In desperate need of some help. Okay here we go....screwed the pooch by drilling out #1 and#2 pilot screws. Now the holes are too big and the screws only allow me to turn them out 3 turns. Tore apart the carbs completely 6 times, not a speck of dirt. Float levels set and diaphragms are good. Checked rear coils, 2.8 ohms on both #1 and #3 (problem cylinders). Carbs syncd, set all gauges to zero per #2 carb The bike runs good at highway speed, no symptoms of being lean or rich. The rear cylinders start to kick in at 1500 rpm but refuse to fire with as much power while idling. Carb joint boots are new and gas tank drained and inspected each time I tore apart the cabs. #1 #3 cylinder fires sporadicly at idle. When I pull the coil connection off of #3 you can notice but #1 barely makes a difference. I ran the bike on each cylinder independently and did notice a negative difference in the exaust pressure on #1. Pulling #2 or #4 plug wires will cause the engine to stumble while 1 and 3 do not have the same effect. 1 problem that I have is that I fried my regulater which was only 3 years old bought new. Could the lack of voltage cause the problem? Battery is new and on a tender charger. 13.36v reading at startup, I put a switch on to turn off the headlights. Heads were done about 3 years ago. Short of taking it to the stealership for a compression check I don?t know what else to do. Have video of the bike running, PM if you wanna take a stab at this monkey.
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one2dmax
Well-Known Member
Did you clean the pilot fuel jets in the jet block? These are under the small rubber plugs so those have to be pulled out (with your fingers) for access (after you have taken the block out of the carb). They are the smallest jet (37.5) in the carb and will not allow for fuel to flow at idle is blocked.
Also check for a vacuum leak or bad oring under the intake to the head.
Finally, you didn't mention anything about carb sync or even if you have checked the valves (if it's got any mileage since the last time it was checked).
Also check for a vacuum leak or bad oring under the intake to the head.
Finally, you didn't mention anything about carb sync or even if you have checked the valves (if it's got any mileage since the last time it was checked).
sdt354
Well-Known Member
pm'd you.
I will recheck for a vacuum leak at the intake. Carbs were completely tore apart and cleaned. Covered the rear carbs with my hand but it does not make the engine stumble like #2 and #4. Carbs seated in joint boots and carbs level. Just wondering if I fried the tci when my regulator got toasted. Glad to have your guys advice, beers on me if you ever make it to hawaii.
Gunnypauly
Member
I was going to say, you can pick up a compression tester for $20.00 or $30.00 bucks, but your in Hawaii. I sure you don't have a Auto Zone right around the corner there..
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We have Napa, Orileys, and Sears. I'll try calling around on Monday. Our yamaha stealership closed last month, good riddence to bad business. Called the dealership 6 months ago to order some A/F screws. They parts guy told me it would cost $18.95 per screw. Needless to say I bought them off the net and got all 4 screws + shipping for $20.00.
Another major problem is my fuel mileage. I get about 20 miles on a full tank of gas before reserve. I do have a lead right hand but only short burst, 35-90mph just to get the blood pumping. Any other heavy handed vmaxers getting the same mileage.
44boyd
Well-Known Member
20 per tank or mpg? With all the troubleshooting you mpg will go to shit. Have you verified the vboost butterflies working properly?
sdt354
Well-Known Member
That kind of fuel usage may be pointing towards thel problem, imho. Time to see what the float height is. Gas might be pouring in and fouling the plugs. I'd do a wet fuel level check to eliminate that as an issue. Of course 2 cylinders not firing is going to make gas vanish. Normal usage is about 90-110 before the light, even thrashing it.
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naughtyG
Well-Known Member
The only time I ever saw such poor consumption was when I had rust in my tank, the rust dust was keeping the float needles from sealing so fuel just kept getting dumped right through. I would kill the spark through flooding at idle and low revs, and gas would pour out of the cylinders through the exhausts. Ran like shit at low revs, cane to life above 4-5000rpm, and went through fuel like crazy!
wildweasel_pt
Well-Known Member
I agree you are pouring fuel and fowling the rear plugs. Don't you get popping in the exhaust?
I can hear the vboost servo cycle and it does kick in a little past 6000rpm. Front plugs are brown, rear plugs an oily black. Rechecked the float levels yesterday.#2 was a little rich 1 3 and 4 were pretty much on. A/F screws set #1 (3) turns #2 (2.5) turns #3 (3) turns #4 (3.5) turns out. Also running closed circuit comp supertrapp slip on's.
