Altering 1200 Carbs ??

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Rat
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Altering 1200 Carbs ??

#1

Post by Rat »

Anybody tried this 1200 carb modification ?

Apparently there’s a 'secondary air supply' arrangement that this guy removes .... he claims it’s a big 'seat of the pants' improvement ....

https://m.youtube.com/watch?v=roDnXSRiYpY

Gord :roll:
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‘14 KLR650 ... not a rat ... yet
‘84 GL1200i ‘R2B6' (Rat to Be 6, the last, adopted by twowings)
My Original 'RAT' was a hybrid '82 CB900/1100F
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wingrider
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Re: Altering 1200 Carbs ??

#2

Post by wingrider »

To my understanding, he basically did a desmog like we do on the Valks. I am not quite sure how that added the boost in power he talked about unless the bike was running poorly before the mod. I have looked at 1200 carbs, and wondered about getting rid of these things, but frankly I don’t have enough experience with them to say if it is a good idea.
2002 1800 Wing
2001 Valkyrie Interstate
1978 1200 EFI Wing with Motorvation Coupe Royale sidecar
1977 1200 Wing cafe/bobber project
1974 Suzuki GT550
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Re: Altering 1200 Carbs ??

#3

Post by ericheath »

Quite a few have gotten rid of the secondary air. I don’t recall anyone else feeling an improvement in performance. Probably something else wrong in the his system as Wingrider suggested.

I did it first when using the 1000 heads, then when I swapped to 1200 heads. I felt the 1200 heads were better down low in rpm.

Then I put the V65 carbs in. They’re a slightly different animal.

There are a few people who swear a washer under each needle help the 1200’s.
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
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Liam
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Re: Altering 1200 Carbs ??

#4

Post by Liam »

Not wishing to bore anybody on this, but what follows are my observations.
I have a few 1200s. All except 2 have no secondary air apparatus fitted.
The first one is a 1200 Standard, which has plugs fitted to the heads similar to what the guy in the video shows.
Except, mine are a black plastic material. I didn't do this, it was like that when I got the bike.
I would have to assume that this was a modification done by a previous owner, goodness knows when or why.
The other is a 1986 Interstate. On this one, the cylinder heads are different in that they are cast without the spacing for the connecter,
so this had no secondary air from day one.
2 of the 1200 standards I have do have the secondary air system, and 1 doesn't. I can't tell any difference in performance between them.
Maybe because I am far too busy smiling the face off myself while riding them.
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Re: Altering 1200 Carbs ??

#5

Post by Liam »

I think the boost in power mentioned is similar to that of a single carb conversion or taking out half the blades from your lawnmower.
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Re: Altering 1200 Carbs ??

#6

Post by Rat »

You mean Honda got it right ??

Gord anim-cheers1
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‘14 KLR650 ... not a rat ... yet
‘84 GL1200i ‘R2B6' (Rat to Be 6, the last, adopted by twowings)
My Original 'RAT' was a hybrid '82 CB900/1100F
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Re: Altering 1200 Carbs ??

#7

Post by CYBORG »

Hard to believe a carb expert who doesn't know what the drain for the float bowls is
1978 custom GL1000
1977 custom with 1200 engine
1985 gl1200
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Lucien Harpress
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Re: Altering 1200 Carbs ??

#8

Post by Lucien Harpress »

If it's anything like the equipment on my KZ, literally all it does it inject clean air into the headers downstream of the exhaust valves, and it only does THAT to meet emissions standards that no longer exist.

Nothing gained or lost if you ditch it, depending on how hard it is to plug everything off.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
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Re: Altering 1200 Carbs ??

#9

Post by 77Gowing »

CYBORG wrote:Hard to believe a carb expert who doesn't know what the drain for the float bowls is
Bingo!!!
You woke me up Cyborg! I asked a lame question about how to tell if your carbs are getting fuel last night & PID was exasperated & rightly so. I seemed to recall that about three years ago I had to stop tinkering with my build for the Michigan winter, and was able to open the drains...doah! What is happening to my memory? Wow!
Under my nose all the time.
Have a great laugh at me fellows, I dont mind.
Secondary air I too assumed was an emission addressing solution. More of a Dilution solution anyway.
"Less is More" Anonymous

77Gowing
1977 GL1000 "O'le Blue." (sold :crying)
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1982 Honda GL1100 "After thought." Gone
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