1974 D4 wont run right...I'm gonna kick it soon!

kbowley

Hi, My name is Kevin and this is my first post yet I have been following the forum since last fall when I began getting a 76 4 wheeler D4 running after setting in a garage for 20 odd years.

Here is my problem/question; When the cart is shut off, for instance going from forward to reverse, it re-starts very hard. I believe it is flooding because I must hold the throttle to the floor and it will slowly start sputtering and clear out and off I go. It also doesnt really peak out well when going for top speed unless it is down hill where it will scream beyond the power band. If not going down hill, it reaches the power band and slightly runs out of go power at about 16 mph. in summary;

1. When the engine is shut off while warm, it restarts as if the choke were on, the mixture is extremely rich.

2. It does not rev up as it should on flat ground, it just runs out of power and wont rev any higher. If I go down hill even slightly, it will reach 22 mph and the engine screams. the engine runs smooth with no sputtering, plug color is a nice light tan.

3. Compression is 115 psi...is this a high compression head? I am using an NGK BP4HS plug, however, the plug I removed was a Champion RC12YC which is a much longer reach plug. Do I have the correct plug or should I be using an NGK BP4ES/Champion RC12YC?

4. Is there a check valve in the carburetor? if so, where is it and whould this cause the flooding when the engine is shut off?

5. If the needle valve was not adjusted correctly, would that cause it to flood when the engine is shut off? I have it set very close to dead level with the carb body...if it where leaking whould it cause the issue?

Here is what I have done so far, rebuilt carb twice and have adjusted the needle seat several times trying to get it just right. I believe it to be very close right now. I tested the coil and condenser, condenser was bad so I replaced it and that made a big difference. I set the points to .022 and timed it with a ohm meter, it is about a degree advanced in forward (when the ohm meter begins to show resistance I can just start to see the timing mark in the hole) and a degree or two retarded in reverse. I have replaced the fuel lines and removed the fuel pick up screen and the elbow and blew out with compressed air...check valve on pick up is working OK. Verified carburetor is pumping fuel very well, it never acts like it is running lean or cutting out, if anything it is running a bit rich. The low speed jet is 3/4 of a turn out, high speed is not adjustable. Carburetor gaskets are new as well as the reed valve and air cleaner.

Help!

Kevin,
Kevins Small Engine service,
South Berwick ME. 03908

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

tew45

This is a big order. First Compression should be around 90 PSI. High compression sometimes indicates a plugged muffler. There is a check valve on the end of the fuel pickup. The plug reach should be marked in the top of the head (High compression head should be a 3/4 reach plug and low compression should be 1/2 reach). It sounds like a plugged muffler is the problem! Pull the muffler off and see how it works. Check compression while the muffler is off. Don't run it long with no muffler. With all timing and compression good speed should be 18 to 20 MPH.

kbowley

OK, on the head it states "3/4 plug reach", so I assume it is a high compression head? I installed a BP5ES which is the 3/4" version of the BP5HS. Plug is new. Compression is 115 both ways...what is the benefit of the high compression head?

I would like to attack one problem that is driving me nuts. If I come to a stop and the engine shuts off, it re-starts very hard...you must hold the throttle to the floor and after a few seconds it will start spuutering like it is flooded and it takes five-ten seconds before it clears out. It will idle right down fine to the point of nearly a stop so I think the low speed is set right...it doesn't seem to load up when barely touching the throttle. But, if you take your foot off and kill the engine it re-starts like its flooded every time. Would the needle valve cause this? check valve in tank (doesn't seal well when you blow back into the tank...I can still push a little air through?). How sensitive is the needle valve height setting?

Thanks ahead of time...any ideas are welcome as I am stumped. Carb is rebuilt with old needle valve, timed it with a multi-meter, points are at around .020, new condensor.

