another 750 problem

[sxi4evr]

hit the start button and at first it cranks really slow then it speeds up and starts...

runs and idles great on the trailer and with the hose but once its in the water it wont start. after trying to start it in the water we pulled it out thinking maybe it had something to do with the load but it wouldnt fire.

this has happened evry time we tried riding it. :rant:

freshly built motor, everything is stock......

any ideas?

 

[Waternut]

Starter is dying or ridiculously dirty. Yank it out and clean it before you buy a new one.

 

[sxi4evr]

did that already:bigok:

 

[Waternut]

The way electric motors work is they have brushes and a commutator. The commutator is the slit copper piece, on top, in the middle. The brushes are spring loaded and should be touching the comm. If the brushes have mechanical resistance (dirt and grime) or the springs are worn or cracked (as the case was on my 750 starter) they can't put enough pressure on the comm to transfer the current properly and the starter is weak.

When electric motors have problems with brush/comm connection or they're wearing out, the motor will have a significant loss in torque. As the load decreases, either from slowing spinning up or in your case, decreased resistance being on the trailer, the starter will build up speed and give the impression that it's fine.

Take some steel wool or fine sand paper and clean all the connections up...including the positive cable bolt connection on the base. Then splash some alcohol on it and give it a whirl. If the battery is good, the engine spins easily without plugs, and that still doesn't fix it...then you need another starter.

 

[Dirtybird]

This is the same problem my buddy is having with his 550 right now. Starts fine on the trailer,put it in the water and it turns over real slow until it kills a perfectly good battery in a few tries.

 

[oren]

you have to clean you start stop plug by the electric box you have corosion by the contact
you can check you batery and starter conector

 

[BruceSki]

you have bad wires. change the positive and negative wires out to new ones or known good used ones.

you are losing the amperage through the wires. too much resistance.


either that or the starter is bad/weak

 

[Waternut]

you have to clean you start stop plug by the electric box you have corosion by the contact
you can check you batery and starter conector

Typically a start/stop switch problem produces different issues like intermitent starting. The start/stop wires carry very little current and can either switch the solenoid or they can't...there is no halfway there.

 

[sxi4evr]

the guy we got it from put b9's in it instead of b8's. replaced them with the right plugs, just got back from the lake and it runs great. but it still cranks slow at first..

 

[BruceSki]

the heat range of your plug has nothing to do with a slow starter.

the 9's are a bit colder plug. you still have a starter or wire issue if it is spinning slower than normal.

 

[sxi4evr]

i think we got it all figured out now. after running it on the hose for a while my cement driveway was black with oil so i think the guy who built the motor put a lot of oil in it anticipating that it might sit on the bench for a while (we bought the ski in pieces with the engine) this would cause the compression to be higher, right?

also, after riding for about another hour today it cranks much quicker :bigok:

 

[Waternut]

Unless it was hydrolocked with fuel/oil, one has nothing to do with the other. I coated the crap out of all my engines with oil when I put them together...no problems and no extra compression. If it ran black the whole time it was running, it sounds like the carb is super rich.

 

[sxi4evr]

hmmm well what ever it was, its fine now haha