New carb isolator and adjustable main jet

David Maner

I just came in from switching my main jet out to the adjustable one that is to be had on eBay from time to time for $9.70 shipped. I also order a new carb isolator and switched it out. The protrusions that the spark plug wire threaded though on the isolator is not used due to the fuel pump pulse connector being in the way so it bothers me to have them sticking there not being used. So I purchased a new isolator and proceeded to remove those 'tits' and clean that little bugger up.

First photo is of that isolator after I cleaned it up and installed it.

Second photo is what my engine looks like after I finished with all this. The rod that goes to the right from the choke lever is my choke. simply sticks out from the body under the seat to the right of the original air intake/choke on this DS. The spring pulls it off so all I have to do is release it once the engine is running and let the spring pull the choke off.

Personally I think my engine compartment is looking pretty tidy.
I painted my exhaust pipe with high temp silver paint with ceramic for the purpose to keep the temps down in that engine area. Made a big difference in temps too. Also it cut down on the noise from the exhaust pipe as a bonus. After I noticed that the paint lowered the noise level the thought hit me to paint my valve cover and that cut down on valve train noise too. In the end its a cooler and quieter running engine.

I started the engine and let it warm up then put a block on the throttle to hold the engine at 2500 rpms and commenced to adjust the main jet. Screwed it in until the rpms started to drop then turned it out until the engine started to slow down again then set the needle midway between the two. Slightly to the rich side. I'll pull the spark plug after a 1/2 mile of running at 25/30 mph and adjust the needle in accordance with if I need to add more fuel or need to lean it out some. Looking for a honey colored spark plug. Much easier than drilling the main jet out a little at a time until I get where I want to be. I had it adjusted prior to this mod today but now if I make any changes to the intake or exhaust all I'll have to do is readjust that main jet needle valve. no more taking the carb off to drill the main jet or put a new jet in and start all over when i go too far as I've done :-)

Attached Images

	460 carb isolator.jpg (154.2 KB, 0 views)
	460 black.jpg (88.0 KB, 0 views)

BGW

__________________
This advertising will not be shown in this way to registered members.
Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum

raydhd

A procedure that worked better for me was to say start @ 1 1/4 turns and run up to max rpm. Then keep going richer an 1/8 of a turn at a time on each run up to max rpm. When the engine starts to stumble back the jet leaner an 1/8 of a turn. You will be slightly rich on the plug BUT you will also notice going any leaner will result in less sharp throttle response,slower acceleration and more fall off at max revs.

David Maner

That pretty much gets us both to the same place.
The way I just described is how I've been adjusting carbs for years. it keeps me from running lean or rich other than a tad one way or the other. Once I get the cart out of the shop, raining here today, and drive it I'll know pretty quickly which way I need to go, leaner or richer. Once I get the main jet dialed in I'll revisit the low speed jet. Having this adjustable main jet makes it so easy to adjust the carb over disassembling carb and drilling the main jet out then putting it all back together. This way its just a matter of turning the screw.
A tach or a vacuum gauge makes adjusting a carb much easier too. On a single cylinder the vacuum gauge kinda fluctuates too much but the tach gives you a good read on which way to turn the jet. Right now I'm within 1/8 turn of being right on. Plug will tell me which way I need to go.

Turn the jet in until the engine rpms drop, make note of where you're at then turn it out past where it runs faster to where the rpms start to drop again then put the jet in the middle between the two, slightly to the rich direction 99 percent of the time is spot on. Stabbing the carb WOT will pretty much tell you if you need to go richer or not. If it takes gas without a stumble, lean it up a tad, try the WOT again and see how it does. If it stumbles then richen it back up that tiny bit you leaned itup and see how it drives or operates. chances are you'll be right on. If you really want to get serious then go back to the low speed jet and fine tune it and then back to the high speed.
Then check the plug and watch for that golden color to appear to make the final fine adjustment. Then throw the screw driver away and leave the carb alone. If it starts to not run right chances are it is not the carburetor. I've had engines that has ran for years and years without as much as a look at the carburetor. Filters and spark plugs is where to go in that order. never the carb or almost never

Airplanes have two complete separate ignition systems for a clue. outboard motors have a separate ignitions for each cylinder for the same reason. Now with the advances made with electronics some of the outboard motors will be different.

David Maner

When I first put this engine in and started it up gas ran out of the overflow so I took the float bowl off and rattled the float up and down a few times to free up the float and needle valve because in shipping one or the other was stuck. I've not had a problem since. I've never had a problem with any small engine because the fuel pump was over riding the float needle valve. according to the physics of it all there pretty much is no way it can over power the float and needle valve.

if it ever happens to me it'll be a first.

I had an old ford that someone had put a high volume/high pressure fuel pump on and it had a carb that had the sight glass float chamber so I put a pressure regulator in line, someone had told me that I had too much pressure for whatever the problem I was having. turned out to be an ignition problem. Any way I adjusted the pressure down and then back up all the while watching the fuel level in the float bowl and no matter where I put the pressure regulator the fuel level stayed the same. Come to find out my points were pitted and barely opening. New points and I was back in the hunt for the fun part of a young mans life rather than piddling with a durn old car trying to get it to run right.

Shepard

The "High Speed Jet" should be adjusted as it's used. It can be adjusted several ways as was described in earlier post and it works for the operators who use it. I adjust mine like a chainsaw. Get it started and warm as you can get it. Pull the throttle wide open and start turning the high speed screw [ most of the time it's open to far] inward. It will spit and sputter -- keep turning slowly -- all of a sudden the RPM will increase - keep turning till you reach your desired rpm [mine is 5500] -- this happens very quickly. Once you get constant smooth acceleration when you open the throttle --- open it a 1/16 turn more to wet it ---- overcoming any leanness. After its driven a few miles check your plug -- it should be a caramel brown with a black soot ring on the base.
This is how I bench tune a saw and the principal works for any tune-able carburetor engine.

David Maner

I'm not sure I have the intestinal fortitude to hold the throttle wide open or not.

Hope you're doing well Ol' Man :-)

PEACE

David Maner

I guess its my turn to say, I learned something new today.
Between you and Shep and how to get there from here I'll have to give each of yah's procedure a try

Peace

Shepard

The weather is finally up in the double digits. Its been 2-3 degrees for weeks it seems. Now its 35 today, great day for a ride.

Rooster59

Subscribed. This will come in handy in a couple weeks after I get the muffler on my VC625. Right now without a muffler it backfires pretty good going down the road. I am sure it will be lean after installing the muffler, but it must be real lean at the moment.

David Maner

It finally got above freezing here yesterday so I took to the woods.
My brother the 400 plus acres land owner of our mushroom hunting grounds and I went on a 10 mile drive. When deer season opens we shut down and pretty much stay out of the woods for fear of being mistaken for a 4 legged creature. We traveled on all the roads/trails, many of which we blazed out with my cart. There is several square miles of uninhabited acres of these Ozarks foothills that back up to his place so we use it like it was ours. With a ton of respect for that land and treating it as we do his. Leave nothing but tracks all the while picking up any trash we might run across from the hunters and pack it out. Most of the hunters are pretty good about taking out all of what they bring but there is always a few jacka$$e$ though
Barely breathing today so I'm paying for all the fun I had yesterday. No problem as I have a new aquarium project to work on here in the house that gives me that something I just have to have to do. You know what I mean on that.

peace
Bro'