1st gen carb diaphragm pricing

[Dano]

www.flatoutmotorcycles.com has the best pricing for slider diaphragms. $55.53 on website as of this morning. That is 20-30 bucks less than anyone else. Web order only, plus shipping. Their counter guys work off of comission, so if you order over the web, that's what you're saving. I live 10 miles from there. But if I order over the counter, they cost me $72.00!

[Guest timshosvt]

Price went up to 65.70 at flatoutmotorcycles...but you can get them at http://www.zanottimotor.com/ for 63.25....You need to look up the part number elsewhere, as they don't have a parts fiche online.

 

Tim

[cimmer]

I found this price for a 89 VR on Flatout today.

9 DIAPHRAGM ASSY

1FK-14940-09-00 (replaces 1FK-14940-00-00)

1 $63.02

Checked on other years and found the same price for them also.

Rick F..

[Dano]

I found out that the '83 diaphragm is pricier than 84 & up. Don't know why, but the 84+ unit is still only 55.53

Dan

[PEIslander]

The Yamaha parts fishe lists the diaghram parts numbers as :

 

1983-1985 part# 41R-14940-09-00

1986-1993 part# 1FK-14940-09-00

 

Does anyone know what the difference is between these diaghrams? Besides the price! Don't all these models use 34mm Mikuni carbs.

 

Just curious. :detective:

[Guest lrayvick]

I used a thin coat of Permatex black RTV to repair a tear on a Honda VF750F vacuum diaphragm (as Honda calls them) and it works fine.

 

Generally the 20 to 25 year old Honda rubber is still good. Is the Venture rubber not so good? Those I have seen on Radian Mikunis have been as good as the Hondas.

 

Also my experince with Honda is not to mix vacuum diaphragms even with slides of the same diameter because (1) there are subtle differences in design that makes them operate differently and (2) if they come with the jet needles those are of various shapes.

[Denden]

The Yamaha parts fishe lists the diaghram parts numbers as :

 

1983-1985 part# 41R-14940-09-00

1986-1993 part# 1FK-14940-09-00

 

Does anyone know what the difference is between these diaghrams? Besides the price! Don't all these models use 34mm Mikuni carbs.

 

Just curious. :detective:

Right, all models '83 to '93 use the same 34mm Mikuni carbs, but there are some jetting differences. There is also a difference in the carb slide. The bleed hole in the '83 - '85 is slightly smaller than the bleed hole in '86-'93. The bleed hole is the hole in the bottom of the slide that is next to the hole that the needle goes into. The bleed hole allows the venturi vacuum to lift the slide.

http://en.wikipedia.org/wiki/Venturi_effect

[Squeeze]

...The bleed hole in the '83 - '85 is slightly smaller than the bleed hole in '86-'93...

http://en.wikipedia.org/wiki/Venturi_effect

 

 

Hi, this would have been my guess.

 

Did you measure the exact Diameter of the '83 Slides ?

[Denden]

Hi, this would have been my guess.

 

Did you measure the exact Diameter of the '83 Slides ?

Using a drill bit to measure...the '83-'85 slide has a bleed hole that is 3/32 inch (2.381 mm).

The '86 to '93 slide has a bleed hole that is between 1/8 inch and 9/64 inch...best I can do. The 1/8 inch drill bit is a little loose in the hole, the 9/64 won't fit in the hole. That makes it roughly 17/128 inch. (3.374 mm)

HOWEVER...as far as I know, you can't get the '83-'85 part anymore. If you order the 41R-14940-09-00 it will be updated to the '86-'93 part.

What I did to replace the diaphram and slides on my '83...I got the '86-'93 part, and filled in the bleed hole with Plastic-Weld epoxy. then I drilled it out to 3/32.

(I still have the original slides from my '83, and some old ones from a '86 Venture, so I'm measuring them now, not guessing.)

[Gearhead]

"I used a thin coat of Permatex black RTV to repair a tear on a Honda VF750F vacuum diaphragm (as Honda calls them) and it works fine.

 

Generally the 20 to 25 year old Honda rubber is still good. Is the Venture rubber not so good? Those I have seen on Radian Mikunis have been as good as the Hondas."

 

 

 

My 87 Virago has Hitachi carbs, and when I last had them out maybe 3 years ago they had some small, developing tears which I patched. Don't know what they look like now; they're harder to remove than the Venture's slides. And on my 87 Venture's Mikunis 3 of 4 were very badly cracked. They were still working reasonably well although cutting top end power some, but they appeared as if they would fall apart soon. The 4th had already been replaced. Maybe they were still patchable, I dunno, but I bit the bullet and replaced. I want to pull the Virago's carbs and have a look. While the Virago only has two of them, they are twice as expensive! I think it's some kind of plot!

 

Jeremy

[Squeeze]

Using a drill bit to measure...the '83-'85 slide has a bleed hole that is 3/32 inch (2.381 mm).

The '86 to '93 slide has a bleed hole that is between 1/8 inch and 9/64 inch...best I can do. The 1/8 inch drill bit is a little loose in the hole, the 9/64 won't fit in the hole. That makes it roughly 17/128 inch. (3.374 mm)

HOWEVER...as far as I know, you can't get the '83-'85 part anymore. If you order the 41R-14940-09-00 it will be updated to the '86-'93 part.

What I did to replace the diaphram and slides on my '83...I got the '86-'93 part, and filled in the bleed hole with Plastic-Weld epoxy. then I drilled it out to 3/16.

(I still have the original slides from my '83, and some old ones from a '86 Venture, so I'm measuring them now, not guessing.)

 

many Thanks Dennis for the precise Measurements.

 

Did you overthink to replace the PAJ#2 against those of a '86 ?

Would be worth a try instead of going to the Process of Epoxy and so on ... I did not check the different Sizes of the Jets, but i think smaller Jets would have been the Answer. I think the '83 might have #145 Jets, the '86 should be #170.

[Gearhead]

I don't see the relationship between the slide lift hole and PAJ#2. The lift hole controls the rate of slide lift, and PAJ#2 gives the pilot circuit its second air source which is cut off for coasting enrichment.

 

Unless I have this all wrong!

 

Jeremy

[Denden]

I don't see the relationship between the slide lift hole and PAJ#2. The lift hole controls the rate of slide lift, and PAJ#2 gives the pilot circuit its second air source which is cut off for coasting enrichment.

 

Unless I have this all wrong!

 

Jeremy

I think you are right, Gearhead. Anyhow, the PAJ #2 for 1200 and 1300 is the same...180, at least in the spec sheets. but I seem to recall working on some 1300 carbs with a PAJ #2 that was 170. But PAJ #2 wouldn't have any affect on slide movement. The "outer" side of the diaphram is vented directly thru a big slot to the top of the carb, open into the airbox.

BUT...the 1200 and the 1300 have different jet needle and needle jet. So it is best to keep the slide hole the right size for the needle jet/jet needle. Also, 1200 and 1300 have different length diaphram spring. It would get pretty complicated trying to sort out all the variables. I try to keep it simple, keep it stock. At least for the diaphram slide and needle and needle jet.

But to tell the truth, I put in the 1300 slides before I noticed the difference in the 1200 and 1300 slides. Then after I noticed the difference, I filled in the hole with epoxy and drilled it to the correct size. But I can't say I noticed any difference in performance...power or mpg's, maybe a slight difference in throttle response (maybe, I don't remember).