Super Jet couple of questions

[alberta guy]

So from looking around with the search button. (yes i did use it) lol. I see everyone is saying that the stock motor compression should be 150 150 psi. But both of mine are dead even at 130 according to my compression tester. Should I be worried about this? It winter so i do have time for a rebuild yet. Also the aftermarket bilage pump is just flopping around how do i mount it down? I was thinking of using slicone and just sticking it to the hull so if need be I could still get it off. It has holes for screws but there is no where to mount it.

 

[Matt_E]

There are a few factors to this:
1. Are you at sea level? 150psi is only at sea level
2. Is your battery and starting system good enough to spin the engine fast and strong? If it cranks slowly, compression will seem to be lower
3. Your gauge is probably borked.

As long as they're even and consistent, I would not sweat it.

 

[TheBuzzard]

your guage could be wrong or higher elevation equals a lower reading. 130 aint bad, but it aint good either. there is supposed to be a little stainless steel bracket that holds the bilge filter in place and it screws to the bulkhead with 1 screw.

 

[alberta guy]

Im at 2250 feet. It was a brand new gauge just took it out of the package.

 

[Matt_E]

There you go. Altitude counts for some of it, maybe a weak starter and some age.

 

[alberta guy]

Just had my nerd moment and some searching with google. Found some charts with some mumbers and came to the conclusion that at my elevation my motor should be around 140+- 1psi so that means my motors ok then????

edit:

Just also realized its winter and the air temp was right around freezing so the air is also a little bit thinner.

 

[Matt_E]

Cold air is "thicker"

 

[wanderer1]

I test compression when cyclometer is warm. Everyone does it different I suppose

 

[munki63]

run your motor for about 30 seconds then do a compression test, If you havent fired the motors for a while and are just doing a test your numbers will also be low, but dont just pour oil in the cylinders because then you will get a false reading thats too high

 

[jnutz]

good charge on the battery, and not all compression gauges read the same..


but you could get a season outta that compression you have now

 

[Proformance1]

Gauges are only good for ref. Forget it even has numbers if they are both in the same spot your fine, it they are different bad. simple as that. I have one gauge that reads 135 and another that reads 190. Neither are correct. Secret is to check the motor, write down the number and save it in case you think you have an issue, then you can reference the past number. That is what a gauge is for.