Can 1300 carb diaphragm slides be used in a 1200?

[safetyguy]

A couple of years ago Condor wrote that the difference between the carb diaphragm slides from a 1200 and a 1300 was one had a larger vent hole.

 

It appears to me that that is the case -- and the vent hole on the 1300 is noticeably larger. I am replacing one cracked slide housing (the black plastic part) on a 1200, so the question is can I use a 1300 slide without any problem?

 

I also thought about using JB Weld and re- drilling the hole to the 1200 size. Has anyone done this?

 

Last two questions - is there any place to buy 1200 slides cheap? If not does anyone have one 1200 slide (even one in pieces that I can reglue) that they care to part with?

[mrich12000]

I saw three on ebay Very expensive :mo money:though.check it out if ya need them.

[jasonm.]

A couple of years ago Condor wrote that the difference between the carb diaphragm slides from a 1200 and a 1300 was one had a larger vent hole.

 

It appears to me that that is the case -- and the vent hole on the 1300 is noticeably larger. I am replacing one cracked slide housing (the black plastic part) on a 1200, so the question is can I use a 1300 slide without any problem?

 

I also thought about using JB Weld and re- drilling the hole to the 1200 size. Has anyone done this?

 

Last two questions - is there any place to buy 1200 slides cheap? If not does anyone have one 1200 slide (even one in pieces that I can reglue) that they care to part with?

Yes, there is a difference.I may have some 1200 slides. One appears to have a good diaphragm. I had this 1983 bike less than a year. Crashed it and I believe I removed the new(1987) good slide diaphragm assy. before the insurance wrecker took it away. PM me if you are interested.

[charlie h.]

I picked up a parts bike, an 83, same as mine, but mine has an 86 engine. The 83 1200 only has 11673 mi. on it, so i pulled the carb tops, and the diaphrams were like new! So, I used my 86 needles, and the 83 1200 slides, and it runs good, however, it high idles from one slide sticking. Should I drill the slides holes bigger, or not worry about it?? BTW, the 83 needles were much thinner, more agressive taper, and had plastic washers like my 86... I was told that 83's had adjustable needles, with 5 pos. clip, like old school bikes. Any ideas why this one had plastic shim on needles like my 86 did? I am using 2 brass washers on 86 needles, and runs good, 43 mpg.

[skydoc_17]

The difference between the sliders in the 1300 Carbs. and the 1200 Carbs. is that the body diameter of the 1200 Plastic tube (slider) is smaller. That is why the 1200 Carb. slider would "fit". (and I use that term loosely) The 1300 slider will not fit in the 1200 Carbs., period. The reason that Charlie's bike is high idling is because the sliders are too small in the larger 1300 Carb. Body Bores. Air is leaking past the Clarence between the slider and the bore of the Carb. The Diaphragms are the same on all of the First Gen. Ventures.

Earl

[charlie h.]

Hi,

I also put the 1300 slides and springs into the 83 1200, and they fit fine. I am thinking maybe the original owner of my 83 used the carbs off the 83 on the 1300 engine... or maybe not. I don't know, but the 1300 had longer springs that would not fit into the 1200 slides, and so I used the respective slides and springs from each engine, and just swapped them as a set from the 1200 to the 1300 and vice versa. the engines both run, and the 1200 runs well with the 1300 slides. I had one slide in the 1300 from the 1200, that was sticky, and if I blip the throttle, it doesn't high idle and 2k any more. But it is consistent, if I don't blip., then it is at 2k rpm so that is why i thought it was sticking.

I will swap the slides(1300) back from the parts bike(1200), and see if it runs better.

[safetyguy]

Not that I would ever questions Earl's experience with these things, but it would be nice to know if there really is a difference in the slide diameters between the 1200 and the 1300 slides. If the "bigger" 1300 slides fit in the 1200 carb body as described, this argues for them being the same diameter size-wise.

 

Seeing that charlie h. has both in his possession at the moment, would you be willing to measure the outside diameter of both (with appropriate calipers) and report back to everyone?

 

Also, if we go with my original assumption that the two are the same (with the difference being in the vent hole sizing), can they be used interchangeably? What is the real impact of the size of the vent hole? Unless I have the way these carbs work backward in my mind, I am thinking that the larger the vent hole is, the result will be a slower throttle response on the low end with a slower return to idle from the high end.

 

 

Hi,

I also put the 1300 slides and springs into the 83 1200, and they fit fine. I am thinking maybe the original owner of my 83 used the carbs off the 83 on the 1300 engine... or maybe not. I don't know, but the 1300 had longer springs that would not fit into the 1200 slides, and so I used the respective slides and springs from each engine, and just swapped them as a set from the 1200 to the 1300 and vice versa. the engines both run, and the 1200 runs well with the 1300 slides. I had one slide in the 1300 from the 1200, that was sticky, and if I blip the throttle, it doesn't high idle and 2k any more. But it is consistent, if I don't blip., then it is at 2k rpm so that is why i thought it was sticking.