Kevin,
Kevins Small Engine service,
South Berwick ME. 03908

tew45

Compression still seems high but timing too far advanced sometimes will cause the problem.

kbowley

Here where I'm at...I double checked the timing and it is dead on in both directions, I was able to remove the muffler and the compression is still 115 psi, I removed the head and cleaned the carbon though it wasnt bad at all.

my carb kit came in yesterday so I plan to remove and rebuild paying special attention to the needle valve and seat as well as the height adjustment for the needle valve.

Two days ago it was in the 90's and I took the cart out. It barely ran and i had to keep the throttle floored or it would die from flooding. It runs much better when it is 70 degrees as the air is denser. I cant believe there is no high speed adjustment, if nothing else than to compensate for ambient temps.

I feel confident that the issue is with the needle valve. It is either not set right or not sealing.

Any advice?

tew45

It sounds like there is a possibility that someone has milled the head too much trying to improve performance and removed too much. Something is not right! Wrong piston or installed backwards or both. Overly high compression seems to be causing your problem. This is a strange problem and more so since it has never run properly while it has been in your possession.

kbowley

Hmmm...The head appears to be stock and certainly does not look to have been milled. Keep in mind, it is the high compression head, I would assume that the compression would be higher than the standard head. 115 psi is not excessive and would not affect crankcase vacuum.

The problem is excessive fuel coming from the carb. the top side is scavaging as it should, the issue is not with the engine, timing, points, coil, condenser. The previous owners son stated it ran great before putting it away, it was used on the large farm to transport workers into the field. The engine had never been apart and ran very well before it was put in storage. The previous owner purchased it new from Seacoast Harley in Portsmouth NH on April 13 1976. It was put in storage in 1997 when he passed.

The fuel tank was left half full and it turned to Tulane and a thick coating of a hard taffy like substance about an inch thick on the bottom of the tank. I cleaned the tank with solvent and removed 99 percent of it. The tank is clean albeit with some cracks on the top of the tank. The fuel lines have been replaced and after plugging a couple of fuel filters, it is now fresh, clean fuel. I rebuilt the carb but did not replace the needle and seat. Since fuel is essentially running into the engine, i believe the needle valve is not sealing and the pump is just pushing fuel through the main/idle jets as it runs so rich, the throttle plate must be full open to run in hot weather. If run in 60 degree weather, it will run decent as the air is denser, though still certainly rich.

When I removed the carburetor the first time, I adjusted the needle valve well below what the manual showed to try and correct the rich condition. This caused it to run very lean and run out of fuel if the throttle was held open full. I pulled it apart again and put the rebuild kit in and re-adjusted the needle substantially higher and it has run like this since.

Tomorrow I am installing another kit with the needle and seat. I will be anal about setting the needle correctly. It is also possible that the crap and solvents that passed through the filter damaged the diaphragm.

I will post an update after I complete the carburetor overhall.

I would love to have some knowledge regarding the high compression head. Was it an option when new? Does it increase horsepower? Change the powerband rpm range? Why would someone ask for that option?

Kevin,
Kevins Small Engine service,
South Berwick ME. 03908

tew45

Most of the carts I see have the high compression head. The compression readings with seated rings run around 90 PSI. I really don't know when they started using the HC head. I haven't seen many low compression heads so I think they were in very early carts. Another think that will cause high compression is excessive liquid in the compression chamber (hydro-lock) I used to get that in my Indian Chief on rare occasions.

ckiguy

tony isnt there a easy way to tell if the head is high compression by looking at it? my fatehr in laws had the a head with the plug at a 45 degree angle to the top, it had the part number for the low compression, nothing about any reach inside of it i was told to look for, the 69 i did had the spark straight out in the middle, it was not marked either. i had to measure the threads in the head and both were at 1/2 inch, so i used the short reach plug. have no issues with them. i saw both harley part numbers and both matched to what i could find out to be low compression heads.

tew45

I'm not really sure but I suspect the angled plug is for the carts that have the engine with the cylinder forward towards the front of the cart. But if the compression is around 90PSI and the cart runs around 18 MPH that is about all you can expect with either head. I know if the compression is too high starting can be difficult. and especially with a weak battery. Craig might know which is which! It has never been an issue with my carts.