84' VF500F Engine trouble

My 84 vf500f has a bad knocking sound and i think it is in the front half of the motor and it does not run on the front 2 cylinders but i have spark up there can anybody help me?

 

Is it a bad knocking sound or a ticking? I wouldn't run it much more until you know.

 

The description you give is a little vague, but it concerns me that you may have dropped a valve. I hate to jump to such an extreme conclusion, but that's VERY common for the 500's. Run a compression test on the affected cylinder(s) and let us know what the results are.

 

The pistons are moving and siting on the bike the left front plug is wet the left rear plug looks like it got really hot and the right side plugs look like the are fine.... I pulled the to front plug wires off of the coil and it ran the same as when the were pluged in and the bike will not fire if the back plugs are disconected even if i use starting fluid in the front with the plug wires hooked up.... I dont have the tools to check the valves but the cam chain is moving fine from what i can see....

 

knocking sound

That sound means trouble. My vf500f did the same thing when I bought i last year paid 300 for it and I knew there was a big problem with the engine but did not find out untill I tore the motor down that is was the connecting rod bearing R front that went .When i tried to get it runnng I rapped loud I thought it was a rod. When I split the case the right f piston rod was loose and I could move it with my finger As a result the crank is now all scored and toast BUT all is not lost. I got 1 20$ crank on ebay that is in tolerance just need to get diffrent size bearings as this crank was a diffrent color code than the OE and most of the engine parts still can be found Bike Bandit has a lots of OEM parts for the baby ceptor including pistons bearings gaskets. The only thing that I could not find was a new cam shaft set mine are a little pitted

This little motor is pretty complicated but it can be repaired just takes a little time..


Mike

 

Good luck with those bearings! Word on the street is that they are drying up quickly. Do not be surprised if you can't get certain colors anymore.