Cold Start - Too Rich? -- RESOLVED --

Burnarr

Many thanks for that information and I can see the logic in what you describe. Unfortunately, my rack is back on right now (although it'll be off again in the near future no doubt!) so I can't look for that pin hole in the side of the enrichment pickup tube. I hadn't noticed it before even though I am now somewhat intimate with the carbs :lol: I have made a "bike sticky" to check that next time the bowls are off.

Thanks again for your reply.
Best!

 

Well if you ever have the misfortune of having to break into the carbs again, take a look and let us know for sure. The only carbs I have are for Mikunis for the 550 so I can't check for myself.

Here's a pic from the Hitachi picture thread http://www.xjbikes.com/Forums/viewtopic/t=3649.html...

If I squint just right, I can convince myself that I see the hole at about the 2:00 position.



Then again, it might just be a spec of dirt. :lol:

Without question, however, you can definitely see the other end of the passageway that provides the atmospheric air to that area. So there's no mystery about where that other hole on the right side goes.

Burnarr

 

There's a Hole in the Siphon Tube close to the Body.
That Hole on the Siphon Tube is like the Air Holes drilled into the Emulsion Tube.

The circled Air Jet regulates the flow of AIR introduced to the Siphon Tube at that point ... REGULATED ... by the AIR Jet that the un-punched-out Gasket blocked.

The AIR from Inside the Fuel Bowl ... Rich with Fumes from the Fuel in the Bowl is Vented into the Port on the Siphon Tube and rushes to the Combustion Chamber when the Enrichment Valves are opened.

Air, already Rich with Fuel Vapors ... gets drawn-up to the open Enrichment Circuit.
As the AIR passes through the Siphon Tubes Hole, close to the Body, it draws-up FUEL from the supply in the WELL that the Siphon Tube extends into on the Fuel Bowl.

Without the Air entering the Tube at the Port near the Body, the entire Volume of the WELL would be "Sucked-up-into" the Combustion Chamber without the AIR breaking-up and atomizing the Flow and reducing the Vacuum which would empty the WELL and likely flood the Engine rather than just provide an additional Rich Mixture to get a cold Engine going.

 

Yeah, that's what I figured as well. That's why CMoney ran so rich on enrichment with that die cut slug plugged the air supply hole.

So did all of the gaskets have that slug still in place or was it just one of them? What about the holes for the pickup tubes? Were they still in place as well?

Kinda wondering if the people who made the gaskets left slugs in there on purpose, or was it was just an accident... :?:

 

They're all like that (punched but not knocked out......a potential hanging chad, for sure........). I think it's it's just part of the mass-production process, or perhaps those gaskets also fit some other made carbs that do not require the holes to be open??

 

Hanging chad... Nice. :lol:

Yeah, I was thinking the multiple applications thing too. Maybe there's another carb where you don't want those holes open. I get rebuild kits for stuff all the time that have two or three very similar but slightly different gaskets in them so that the kit can be used in lots of different applications. It's simply cheaper for the mfgr and all the people in the supply chain to standardize on it despite the waste.

I'm thinking that maybe they're doing the same thing with these gaskets and we may be getting caught in the middle if we don't know what we're looking for.

 

My carbs had that hole blocked when I first took them apart. I only punched out the hole where the tube passes through when I put new gaskets on. Too bad you were not able to try to push start your bike. Mine starts cold in 1 foot of dumping the clutch. It did eventually start if I cranked the p out of it. I tried that once because I thought I was going to be into the starter after I saw how easily it push started. I rode the bike for 1200 miles in this condition. I had it tuned to compensate for whatever that blockage caused. 50mpg with a wind screen and able to do burnouts all the way through 1st gear. Crap. More colortuning, syncing, and the carbs must come off again!