wondering if a set of mikuni carbs will be worth it???

just wondering if buying a set of mikuni carbs for my 82 xj650 will be worh the price. anyone know what they go for? if they are even available? i have issues with keeping my carbs in tune and cant figure it out. the idle fluctuates i turn it up its too high turn it down and it dies, wont run unless choke is on now? help?

 

What kind of Mikunis are you talking about?

The 550s and 900s as well as the 650 Turbo have Mikunis, but they're CV carbs just like the Hitachis. And even more "finicky."

Unless properly maintained.

It sounds like you need to:

-Thoroughly clean the carbs.
-Check the float levels using clear tubing and fuel, and adjust if needed.
-Bench sync the carbs.
-CHECK YOUR VALVE CLEARANCES AND ADJUST IF NECESSARY.
-Vacuum sync the carbs.
-Fine tune the mixtures.

Do all of that, plus ensure you have no vacuum leaks anywhere, and the bike should run fine.

Try to shortcut the process or leave anything out and you'll keep doing it until you've done it all anyway.

Or, try to find a different set of racing carbs and spend nearly as much time and 4X-5X as much money after getting them jetted right for the bike.

Cleaning the carbs and doing the other required maintenance is a lot more practical, honest. The reason you're having issues is that the things I've listed have never been done, or not for a long time.

So the short answer is, no, it's not worth it. It makes a lot more sense to properly care for what you have; but it does require some time and effort. (Lots less money though.)

 

i havent had the bike for long and got it real cheap, i think it sat for a long time without being ran so I will clean the carbs etc. i would suppose i need to buy a colortune plug and a tool to vacuum sync the carbs? also i should probably have the valve clearances adjusted at a shop or is ir possible to do myself?

 

also how is the float level adjusted. sorry im a noob

 

also how is the float level adjusted. sorry im a noob

 

The FAQ section have some fantastic write-ups on everything you need also get you a manuel or two. Read read and read somemore before you dive in.

 

You really need to do a forum search, and look in "FAQ Suggestions." ALL of that is covered, in detail, and there are two or three threads on float levels running right now, including one called "setting float levels."

THE FIRST thing you need to do is check the rear brake for delamination before it wrecks you; http://xjbikes.com/Forums/viewtopic/t=15874.html

Then get a service manual. You have some work to do. Finding a shop to work on a bike this old is nearly impossible, and those that will often make matters worse for more than your wallet. You'll need to do the work yourself or spend a whole LOT of money, and then possibly end up doing it yourself anyway.

This isn't an old car, it's an old motorcycle. Different game. You need to read the first six or so links under "Cool Hand Luke" in here: http://xjbikes.com/Forums/viewtopic/t=27544.html

Or start saving for that $1000 set of slide valve carbs you were asking about...

 

ok thanks for all the help guys. sorry i feel like a tard. $1000 dang i figured they would be at tops $500. i have rescued a couple old bikes from the grave, but nothing with carbs that are this tricky. would one small crack in the intake boots in between carb and motor cause issues?I have heard that it is nearly impossible to get ahold of these boots is this true? any good solutions to fixing old ones? will boots from 750s fit the 650?

 

If your bikes been sitting for a while, and the idle is out to lunch, smear a little vaseline around the throttle shaft where it exits the sides of each carb and see if it gets sucked in when running - this'll tell you if your throttle shaft seals are leaking - something that's missed all too often in carb cleaning and rebuild sessions, and results in 'impossible to tune' situations (vacuum leak). Chacal (XJ4EVER) sells replacements. If they are leaking, you'll see greasy smears on the sides of the throttle plates when you pull the carbs. Be sure to read up on carb cleaning and note all settings prior to/during disassembly - Good Luck!

 

Another thing to make note of, if you buy a set of carbs that the PO says are rebuilt and in tip top condition you could still be buying junk. At least if you invest the time and money in your own then you know for a fact that it's been done right and you have learned something along the way, and that my friend can't have a dollar sign hung on it!
There is a ton of info here and lots of people to help you, but if I were you I'd put a bit more info in your profile, there may be a forum member less than an hours ride from you.
We don't need your social insurance number, but put as much info as you're comfortable with and it will pay dividends. Just sayin'.

 

Hi Bigfitz...

You mention mixture screw settings above - will you just enlighten me as to adjustment.

ie: does turning them OUT lean the mix (as I'm not sure whether they meter AIR or FUEL).

Thanks, Nige

 

They meter fuel.

 

Thanks...

So does turning them IN (ie: clockwise) LEAN the mix - ie: REDUCE fuel to air ratio?

Nige

 

Yes. In=leaner; out=richer.

 

Funny you should ask...

 

In your Initial Post, ... you stated: "Won't run without Choke!"

This is like the Commissioner turning-on the SearchLight and sending the Bat Signal.

It's such a profound signal that you need your Carbs Cleaned and tuned.

A 100%, Cleaned, every detail attended too ... Carb Cleaning, Bores Scrubbed, no corners cut, like-new again Cleaning.
Bench Syncing.
Tuning.

And you will be very happy.

 

Thanks for the above info re fuel ratio metering.

Wanted to get it right way round, as the mixture screw on my Bonnie's Amals works the other way - ie: IN for richer/OUT for leaner, as it meters AIR.

Thanks again,

Nige