The Barzu Bike - XJ750

I tried to do it with mine, but it cuts the engine off Gotta find the switch to bypass.

In the mean time, I wrote Chacal an email with my woes and here's his reply: (I'm off to the garage)

******************************
Well, you've got too much fuel OR NOT ENOUGH AIR getting into your cylinders.

Obviously, just as it's a fine line between pleasure and pain, so also it is between the
"too much fuel" vs. "too little air" issue.


What could cause too much fuel?:

* choke is engaged; choke plungers stuck open and not closing fully, choke plunger valves
horribly worn.

* fuel jets are the wrong size, regardless of how they are marked (they could have been
previously drilled open), or in reversed positions.

* air jets are placed incorrectly, so that the large pilot air jet is in the main air jet position
(and, obviously, vice versa). Please note that although the photo in the Haynes Workshop
Manual showing the air jet positions is a "correct" photo (the jets are physically placed
correctly), the caption which labels which-jet-is-which is reversed.

* the fuel level in the bowls is extremely high, thus it takes much less engine vacuum to
pull a greater amount of fuel into the system....... in essence, your carb(s) are "always
flooding".

* the main fuel needles are incorrect for that engine or are very worn (rare), thus allowing
much more fuel to enter.


What could cause too much air?:

* "Pod" air filters or no air filter.
* Air jets that are much larger than specified.

Now, although it is conceivably possible that your idle mixture screws are too short, that
is not normally an issue. For reference, originally mixture screws are approximately:

Overall length: 20.45 - 20.70mm (20.55 average length)
Length beneath head: 14.60 - 14.90mm (14.70 average length)
Shaft Diameter: 2.93 - 2.97mm OD (2.94 average diameter)
Tip length: 2.30 - 2.50mm (2.40 average length)
Tip bottom diameter: 0.55 - 0.61mm (.58 average diameter)
Tip top diameter: 0.72 - 0.75mm (.73 average diameter)



My first guess would be since you are having difficulties getting the idle mixture circuit to
ever go "lean", even when turning the screws to full closed, would be that for some reason,
you are getting extra fuel either through the pilot circuit or through some other circuit. The
most probably causes of such a situation are that the fuel levels are way too high, or that
the choke system is active even when you think it is "closed".


Also, I assume that the valves have been adjusted and the engine synched? I not, as
much as you may not like to hear it, I would start there.

I would ALWAYS start there.


Let me know what you find.


Len
******************************

 

didn't you put bigger jets in? I am a total noob when it comes to this stuff but earlier in this thread you said you put larger jets in, what about changing those out to smaller ones?

 

I don't think the center stand has a switch... hmmmm. I know the side stand does, but not the center stand to my knowledge.

Your bike was running fine until when?

 

I think you're right, I might have kicked out the side stand by accident 8O Noob.

The Barzu Bike never ran fine since I got it on July 29th.

I'm working through all the issues one by one, as they're all carb related. I AM making significant progress. The carbs are pristine, and there's nothing left to clean on them. But as I cried to Chacal, the friggin' beast has no power when I want to get out of the hole. Tons of hesitation, tons of noise and no power. Plugs are black as night. Rich, rich, rich. So rich that I cannot colortune the orange out of idling. Even with the mixture screws all the way turned in.

I know the bike is getting plenty of air.

I do have a suspicion though, after reading Chacals reply to my email.

Three things I will check tomorrow is:
1. Fuel levels - i set the floats perfectly, but never actually checked the levels live.

2. Do the DIY synch tool thingie with the carbs. They've been bench synched to perfection. (I have OCD about things that I work on,so I can say that)

3. Jet needles - I think this is my issue. Let me explain. In my thirst for power I threw that stage 3 dynojet in the carbs. The stage 3 has you move the clip on the needle by three spaces, maybe like 5mm up or so. Which allows for more fuel to enter the main jets quicker. I bet that's what's causing all the richness. Tomorrow, I'm moving the clip back to "stock" depth and will take it for a run.

Mikegustus, you're absolutely right. If I get better response, but not there yet, I'll switch out the main jets.

Why did I not think of this sooner? Because I would never suspect "Dynojet RESEARCH" to get it wrong. I don't know.I just don't know.

Some of you don't subscribe to the DynoJet thing, but hey, it's my first bike and I wanted to make my first purchase for it something really significant. Something I could brag about.

Hopefully I'll have great news tomorrow. Thanks dudes, I'm glad the forum is here for help!

