Measured from the gasket (gasket is in place in the photo) to the end of the jet is almost exactly 3/4".
Is this a Z-6 Long or a Z-6 Short needle jet?
Thanks.
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is this a Z-6 Long or a Z-6 Short needle jet?
- Thread starter DogBunny
- Start date
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- carburetors
Measured from the gasket (gasket is in place in the photo) to the end of the jet is almost exactly 3/4".
Is this a Z-6 Long or a Z-6 Short needle jet?
Thanks.
You can't really tell from the bottom part of the jet as it is the top half that differs. According to the carb data on the Australian club web site, the long (top) is 12.5mm, the short 8mm .....
http://www.xs650.org.au/XS-TX650 Carburetor Evolution.htm
To determine which is correct for that carb, you need to look through the main bore to see if it has the raised floor (which would require the long jet).
http://www.xs650.org.au/XS-TX650 Carburetor Evolution.htm
To determine which is correct for that carb, you need to look through the main bore to see if it has the raised floor (which would require the long jet).
The long or short is on the other end of the jet. The very early carbs had a raised floor under the slide. It came up very close to the slide and needed a longer jet to reach above the floor.
If you look into the air cleaner side of the carb, does the area coming up to and under the slide look round or does it come up flat under the slide.
Here is a pic of the flat floor carb I have.
One is a round floor carb, kinda crappy pic. But if you look in your carbs, you can see it.
Leo
If you look into the air cleaner side of the carb, does the area coming up to and under the slide look round or does it come up flat under the slide.
Here is a pic of the flat floor carb I have.
One is a round floor carb, kinda crappy pic. But if you look in your carbs, you can see it.
Leo
Attachments
There may be better pics around that show a round floor carb.
Leo
Leo
Excellent. Great answers.
I appreciate the fast responses and the pics.
I was never aware of that raised floor before. I'm sorting out what must be a 1973 carb set, with raised floor, it all makes sense now.
I appreciate the fast responses and the pics.
I was never aware of that raised floor before. I'm sorting out what must be a 1973 carb set, with raised floor, it all makes sense now.
Someone put the 1973 set on a 1974 bike, that helped to confuse me.
I had the 73 set on my 75 when I got it. The only thing wrong with them is the throttle shafts have worn the holes in the carb bodies. It takes the first 1/8 to 1/4 turn of the throttle to lift the shafts before they start to turn. They leak air very badly. Seals can't seal with that much movement.
Leo
Leo
One more thing. The needles are different between the long and short, the long uses the 4JN19 needle, the short uses the 4N8. They are different lengths to match the length of the jet. Can't swap them.
Leo
Leo
Yes, very helpful.
I noticed that straight off -- the shafts on this 73 set I am working on are sloppy. I'll try, but I'm going to recommend to the owner that he get better carbs.
I do know about the different length needles, thanks.
Lots of people say the early bike ran better than the later. Some say it's the cams, some the head porting. I think it may have been that but I also think the raised floor carbs were part of it too. The raised floor increased the air velocity across the needle jet and under the slide. This increase in velocity creates a stronger vacccum to draw gas as well as better vaccum signal for the slide.
I want to get this set fixed sometime just to compare then to the 76-77 set I have.
Just to see if there is a difference.
Leo
I want to get this set fixed sometime just to compare then to the 76-77 set I have.
Just to see if there is a difference.
Leo
bluebikerblan
Geezer
The early year carbs with raised throat floors were, I believe, all of the unlinked variety.
That linking angle iron mounting section says 76' or later linked carbs/no raised floor and
long needle jet to me. Blue
That linking angle iron mounting section says 76' or later linked carbs/no raised floor and
long needle jet to me. Blue
Your right blue his carbs are linked so they are 76 or later. The screw in float valve seat means they are 76-79.
Just had another thought. Dogbunny, what made you think they were 73 carbs? Did you go by what the brass parts are? The 76-77 carb set I have gave me fits, until I realized they were 76-77 carbs with 74 brass parts in them.
Just saying, they may have the right jets for a 73 but they might not be 73 carbs.
Leo
Just had another thought. Dogbunny, what made you think they were 73 carbs? Did you go by what the brass parts are? The 76-77 carb set I have gave me fits, until I realized they were 76-77 carbs with 74 brass parts in them.
