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XS1100UK Forum  |  Technical  |  Hints and Tips  |  Topic: Cleaning carbs with a spray
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Author Topic: Cleaning carbs with a spray  (Read 3483 times)

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Brian

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Cleaning carbs with a spray
« on: September 20, 2010, 11:34:25 AM »
The following is a good technical guide to cleaning your XS1100 carbs using spray cans of carb cleaner.  

I'm not the author, it was written by Skids, I found it ages ago on his website and copied it into my 'hints and tips' library, now the original website has gone  :hitme:  So, it's a big 'Thank You' to Skids.

==========================================
How to clean your XS1100 carbs with spray cleaner
==========================================

Crud can migrate in the passages kind of like arteries and heart attacks (sorry for that analogy). I wouldn't bother disassembling the whole set of carbs for a soak in carb solution unless absolutely necessary. Instead, I would clean them without full disassembly as follows:

You need:

about three or four cans of carb spray cleaner.
shop vac with a hose that fits the carb inlet.
rubber gloves
eye glasses
glass jar
caliper for float height check
care so you do not mess up the floats (or just remove them)

Step-By-Step Procedure:

1. Remove the bank 'O carbs.

2. Remove the tops and the diaphragm assemblies with springs and keep them in order.

3. Remove the float bowls.

4. Remove the main jets and toss them into a small glass jar.

5. Push the nozzles (the brass emulsion tubes that the mains screw into) upward into the bores that the diaphragm cans were resting in, and pull them out. Do not pull them out with needle nose pliers as shown in the Clymers manual, or you will mar them and the main needles will not slide in the nozzles smoothly! Toss the nozzles into the glass jar.

6. Remove the screwed-on caps that cover the pilot jet if your model vintage is a '78 or '79. If your model is '80 or '81, they will not have caps.

7. Remove the pilot jets with a good-fitting screwdriver. I had to grind the sides of a screwdriver to get it to fit properly. Tap the handle a few times with a hammer to help break them free. If your mechanic did these already, they will be bright and clean-looking and will not be stripped or buggered up. Toss them into the glass jar. If your jets are suspect, get new ones. They are cheaper from Honda than Yamaha. but you must take one in for the style match-up.

8. Put on some rubber gloves and glasses to protect your eyes.

9. Spray out the holes in the carb bowls with the straws on the cans of carb cleaner. This is where eye glasses might save you!

10. Spray enough liquid cleaner into the glass jar to submerge the brass parts and let them soak.

11. Remove the pilot screws (aka air/fuel mixture screws), springs, washers and orings (80 and 81's). Note that 80 and 81's have covers over the pilot screws, which are recessed, when in factory configuration. You must remove the covers to properly clean the carbs.

12. With the carb body upside down, spray into the starter jet (aka choke) tube. It is that one-inch long brass straw that fits into the hole in the float bowl. While doing this, open and close the choke to flush it out. Don't worry too much about the pinhole in the base of that brass tube at the base of the carb body, it is supposed to be there to entrain air into the fuel.

13. With the carb body right side up, spray down the pilot screw bore and it should spray down the pinhole beneath it into the ventouri bore by the throttle plate.

14. Cover that pinhole with your finger, open the throttle plate to expose the other three pinholes, and force carb spray into the idle circuit passage. It should at least drip out of the three pinholes, and will run out of the opening for the pilot jet and if you have a 78 or 79 model, it may also run out of the main jet bore.

15. Spray into those three pinholes from the inside of the ventouri bore. You will have to hold the throttle plate open to do this.

16. Now turn the carb body so that the bottom of the body is toward you (for reference) and the inlet of the ventouri bore is up (this is the side with the holes around the perimeter). Spray the hole at 10 o'clock. This is a hole that vents the float bowl to equalize pressure. Cleaner liquid will run out of the hole on the lower-left corner (relative to the position you are holding it) of the float bowl gasket seat of the carb body.

17. Remove the air pilot jet and put it in the glass jar. Spray the perimeter hole at 8 o'clock. This is bore for the air pilot jet. Carb cleaner will run freely out of the pilot jet hole, next to the main jet hole, and some may run out of the pinholes and pilot screw bore.

