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Carb's -- BS34-BS38's ID. Push Rod Bushing Replacment
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650skull
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PostPosted: June 12, 2009, 8:08 am    Post subject: Carb's -- BS34-BS38's ID. Push Rod Bushing Replacment

From xs650.org carby evolution, all specs. Web Page Name

From Mikes XS. Pictorial of carbs and push rod replacement Web Page Name

Carb Tuning -- Stock/VM's --- From 650 Garage, by Grizld1, 5twins and Pamcopete Web Page Name Must read
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650skull
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Joined: Jul 19, 2007
Posts: 1186

PostPosted: October 24, 2009, 3:37 am    Post subject: Re: Carb's -- BS34-BS38's ID. Push Rod Bushing Replacment

Quote::
A good read for Do's and Don'ts when Cleaning your Carbs

Quote::
Question by: heckienawjoe
well, i adjusted the idle screw on the left carb to result in higher idle speed, but the problem remains only this time, there are no high rpms on choke. in fact, choking results in killing the engine (when running) or inability to start (when not running). I can get the engine going with really weak idling (around 1000) but when i shift to first it dies (when giving normal amounts of throttle -- will engage and run with excessive throttle but is really jerky and u can tell the engine just wants to die).


Quote::
Answer by: Xumi

Just confirms the need to clean the carbs, especially the pilot circuit (the smallest passageways that handle fuel and air flow at idle up to 1/4 throttle, also called the idle circuit, pilot jets or idle jets in other writeups)

Just make sure of a few things for your first time through carbs...

Take pictures before you disassemble anything, and take more along the way.

Take your time and don't rush.

Get a couple cans of spray carb cleaner and be generous with it. Let dry thoroughly, or blow it out with Mildly compressed air (about 20 psi).

If it is brass (yellow or light brown depending on the condition), it is SOFT - be careful removing, cleaning and inserting, as it can be an ex-part very easily. The jets (little tubes with screwdriver slots in them and holes through the length) are made of Brass.

Be gentle. If it doesn't come out, soak it for a little while in carb cleaner and try again. If it is a Jet that is truly stuck, then make sure your screwdriver is fat and the blade fits the whole width of the slot, so you don't disfigure the brass by torquing it.

If a gasket or o-ring is torn.. replace. I tried to make my own gaskets for carbs once.. many many hours later I wished I'd just purchased a set.

The funny rubber things under the top lids are called Diaphragms. They are VERY sensitive to tear, being a very thin rubber. Very small tears can be repaired, large damage cannot. They don't handle carb cleaner very well either. Be very careful taking them out and inserting them. When installing, make sure the lip fits the groove all the way around.. be patient, and it will usually go in fine.

DO NOT SOAK YOUR CARBS!

Let me repeat that...

DO NOT SOAK YOUR CARBS!

I'm sure that your neighborfriendunclebrotherbosscoworker has repaired at least 50 carburetors in his life and swears by supergunkcleaneverything carb dip at your local chucksnapautozonemomnpopshop store, and swears that you should soak your carbs overnight.

Well, as many great carb guys here will tell you.. don't do it. You'll end up needing new carbs instead of just clean carbs. There are exceptions of people soaking their carbs in things like Simple Green and a few other mild cleaners.. which is probably ok, but I've never found it necessary, including cleaning out the bug and mud infested carbs that were on my barn find.

99% of the time, a thorough cleaning of the bowls (the bottom containers of the carbs), the jets (funny looking brass screws with holes in them), the little air holes that go everywhere, and the float assembly and valve(looks like a Siamese twin version of an old-school toilet bowl float) will fix the problem.

Don't try to disassemble the butterfly assembly the choke assembly or separate the carbs unless things are REALLY nasty... because it makes the job of reassembly harder, and as I said above, 99% of the time isn't necessary.

What happens during that 90% is that the bike sat with fuel in the carbs.. the fuel evaporated, and left behind something very similar to what's left when coke evaporates. It clogs up the fuel passageways and jets, and sometimes even the small air passageways in the bowls. It gum's up the float valve, which leads to carbs leaking when the valve can't shut off the fuel flow.. Get this varnish/crap/whatever out of the way of the fuel and air, and you have working carbs.

The other 9% is typically bad gas, old gas, rust or some type of contaminant that has gotten into the bowls and fuel passageways and prevents the smooth delivery of fuel. Same solution - clean thoroughly, but now you at the least need to drain your tank and replace the fuel (and buy a good fuel filter)... and at the worst have rust in your tank to deal with. If you find a brown/red powder at the bottom of your bowls.. you have rust, and if you don't deal with it before trying to ride again, you'll be taking those carbs apart again soon.

Last piece of advice... Read every write up you can get your hands on.. Twice. Ask questions if you don't understand. Take apart your carbs, cleaning everything as you go, and then read those write ups again, because (for me anyway) until I had seen the things apart, I didn't understand the writeup very well. Put things back together... and of course adjust and sync according to manual (or there are great write ups here on the subjects), and enjoy.
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