Knocking in Tennessee

[packsfan]

I recently purchased a 1999 Vstar that I was told needed a carb rebuild to get it running. I did the rebuild and gas squirto out of the top jets into the air breather. I have gotten it running but it has a scary knock in the top end of the rear cylinder . It is a steady constant knock that seems to remain steady with acceleration. Is there a way to determine if this is a rod? Should I just kill some time and rUn it to a mechanic for a opinion? I know my way fairly well and bought it to build myself , but the noise has me hesitant to continue without opinion.

 

[weaselbeak]

Sounds like a cam. In my experience there are 3 basic knocks. A rod knock will generally disappear for a half a second while engine speed is under brisk acceleration, in other words, give it quick throttle and the knock should lighten up or go away while engine speed is climbing. It will return as the RPMs level out. A crank bearing (not likely) usually knocks loudest at low RPMs, most prominent at idle. A cam bearing just plain does it all the time. This is from my personal experience of owning a lot of old junk cars and bikes. Others may not agree.

 

[TwoManyXS1Bs]

I'll double-down with weaselbeak.

This is one of those situations where using a mechanic's stethoscope helps to add info...

 

[packsfan]

Where and what should I be listening for? Is it a major teardown to repair?

 

[TwoManyXS1Bs]

Maybe a Vstar forum would know more?

 

[packsfan]

My bad I thought this was a vstar 650 forum. That sucks, this is one of the better forums I have found on 650s

 

[weaselbeak]

Only a couple of forums can match this one.

 

[Ruger]

Most VStar have a knocking sound to the motors, it comes from the valves on top of the engine. It should sound like a ticking sound and increase when the throttle is increased and settle back down when the idle goes back down. I used to own a 2003 VStar 650 and now own a 07 VStar 1100 and both bikes have the ticking sound.

I would get a manual and check the valve clearance on the valves. They are located under oval brushed cover in the top of the heads. There are 4 total, 2 on the outside of heads and 2 on the inside of the heads. The front ones are for the exhaust and the ones on the rear are for the intake valves.

Some ticking is normal but if it is a loud knocking sound might have a mechanic check it out or adjust the valves and see how it sounds.

 

[weaselbeak]

The 650 V Stars also had a high gear whine from the trans that was a bit annoying to some, but normal and harmless.