18. Spray the pressed-in main air jet in the perimeter hole at 4 o'clock. This bugger is difficult to get clean. Fluid should run freely out of the main jet bore, but on '78 and '79 models, it may also run out of the pilot jet bore because of the interconnecting drill hole. Note that on those models, the main jet size has a direct effect on operation of the idle circuit because of that drill hole (near the main jet location).

19. Only '80 and '81 models have perimeter holes at 2 o'clock. This hole serves to vent the float bowl area (yes, another one). The '78 and '79 models instead had hoses to ran up to the air box to serve the same function. I disconnect and spray out the inside of the air hoses on those models.

20. Note that while spraying the air pilot jet bore (step 18), you may have forced particles back into the pilot circuit. Repeat steps 13, 14, and 15.

21a. If you removed the floats and fuel valves, clean the valve needles (I wouldn't soak the ones that have the rubber tops used in the later models and provided in some rebuild kits). Make sure the spring action of the needles works as it should. Clean the valve needle seat area with a q-tip wetted with cleaner. Do not soak the valve assembly in cleaner because the screen retainer will weaken and may fall apart. If you have the later model carbs, replace the O-rings of the seats of the valves.
DRYING: Now, use the shop vac to dry the passages in the carb body. This is important to suck out any loosened particles and to suck out any liquid that could be ladened with gasoline tars. If you do not do this, the tars may "puddle" and re-solidify in troublesome places. Note that the carb body has little brass balls pressed in at various places. They are there because Mikuni interconnects straight holes to make angular turns in the passageways of the carb body. The unused openings to the outsides are sealed off with the pressed-in balls. The problem is that the portions of the lengths that are dead-ended are crud accumulators. Vacuum-dry the carb before it has a chance to do this. If you have the earlier models, you can replace the fiber washers but you should take care in finding some that are the correct thickness, or your float height will be way off.

22. If you removed the floats (recommended), place the vacuum hose over all of the fuel inlet openings on the bottom of the carb (pilot jet opening, main jet opening, brass straw, fuel valve opening, and work the choke back and forth. Give it a good amount of drying time.

23. Hold the shop vacís hose to the inlet of the ventouri bore (the side with the perimeter holes) with your right hand. Hold your palm against the outlet of the carb. While sealing top of the carb against your belly (because you are now out of spare hands!), work the throttle plate back and forth to open all of the pin holes. Hopefully, any particles that are left will be sucked out as it dries. Give it a good amount of drying time.

24. Clean up the nozzle tubes, that have been soaking, with a wooden tooth pick.

25. Hold each pilot jet carefully with forceps and spray into the threaded end. The carb spray should be about equal for each hole in the side and should stream out the other end. If they are questionable, buy new ones.

26. Reinstall all of the brass into the body.

27. Adjust the float heights with the gaskets removed from the carb body. I use a caliper that has a slider in the handle for this measurement and measure the height (carb upside down) from the gasket mating surface (no gasket) to the top-most part of the float. Do each side and use the average. Adjust if necessary. I have never used the manometer method described in Clymers for the 1981 models.

28. Reassemble all other parts, except for the bowls, and prior to putting the diaphragms back in, inspect them up to a light for holes. Repair holes with RTV Ultra Black, rubber dip, or similar. Never clean them with carb cleaner. Wipe off the cans with cleaner on a rag. You might want to clean the main jet needles at the bases if necessary.

29. Test the float valves for leakage by blowing into the fuel inlets with the bowls off and the carbs upside-down. There should be no leakage. I am informed that, while blowing, as you tip the carb bank, the fuel valves should release all at the same angle (if they are balanced).

30. Replace the bowls onto the respective carb bodies. Turn them upside down again and blow into the fuel hoses to test for leakage. The reason for the retest, is that floats do not have much clearance in the bowls, and if they were bent, they may stick against the sides.

31. Install on to the bike with a clean air filter and air box, inline fuel filters, and non-rusty gas tank.

« Last Edit: October 20, 2011, 12:07:03 PM by Brian »
XS1100 LG & SG, FJ1200

I'm a demon for modifying (erm, posts that is)

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petejw1966

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Re: Cleaning carbs with a spray
« Reply #1 on: September 21, 2010, 12:48:40 PM »
Hi Brian,
Thats a really good write up, the only thing that
i would be worried about is using an electical shop vac
to suck out the carb cleaner, compressed air would be much
safer to use instead.
Peter
1981xs1100rh.

