How much Cyl Head PSI should I have

[Bilito]

On the original Baja Doodle Bug DB-30, 97cc motor: Two questions,
What should the psi on a compression test read ? I have 85 psi (wet} and 65 psi (dry)
How much horse power does that little 97cc engine develope?

 

[Colemanman]

On the original Baja Doodle Bug DB-30, 97cc motor: Two questions,
What should the psi on a compression test read ? I have 85 psi (wet} and 65 psi (dry)
How much horse power does that little 97cc engine develope?

It should be a 3 or 3.5hp engine. I dont know the psi specs for your specific engine but the predator 212 usally has a round 110 to 120. Is your motor burning any oil at all?

 

[Bilito]

It should be a 3 or 3.5hp engine. I dont know the psi specs for your specific engine but the predator 212 usally has a round 110 to 120. Is your motor burning any oil at all?

No the motor is not burning any oil

 

[Colemanman]

No the motor is not burning any

Thats good. These motors also have a compression release when their not running to make them easier to pull start. That could be a reason why your reading is low.

 

[Bilito]

How do I check for a compression release????

 

[Strigoi]

How do I check for a compression release????

Open the engine up and see if there's one on the cam. I've never messed around with those engines so I can't say if they have one.

This isn't for your engine, but you can see the compression release setup on the cam in the pic: https://www.gopowersports.com/hot265-camshaft-for-212cc-hemi-predator-196cc-clone-gx200/

 

[Colemanman]

Compression release mechanism is on the camshaft. It cracks open the exhaust valve on the compression stroke to make pull starting easier. It operates with centrifugal force and will deactivate when the motor is running at a high enough rpm. Im not to knowledgeable on the subject so thags my understanding of it.

 

[SAS289]

How do I check for a compression release????

If you want to check compression without the compression release take the rocker cover off and add lash to the exhaust valve. Once you add enough lash the exhaust valve will not open during the compression stroke and you could get a full compression reading.

For example if your current lash is set to .005" change it to .025" then check compression. If that is not enough add more until you get a full compression reading. After you are done you will need to set lash back to correct settings with the piston sitting at TDC.

And when you check compression make sure the choke is open and hold the throttle wide open.