Carb questions

[TexinMaine]

I did a search and dint come across my predicament. I have an 81 Venturer. It has stock air filter and exhaust. When I purchased it the PO said he had just cleaned the carbs but after it didnt seem to idle well. He is correct as it would not idle without the choke on. Today I decided to dive into the carbs and came across some oddities. So according to the Models and jetting section my main jets should be 115 on 1&4 and 120 on 2&3 for the 81 H. I found that all 4 are 110's. I also found that my pilots did not have the rubber plug and the pilot on #4 was different from the other 3,



So I am sure I need all new 42.5 pilots but do I leave the 110's or search for the original 115's and 120's? These are the carbs I have.



On as side note the PO had lost the ball and springs for the choke rod. Luckily I found one sprig and from reading was told that ACE hardware carried the necessary 1/8" ball bearings. I have been to 3 Ace hardware's and the smallest they have is 5/32, which is 1/32 larger than the 1/8. has anyone drilled the hole to 5/32 and used the lager baring?

Thanks to all.

[jetmechmarty]

The factory service manual calls out jet size. I would not take the bet that 110 is correct across all four. Specials are jetted differently than standard. 110 across sounds correct.

Don’t drill. Find a 1/8 ball.

[TexinMaine]

Thanks Marty. I am ordering 115 and 120's right this moment. Then gonna check Ebay for the ball bearing.

[TexinMaine]

I think even the specials call for 110 and 120.

[Radioguylogs]

FWIW, My '80 Special has 110's across the board.

[bikerphil]

If they are truly 81 carbs, you won't need the rubber plugs in the pilot jet towers. There is no crossover passage.

[skids]

FWIW, My '80 Special has 110's across the board.

I have taken apart two 80 Special carbs and one 81H carb set where none have been apart before. ALL had 110 mains. None of those had the rubber plugs. (None of the 80’s were the transitional carbs with rubber plugs)

[soccer4m]

81 special, venture

I have the same bike 81 vent. and I faintly recall the 2,3 were different because of the oil cooler factory installed that isnt on the special. IF MOTOMAN can read this please allow some of your mastery of the 81 venturer carbs, as he has done so many times......MOTOMAN we need you......I recall, years ago I had the larger size jets in the 2,3 cylinders,,,,,,,,,probably still run ok with the 110 across all four, but the oil cooler does change the cooling draft effects on the 2,3 cylinders.....Mike in SUnny DIego

[soccer4m]

carbs

HOwdy,,,just called Motoman and got some info....the actual stock venture carbs use 115 outer, 117.5 on 2,3 cylinders, the stock special carbs are slighty different with 115 across all four, the xj1100 also uses a diff. set across....anyway, from what I can get out of Motoman, if you have a stock venture carb, 115 and 117's should get it back to stock.....Mike in Sun DIego

[TexinMaine]

This is what I was using as a guide to main jet sizes. It in the "maintenance" section.



I have already ordered the 120's so hopefully it will not be a problem.

[jetmechmarty]

I checked last night. My SG has 115 main jets across all four. I put them there for some reason. It was a long time ago. No logbook.

[MPittma100]

1981 XS1100H Venturer

I have not had carbs apart on this bike before. I have a Yamaha service manual that shows 110 main jets on 1-4 cylinders.

[MPittma100]

SG Jets

I checked last night. My SG has 115 main jets across all four. I put them there for some reason. It was a long time ago. No logbook.

Marty, Yamaha manual says the SG came with 110s 1-4.

[motoman]

For Texin and you alls information, the Specials ONLY uses 5GL16 metering rods...numbering/lettering found on side near top of metering rods. Venturers use a different numbering metering rods. Also, 80-81 Specials metering rods ARE a bit shorter and tapering is a bit steeper and comes to a point. Venturer metering rods ARE a bit longer and a more gradual taper coming to a more rounded point. So, for Texin's help, the replacement main jets you have gotten ARE correct for the Venturer, as long as someone hasn't changed the metering rods. The shorter, quicker taper of the 80-81 Special jets is what made the Special the 'bar- hopper', and the longer more gradual taper of metering rods on the Venturer(Standard) made it the LD touring model, having the non-noticeable for and aft when touring interstate roads and going through the gradual dips of the Interstate roads. In other words, that least bit of throttle movement is un-noticed on the Adventurer, wher-as the Special with ever so slight throttle movement IS noticed. I know this cause since having bought my Venturer new, and decades later installing 81 SPECIAL carbs with the ORIGINAL factory 110 mains, I definitely noticed that slight surge for and aft on LD Interstae rides. LD rides, I mean some 12-1500mile rides, ALL Interstate. Hope that helped those who ARE mis-informed. BTW, as Soccer4m stated, Yamaha did that staggered main jetting(1&4 left leaner than 2&3) cause of the cooler restricting cyls. 2&3 from air flow across cyls. AND the expected heavier loads it WILL carry. Venturer also had slighty larger diameter rear shock springs along with FOUR positioning dampening adjustments on each rear shock. Also Venturer has progressive and stiffer front fork springs than the Special did, along with the air-fork valves. Also Venturer's rated load rating is WAY higher than the factory full-dresser Hardly-Davidson, which to this day is second rated load carrying ability compared to the Venturer 1100.

[jetmechmarty]

Marty, Yamaha manual says the SG came with 110s 1-4.

Once upon a time, I had a lean condition. I went through the carburetors. I probably went to 115 at that time.