hi new to yamaha need some carb help

hi new to the Yamaha xj bikes I just got a 82 Yamaha 650 shaft drive best I can tell it's a maxim 48k miles on it runs like new but has carb issues like flooding from the over flow I've checked the floats and no leaks or sinkers ao I'm just assuming the float level is off on all 4 carbs the bike sid sit for 2 years but fired right up the shop I got it from did a basic run threw on the breaks tires and oil for a grand total of 1k bucks but it still has a few issues like the head like going in and out I assume is a bad relay and a thick little black Box in the head lamp that gets hot and at least once started to smoke on me wondering what that thingy does I'm use to KTM bikes this is my first Yamaha project so any help is appreciated

 

The black "box" in the headlight bucket is the "diode block", it has a bunch of diodes ("one-way valves" for the electrical system) that is used to control the safety system on the bike (i.e. can't start the bike in gear unless the clutch lever is squeezed, etc.). Smoke is not a good thing to see coming from it. But replacements are available!

 

Welcome aboard!
"We can fix that"

Start reading this, it will put you in the XJ mindset.
http://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

 

holy over load stumpy thanks for the 1/4 night of reading on my phone where would I find a diode block for a bike this old A and B more importantly why is it over loading I did delete the clutch and kick stand switch as they where faulty any ways (just un plugged and removed them)

 

and dont mind the broken turn lights I dumped it and broke a foot with the ape hangers it came with

 

it now has my old KTM dirt bike bars on it

 

You are on lucky fellow Jamie.
They guy who wrote the article is also the guy who replied just before me.

He is THE MAN, for all of you parts.

 

Send him an e-mail (in his signature).

 

lol well I'm balling on a budget dobt rape me

 

Prices are fair, customer service is superb - and that you can't put a price on.

Ask anyone here, Chacal is the best source for these old XJ's.

 

Welcome aboard.

If all the floats were not getting stuck there would be no fuel dripping from the over flow.

What all did the shop do?

Intermittent power maybe? Did you check the fuse?

It's a diode that keeps power moving in one direction. It should have a sleeve over it. Hope this helps.

Gary H.

I was typing when the other replies posted. Yes, Chacal is the parts guru and is very knowledgeable about these bikes.

 

floats seem to be free moving both right side up and up side down

the shop basically got it running. New battery. Grease the cables. Fix the rear brakes, they were delaminating. I saw that post. They check the front brakes. Said they were fine for now, but 6 months down the Rd. I'm gonna need new pads. I did Wanna swap handlebars before I picked it up, but didn't have any handlebars. The swap before and I wasn't tearing down my ktm just then really the bike 3 hours. Did notice the carburetors are overflowing went to got it making a right hand turn in broke a left foot in the ensuing chaos

I did a quick merry go round the relays it's a bad relay. Basically, I grabbed one relay and swap it with another in the head light came on at work just fine.

Yeah, I learned it was and I will need to learn More importantly, why is there too much amperage going to it and why is it burning up?

Stupid speech to text is not always 100% right. but it works

 

We are perfect when we understand that we will never be perfect. I understand.

Gary H.

 

so back to the float issue what's the factory spec on the float height of the floats

 

If you have gas running from the overflows, you DO have at least one sticky float.

Anyway-----

Float height INITIAL setting:

AFTER CHECKING AND ADJUSTING YOUR VALVE CLEARANCES

AND

AFTER DOING A CHURCH-of-CLEAN CLEANING is 17.5mm

Then you do your wet-setting.

Don't need to worry about that here.... Besides--- your shop already did it to you.

 

There are three relays on your bike. Two are color coded; one blue, one yellow. They are not the same.

Gary H.

 

you cannot just unplug the clutch safety switch will prevent you from putting it in gear the bike will stall. cut the connector end off solder the 2 wires together and plug it back in

http://www.xjbikes.com/forums/threads/the-ultimate-relay-switch-sensor-and-diodes-guide.27543/
haynes manual free download
http://www.manualslib.com/manual/837861/Yamaha-Xj750.html

you sound like the minimal wiring type. here are wiring diagrams for that the other file is a pdf of your full wiring

 

Ok well the staling parts good to know maybe the relay swap caused my diode to pop I swap a blank one (no color to be found with a yellow tabed one

 

wow lot more to this bike then any KTM iv had but they where basic enduroa

 

The knowledge and experience you have from wrenching and riding on KTMs combined with what you'll learn here will have you knowing your XJ inside out in short time. You've got this.

Gary H.

 

sometimes there is yellow or blue tape on the harness where the relay came from

 

ok the new used dioed box came today ill put it in tommrow i'v all ready swaped relys back to where they came from my yellow ones on the head light socket next to the cdi box the other 2 under the tank are so old i cant find any blue markings threw the rust but they seem to be working fine i can feel a good solid click from in side when i add 12 V to them and they pop off now so much for the yellow one i took the cover off it and did a closer inspection it seems dead copper has some carosion on it like moisture intrusion over the years let me know if any of this seems right as to where im findinf my relays and the right color is in the right socket

 

next question petcock valve mine only seems to have fule flowing on the prime setting i took it out and the plastic straws that stick up are gone so no real setting there for on/res meh my kets are the same way just time it by millage but i took the little pulse pump apart and cleaned it out the diaphram seels fine and seems to work when i apply a little lip suction to the tit but dosnt seem to work when the bikes running ie i need i new petcocke one day just trying to salvage what i got on the cheep for the moment

 

This really came in handy by the way I'm IPC 610 class 2 certified for soldering electronic assembly I got much more use out of the full diagram

 

In On and Reserve (normal) positions, the fuel flow is opened by vacuum from the intake manifold. This is to ensure that fuel is only flowing when the engine is running. This is both a safety measure, and prevents carburetors from overflowing if the float needles don't seal well.

