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Bville-Bud

87 600 Carb question

13 posts in this topic

I just bought a 87 and have a ton of questions. I keep reading about the problems with the carbs and that the later single carb works better. Can I just swap the carbs out?

Thanks,

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I just bought a 87 and have a ton of questions. I keep reading about the problems with the carbs and that the later single carb works better. Can I just swap the carbs out?

Thanks,

Is the bike running poorly? My 87 runs perfectly, dual carbs and all.

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I just bought a 87 and have a ton of questions. I keep reading about the problems with the carbs and that the later single carb works better. Can I just swap the carbs out?

Thanks,

The thing about dual carb setups not being reliabel, or allowing geed power is a myth. They work great if you maintain the bike and keep the carbs clean. The only problem is if you jet them wrong you can get into trouble since they have to be synced. Once setup correctly they will allow the bike to run strong forever. Actually the HRC race teams ran the early dual carby heads thru 93 or 94 because they provided way better flow and as such power.

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No, the carb is not a direct swap. Ideally you would get a later cylinder head also, but the swap can be done with a fabricated intake tube.

The people who have dual carb 600s often say how great they are, but none of them seem to know how to tune the duals.

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Thanks for the replies. I am taking it to the shop monday and see if they can check them out.

You never mentioned what the problem was.

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No, the carb is not a direct swap. Ideally you would get a later cylinder head also, but the swap can be done with a fabricated intake tube.

The people who have dual carb 600s often say how great they are, but none of them seem to know how to tune the duals.

Why would you need a head swap? Why not just swap intake manifold from XL dual carb to XR Single carb and then run a pod filter or just block off the left side air boot and seal it with silicone.

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The intake boots are not interchangable between single and dual carb heads. The dual carb head has two seperate intake ports, one for each intake valve. You can't block one off without seriously reducing the engine's output. My old man has a dual carb 600 and I have a '95 single carb 600, so I'll see about getting some pictures.

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The intake boots are not interchangable between single and dual carb heads. The dual carb head has two seperate intake ports, one for each intake valve. You can't block one off without seriously reducing the engine's output. My old man has a dual carb 600 and I have a '95 single carb 600, so I'll see about getting some pictures.

They have the same 3 bolt mount intake manifold plate so why wouldnt the XR600R single work in replacing the XL600R dual? I have measured it and they are identical bolt pattern!

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They have the same 3 bolt mount intake manifold plate so why wouldnt the XR600R single work in replacing the XL600R dual? I have measured it and they are identical bolt pattern!

Yeah, I know they have the same bolt pattern, but the sealing surface under the flange is far from the same.

dualcarb1.jpg

dualcarb2.jpg

This is a dual carb head. It has two individual intake ports with an empty space between the sealing surfaces. A single carb head has one big open port. If you try to use a single carb intake boot on a dual carb head, you'll have a vacuum leak like no other.

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Well no; if you're a decent fabricator, a custom intake manifold wouldn't be too difficult to make. It would be hard to make it fit in the same space as a single carb intake boot, though. A single carb head would be easier for someone without the ability to customize whatever needed it.

.....I'm a machinist and sometimes have to be careful what I recommend since it is often not practical for many with normal garage workshops. :p

I have a wideband oxygen sensor which would be very effective at ironing out a tune for a dual carb engine, let alone any 4-stroke. Maybe I should try it and see if I can't become a dual-carb specialist. :cheers:

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Actually if you use the XR600R manifold and the XL600R fanolic spacer it should work! Therefore no vacuum leak.

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