Carb servicing time! - Success!!!!!!!

the_Journeyman · March 12, 2011, 06:43:10 AM

Thanks dp, I'll give it a shot!

JM

the_Journeyman · March 13, 2011, 03:35:44 PM

Ok, so after spending the day draining fuel, removing tank, removing airbox (this requires the battery to come out, the coil rack to be removed from the airbox, and then the ignition switch removed to allow the airbox to slide free) as well as various electrical connectors and a few wires.

Removing the carbs completely from the bike requires disconnecting the fuel line, both throttle cables, choke cable, and the various vent lines. Ducpainter mentioned it didn't remove the carbs for changing the emulsification tubes, and next time, I won't either. You can get to everything with them on the bike, just work around the frame tubes and I'll probably move the oil cooler out of the way.

The carbs themselves are reasonably simple. I did find a T-handle phillips head driver was very handy for removing the very tight bowl screws. Once the bowl was off, I removed the diaphragm & slide. Emulsification tube just pushes up through the carb and out. Slide the other in, line up properly with the main & pilot carrier and you're good to go. Put retainer back on and reassemble.

Compare the two tubes:
Old on left, new on right.

Now, off to source diaphragms since mine have cracks. I'm very interested to see how she'll run with good emulsification tubes and not cracked diaphragms.

JM

WarrenJ · March 13, 2011, 06:57:01 PM

I had that work done at the dealership on my 2000 750 last fall and the results were great. Mileage is back up to 48 - 53. The bike sounds better, responds better. I think you will be pretty happy. Not enough guts or smarts to dig into the carbs yet on my own.

hooligan machinist · March 13, 2011, 09:08:53 PM

Quote from: WarrenJ on March 13, 2011, 06:57:01 PM
Not enough guts or smarts to dig into the carbs yet on my own.

Go for it. It's really a lot more simple than most people think. Took me a year to build up the courage due to the many horror stories i'd heard. But once in, no sweat at all.
Fine tuning the mixture and balancing is more of a challenge but still well worth the effort.

WarrenJ · March 14, 2011, 04:13:59 PM

I studied up on the valves and that went pretty smooth so next time, I'll dig into the carburation.

the_Journeyman · March 14, 2011, 07:29:33 PM

Yea the carbs themselves are relatively simple. All the stuff you have to work around to get to them is more frustrating than the carbs. These are the most modern carbs I've work on, and I didn't find them very difficult to work with.

JM

MaaloX · March 15, 2011, 06:08:42 PM

Quote from: the_Journeyman on March 11, 2011, 05:04:14 PM
Ok. Emulsion tubes .

Journeyman...I am doing this exact same thing this weekend and wanted to get a head start on cleaning and tore one of the O-Rings...where did you purchase the emulsion tubes ? I bought my gear from CA but did not see those specific items...Bought the
Factory Pro titanium kit
Pilot Jet for Mikuni CV Carbs, #37.5
scarce main jet o-ring

the_Journeyman · March 16, 2011, 04:57:59 PM

The tubes I bought came from Ca-Cycle works, they also supplied the main jet o-rings. My mains refused to budge, so I didn't bother using my main jet o-rings. I'm using the stainless Factory Pro tubes with the stock needles. I also had to replace my vacuum diaphragms.

Which o-ring are you referring to? There are several in the carb.

JM

MaaloX · March 17, 2011, 02:33:46 PM

I tore the o-ring on the main jet. I am waiting on those to arrive from CA. But I did not see the tubes on the site.

ducpainter · March 17, 2011, 02:42:41 PM

Quote from: MaaloX on March 17, 2011, 02:33:46 PM
I tore the o-ring on the main jet. I am waiting on those to arrive from CA. But I did not see the tubes on the site.

They sell factory-pro and the tubes are available separately from them. Maybe call Chris and ask.

the_Journeyman · March 19, 2011, 05:13:30 PM

If you search for "needle jet" on CA's site, you'll find them.

JM

the_Journeyman · March 20, 2011, 04:58:44 PM

Everything is back together. Starts easily but doesn't want to come on the throttle. You can see the slides hopping up and down as you try to increase the RPMs. In the first video, she chokes out and dies.

New emulsification tubes, new diaphragms too. Everything else in the carbs looked good.

In this vid, it chokes and dies when I get on the throttle, but you see the slides kind of hopping up and down as it attempts to throttle up
0320111911a.3g2

In this vid, around 0:14 you see what happens really well.
M750 with fueling issue

JM

ducpainter · March 20, 2011, 04:59:56 PM

How old is the fuel?

the_Journeyman · March 20, 2011, 05:40:21 PM

Couple months. However, turns out not the be the fuel.

Total dumbass move on reassembly. Turns out, while I had the diaphragm cap off the right hand side carb I had a dumb. When I put the cap back on, I managed to catch the choke cable between the cap & carb both. Totally killing my vacuum. Responds very nicely now. I'll take another test ride tomorrow and see on the road, but it was way better in the garage.

JM

the_Journeyman · March 25, 2011, 04:40:37 PM

Jetting is the combustible devil.

So... Good response mid-high RPMs. Just off idle, not so much. Sputtering, won't take throttle, killed it a couple times by just twisting the throttle from idle. Not sure if it's rich or lean. Less engine braking at low RPMs, like almost non-existent, popping if I barely open the the throttle. Very unstable at small throttle openings, if I try to maintain a small throttle opening, it is very choppy.

I'm leaning rich, even though I think it was a 70 in the pilot spot. I say rich, because after shutting motor off when warmed up, I can just barely tap the starter and it's idling again. Idles ok, sometimes really low, sometimes hangs a bit on closing the throttle.

I suspect the pilot, because once I really open the throttle, everything is fine. Mid to full throttle it responds fine.

JM

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Carb servicing time! - Success!!!!!!!