help please with 79 srx 440!

6

68chevytruck

New member
Joined
Dec 5, 2010
Messages
6
Age
50
Location
michigan
Hi everyone, i just purchased a 1979 srx 440. my problem is the sled will start sometimes and when it does and i guess when it doesnt the plugs are just way too wet with fuel. I have 150 psi of compresson on both cylinders, the carbs look like they are factory yamaha japan carbs. The couple of times that i got this sled running it seemed to run real doggy, hence the rich fuel mixture. I took the carbs off and cleaned them and everything seems to be free of debris. Any suggestions would be great. Maybe i should start with does anyone know what size jets and needles i should have? I live in lower michigan so i would be around sea level. Thanks is advance.
 

I CAN GIVE YA ALL STOCK CARB SPEC, BUT I THINK CARBS STILL HAVE A ISSUE. YOU CHECK YOUR NEEDLE AND SEATS. 3:16 (yammie tony)
 
carbs are not overflowing fuel, do you think i need to put new needle and seats in? will that take care of a rich problem?
 
a high float level will make it rich
a incorrect air screw setting will make it rich
a choke plunger that doesnt seat will make it rich
 
probably best thing to do is get a rebuild kit for both carbs then isnt it? or should i bend the tabs down on the seat to stop the fuel earlier?
 
GET YOUR CARBS BACK OFF AND PULL YOUR BOWLS OFF. AFTER YOU DO THIS YOU CAN MEASURE YOUR FLOAT HEIGHT AND CHECK AND SEE IF CLEAN AND AT SPEC. ALSO THAN CHECK YOUR CHOKE CABLE WHERE IT SCREWS INTO CARBS. MAKE SHURE YOUR FREE PLAY IS CORRECT. I,LL ADD HERE SOME STOCK CARB SETTING FOR YA.
MAIN JET - 340
POWER JET - 80
NEEDLES- O2
PILOTS- 30
AIR SCREW- 1.0
FLOAT HEIGHT- 18+/-1 mm
CHOKE FREE PLAY - 0.5-1.0 mm
NEEDLE POSTION - 3 GROVE (can maybe clean this up by going to 2 grove )
ALSO CHECK AND SEE YOUR CARB SLIDES ARE OPENING AND CLOSEING TOGETHER WHEN OPENING THUMB TROTTLE. ANOTHER THING YOU GET A SERVICE MANUAL FOR THIS SLED ? 3:16 (yammie tony)
 
thank you, ill pull them off and check that stuff and the numbers on my jets and needles,pilots, etc. which plug is recomended? b8es or b9es? or should i use another #? Thanks again
 
check fuel pump, sometimes they have a small tear in diaphram and leak fuel into crankcase. Small leak might not show up until you start sled. Just look for fuel in vacum supply line.
 
ok heres what i have:
needles 6dh16
main jet 320
power jet 80
pilots 30
on side of carbs stamping: Q8
71

fuel pumps are pumping fuel, i put vacuum on the hose that leads to the cases from the fuel pump and im not getting any fuel out of the pump which in turn means that the gaskets or pump is not bad and not leaking fuel into my cases (hense the rich fuel mixture)
the exhaust pipes are not clogged, and as a matter of fact one side had alot of fuel in it that i dumped out of it tonight.
the chokes are not stuck, i even made sure i had the choke all the way down so i coul eliminate that problem.

i have great spark, and i just cant get this thing to run. Should i buy new carbs? or maybe should i start down sizing the jets and needles to make right? any more suggestions are welcomed
 
I would try pulling the pilot jets out and hold them up to the light and see if they are blocked. If so clean them out gently with a single wire from a wire brush.
Todays gas turns to varnish too fast for my liking.
 
There is a member on VintageSleds.com that is trying to register here and help you but never receives the email to confirm registration. If you want to read his help, visit this link:
http://vintagesleds.com/bs/index.php/topic,50374.0.html


Here is what he said:

"been tring to get access to totally yamaha but all I get is awaiting account activation, there is a guy with a 79srx with carb trouble and people over there are telling him to do thing that are not even close someone try and help him .Tell him to check the o-ring on the bottom of the carb and make sure the slides are in the right carbs the srx stock carbs have a right and left slide. he has so much fuel that he said he dumped gas out of the pipes. one person said to make sure tha pilot jet are not pluged!!!!!!!!!!!!!!!"
 
As Tony said, check needle and seat to besure it closes off fuel flow
I have held the carb in my hand, float bowl off, with a short piece of fuel line conected to the carb, gentley blow in the hose. As you push the float up with your finger, the flow should stop.
You can clean the inside of the seat with a Q tip, use some valve lapping compound if needed, clean it all out then. The tip of the needle needs to be clean also, no gouges in it. Some are brass, some have a rubber tip.
I had an issue on my V Max where the pin that pushes threw, and holds the lever the floats push up on, was bent, just enough to not allow the needle to close. Might want to check that
 
Sorry to bring back an old forum but I am having the exact same problem with my srx My question is how do you know which slide is the right and which side is the left?
 
IF THEY ARE THE STOCK YAMAHA CARBS, THERE ARE MARKED L AND R RIGHT BELOW CHOKE PLUNGER. EXAMPLE 8J0-00L / 8J0-00R 3;16 (yammie tony)
 
I used to buy old sleds and littery bring them back to life after they sat outside for years. I have seen the same problem with exciters,Vmax's and latest was my RX1. Fuel in the pipes almost always meant "Needles and seats sticking or stuck". If sled sat with old gas for a long time and gum those parts up and are real heard to see or catch. remove all carb parts and soak in carb cleaner for a few days and clean all jets and any seating areas, hole in jets...... I agree might be time to buy a rebuild kit depending on how bad parts are.
good luck but have fun!
 
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