 

Emmer effer. I took the intake manifolds off today because that's the one thing I've not quadruple checked. Under a really bright light...lo and behold, there's cracks on the BOTTOM of the manifolds. By bottom, I mean when they're installed the cracks are on the outside of the manifolds, opposite side of the vacuum valves. I don't know if they go all the way through, they might.

My question is, could these be the reason my idle is so rich? I though if the manifolds were cracked, that would introduce extra air before the gas mixture and the bike would run lean. This is the reason why I didn't think to pull these again to look at them.

Any thoughts on this?

 

Cracked manifolds = intake leak = lean

 

I know. Does not make sense. There's nothing left for me to look at though.

I've rechecked:
Jets - went down to Dynojet 132's from 136's. (per Dynojet)
Needles - put the clip on the next groove up. (per Dynojet)
Float levels - decreased by 2mm (per Dynojet)
Choke - line, valves, plungers, etc.
Jets - pilot and main, everything
Pilot circuit- everything
Throttle cable
Bench synch.

NO matter what I do, I can turn the fuel mixture screws all the way IN and the colortune still burns orange. No blue. I need more air, but I've even got the pods off and still no better.

When I throw the tank on and go for a ride, there's no power. Ever.
I take it around the block and when I pull in the bike dies. Plugs are black.

I've got RTV sealant curing on the intake manifolds now. It's a band aid fix to see if there will be any improvement.

I've never felt so helpless. I've cleaned the crap out of everything. Everything.

 

BTW, what the hell are "throttle plate shaft seals?"

 

The seals on the shaft that has the butterfly on it

What cylinder do you have the colortune in?

 

Ill check the seals.

Cylinder 1. Should I start with 3? The vacuum valve is plugged on 1.

 

Vacuum valve as in fuel valve? If that's the case, you've probably got a leaking petcock diaphragm that is allowing fuel to travel through the vacuum line directly to the cylinder. Remove vacuum line from intake manifold and plug off the vacuum port. If it feels like the inside of the hose is wet, this is your problem. Run the bike on prime and try to tune it again. You can continue riding it on prime as long as that vacuum hose is not connectedto the engine and the vacuum port is plugged off. Order a petcock rebuild kit and ride around to burn the gas before you pull the petcock out.

 

I'm gonna throw this at you cuz I kinda had the same problem on my 85X, loosing power and hitting the throttle and nothing! I had a $#@%ed up fuelcock, and my carbs were overflowing into my motor, bike would run, but like crap. drained the oil, filled it back up and away i went, since i fixed the fuelcock, it worked, until it failed again ... hence i am looking for a custom tank and newer fuelcock.

 

Earz,

Clarification - I'm tuning with the gas tank off. I have a container suspended off the handlebars with one hose running right to the carbs gas "in" valve. The vacuum ports are always plugged off on the cylinder I'm colortuning.

 

I'm right there with you. I'll pull the pc out and take it apart. I'm willing to try anything at this point. Although when the vacuum hose is off and the fuel line is off the pc, it does not leak. Does not that mean that it's good?

 

Gotcha. Did your carbs overflow since your last oil change? I'm with zack - I've had problems in the past with fuel in the oil causing a rich condition.
Also, have you checked valve adjustment? Here's a tread showing how

http://xjbikes.com/Forums/viewtopic/p=152293.html




Zack - you may consider this route instead of a custom tank.
http://xjbikes.com/Forums/viewtopic...der=asc/highlight=petcock+repair/start=0.html

 

Well, after coming to terms with the fact that I might not get to ride this season at all and then something compelled me to check the air jets.

If the Hayes diagram is right, then my air jets are backwards. I put them in exactly as the PO had them. Assuming he had them in right in the first place was my mistake.

This would explain why the bike ran like crap when I bought it.

Rickomatic did mention in another thread the either the diagram or description in the hayes manual is wrong. I'm gonna try and find that thread and see which one it is.

Again, if the diagram (picture) is right, that's exactly my problem...

 

I think this is the link you need:

http://www.xjbikes.com/Forums/viewtopic ... cture.html

or atleast has the info.

 

gameover - yep, mine are backward. Thanks for the link thread. I'll give it a go tomorrow and hopefully put this frustration to rest...and find something else to gripe about.

 

Wooohooo, cant wait to hear about the results.

 

Can anyone tell me where I can get some Unobtanium spark plugs?

 

???WTF is an unobtanium spark plug. I used to work at a cycle shop and have a degree in auto tech. I like to think that I keep up on new products but I've never heard of such a thing.