Another beautiful beach day spent in the garage with Mr.Max. Reset the float levels on all 4 carbs to. 16mm wet and rechecked the level with the bike running. Right on the nats nuts. My bike sounds like a harley at idle (and yes I am complaining not bragging) what was once a rabid rottwieler is now a sickly puppy at idle. Here's a link to a video I took today. I greatly appreciate all your help.
http://www.youtube.com/watch?v=TkPF4BnlnhE&feature=youtube_gdata_player
http://www.youtube.com/watch?v=TkPF4BnlnhE&feature=youtube_gdata_player
Can someone who has had this problem tell me how you resolved it.
Covering the rear carbs make no difference in the idle of my bike. Covering #2 or #4 makes the engine stumble. I get gas on my hand and I can feel a slight vaccum but not as strong as the front carbs. Could not find a vaccum leak anywhere. Would'nt a major vaccum leak increase the idle??
Found out something weird..... rechecked my float level (again):ummm: on #1 carb (problem carb) and it was 22mm. turned the key off and on to activate the fuel pump and got a reading of 12mm. I tried blowing air into the clear measurement tube and the level changed back to 16mm. Guess I need to replace the float needle assembly.
Covering the rear carbs make no difference in the idle of my bike. Covering #2 or #4 makes the engine stumble. I get gas on my hand and I can feel a slight vaccum but not as strong as the front carbs. Could not find a vaccum leak anywhere. Would'nt a major vaccum leak increase the idle??
Found out something weird..... rechecked my float level (again):ummm: on #1 carb (problem carb) and it was 22mm. turned the key off and on to activate the fuel pump and got a reading of 12mm. I tried blowing air into the clear measurement tube and the level changed back to 16mm. Guess I need to replace the float needle assembly.
naughtyG
Well-Known Member
Have you taken a good look inside your tank and made sure there is no rust at all?
When you empty the fuel bowls, can you see any dirt at all in the gas?
Have you had your carbs apart yet to clean them properly?
Have you checked you are getting a good spark on all four plugs?
Have you tried swapping the front and rear plugs after cleaning them and then look again?
Also bear in mind Max doesn't like running without the airbox on much - you'll get much better idle/readings etc with it on.
When you empty the fuel bowls, can you see any dirt at all in the gas?
Have you had your carbs apart yet to clean them properly?
Have you checked you are getting a good spark on all four plugs?
Have you tried swapping the front and rear plugs after cleaning them and then look again?
Also bear in mind Max doesn't like running without the airbox on much - you'll get much better idle/readings etc with it on.
Thanks Naughty G, carbs tore apart repeatedly. Gas clean and inspected thru a aftermarket glass fuel filter. Here is 1 thing I need to note- I ran my bike with the pilot screws seated all the way in for a month. PO stripped the heads and the screws were ceased. The PO also seemed to think that sand and twigs added to the gas tank would increase performance. I cleaned the tank spotless but can't figure out how to clean the fuel passage to the pilot screw. I even rented a high pressure compressor from home depot and blew air thru each hole. If you or anyone else has a idea how to get the passage clear I would appreciate it. I tried using a guitar string thru the hole closest to the butterfly valve but got only 1/8" in before the wire bent.
Spark plugs are new, wires and caps swapped out. Secondary coil test on coil #3 tested 30.9 instead of the spec 13.7 ohms. Swapped out the rear coils but it made no difference. Its strange how the rear cylinders seem to fire with half the power compared to the front.
naughtyG
Well-Known Member
How do you mean by 'firing with half the power'?
Did you check you have full spark on all four?
If small passages in the carbs are blocked that would explain most of your troubles I think.. The only way I can think of for cleaning such small orifices is to completely strip the carbs of ALL rubber parts, and then marinate them in an ultrasonic bath, followed by repeated blowings with compressed air.
The only way to check that all holes are clear is either to blow in and make sure it's coming out the other end, or use a string very carefully - maybe piano string might be better than a guitar one..
Did you check you have full spark on all four?
If small passages in the carbs are blocked that would explain most of your troubles I think.. The only way I can think of for cleaning such small orifices is to completely strip the carbs of ALL rubber parts, and then marinate them in an ultrasonic bath, followed by repeated blowings with compressed air.
The only way to check that all holes are clear is either to blow in and make sure it's coming out the other end, or use a string very carefully - maybe piano string might be better than a guitar one..
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