I will swap the slides(1300) back from the parts bike(1200), and see if it runs better.

[CrazyHorse]

Not that I would ever questions Earl's experience with these things, but it would be nice to know if there really is a difference in the slide diameters between the 1200 and the 1300 slides. If the "bigger" 1300 slides fit in the 1200 carb body as described, this argues for them being the same diameter size-wise.

 

Seeing that charlie h. has both in his possession at the moment, would you be willing to measure the outside diameter of both (with appropriate calipers) and report back to everyone?

 

Also, if we go with my original assumption that the two are the same (with the difference being in the vent hole sizing), can they be used interchangeably? What is the real impact of the size of the vent hole? Unless I have the way these carbs work backward in my mind, I am thinking that the larger the vent hole is, the result will be a slower throttle response on the low end with a slower return to idle from the high end.

 

Are you talking a bout one of the jets? The one in diaphram area called the main jet? I used the original 1983 needles and pilot jets in my 1990 and used skydocs lowering kit. I then wanted to use the original 1983 main jet which I believe is #180 throttle response was not as good as my original #170 main jet so I returned to that. I ve thought about trying out a #160 size jet. I ve got good power and good mileage.

Edited September 24, 2010 by CrazyHorse

[skydoc_17]

Hey Mike,

I take no offense at your statement that you think that the answer I posted is incorrect.

I would like to add some additional information so you will understand why I said what I said.

First off, you are Assuming that the Carb. Rack on the 1200cc motor you are trying to repair is the original rack for this motorcycle. Unless you check the bore diameter of the Carbs. on that bike you can't tell the difference between the MKI and MKII Carb. racks with the naked eye.

Here are some part numbers for the MKI and MKII VR's Carbs. (I selected the #1 Carb. for this comparison for both Carb. Racks.)

 

1987 MKII VR #1 Carb.

Diaphragm Assembly: 1FK-14940-00-00

#1 Carb Body: 1UN-14901-01-00

 

1984 MKI VR#1 Carb.

Diaphragm Assembly: 41R-14940-00-00

#1 Carb Body: 41V-14901-00-00

 

These part numbers plainly show that the Carb. body is different as well as the Diaphragm assembly between the two Carbs. Now we also know for a fact that the rubber Diaphragm is the SAME for both the MKI and MKII VR. So the difference MUST be in the plastic slider part of the assembly. Because of the larger engine displacement of the MKII VR the slider bore is also larger to allow more fuel and air to pass into a larger engine. So if the slider bore is larger on the MKII VR then it would stand to reason that the slider would be larger as well. The difference in the part numbers above would prove this fact.

 

If you would measure the slider bore on BOTH of your engines, and find out that they were the same size, then you either have an MKII Carb. Rack on your MKI engine OR you have an MKI Carb. Rack on your MKII engine. If your measurement shows that the slider bore is different, then this would prove that you do indeed need a different slider for the MKI as apposed to the MKII Carb. Body. Without these measurements, It's basically a crap shoot and it will be hard to send you the proper parts you need.

 

At this point, you are either MORE confused, or you know EXACTLY what you need to do to provide the information WE need to send you the correct slider to get you up and running.

 

By the way, I have good used, MKII sliders that I would be happy to send if it would get that bike running!

Earl

[safetyguy]

Thanks Earl- I am good on slides these days. (I replaced 4 on my 88 with new ones) and just picked some up for my little Yamaha Virago 535 (which I haven't put in yet).

 

The temporary patch that I made to the slides in my 87 Virago 535 (XV535) adds more to my confusion over the diameter size of the slides.

 

The 535 wasn't running well and it turned out one of the slides came apart (i.e. keeper out of the black slide body). I glued this one back together. About 200 miles later, the other slide on this two cylinder beast came apart in the same manner as the first. I glued this one but dropped it while handling and it broke. So I needed a slide in a hurray to keep it on the road.

 

While researching the purchase of a replacement, I found somewhere on-line that said the 535 carb slide was the same as a slide for a Venture 1200. Being experimental, I looked at the old 1300 slides that I had taken out last year. It seems to me all dimensions (except the vent hole adjacent to the needle hole on the 1300 slide is significantly larger in diameter) were the same when I measured it. So I glued up a 1300 slide and installed it in the 535 to get it back on the road. (I had recently done the same with an old 1300 slide for a friend with a 1200 back at the beginning of this thread).

