Xj750 CARBURETORS

So I've got the bike running with no carbs when I stuff a gas soaked rag into the intake on the motor itself I cleaned the jets (small jets wouldn't allow a cleaning tool to go through) I used a can of carb cleaner, the bike won't run still what's wrong with the carbs any ideas? Idk where to buy a brand new set

 

Also yes they're bench synced

 

I would suspect they are gummed up.
There are tiny passages in the body which can get plugged and the only way to clear them is to completely submerge it in a strong cleaning solution, an ultrasound tank helps. Time for:

 

Don't take this comment poorly but you have 4 threads now on the same issue. You should keep the conversation within one so that new readers can see the history and offer their feedback intelligently. When you post to the old thread it will pop to the top of the forum for new readers to see. This also alerts others that have commented on your previous threads that there is new information.

That said. If it runs when you dump a bunch of fuel in the intake by spray or put an extremely rich mixture in (i.e. gas soaked rags) you are confirming that you have spark. It still sounds like carbs are an issue BUT we'd love to see your compression numbers and valve shim clearances. If you have low compression it may still fire but it won't run properly and you need vacuum from the motor for the carbs to work. In another thread you commented that it has been run for 5 minutes without oil, I would really like to see the compression numbers now that we know that. Valve clearances will lower compression if ignored and are too tight.

You most likely won't find any, and if you did they would probably cost more than 3 to 4 times what a professional rebuild would. There are guys that restore carbs to better than new for a reasonable price, I've had many sets done. I wouldn't spend that money until you go through the other tests and determine the state of the motor.

She won't start if those are clogged. See the link provided, much information on how to clean and test those.

 

If the enrichment tube jets are clogged, the engine will not want to start. Spray carb cleaner will not do the trick, you need to use a wire.

 

Same bike different issue therefore new thread but ok I'll leave all issues in this thread I'll tear down the carbs later tonight or tomorrow and soak everything in carb cleaner. Question after soaking do I rinse them water gas etc or wipe each part or shoot compressed air on everything and through the jets? Or just simple soak and reinstall after sitting overnight

 

You need to strip everything off the body.
The body should be void of everything.
Soak them for a couple hours, blast the passages with air then soak them again.
Blast them with air again, then spray carb cleaner through the passages. Then reinstall the jets, o-rings etc.
You need to allow many hours for this.
Did you read everything in the church of clean?
You need to order replacement parts before they go back together. New screws for the butterflies are highly recommended, throttle shaft seals . It’s a big job but must be done right

 

Man one of yall just clean a carburetor and ship it to me I got money ready for em don't tax too much ready to have this bike done

 

@hogfiddles will rebuild them for you if you’re not willing to tackle this. These carbs are nearly 40 years old. They don’t need a cleaning, they need a rebuild.

 

These are hsc32 hitachi carbs correct? 1982 xj750 maxim just wanna make sure cause I'll be ordering a rebuild kit also the small brass tube that's next to the jets what's that and how do remove them

 

The tube you’re referring to is not removable.
The commercial rebuild kits do not include throttle shaft seals or the fuel tube o-rings.
Tear them down and you will see what is needed before ordering.
The carb bodies need to be completely stripped before dunking them. Any solution strong enough to do the job will destroy the rubber components. This is all explained in the church of clean.
Do it all, don’t cut any corners or you will be doing it all over again. This is not a 1 or 2 evening job.

 

And I HIGHLY recommend you get the complete deluxe rebuild kit from Len Chacal. That is the ONLY source I use. All others gave me nothing but grief. Get the right parts the first time.

dfox

 

My question was what model carbs comes stock on these 82 maxim xj750 I think its hsc32 Hitachi right

 

HSC32 version 15R00

Info on carb model, fuel levels, parts etc. all here:

https://www.xjbikes.com/forums/threads/xj-parts-catalog-section-c-fuel-system.44642/

 

On all up-to’83
xj650 maxim/Seca, xj750 maxim/Seca

the carb bodies and racks are the same.... it’s the jetting that’s different between them

 

If the carbs worked before I had relay and wire issues now that relays and wires are fixed what could all of a sudden go bad in carbs?