Just saying, they may have the right jets for a 73 but they might not be 73 carbs.
Leo
Check this out. It may help id your carbs. Migt want to save it to your computer, I did. The translation makes for interesting reading, but you can figure out what they mean.
www.xs650.fi/pohja_files/fi/XS650carbs.htm
Leo
www.xs650.fi/pohja_files/fi/XS650carbs.htm
Leo
Sorry for the confusion.
That picture was just a handy carb set that I had lying around to show how I was measuring the length of the part of the jet that is in the float bowl area. I was in a rush, and it didn't occur to me that I was creating a red herring.
The carbs that I am actually working on are clean and are on the bike. Therefore, that photo would have been difficult to get with them. I have never worked on anything earlier than a 1974 carb set until today, that is why I was unaware of the raised floor style. I am now positive that the actual carb set in question that I am working on is 1973.
Thanks for the heads up.
That picture was just a handy carb set that I had lying around to show how I was measuring the length of the part of the jet that is in the float bowl area. I was in a rush, and it didn't occur to me that I was creating a red herring.
The carbs that I am actually working on are clean and are on the bike. Therefore, that photo would have been difficult to get with them. I have never worked on anything earlier than a 1974 carb set until today, that is why I was unaware of the raised floor style. I am now positive that the actual carb set in question that I am working on is 1973.
Thanks for the heads up.
By the way, to further add to the confusion, the 1973 carbs I have (single enrichener that is linked to the other carb, separate throttle cables, raised floor, etc.) are linked at the slide chamber caps with a "butterfly" from a later linked model. This might actually be a good idea, as it adds rigidity.
Adding the Butterfly plate at the top will help stabilize the carbs as well as help keep them level.
As far as the enrichener, my 73 carbs are that way to. Hiose to feed enrichened mixture to other carb. Mine also have chrome plated tops and brass plated throttle cable holders.
Leo
As far as the enrichener, my 73 carbs are that way to. Hiose to feed enrichened mixture to other carb. Mine also have chrome plated tops and brass plated throttle cable holders.
Leo
I tried, but the 1973 bodies with the sloppy throttle shafts proved to be unusable. Just as you said they would be. I rebuilt a set of 1976 carbs, and the bike in question now runs better than mine.
I sure learned my lesson on that one. I will never again tell someone I can fix their carbs without first grabbing the throttle shaft and testing it for play. I also agree with 5twins when he said he would never use unlinked carbs except for a restoration.
I sure learned my lesson on that one. I will never again tell someone I can fix their carbs without first grabbing the throttle shaft and testing it for play. I also agree with 5twins when he said he would never use unlinked carbs except for a restoration.
Interesting. The 1976 set I rebuilt had chromed float bowls. What's funny is that they didn't bother to remove the jets before chroming. One jet had to be removed with an easy out. Fortunately, the jets protected the threads in the bowl bodies, but I had to chase the drain plug hole threads.
I like the '76-'77 carb set and feel it's one of the nicest. Very nice midrange with those large Z-8 needle jets. You would think the top end might suffer due to the smaller mains but I don't feel much difference (if any) compared to my '78 set.
If you need to rejet that set because your buddy has mods, be aware that you won't be able to run mains up around 140 like on newer sets. That large Z-8 needle jet will prevent that. Best I could do was mains in the low to mid 130s.
If you need to rejet that set because your buddy has mods, be aware that you won't be able to run mains up around 140 like on newer sets. That large Z-8 needle jet will prevent that. Best I could do was mains in the low to mid 130s.
Interesting.
The bike has pods and what I think is a MikesXS 2 into 1 exhaust system. I went up one size on the pilots, leaned the needles by one slot and went up 6 on the mains to 137.5. I thought that might be too much for the mains, but I know that rich is better than lean and that these bikes can still run pretty good with a too big main (thanks to your and grizld1's carb guide), and I had already spent way too much time on this bike and I needed to get it out the door, so that's what I ran. I didn't do extensive fine-tuning -- didn't do any fine tuning at all. Bike runs great. Plugs look good. The owner is extremely happy. The bike had never, ever run right for him, he can't believe what it's like now.
I might do a 5,000 rpm throttle chop the next time I see it to test that main jet size.