 

Basically, the 1300 slide works fine in the 535. The diaphragms are the same size and are interchangeable as well. It seems like the low end power is off a bit but I figure it is no worse than having some pinholes in the diaphragm. I will replace both of the carb slides soon with ones purchased recently from another VentureRider.org member.

 

Ater I did this, I found that the 1200 slides are interchangeable with 1990 and newer 535s (i.e. through Yamaha part numbers). The part number for the 1987 and 1988s are completely different. More confusion --

 

So this begs the question - even if the part numbers for all of these slides are different, it seems to me that the only variable is the size of the vent hole. (my guess remains that the exterior dimensions is the same for all. ) The needle retention plastic screw is the same.

 

If someone can post the diameter and overall length of a 1200 slide body, I can do the same for a 1300 and 535 slide body. By slide body, I mean the black plastic piece with everything off.

 

While this seems an academic question, I wonder if other slides for Mikuni BS34 carbs could possibly work. For instance, here is a link to a carb slide for a 80-84 Yamaha XS650 which also uses a BS34 carb. The replacement slide is $62 not $150.

 

http://www.mikesxs.net/products-75.html#products

 

Another variant of the Mikuni BS34 carb was used in 1985 Kawasaki ZN1100B2 LTD's (as an example). I think that the BS34 carb was used in some Yahama outboard motors as well. Could something like this work? How does one research this?

 

I guess what I am wondering is - have we missed other possible (and cheaper) sources for these slides? The other question is: is the vent hole sizing really that critical? Maybe Mikuni developed a solution to the problem of the slides coming apart in subsequent years (e.g. the 1990s) and these parts could work as well.

[charlie h.]

OK, Mic'd the slides, they are both 30.00 mm diameter, the 1300 slides have bigger hole in the bottom of slide, and longer springs, that don't fit well in the 1200 slides. The 1200 slides have a shorter spring, and they are narrower. I swapped both sliders and springs, as a pair, and they worked fine. My prob with high idle is still there with the original sliders, I put them back in, so it is a sync prob, I think. So, the 83 parts bike has plastic shims on the needles, like my 1300 engine had, but a more agressive taper. I was told here that the 83's have circlips and 5 positions, like old school or mikuni VR round slides do. Hmmmmm.... Anyway, they are both same diameter slides!

[savannahgman]

Yes, there is a difference.I may have some 1200 slides. One appears to have a good diaphragm. I had this 1983 bike less than a year. Crashed it and I believe I removed the new(1987) good slide diaphragm assy. before the insurance wrecker took it away. PM me if you are interested.

 

was wondering if you still had them slides? I have an 1983 venture 1200 Yamaha.

 

just need one if for sale? thanks..

[savannahgman]

Hey Mike,

I take no offense at your statement that you think that the answer I posted is incorrect.

I would like to add some additional information so you will understand why I said what I said.

First off, you are Assuming that the Carb. Rack on the 1200cc motor you are trying to repair is the original rack for this motorcycle. Unless you check the bore diameter of the Carbs. on that bike you can't tell the difference between the MKI and MKII Carb. racks with the naked eye.

Here are some part numbers for the MKI and MKII VR's Carbs. (I selected the #1 Carb. for this comparison for both Carb. Racks.)

 

1987 MKII VR #1 Carb.

Diaphragm Assembly: 1FK-14940-00-00

#1 Carb Body: 1UN-14901-01-00

 

1984 MKI VR#1 Carb.

Diaphragm Assembly: 41R-14940-00-00

#1 Carb Body: 41V-14901-00-00

 

These part numbers plainly show that the Carb. body is different as well as the Diaphragm assembly between the two Carbs. Now we also know for a fact that the rubber Diaphragm is the SAME for both the MKI and MKII VR. So the difference MUST be in the plastic slider part of the assembly. Because of the larger engine displacement of the MKII VR the slider bore is also larger to allow more fuel and air to pass into a larger engine. So if the slider bore is larger on the MKII VR then it would stand to reason that the slider would be larger as well. The difference in the part numbers above would prove this fact.

 

If you would measure the slider bore on BOTH of your engines, and find out that they were the same size, then you either have an MKII Carb. Rack on your MKI engine OR you have an MKI Carb. Rack on your MKII engine. If your measurement shows that the slider bore is different, then this would prove that you do indeed need a different slider for the MKI as apposed to the MKII Carb. Body. Without these measurements, It's basically a crap shoot and it will be hard to send you the proper parts you need.

 

At this point, you are either MORE confused, or you know EXACTLY what you need to do to provide the information WE need to send you the correct slider to get you up and running.

 

By the way, I have good used, MKII sliders that I would be happy to send if it would get that bike running!

Earl

 

 

 

I need a slider for my 1983 venture 1200, anyone have one for sale?