 

You mean like this?
https://xjbikes.com/forums/threads/owww-my-eyes.112790/

Well, reading all the way back to the beginning of the thread, it seems to me that YOU are the one that’s been questioning the carbs right from the first post. Maybe I’m just missing something here.....

dfox

 

Naw your misreading. I'm asking a question in that comment not debating or making a statement it's odd to me how one day carbs work next day they don't and I'm asking what would go bad all of a sudden?

 

And yeah them carbs look pretty good how much for a set? Any discount if I ship you my set to rebuild and resell?

 

I'm thinking soak the carbs in gunk after I remove everything let it all sit in gunk overnight (except rubber components) then boil it all in water (to try and break up any loose rust or dirt) then another soak overnight and shoot air all over the carbs...never went this much in detail cleaning bike carbs what's yalls thoughts on my idea?

 

PM sent

 

Asking again.
it's odd to me how one day carbs work next day they don't and I'm asking what would go bad all of a sudden?

I'm thinking soak the carbs in gunk after I remove everything let it all sit in gunk overnight (except rubber components) then boil it all in water (to try and break up any loose rust or dirt) then another soak overnight and shoot air all over the carbs...never went this much in detail cleaning bike carbs what's yalls thoughts on my idea?

 

That’s not going into detail. THIS is starting to go into detail.


as far as carbs going bad overnight, it’s unlikely, but things can happen. Bad fuel, rust sediment in a tank, anything CAN clog jets but yes....that usually takes place over time. But, there CAN come a time when the last time out was literally the LAST time 0ut, tIl it’s fixed.

dfox

 

Think my idea will work?

 

Either it will, or it won’t. Keep in mind that there are a lot of passages in the carb body than can trap stuff or clog up. You’ll have a hard time blowing air through those. There are are usually filter screens on the back of the fuel valve bodies, too.if you you start removing the bodies, then you will break seals with the o-rings if they are still sealing. If you remove any throttleshafts, chances are the shaft seals won’t seal anymore when you put everything back together.

but try it. The worst that can happen is that it doesn’t work

 

Do these brass pieces come out too they look like jets of some sort I'm gonna soak em all in gumout carb cleaner overnight

Also one jet near the floats is stuck and wont unthread ideas?

 

What you need to do is go back and test your relays per the manual. If the bike was running and carbs working and all she did was bypassed the relays. You should look and see if you broke any wires or caused any trouble when removing the relays. Your problem may be electrical

Having somebody rebuild your carbs would be a lot cheaper and buying those are my eyes beautiful carburetors. The occasional New old stock carburetors that come on eBay sell for $1,500. It could send an email 2 XJ forever and ask him how much for the restored carburetors. But be sitting down when you read the quote those carburetors of the people who go in for full restoration of the motorcycles.

 

I'm cleaning these ones cause I think they got gummed up somehow seeing as bike runs with gas soaked rags directly in the intake of the motor (without carbs attached) and not at all with them attached
Can u look st those pics I included and answer the questions listed in my other comment

 

I'm not paying $1500 or anything more than maybe $100 for a dang good set of carbs I didn't pay but $200 for the whole bike I can get another whole bike right now for $100 an acquaintance has

 

The two Jets are air Jets the ones with the number 80 and 225 on them. I can't really see the main jet in the photo but it looks like you're going to have to take a set of vice grips two of them squeeze tighten twist off you might have to push down on the other side that would be the brass thing you see inside of the carburetor just below the air Jets with a wood dowel to keep it from spinning that's an aspirator tube under there and it just what the main jet is screwed into

 

You wanted tight-fitting screwdriver for the air Jets you might have to grind one down to get the proper width worst case scenario you don't remove them you split spray cleaner down them and backup from the other side from the main and pilot fuel jet. Under the supporting vendor form look at the thread called something new and something naked it is cutaway of the carburetors it should give you a good insight as to what it is you're trying to clean

 

https://www.xjbikes.com/forums/threads/something-new-something-naked.36344/

 

Did you see the pics? I've got the stripped jet out but do I remove the 2 in the other pic I already have but what do they go to are they supposed to come out when cleaning these carbs

 

?

