Worn johnson V4 1990 90HP.

[generalleeuk]

Hi all, thanks for having a look.
I have a xflow 1990 90hp V4, running on 50:1 premix. The bores/pistons are worn and if you crank the engine over cold you can hear 1 of the pistons slapping loudly. I have removed the exaust cover plate and the left hand cylinder head and you can press/move the pistons sideways! I first heard this sound last year and I have reassembled the engine and put about 30 hours on since, she was ( 50 hours ago ) doing 95 psi per cylinder with 1 psi variation between cylinders when cold. When she runs cold shes a bit clattery on start up, but when warm pulls well is responsive and sounds sweet as a not!
The questions I have are; Are these V4's worth reboring ect be about ?650 to do it my self, or should I run her till she blows, or sell her on and be honest to the buyer (I would be up front about whats wrong)?

I do like the engine, its been very good in the 3 seasons I have had her. Quite trouble free and has loads of power and torque.

Thanks in advance for any input!

 

[MAW31]

Re: Worn johnson V4 1990 90HP.

IMO, if the rest of the motor has been well cared for, its well worth it to get a fresh rebuilt head...then you KNOW is as good as it gets.

You didnt mention a recent psi and I imagine it might reveal some excessive wear since you did mention piston slapping a year ago with continued use.

The bigger problem about running a motor while its slapping is that it'll wear the cylinder bore heavily and unevenly, and a simple 010 over rebore may not be enough to bring the bore in tolerance.

current psi numbers would be a great help.

 

[generalleeuk]

Re: Worn johnson V4 1990 90HP.

Can do that at the weekend, will post the results.

 

[James R]

Re: Worn johnson V4 1990 90HP.

These motors are quite resilient. The main concern in your rebuild would be the crankshaft and bearings. if the crankshaft is good then replacing bearings and seals, plus gaskets, will add to the cost. If the crank shaft is shot then it is a parts motor. .030 over sounds a better option on re-boring. If you do rebuild then don't skimp.