1984 venture Carb problems

[Tiresmoking]

Had a problem on my 84 venture where gas was pouring out of the bowl. So I filled the carb bowl up with carb cleaner.

Drained it and fired it up and # 1 cylinder will backfire out the carb till it’s warmed up. I pulled the diaphragm out and it was separated from the slide. Put it back together and it still does it. Think the carb is still dirty or just out of sync with the rest. Like I said when it warms up it seams like it runs fine. What’s causing the backfire?

[BlueSky]

When were the valve clearances checked? I'd put a bottle of Gumout for high mileage engines with PEA in the gas and run it through. Have you confirmed the float levels?

[Tiresmoking]

I put a cap full of sea foam in it yesterday but haven’t riden it yet. Noticed a coolant leak. Need to fix it before riding sea foam through. Don’t want to pull carb apart but may have too

[Freebird]

Cap full? Most of us use MUCH more than that. I put a full can in my tank twice a year. One in the fall before I store for winter. I run that out in the spring and then usually another about mid-summer. I don't think a cap full is going to do anything at all to help you.

[bongobobny]

Yup! One full can in a tank of gas and drive it like you stole it!! As preventative maintenance, I add a can to the gas tank at every oil change. If your carbs are really gunked up, you may want to try a second treatment after doing the first tank of gas or do a search here about the "shotgun" method of cleaning the carbs, but if they are really bad a complete overhaul of the carbs may be in order.

 

Have you looked at your plugs yet? A fact of life is these bikes are rough on plugs and need replacing every 10,000 miles or sooner. Also, invest in a spark gap tester which costs around $15 at most auto parts stores and evaluate the condition of your spark on each plug. You should be able to draw a minimum of 0.100 inches of spark on each cylinder. Also, do a compression test...

[Tiresmoking]

Yup! One full can in a tank of gas and drive it like you stole it!! As preventative maintenance, I add a can to the gas tank at every oil change. If your carbs are really gunked up, you may want to try a second treatment after doing the first tank of gas or do a search here about the "shotgun" method of cleaning the carbs, but if they are really bad a complete overhaul of the carbs may be in order.

 

Have you looked at your plugs yet? A fact of life is these bikes are rough on plugs and need replacing every 10,000 miles or sooner. Also, invest in a spark gap tester which costs around $15 at most auto parts stores and evaluate the condition of your spark on each plug. You should be able to draw a minimum of 0.100 inches of spark on each cylinder. Also, do a compression test...

I just replaced the plugs after I cleaned the carbs with cleaner sitting in carbs. I’m afraid of using sea foam in tank because I see cars that smoke badly after using it. Not sure if they did something wrong or what. They plugs looked rich on #3 &4. But the main problem is #1

Edited July 19, 2018 by Tiresmoking

[bongobobny]

If you are referring to cars smoking while Seafoam is still in the gas tank, well that is the whole idea!! That smoking you observe is all the crap in the engine getting burned away!! That is quite normal and to be expected. Once the Seafoam is all gone the smoking will go away! Most members here swear by Seafoam and use it often to keep carb problems from developing or to fix some problems that may have developed.

 

Well, we need to analyze and troubleshoot your issue with the number 1 cylinder. Most likely it is an issue with the carb but other possibilities should be eliminated first as properly rebuilding these carbs is a complicated and expensive process to do it properly! These carburetors are very complex with several "circuits" that come into play depending on conditions. They also have to be properly balanced with each other for proper engine performance and fuel efficiency. There is an excellent DVD out there by a guy named Damon Ferrulo (sp?) that describes the proper way to rebuild them and set them up complete with the theory on why they need to be set up the way they are.

 

So, I strongly suggest doing a spark gap test on all the sparks, I believe the actual factory spec is 0.109" minimum to eliminate the possibility of a bad spark plug cap (there are parts inside the cap that can get corroded and weaken the spark) or possibly a weak coil or corroded output cap. A good thing to do is physically inspect the coils by removing the wires and look for the dreaded green disease, and before reinstalling the wires snip about 1/4 to 1/2 inch off of the end of the wire so that you make good electrical contact as once the end has been disturbed it will not make a good contact anymore.

 

A proper compression test is also important to help determine if you need a valve adjustment or if you have issues with bad rings, etc. With these engines, as the valve clearance wears, the valve clearance actually gets tighter, not looser! This would mean that a valve is not completely closing which can and will cause problems but it usually manifests itself with poor starting. The valves need to be checked about every 40,000 miles give or take.

 

I am just suggesting you check out these other issues first before getting involved with a complete teardown of the carbs. Run a can of Seafoam per tankful for a couple of tanks and drive it hard first. As I mentioned, try the "Shotgun" method on the suspected carb as well to help expedite its cleaning. Inspect the diaphragm very closely for any pinholes as these can cause improper carburetor operation.

