Plugged Enrichment Valve?

Status
Not open for further replies.
Joined
Jul 10, 2008
Messages
237
Country flag
I have a VM34 carb that I believe has a clogged enrichment valve. It's far easier to start the bike without it than with. In fact, using it at this point appears to make the starting process all the more more difficult , rather than easier. I just cleaned the pilot and main jets. It fires up 1st, 2nd or 3rd kick usually, not using the enricher. If I employ the enricher, I can kick forever, and no joy. Then I spend another 6 or 7 leg exercises with the valve turned off to get the bike to fire. Once it starts, however, it idles wonderfully, runs like a scalded dog, and any subsequent starts after warmed during the course of a ride are no exception. Starts 1st kick w/ no enrichment. Does the enricher ever get clogged? How do I check for that, other than the symptoms described? If plugged, how do I go about cleaning it? It wasn't always this way. It had previously fired up 1st or 2nd kick with the enricher all the time, and no, I haven't changed any settings at all. Only change I can think of are using platinum plugs, which should prevent clogging and failed spark, not the other way around. Is spark plug gap set the same v. regular plugs?
 
Joined
Oct 19, 2005
Messages
18,978
Country flag
Its been awhile since I checked in on the enricher but do remember is was pretty obvious how it came apart and back and how it functioned. A plunger type affair.
Sudco may have exploded view on line. Main booger is fiddling with the cable version of lever.
 
Joined
Nov 10, 2006
Messages
1,415
Country flag
Once running if you operate the enricher does the motor 8 stroke?

If the primary system is correct, It might be the float valve has a slight leak raising the float level rich enough to enable cold starting, once the bike is running not enough to cause problems. Or perhaps a petrol tap is leaking wetting the whole inlet.

Just a thought.

Cash
 
Joined
Dec 19, 2004
Messages
413
Country flag
Hi slupdawg,
The enrichening circuit in a Mikuni carb can become plugged up. The starter jet is located in the float bowl itself. Remove the float bowl and along the front edge of the bowl wall you will see a hole into which slides the brass pick up tube for the enrichener when the bowl is installed. At the bottom of that hole is a small brass jet, using a wire, guitar string, small drill bit, or jet cleaning tool, you will be able to poke through it. Then you will be able to use a spray can of carb clean or brake clean to rinse it out (squirt through it from both directions.
There are different size starter jets (usually sized to application from the manufacturer), unfortunately once pressed in they are pretty much a done deal. The 34mm TM flatslide that I have recently installed on my 850 is in need of a smaller jet, the enrichener is much too rich and the engine starts blubbering right away (8 stroking) and loading the plugs up. Of course if I switch it off the engine goes lean and stalls, so I end up sitting there for a few minutes playing with the enrichener control up and down till the engine becomes warm enough to idle. I do not know if the starter jets are available seperately or must be purchased with a new bowl. I have changed them by drilling a small hole in the bottom and driving it out, drive in a new one, then plug the hole with a small set screw. Come winter I will change mine to a smaller one (even if I have to make it myself).

GB
 
Joined
Oct 31, 2009
Messages
5,193
Country flag
I have had an issue with the detent device the is attatched with the same nut as the plunger. It has taken some tweaking the get the choke lever to function correctly with that detent plate, device, thingy, what ver you want to call it. Anyhow it can and will get out of line.
 
Joined
May 19, 2009
Messages
644
I put the cable operated plunger on my VM34 a few months ago. I've fond that you can feather the enrichment circuit with the old bar mounted choke lever in a way that is pretty difficult with the carb lever. I found it won't start without the choke, (60f around here), but 8 strokes within 5-10sec on full, so a taper over around 30sec does it. I still need to bump up the idle screw for a few minutes or it's liable to stall. Because of this and the fact that I can't get it to transition cleanly to the slide , where it really starts to pull, has made me order a TM. It should be here next week. They ship way overjetted, according to Sudco. This should be fun to dial it in.
 
Joined
Jul 10, 2008
Messages
237
Country flag
Good advice, all. I did find and clean the valve and voila! Fired 1st kick. I'll see if the bike was just showing off or intends to behave that way from now on. It never 8-strokes with the enricher engaged and if I start without using it, I give a little throttle as it catches and it idles nicely straight away. If I flip plunger down at that point, the idle increases, no stuttering at all. So for the moment, I'm happy with it. Thanks.
 
Status
Not open for further replies.
Top