Signs that indicate you need a valve adjustment done

I just pick up my first bike ever and it is a xj700n (1985). It runs fairly good to very good in my opinion. I change the sparkplugs, oil, and filter the other day. All spark plugs were fairly dark and I hope it is due to the very old and dirty filter. Bike starts and idle perfect at 1k after I found that idle adjustment screw under the gas tank.

While it runs good, I don't like the sound of the engine when at idle and when I trottle it, it is a bit vibrate/shake (feels like tiny missed) until it hits 2K rpm. I was just wonder if that is a sign of valve adjustment or something else. So far I'm loving this old bike. Great forum by the way....

:lol:

 

Typically, I think the idle runs at 1500 rpm I think.

But someone here will probably be able to give you better advice.

 

Idle spec varies from model to model, not sure about the 700s. It's 1200 rpm for the 550s, some others are 1100 rpm, you need to check your manual.

SIGNS YOU NEED TO AT LEAST CHECK YOUR VALVES:

The bike has more than 5000 miles on it and you are not the original owner.

You have no documentation or first-hand knowledge of the valves having been adjusted.

That's it. If you don't absolutely KNOW they've been done (and "the PO said so" is NOT knowing) then you need to at least check. It's not worth the amount of money you'd have to spend to fix a burnt valve.

SIGNS THEY NEED TO BE ADJUSTED:

You checked the clearances and some of them are tight.

 

2k? Heck I'm out of my SHORT driveway at 2k

I'm not sure about YOUR model, but the average cruising RPMs to aim for with an XJ is like 4500-5500 (give or take).

These are higher rev'ing rides than a harley or other bikes.

You make also need a full carb cleaning, syncing, etc.

Typical recommended (per posts here) idling revs are like 1100-1500 when thing else is running smoothly.

 

My 85 xj700n had a slight ticking that tipped me to check. After doing my valves I no longer hear that sound.

 

Signs that indicate you need a valve adjustment
after a run at 65 for a few minutes then stop for a redlight or something you get a miss or it just stalls, won't start till it cools off a bit

 

bigfitz52, You have a good point there. The bike does not stall or anything even after cruising over 65 for a little while and coming to a stop. However, I hear a little click/clack or tic-tic so I will consider doing it this winter. So far excellent advise so thanks.

For one who's never had a bike before, this bike really fly.... I hit 75 mph super fast. By the way, my bike had only 14K miles. Probably will not go past 75mph until new tires are in.

 

With 14K miles I would not wait on the valve adjustment. If it's never been done (quite likely) then you are right on the edge of damage time.

Keep whaling on it with a tight valve or two and you're going to have a burnt valve or two. REAL soon.

I would at least check them immediately; then you know where you're at. If you've got one dead tight that hasn't cooked yet you got lucky.

All that being said, the valve train in an XJ tightens up with wear, the opposite of what you might expect. QUIET valves are a real concern, these motors are very "busy" sounding when everything is correct. But that tightening up is why it's so important to not neglect the valve train. If it were loosening and all that it was doing was degrading performance, that would be one thing. But it's not, and once a valve stops closing fully it's doomed.