The highest quality plug I've heard of is iridium. The plug for your bike is a NGK BPR7EIX

If you read about these "unobtainium plugs" on a forum, you may check out this link Unobtanium

 

Earz,

I was just screwing around. :mrgreen: It's my play on iridium plugs.

Actually, I'm surprised that the term IS used in manufacturing and materials. The "unobtanium" joke started back when I was 20, working in Philly, and one dude was bragging that he just got a Platinum credit card.

Well, my friend Bobby and I did not like this dude so without missing a beat I looked at him dead serious and I was like "PSHH! That ain't nothin! I've got an UNOBTANIUM card."

Very funny, if you were there.

Thanks for the Wiki link, I think that completes the funny.

 

HAHAHA, is you bike running yet? LOL

 

Some of the parts for my old Challenger R/T convertible were considered unobtainium back in the day.

 

I bought some unobtanium spark plugs and now my bike actually hovers a few inches of the ground when I ride it.

 

I'm so jealous. I cannot afford them.

To update, I colortuned the bike today and took it around the block. Idles great, rides great and no more black spark plugs. I cannot believe my air jets were reversed.

From here on out, it's minor tweaking until winter.

My bro and I are going for a ride in a bit, this way I can get her fine tuned.

If you see us out there, throw up some gang signs! We'll holla back.

I'm the one with the skulls on the helmet on the loud beast. My bro is the "douchebag on the scooter." (his words)

Peace :twisted:

 

LOL well I'm glad you got that sorted out. Let me know how she runs.

 

Alright d00dz,

Just got back from a two hour ride. Here's the verdict:

The header pipes are loud. Holy loud. I swear the sound travels right up the helmet into my ears and nowhere else. I can handle it, but I'm sure tinnitus won't be that far off.

I'd like to find a pipe shop that would bend me four custom tubes (two on each side) in a shotgun fashion to the back wheel. I'd like to go over/under right in the middle of the bike, right about where the current pipes exit from the engine.

The bike screams when you open the throttle from 1 to 4K rpm. Then it gets too much air and bogs down. I know why.

When I called DynoJet and told them of my woes, (before I knew my air jets were reversed) they had me move the clip on the needles. I've got to move the clip back to where it was because now there's not enough gas getting in there from 4K rpm on...

Once I get the needles in place, I'll colortune again, carb sync again, and should be good to go.

 

damnit barzu!!! i was coming to post a "HAHA i beat you" but it looks like you were riding yours as well.

funny, i was going to say my pipe is too loud! open primary tubes just seems like it should rattle your bowels out.

so how many dirty looks did you get with the open headers?!

 

Let me know when you want to get out again. I am diggin' this nice weather.

 

Cooter, I'll be ready to go next week. I just want to raise those needles by a clip and tune it again. I'll get all the minor stuff ironed out this week and we'll figure out a ride. My bro will come as well.

Zookie, I gotta tell you dude, they're soooo loud. My bro was riding behind me and said that every time we passed a car, they all immediately followed me with their eyes.

We stopped for gas an a 12some of harley riders pulled up to gas up and buy laxatives or something. When I fired my bike up, I got their immediate attention.

I laid off the gas while passing the PO PO as well, just in case. If they were trying to pull me over, I wouldn't know because of the pipes. Aaaand I can't see anything out of my mirrors...so my bar ends are on the way.

 

so are you going to keep them zoomies, or change to something a little quieter? :lol:

 

I'm keeping them the way they are. I'll try to find some place that bends pipe over the winter and do the shotgun over/under on each side. In the mean time, they'll have to do.

Some dude in our subdivision got creamed on his orange crotch rocket by a minivan mom. Seems like he tried to pull out and didn't pull out in time. His leg was bent the wrong way. Jeez.

 

are your guys carbs CV carbs as well? if they are this may help you if you have the dyno jet kit.

http://www.factorypro.com/tech_tuning_p ... gines.html

this guide from factory pro is not factory pro product dependent. you just may have to mentally adjust the RPM ranges mentioned in the guide.

 

Very busy but time for an update. I've had the bike out a couple of times. I just changed the needle positions to what I had them at before.

I think I'm getting used to open headers as they don't seem to be so loud anymore. Either that or I started to lose my hearing already

I decided to take the tank off and put the final couple coats of paint on it. I've got this week to tune and am going for a long ride with some dudes on Saturday.

But it never ends...now my headlight and (running) tail light won't come on at all. I've checked the bulbs and the filaments are intact. This probably means that I have to take the electrical leads apart and hit them up with some fine grit sandpaper.