 

EVERYTHING comes out when cleaning the carburetors. The only thing you don’t remove is the enricher pickup tube—- the little brass tube the sticks out of the carb body.

did you look at the pic I posted?

550h already told you what to do for the two air jets that you showed.

 

I just seen it, Idk where 80 and 225 are supposedly printed but I've got everything except the floats disconnected and soaking in gumout I'll be reassembling in the morning, I only had one can so not enough to submerge carb body ill just spray it good and let it dry on the porch then put it all back together and try it out

 

Can you picture a enricher tube? Wanna make sure I've not removed it

 

The numbers are stamped right into the top of the jets. Look at the picture you attached. They are very clearly visible. Go look at the pic I attached, and look at the bottoms of the two carbs on the right. The little brass “straw” sticking down is the pickup tube.

 

Wow I did not even see the numbers for the jets until you pointed them out I think I see the enrichment tube it's the bottom right of my 2nd pic correct?
If so how do I clean those thoroughly

 

Yep, that’s it. I use instrument wires, and a lot of carb cleaners, and compressed air

 

Ok thanks, are there any other things inside the carburetor that absolutely have to be cleaned in order to make the bike run?

 

?

 

Why do you continue to ask the same thing over and over?
Everything is discussed in the "church of clean", read this and you will be an expert.
The carb bodies need to be isolated from everything else.
The carb bodies need to be clean, all passages clear.

 

Same question never got answered seeing as the jets were clean and floats etc I was asking if anything else needed cleaning to make the bike run. Why u got an attitude?.. anyways.
I've heard people mention little filter screens inside the carb itself and other things I don't see any small screens or anything else that needs cleaning just wanna be sure before I get it all put back together and get aggravated putting the carbs back in

 

Ok so I'm rolling with the carbs as is but I noticed there's 3 threaded holes and since I've owned this bike no jets were in the bottom 3rd hole but it is threaded am I missing a jet or?
(Picture below)

 

Some hitachi carbs had a cover over the air jets, later ones did not. That was the mounting screw hole. You’re good to leave it unoccupied.

 

Alright by the way if anybody needs an easier way to mount the carbs lol redneck ingenuity check out the pictures easiest I've ever got the carbs on..

Update the bike (with a temp gas tank a 20oz coke bottle) will still not crank I've let all the jets soak over night and sprayed them again. Bike sounds like it's about to crank like it wants to crank a steady rumble but no VRAM VRAM sounds even more like it wants to crank when I took the now empty temp tank and squeezed it and it sucked back to normal shape it really sounded as if it was going to crank then yall keep in mind without the carbs on it at all it did fire up with gas soaked rags in the intake but now I've cleaned them pretty thoroughly and I've cycled the choke and still nothing

 

Did you;

1. disassemble the rack to the condition that I showed you?
2. Did you spray carb cleaner through every single passage so that it would spray out somewhere else?
3. Did you do that with EVERY hole?
4. Did you use compressed air EVERY hole to verify that every passage is clear?
5. Did you verify that every jet is clear?
6. Did you replace the throttle shaft seals?
7. Did you replace the fuel rail o-rings?
8. Did you bench-sync the rack?
9. Did you do anything with the mixture screws?
10. Did you do anything with you float heights and fuel valve needles?
If the answer is NO to any of those, that’s a big clue....
11. Have you capped the #3 vacuum port yet? In the pic it is still open
12. Your cable going to the throttle is not seated in the cup.
13. Are you sure you have the cables going to the correct spots?

btw, easiest thing to pop the rack into the boots—- use a hot air gun, warm the boots, and use a light coating of oil or Vaseline. They pop right in by hand.

 

Bike runs changed plugs fired up good can the bike run around the block without the airbox?

 

probably but it won’t breathe right