Brian

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Re: Cleaning carbs with a spray
« Reply #2 on: September 21, 2010, 12:55:53 PM »
Yep, I used an air jet rather than a vacuum, it seemed to work fine.

Maybe I'm tight, but I managed to do my carbs with only one can of spray, but then I lashed out and used four glass jars to keep the little bits from each carb separated.  :grin:

And I would say that the use of safety glasses is highly recommended, some of them channels point straight back at you  :cry:
« Last Edit: September 22, 2010, 10:20:58 AM by Brian »
XS1100 LG & SG, FJ1200

I'm a demon for modifying (erm, posts that is)

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garym

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Re: Cleaning carbs with a spray
« Reply #3 on: September 21, 2010, 12:57:36 PM »
Brian, How much improvement do you think it made ... On a 1 > 10  ?
1978 XS1100 2H9 E
1978 K2 'PLAIN JANE' GOLDWING
Hanging around, nothing to do but frown.  Rainy days on Sundays always get me down.

Brian

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Re: Cleaning carbs with a spray
« Reply #4 on: September 22, 2010, 10:20:37 AM »
Brian, How much improvement do you think it made ... On a 1 > 10  ?

Can't say 'cos I did mine for preventative maintenance rather than performance.   So, hopefully, future problems were avoided  :beg:
XS1100 LG & SG, FJ1200

I'm a demon for modifying (erm, posts that is)

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garym

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Re: Cleaning carbs with a spray
« Reply #5 on: September 22, 2010, 11:58:01 AM »
Mmmm probably leave mine alone then....   :grin:
1978 XS1100 2H9 E
1978 K2 'PLAIN JANE' GOLDWING
Hanging around, nothing to do but frown.  Rainy days on Sundays always get me down.

spanner1954

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Re: Cleaning carbs with a spray
« Reply #6 on: September 22, 2010, 09:25:37 PM »
hmm!! if its not broke bro !! dont try and fix it  :rofl: :rofl: :rofl: :rofl:   works for me ...     :hitme:  .
xs 1100s 5k7 streetfighter trike , old hippy biker n triker .
sheffield south yorkshire.

Tom

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Re: Cleaning carbs with a spray
« Reply #7 on: September 23, 2010, 09:59:33 AM »
hmm!! if its not broke bro !! dont try and fix it  :rofl: :rofl: :rofl: :rofl:   works for me ...     :hitme:  .

I must admit, I always wait till my engine seizes solid before changing the oil :rofl: :rofl: :rofl: :rofl: :rofl: :rofl:
It makes you look a cnut but question everything!!


Tom, belligerent old tosser!!
Dazed and confused

Graeme

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Re: Cleaning carbs with a spray
« Reply #8 on: September 23, 2010, 04:41:21 PM »
I must have broken dozens of things that never needed fixing in the first place.

Trouble is I can't resist the pull of the 'wonder whats inside that' or 'how does that work then'.

Not limited to mechanical things either, but don't tell the wife!
1979 F 2H9 Blue/white
1999 V-Max Carbon Canadian import / 1982 10M XJ Maxim Blue

Miti

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Re: Cleaning carbs with a spray
« Reply #9 on: September 23, 2010, 07:23:31 PM »
Graeme

You have personal mail...

Miti
Jeff Mitchell
Glasgow

1974 Triumph Trident T160
1981 XS1100 Sport (x2)
1982 Hesketh V1000
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Mick

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Re: Cleaning carbs with a spray
« Reply #10 on: September 24, 2010, 01:23:54 AM »
I used two cans of spray type carb cleaner on the Midnight carbs, + redx in fuel

  looks like its working  :grin:

2H9 standard US import (Shropshire re-reg.1999)
4H3 LG Midnight special
SG frame and Engine (3U9)
LH 4W1 Midnight Special
Stoke On Trent


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 Don't let me forget tell you the motorcycle run on petrol, like sex is all so beautiful

XS1100UK Forum  |  Technical  |  Hints and Tips  |  Topic: Cleaning carbs with a spray
 

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