 

You mentioned that the diaphragm became separated from the slider. recheck it and make sure it is still attached properly. Also, make sure the slider is not binding and is working properly. With the airbox cover off and the air cleaner removed watch all 4 sliders as you rev the engine. All 4 should "do the dance" evenly and smoothly. Word of warning, the bike runs like crap with the airbox open as the airbox is crucial to proper air/fuel ratio.

 

Also, check all of your vacuum lines, and pay special attention to the caps that plug the sync ports as they have been known to crack and cause leaking. Another possibility is your YCIS plastic box that equalizes the vacuum on the carbs may have a crack on the seam of it. Although in theory the YCIS system works, in reality, it doesn't do much. Yamaha eliminated them with the MK2 model...

[Patch]

Had a problem on my 84 venture where gas was pouring out of the bowl. So I filled the carb bowl up with carb cleaner.

Drained it and fired it up and # 1 cylinder will backfire out the carb till it’s warmed up. Well if I didn't know better I would say we are discussing a Suzuki You have 2 intake valves one or both - likely one tho that has chit on the seat! so what you can do is (lets make it easy) remove all pugs take the compression test, you will find that 1 is slow to build any pressure. After you have completed the test - place your finger over the spark plug port and spin the engine till you feel or hear compression come up past you finger _ stop turning it over. Take a can of DeepCreep and from the top of the carb using the straw with the can fill the carb till you see it level around the throttle plate. It will foam up then settle down!

Now leave it soak refill after a couple of hours and let it continue to soak for no less than overnight. So a couple of points: sometimes a valve will distort or the seat becomes flawed, most often tho it is usually crap on the seat so soaking can/may fix this for you!

 

I pulled the diaphragm out and it was separated from the slide. Put it back together and it still does it. This is related to the above valve not sealing! This is due to the compression backing up and through the venturi then interrupted at the throttle plate so it literally blows the diaphragm off its seat. Which leads me to think it is a tight but long gap leak from the valve seat! I guess she may have been parked for a while and the seat and valve were just close enough to form some crusting?? As the valve heats it grows in diameter then seat enough to seal combustion.

 

Think the carb is still dirty or just out of sync with the rest. Like I said when it warms up it seams like it runs fine. What’s causing the backfire?

 

The details that Bongo provided above are well detailed and worth your consideration.

 

If you follow the instructions for soaking you will need to change oil after so I would make the best use of this and soak the rings as well.

Patch

[Freebird]

I just replaced the plugs after I cleaned the carbs with cleaner sitting in carbs. I’m afraid of using sea foam in tank because I see cars that smoke badly after using it. Not sure if they did something wrong or what. They plugs looked rich on #3 &4. But the main problem is #1

 

I can tell you that I have never seen my RSV smoke with a full can of Seafoam added to a full tank of gas.

[Tiresmoking]

The video I seen on tube must had some carbon drop down and scratch the walls or the car might have been junk and they are just trying to pin it on seafoam. I just never used the stuff. The guy I got my venture from said to use a cap full. So I might try more than that. I will check the gap on the valves too this weekend. Where’s the best place to get shims if I need them I heard a lot of thing use the same type of shims.

Thanks everone for helping me out!!

[camos]

Run a can of Seafoam per tankful for a couple of tanks and drive it hard first. As I mentioned, try the "Shotgun" method on the suspected carb as well to help expedite its cleaning.

Lots of good advice in this post. Referring specifically to Seafoam though, it is my opinion that putting a whole can in a tankful is a waste. I commute daily on my VR all year and have found adding a quarter can of Seafoam every three or four months was necessary to keep the motor running properly. Thank you ethanol. I followed that process for five years or so with good results. For the past year I've been doing it differently, adding 2 oz to each tank. That seems to be working as well although I can't say it is working better than the other way but there has been no apparent degradation in performance like with the first method.

 

When it comes to resurrecting the carbs, the shotgun method of filling each carb through the drain hose should be done first. Let it sit for a day or so then drain it. Put 1/4 to 1/3 can into a full tank and run it down to almost empty over the course of several days. Make sure to do some WOT runs to get the mix into the main circuits.

 

If it is still not running properly do it again with another tankful. If you get through the whole can of Seafoam and it is still not running properly then there is most likely a more significant problem than Seafoam can handle.

[camos]

I can tell you that I have never seen my RSV smoke with a full can of Seafoam added to a full tank of gas.

When I first got my 90 VR I added a half can to a tankful and it smoked so much my neighbour came running over to see if something was on fire. I guess it depends on how cruddy the fuel system is.

[BlueSky]

Some car owners disconnect the vacuum hose connected to the brake booster and put a can of seafoam into the intake manifold and let it sit over night. When the vehicle starts, it will smoke a lot because of all the crud that breaks loose in the dirty intake manifold.

 

From what I have read on the F150 forum, Seafoam can harm the catalytic converters and Ford only recommends Chevron Techron.