I'm working with a friend who has worked on small engines. The problem is that someone semms to have messed with the engine before I got to it. Is there something in the crankcase (spring) that would make the starter engage the motor the other way? I had to reverse the polarities from what I thought it would be to get it to turn over with the starter motor. Because of that I'm just wondering if the previous owner tried to fix the engine and reassembled it the wrong way.