1st gen MKII carb question

[dingy]

Does anyone know what size the MKII carbs are.

 

The service manual shows they are 34mm Mikuni's, but I have been told that they are 35mm Mikuni's.

 

I would like to put a set of 35mm's on the bike, but I would want to verify this before getting a set.

 

The Venture History tab also shows them being 34mm.

 

I know the sliders are not interchangeable between MKI & MKII's which might indicate a venturi size change.

 

Gary

[Grisolm1]

I have several period road tests for the 86 MKII. They all state 35mm. One states they went up by 1mm to get there.

 

To my knowledge the 86-92 carbs use the same body as the VMAX but with different jetting.

[greg_in_london]

I ran a thread on details of carburettors and their innards a year or so ago. I'll do a search and see if I can find the link.

 

Well I found the thread (http://www.venturerider.org/forum/showthread.php?t=20950&page=14) but it didn't have as many details on specific bikes as I remembered. It did confirm though that Mk1s mostly had 34mm carbs and later ones and 1300s switched to 35mm.

 

If you have 35mm, then check the parts lists on the site, but I reckon they'd be 35mm.

Edited November 27, 2010 by greg_in_london

[mbrood]

The carbs are listed as BDS 34mm (down draft) for all 1st gen bikes in the service manuals.

 

The jets were changed a bit with the increased cubes.

Edited December 2, 2010 by mbrood

[GaryZ]

I researched the differences in

 

Venture MKI - Venture MKII - Vmax - Venture Gen 2

 

The cross-ref shows the Royal Star has 32 mm carbs and all others were 34mm.

This info mostly came out of the repair manuals.

Edited December 2, 2010 by GaryZ

[Condor]

I researched the differences in

 

Venture Gen 1 - Vmax - Venture Gen 2 - Royal Star

 

The cross-ref shows the Royal Star has 32 mm carbs and all others were 34mm.

This info mostly came out of the repair manuals.

 

I noticed in the pfd file specs that the hp rating for the 1200 MkI and the 1300 MKII were listed as the same at 97hp, and it's been a while, but I'm sure I found a listing for the hp on the 1200 @ 94hp in a service manual or owners manual somewhere... The extra hp came from the +100cc's and caming maybe?? More weight needs more low end grunt. So it made sense to me???

[GaryZ]

I noticed in the pfd file specs that the hp rating for the 1200 MkI and the 1300 MKII were listed as the same at 97hp, and it's been a while, but I'm sure I found a listing for the hp on the 1200 @ 94hp in a service manual or owners manual somewhere... The extra hp came from the +100cc's and caming maybe?? More weight needs more low end grunt. So it made sense to me???

 

The Service and Owner's manuals do not list HP (What's the deal?) and I found the listed numbers by searching "specifications" on the web. I checked and double-checked. 97HP is the most common listing for both the MKI & MKII. I think the cam specs on the MKII add a little torque down low for the massive weight increase. Of course there is a loss on the top-end

 

I rechecked the Owner's manual for my XVZ12DN and updated a couple of things on the pdf. The biggie is the wet weight . . . the Owner's manual says 769lbs and the web specs had 30lbs less. I have attached the latest version of my pdf for your use and abuse.

Edited December 2, 2010 by GaryZ

[dingy]

I received the 86 carb set today.

 

They are 35mm, as opposed to what the service manual calls out at 34mm.

 

Also got the Vboost unit and VMax air cleaner box.

 

Got a bonus with the Vmax air cleaner, it has a nice K&N filter in it.

 

Gary

[GaryZ]

I received the 86 carb set today.

 

They are 35mm, as opposed to what the service manual calls out at 34mm.

 

Also got the Vboost unit and VMax air cleaner box.

 

Got a bonus with the Vmax air cleaner, it has a nice K&N filter in it.

 

Gary

 

 

How do you identify the size of these carbs when they are right in front of you?

Inquiring minds want to know . . .

[bkuhr]

The Service and Owner's manuals do not list HP (What's the deal?) and I found the listed numbers by searching "specifications" on the web. I checked and double-checked. 97HP is the most common listing for both the MKI & MKII. I think the cam specs on the MKII add a little torque down low for the massive weight increase. Of course there is a loss on the top-end

 

I rechecked the Owner's manual for my XVZ12DN and updated a couple of things on the pdf. The biggie is the wet weight . . . the Owner's manual says 769lbs and the web specs had 30lbs less. I have attached the latest version of my pdf for your use and abuse.

 

Cool info, maybe should be added to Venture History tab.

[dingy]

How do you identify the size of these carbs when they are right in front of you?

Inquiring minds want to know . . .

 

I measured the throats on the bottom of the carb rack.

 

Measures 1.370" inches, 34.925mm.

 

34mm would be 1.338"

 

Gary

[greg_in_london]

I need to withdraw from this discussion - from memory I had been pretty sure that the Mk1's changed from 34 to 35mm carbs, but it was 2 1/2 years ago that I researched carbs in detail (time flies) and I can't remember what all my sources were.

 

Without access to the specs, I won't claim that my information is accurate.

[mbrood]

Is it just coincidence that they came with V-Max parts? The 86 V-Max has the BDS35 carbs ! (???)

[dingy]

I have compared the 86 Venture carbs parts list to the 86 VMax carb parts list and they are very similar.

 

Jets and choke setup are main internal difference.

 

All the parts that come in the rebuild kits are the same. Gaskets, O-rings, etc.

 

Gary

[mbrood]

My "American" service manual states BDS34 while this UK pdf service manaul clearly states BDS35... Sure wouldn't be the first time our manuals have been wrong, though !

 

http://www.yamahaventureclub.co.uk/downloads/19861987XVZ13DSSCTTC.PDF

 

Without any hard current evidence, I would think that any design team, taking her from 1200 to 1300cc by changing the bore, keeping the stroke the same, would opt for a step up in carburation, volume in - volume out. The seach goes on.

Edited December 5, 2010 by mbrood