what is a "normal" idle rpm? (xj750 '82)

Here is what Im seeing:
Cold Idle: 1.4k
Warm Idle (10-20 minutes in city): 2k
Hot (??) Idle (20 minutes highway speeds): 3k

Is this the norm? what's common for you folks?

I've been trying to learn the bikes nuances such as normal RPM ranges.
3k seems high to my untrained 'eye'. Can anyone enlighten me?

This has been at air temperatures ranging from 60-90 F.

 

Your cold idle is ok 1000-1400 is the answer I got when I asked.

Warm and hot should be about the same.

I have the same hot idle problem.

I have not tried to fix it yet.

Have you cleaned, clunk tested and sync carbs as described HERE? adjusted valve shims? Lubed throttle cables? Etc...

If you bought recently, you probably need to do all of that and more for excellent running engine.

 

Hanging/high idle is usually a simple sync issue IF everything else is OK.

However, you are correct in that there are a number of steps that need to be taken to eliminate all of the other causes BEFORE attempting a running vacuum sync. You won't get a decent sync with dirty carbs or out-of spec valves.

 

normal idle is around 1100 for most bikes.

full choke and they usually climb to 2500 or better. (when cold)

 

I have not done much maintenance yet as Im new to this and not sure where to start/what is going to keep me off the road. With the weather turning cold here in Florida, I may just start working on them.

I have a speedo problem at speeds above 40 (apparently) and I think i hear a rattle at rpms around 4.5k-5k (assuming its the howling speedo problem.
Since I have to open the cluster I figure I will be down for a little while and will lube cable etc.

Im no mechanic, so syncing, clunk test, shims, et al is like a foreign language to me. This site has been wonderful with information and I have spent countless hours digging around trying to understand as much as possible.
Thanks for the responses. I enjoy getting to know my new (old) bike through others experiences.

 

Search this site for the terms in your last paragraph.

You can do the services with very basic or even homemade tools.

bigfitz has a great writeup on the shims. Even has pictures. As well as a writeup on gauges.

RickcoMatic is the man for the cleaning, synching and clunk test.

Look for the posts. Then try it and ask questions.

Chacal XJ4EVER has all the parts you need. Good prices and probably overnight USPS delivery to florida (He's in GA)

And be sure to check your rear brake shoes for delamination.

 

FYI: Sent your a pm about an auction for an oem service manual. (Assuming you have a maxim).

 

Once warmed up, your 750 should idle at 1050rpm. (OK, 1100 is fine.)

It should snap right off idle with any application of throttle, and immediately return to idle once the throttle is released.

If it balks, stumbles, or doesn't immediately return to 1100 rpms, then you need carb work, pure and simple.

You probably need more than that, actually. The rear brake thing is MUCHO important, it happens way too often. http://xjbikes.com/Forums/viewtopic/t=15874.html You don't want to get hurt.

And your front brakes need to have all new fluid; the lines have a four-year life span so if they're original they gotta go. Front pads are like the shoes, they can and will crumble from age and it's your life we're talking about.

Also, your tires: these bikes have tubeless tires. You do not want a blowout. Please check the date codes on the tires, and if they're more than about 5 years old replace them and NOW. If they have no date codes they are WAAYYY TOO OLD stop riding the bike until you get new tires, honest.

Please read the articles in here: http://xjbikes.com/Forums/viewtopic/t=27544.html while you track down a workshop manual.

And use the search feature, plus look through "FAQ Suggestions." We have tech articles on stuff you won't find in any of the books, even the factory manuals.

And most of us speak from (rude) experience.

 

check your idle set screw wrx. its behind the carbs near the airbox. do you own a subie? i got a impreza

 

if all else is well you should set the warm idle at 1100, your 2K to 1.1K
then use enrichment while it's cold for the first few miles and see what you get hot and take it from there