seadoo 720 gs 1999 is the compression low

[daz20vt]

hi guys can you tell me what my 720 gs 1999 model compression should be when its cold ,its showing 160 psi or 11 bar is this low ? it wont start in water only if i tilt the ski so the exhaust is out of the water, takes about 10 seconds to start when it cuts out, as soon as the exhaust goes into the water it cuts the engine out but it will run on the drive with the hose pipe no problem, has had full engine rebuild inc pistons and crankshaft but as the barrells looked good and no scores I put standard size pistons back in, may be i should of gone 1 oversize with the pistons or has anybody else had the same problem please help guys

 

[kustomkarl]

The compression ideally should be 150 psi per cylinder.Is the battery full charged and in good shape. If the battery has a bad cell it won't have enough power to crank the engine under load in the water. Have the battery load tested at like Auto Zone and check the wire connections also so it is getting a good connection.
Let us know if this helps.

Karl

 

[daz20vt]

seadoo 720 gs

hi mate good battery and all connectins are good also replaced rectifier but still no different will crank over all day in the water but wont start, getting good spark regards daz

 

[timmyboy76]

Check the volts at battery before running and running (on hose), 14.5 while running. also, wonder if timing on RV is right?

 

[daz20vt]

showing 14 .5 volts running and on hose, once i get it started by tipping it over ,it runs fine at mid range and high range but takes a while to build up to the range low range poor wont tick over in the water but will on the hose, done the timing by the seadoo manual, would this be the sympton if the timing was out ?

 

[timmyboy76]

motor was rebuilt, what about carbs? here's your specs......1999 GS 717 BN-40I-38 MAIN-167.5 PILOT-75 2.0n/s 36 - 40psi LOW- 1 HIGH- 0 ACCELERATOR PUMP.

 

[daz20vt]

hi yes carb was done at the same time full kit installed regards daz