First time working on my carbs. Ever.

Ok so I bought a xj750 from a guy last year and one of the things I liked about getting it from him is that he had a nice clean hot rod sitting in his garage which seems to suggest to me that he probably does his own work and keeps things in good shape.

I pulled the float bowls off and saw this. Since this is the only carb rack I have ever pulled I have no benchmark. Do these floats look half way decent? They don't looked gummed up at all so....


IMG_8960 by IAmMoen, on Flickr

 

I would rebuild them....take your time & do it right the first time...

Excellent instructions by Rick-o-matic

http://www.xjbikes.com/Forums/viewtopic/t=2908.html

or Chacal

http://www.xjbikes.com/Forums/viewtopic/t=14692.html

Both are excellent write-ups on carb rebuilding...

 

Its hard to see the shape of them from that pic but mine looked way worse when I pulled mine apart. I guess the biggest thing is to make sure you clean them properly though. you really gotta take your time and I suggest takeing pictures every so often so you remember how they go back together. The guys on this site have made up some good "how to" posts....check em out.
Good luck!

Bugz

 

+1- Carbs can "look" great but still have a passage blocked.

Why are you doing the carb's?, are you having performance
issues or just cleaning for the skill.

 

The how to's posted above are great. Follow the procedures to the letter, do each in order and you'll have a great running 750.

 

A little bit of both. I always think that knowing the condition of everything on anything mechanical will help you in the long run so I figured I should dive in and figure everything out about the carbs.

I am having an issue as well. It takes quite a while to get started (which very well might be normal for these bikes) but I am also having an issue where I would pull up to a stop light and even though the idle is set even a little high the engine would slow slow slow and stop. Sometimes when you stopped and got off the gas it would even die much faster.

I will certainly be looking at the fuel enrichment circuit closely as it seems things that are wrong with idle are mostly that and the idle set screw position.

I have about 10 tabs open on my browser right now and they all have things about carbs and rebuilds. Hopefully I can get it done right the first time!

 

Well I'm going to throw my two cents in. Well 1.3 cents anyway, as I'm in Canada.
I just did mine about a month ago and this what I did. Pulled my rack and did not disassemble it. I took all the float bowls off but only cleaned one carb at a time using the next one as a reference. Removed everything carefully. Cleaned all the jets, cleaned all the passages made sure the float needle suffered no wear. If there is ANY wear on the rubber tip replace ALL of the float needles in all four carbs. Cleaned all the crap out of the carb. Soaked them with greaser and flushed with carb cleaner. I used a dremmel tool with a brass brush to clean everything.
Also clean and polish the Vacuum Piston and the Vacuum Piston carb bore as out lined in the forums. Just do a search for carb cleaning.
I didn't go through all the carb boiling and that I don't think it is needed unless your carbs are in extremely bad shape. But having said that I'm looking for anther rack of carb to do a complete rebuild on and will try it then. Now everyone will jump in and say you must boil of ultra sound clean. I think this is more to get a showroom look then a get it running and on the road move.
No matter how you do it be carefull, clean everything, and take your time. I took two days to do mine but I know they are clean.

 

It has been a long time since I rode and I realized that the engine not idling was not my biggest concern. I ALWAYS GOT GAS IN MY OIL!

As I am going through everything it really looks like this guy took pretty good care of the bike. But something is leaking somewhere. To the best of my knowledge we would be looking at a leaking petcock or something in the carb not seating well. Is there anything that I should be looking for? I am about to submit an order to Chacal and I am trying to get this all in one fell swoop but the questions invariably come up of, "If this petcock looks good, do I really need to buy a $52 rebuild kit?" and "I wonder how new all this stuff is anyways..."

Don't get me wrong, spending $150-$200 isn't that bad, IF it fixes the problem. But spending money to replace something that is in great condition and not fixing the true issue is going to drain the bank account really really quick. Here are a couple pics of what everything looks like. Oh and if you want any really big versions of the photos just let me know



IMG_8974 by IAmMoen, on Flickr

IMG_8975 by IAmMoen, on Flickr

IMG_8976 by IAmMoen, on Flickr

IMG_8977 by IAmMoen, on Flickr

 

Looks very rebuildable. Kind of hard to see the actual seat but it looks decent from what we CAN see...

Here's how: http://xjbikes.com/Forums/viewtopic/t=25058.html

 

Well here is a closeup of the same picture. You can see it a bit better. My question to you guys, who have been doing this a lot longer than I have, and have probably forgotten more knowledge about it than I will ever know to begin with;

Should I just say screw it and get a manual petcock or is this vacuum petcock worth it? Does a person have to constantly fix it or is this a once in a half decade?


Seat by IAmMoen, on Flickr

 

The fuel petcock is tricky sometimes. It looks good but it leaks. It's always seems to be around the diaphragm. It either doesn't seal well when assembled or it stays open when not running. I had that issue after parking my bike at my parents for over 19 yrs. I went the cheap route and applied sealer with a toothpick and reassembled it and it worked. I feel sorry for my son-in-law if he ever has to disassemble it. He will have to buy a rebuild kits.

As for cleaning the carbs I used alcohol on everything except for the rubber or plastic parts. It ran as good as the day I got it.

 

I have been looking for a smoking gun to decide on what to replace. My petcock diaphram has a small rip right in the middle of it. Would that do it? It is right next to the silver middle with the rubber ending that gets seated in that hole above. I would think that this would result in leaking to the outside of the petcock not the inside but I could be wrong.