88 carb

[FES92xl]

Can someone tell me if there is a difference between a 88' and a '92 kehin carb?
my buddy's 88 is running like crap and i expect it might be the accelerator pump diaphram, my old carb is sitting on my bench and we were thinking of swapping them out
Thanks

[xlron]

Try it. And if that doesn't work, the diaphram is 5 bucks at HD. Just bought one last week. Keep in mind, that if you see gas squirting out the nozzel, you don't need a diaphram. And your check valve could be stuck ( right under the mast). Do not shoot any fluids under pressure, or air into the diaphram circuit while the diaprham is in there, or you will definetly need one.

[FES92xl]

cool thanks, my old carb worked decent so we might swap the carbs entirely, I dont have a manual that covers 88's so i'm not sure if there is any differences between the '92 i have

[ted]

88 has no accelerator pump.

[83XLX]

88 has no accelerator pump.

Yep. First year of the CV on a Sportster, and it had no accelerator pump. The '89 and newer ones do.

[xlron]

Thats why I'm saying it might require a new throttle & cables, and possibly a boot. (transition)

[ptotoole]

I managed to install a newer (used) CV Kehein on a 1986 sportster. The 86 had a pre- CV carb. I had to use a rubber 'boot' to attach the newer carb to the 86 manifold, and I ended up replacing the older air assembly with one that would fit to the newer carb. Also the different air and carb assemblies required a $25 bracket to secure the carb to the heads.

Then there is the breather assembly to deal with. Newer sportsters (90's) breath through the heads, via the air filter assembly, while the 86 breaths through the crankcase, via the air filter.

The assembly works, but I keep experiencing other problems, which are not directly related to the carb. I just keep fixing them as I go

[FES92xl]

thanks.. i do have my manifold, which should bolt right on the heads of an 88, also what is the air assembly? you mentioned the breather assembly seperately, so is the air assembly something different?

[ptotoole]

Air filter assembly includes 1)air filter
2)filter cover, that chrome ham can, which fits over the air filter and attaches to -
3)a backup plate, which attaches to the input of the carburetor.
4)The backup plate also attaches to the heads, which secures carb/air assembly to the engine (the heads).

Perhaps an 88 air assembly will fit to a CV carb. So the one you have might fit ok. My experience was with an 86 sportster, which had an older model non-CV carb, and the air assembly backup plate wouldn't fit.

I'll try my best to explain the 'breather system'; I am not an expert.

When the pistons move up and down within the cylinders, some air(gas) is forced past the pistons into the crankcase where it builds up pressure. Nonetheless, gasses get into the crankcase, and the resulting pressure must be equalized. So a 'breather system' was set up to do so. On my 86, a hose runs from the crankcase to the air filter assembly (it has nothing to do with the air/fuel system, the system just uses the air filter to filter those crankcase gasses, I'm not sure why)

On my 97 sportster, the breather system runs through the heads, via the air filter assembly. On the 97, those bolts that attach the air filter assembly to the heads are hollow so that crankcase gasses can be equalized that way.

I hope this helps, and I hope I haven't overwritten the whole thing.

Patrick

[FES92xl]

Thank man...
I figured you might have been talkin about the breather when you mention "air assembly"
The "ham can" is long gone and has the tear drop breather on her now, the crankcase breather line was always better in my opinion opposed to the head breather bolts.. Typical over engineering by HD