 

I'll check on the location of the relays and reply if another member doesn't beforehand.

Install a briggs & stratton yard mower shut off valve (auto parts store) in the fuel line until you rebuild the petcock. Don't forget to shut it off when you're not riding. It'll prevent the carbs from overflowing if any of the valves get sticky.

Gary H.

 

I'm got the flooding under control and it was just the floatt heights but I got a new issue muy throttle cable seems 1/4 in to short now and my throttle
Plates won't close andcme down past 5k rpms

 

so new issue i swaped hadle bars and now my throttle cable seems to be holding the throttle plates open to the tune of 5k rpms how do i make it longer or drop the idle i tried the idle screw in the middle of the 4 carbs and got nothing i cant seem to find where its sticking or hung up and the cable it self isnt tight i got play in the black sleave and i dont see any thing stoping the macanis of it from moving

 

Make sure that the pivoting "arm", where the cable attaches to the carbs, is not hanging up on the cylinder head fins or any other obstruction.........

 

did you misplace the cable jointing piece?

stu

 

The 650 does not have that part. Instead it uses a 2-part linkage that is part of the #3 throttle connecting plate.

 

What bars did you swap to?

 

idk they where on my ktm 620 rxc-e i got alpha drag bars coming

 

i dont see any hang ups there

 

btw so glad i found the right fourm the first time

 

ok i got it to idle normaly with a new throttle cable mine was repaired nicly at one time but was missing the 1/4 in of cable i needed to fully close the butterflys now next issue she still takes for ever to come down from 5k rpms im thinking air leak but from where its a new vac line from the intake to the fule pump the other 3 nipple caps look solid and are in place with factory clapms on them still the intake boots from the head to the carbs look to still be in good shape a little dry roted but no leaks i can fins with a can of starter fluid

 

Have you performed a vacuum (running) synch on the engine? An out-of-synch engine can exhibit a runaway-idle condition.........

 

no I havnt and ive had a feeling thats what it is my ktms are all thumpers so iv never done it nor have the slights clue as to how

 

yo mates i think ivw sorted out the head lamp relay its not getting enough amprage i hooked up my battery charger set it for 5 amp and the lights fired right up once i tap the starter

 

Engine Tuning Tools:

j2) Aftermarket Morgan CARBTUNE PRO 4-COLUMN SYNCH GAUGE TOOL.......brand new, no display box, includes all accessories and instructions. This is the one that professionals use and recommend, and is superior in design, ease of use, and accuracy versus vacuum gauges and all other versions, whether fluid-filled or otherwise. Uses damped stainless steel sliding dowel rods instead of mercury or the "blue mystery fluid", giving accurate, safe, and easy-to-read measurements. More expensive than other synch tools and worth it. Use it even once and you'll wonder how you lived without it.

NOTE: this tool is used on all XJ engines, regardless of whether it is a "YICS" engine or not, and is necessary to perform the “running” or vacuum synch. If your carbs have been removed from the engine for a rebuild, then it is also suggested that a “bench synch” procedure be performed, which does not require this (or any) tools perform….the only purpose of the bench synch procedure is merely to get the carbs set up “close enough” to allow the engine to start and run, at which time a running (vacuum) synch of the engine should be immediately performed, using the HCP96Q synch gauges, A great visual guide to the bench synch process can be seen at:

http://xjbikes.com/forums/index.php?threads/6366


Please note that Yamaha specifies that the engine synchronization procedure should be performed every 2,500 - 4,000 miles to insure the maximum performance and life-expectancy from your engine.

Please note that Yamaha specifies that the engine synchronization procedure should be performed every 2,500 - 4,000 miles to insure the maximum performance and life-expectancy from your engine.

Also, please note! you can sometimes find these same sticks selling at a discount at various places, but most of these places are offering a much older, now-discontinued Carbtune II version, rather than the latest, much-improved Carbtune PRO version that is offered here. The PRO version is much more durable, accurate, and easier to clean and service than the older version.


Here's a great tutorial on using the Carbtune Synch Gauges:

 

think i might just drag it to a local shop and have them do it this time the carbs seem to have other problems as well like random over flowing now

 

Just a reminder. I can relate to your frustration but if you don't learn to do what's necessary to get and keep your bike running you'll continue to pay large amounts of money to a shop that far exceed what your bike is worth. It'll take some time to get it back right. The carbs need to be rebuilt (see Dave's post for link).

Gary H.

 

iv run threw the carbs with new seals and needles and jets even new diaphragms at this point I think there just to far out of sync

 

Did you bench synch the carbs? Also, the new needles (valves) and seats should stop the overflowing issue.

Gary H.

 

no I didn't I just saw thous instruction late last night I need a few paper clips

 

Do you think I could use tooth picks in place of paper clips?

 

Cut 1/4" strips from not needed business cards and use those. A good bench synch will put the carbs within 1" hg (or better) of each other and will allow your bike to idle without backfiring, popping and sputtering. Then you can do the running synch.

Gary H.

 

no i just learned how I've been hunting for 2 paper clips do you think tooth picks would work?