Feel free to chime in.

 

Barzu, check your fuse inside the headlight bucket, light blue wire goes to it I believe. That should be it. Did you replace any turn signals lights lately?

 

Xulf, dookie!

No, did not replace turn signals. Changed that fuse because it was indeed shot, and I got a new bulb just in case. Still nothing.

I really did not want to delve into this crap until winter...jeez.

To clarify, I have no running lights. Turn signals work great and the brake light does come on when the foot pedal or hand lever is depressed. Why me? Whhhhyyyyy meeeeeeeee? :cry:

 

Not sure if you have a wiring diagram but I found this one. It's for a UK model but most of it should be the same. Hope it helps.
XJ750 wiring diagram

 

Thanks Earz,

Here's my gifts. Scroll down to the bottom after clicking the link to download it. Enjoy!

Filename: YamXJ650750HayMan.pdf (174MB)
Download Link: http://www.filefactory.com/file/a0b7egg ... HayMan_pdf

Filename: Honda_CB750SC.Nighthawk_84.pdf (13.99MB)
Download Link: http://www.filefactory.com/file/a0b7d21 ... awk_84_pdf

Filename: CarbElecMan.pdf (61.93MB)
Download Link: http://www.filefactory.com/file/a0b7e5d ... lecMan_pdf

Filename: MotoMechMan.pdf (45.06MB)
Download Link: http://www.filefactory.com/file/a0b7e7e ... echMan_pdf

Filename: CarbMan.pdf (20.34MB)
Download Link: http://www.filefactory.com/file/a0b7eh8/n/CarbMan_pdf

Filename: Motorcycle Mechanics General Manual.pdf.pdf (45.06MB)
Download Link: http://www.filefactory.com/file/a0b7f14 ... al_pdf_pdf

Filename: YamXJ650750ManPt1.pdf (76.53MB)
Download Link: http://www.filefactory.com/file/a0b7fbc ... ManPt1_pdf

Filename: YamXJ650750ManPt2.pdf (38.45MB)
Download Link: http://www.filefactory.com/file/a0b7feb ... ManPt2_pdf

 

Went riding yesterday with four other dudes. Ended up putting 400 miles on the bike. Wow, I was NOT ready for that, and my body is very clearly telling me that this morning.

The header pipes will not do at all. My ears are still ringing. Fortunately, one of the dudes I met yesterday is a pro welder and has a shop, so I'm going out there and we're going to lengthen these pipes to the back tire.

Originally, the header pipes were not that high on the priority list, but after yesterday, they just jumped up to number one.

 

Get them lengthened just a bit and aimed to the ground. Should help quite a lot. We did a similar thing with a '32 ford, and ended up turning the chevy 350 we put in's pipes straight to the ground. off the head and down to the ground, aimed away from the cabin (just forward and to the side, funnily enough. You hear it coming for sure!)

Surprisingly enough, after we did that, the car was pretty quiet (for a 350 with straight pipes)

 

Poprider,

I saw a dude in the city the other day with an XJ650. He was too fast for me to catch up to him, but I did notice that he had a 4 into 2 setup. He rolled two of each header pipes into a single, fat, 3" exhaust. Then he ran it along the bottom of the bike and once past the center stand, kicked them upward at 45 degrees so both pipes on either side stuck out a few inches past the tire. It looked amazing.

I will say that since that last post I've raised the needle by one clip and the bike sounds much more throaty and the sound from the pipes is much more tolerable.

I will however try and get the same look that I saw dude with this winter when it's choppy choppy time.

In the mean time, I'm still crying over my electrical problems and am getting a voltmeter today.

 

earz_cd Can I ask you why you need to put light oil in the pilot mixture screw?

Carvall

 

I didn't, but I assume it is to lubricate the threads of the screw so you can make fine adjustments

 

That is what I was thinking but I thought I better ask. With bikes procuderes you miss a little detail and nothing works! LOL

Thanks for your answer!

Carvall

 

HAHAHAHA! i knew it would get old.....my muffler is in need of another baffle. no ride is worth a 2 day headache! straight pipes are cool for about 5 minutes.

 

Hey dudes. Still here...and now that winter is passing on, it's gonna be time to start working on the bike again to get it ready to ride. Looking forward to discussions with you all.

 

whoa
you're back.

cool

 

Winter's a bitch. I sold my 650. Still got my 700 though. I'm in the early stages of a XS650 build. Still lots of work to do and not enough time.

 

Wondered what happened to ya'! Glad you're back...

skillet