89 Vmax tries to start be won't

rspauldi1 · Nov 21, 2015

The problem: The motor turns over and it tries to fire off and sometimes will even idle for 5 to 10 sec.

a little more information:

Ran fine a year ago but has been sitting and hasn't been started in that year.
I drained the old fuel from the fuel tank.
Replaced the fuel filter.
Replaced the starter clutch (flywheel was a PITA, 7 ton puller and air tool with tons of TQ and massive heat applied).
Battery has been replaced.
Spark plugs replaced
Carbs rebuilt surprisingly they were pretty clean. All of the rubber was in good shape. A/F screws set at 2.5 out, and floats appear to be correct as there is no overflow. each carb was soaked overnight in a gallon of carb cleaner, then rinsed, the used compressed air on all orifices and jets.
Replaced the 2 rear coils from my 95 parts bike.
Check all electrical connections that were disconnected during the battery install. I didn't spray with contact cleaner but they appear to be in good shape.
The vboost cable moves back and forth be didn't look in the manifold to see if they were actually moving.
Every now and then I get a backfire
And, this ones tough to explain but air pushes the other way threw the carbs sometimes. kind of like an intake valve stuck open, but it does it on all carbs.
Did a compression check and all cylinders are at ~170 +/- 10.

I am at a loss, anyone of you Vmax guru's have any ideas ?????

Thanks,
rick

blaxmax · Nov 21, 2015

Did you clean the two jets in the jetblock when you took each carb apart?
Coils crossed?

rspauldi1 · Nov 21, 2015

Yep, got those, one looks like a pilot jet and the other is very small. I did try swapping the coil connectors and surprisingly got the same results.

also, pulled the plugs to take a look... it's ready hard to read but I think one of the was a little wetter than the others...

Traumahawk · Nov 21, 2015

Have you tried to start it with the airbox off? That way you can see if the slides are moving?

Well the old fashioned way to get something difficult to start, was just a quick spray of starting fluid (with upper cylinder lubricant) into each of the carbs......and use the choke. Please remember that starting fluid is EXTREMELY flammable if you chose to use it.....and handle everything else accordingly.

Are you getting a clicking when the key is first turned on....like the fuel pump priming? If not....move the fuel switch to reserve, it will over ride the fuel pump, incase your low on gas.

rspauldi1 · Nov 21, 2015

Yes, the airbox is off, I can't really see the slides moving. most of the time the bike will just idle for a few seconds before stopping.

oh yeah, did the starter fluid technique, little squirt in each carb and it will start RPM's go up and then dies. That's why I thought it was a fueling issues and rebuilt the carbs.

I have one of those glass fuel filters and when I first put the carbs back on I had to turn the key on and off about 3 times before the float bowls were full. so now when I turn the key I may get a click or 2 and can see the fuel filter is full.

thought about low fuel as well, so I filled her with ~2.5 gals of 93 octane.

Traumahawk · Nov 21, 2015

Well here is a long shot. Take the fuel cap off. If the vent is clogged it will say running until it draws a vacuum, and then it will die.

Taking the cap off, will allow it to suck air.

Traumahawk · Nov 21, 2015

One other question.....what are the volts at the battery when you try to start, and for the few seconds that you do get it started.....can you see what the volts are then?

rspauldi1 · Nov 21, 2015

I did leave the gas cap off after I put more gas in it.
I haven't looked at the voltage though. I figured since the starter was rotating without issue that the voltage is ok but I will certainly ck.

one other tid bit. When I was removing the flywheel I basically destroyed it. I replaced it with one from the 95 parts bike. Could that be an issue? They looked identical .

davesax36 · Nov 21, 2015

how bad is the sync?

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Traumahawk · Nov 21, 2015

rspauldi1 said:
I did leave the gas cap off after I put more gas in it.
I haven't looked at the voltage though. I figured since the starter was rotating without issue that the voltage is ok but I will certainly ck.

one other tid bit. When I was removing the flywheel I basically destroyed it. I replaced it with one from the 95 parts bike. Could that be an issue? They looked identical .

As far as I know of, the 93 to 95 flywheel shouldnt be an issue. I had a weak battery and it would spin over, but not start......another time had a battery that was weakening....so it would start...and then die. I believe that with the key on, you should have 12.55 volts, if I remember what Sean told me.

Like Dave said.....hows the sync? If the sync is way off.....you could have trouble starting and idling.

Miles Long · Nov 21, 2015

Did you check the resistance of the pickup coil?
Very good chance your problem is related to the starter clutch replacement - IF the bike ran fine before this job was done.
Cheers!

DMAN999 · Nov 22, 2015

Put the air box back on, our bike does NOT like to run without the air box on.

Hellboy · Nov 22, 2015

I vote carb sync. The problem is, how do you sync them if you can't get it to run?

Matt

dannymax · Nov 22, 2015

rspauldi1 said:
Yep, got those, one looks like a pilot jet and the other is very small. I did try swapping the coil connectors and surprisingly got the same results.

also, pulled the plugs to take a look... it's ready hard to read but I think one of the was a little wetter than the others...

The little tiny jet is the pilot jet....the other one is the bleed pipe.

+1 on the sync, did you bench sync before installation?

dannymax · Nov 22, 2015

Hellboy said:
I vote carb sync. The problem is, how do you sync them if you can't get it to run?

Matt

With the carbs upside down, put a trouble light (or some form of illumination) under them and adjust the amount of light showing between the throttle plate and carb throat so they are close to the same. That should get them in the ballpark.

rspauldi1 · Nov 22, 2015

I'll do the voltage ck today.

as for the sync, I sync'd them up last year when it was running and when I rebuilt the carbs I didn't turn those screws. But as it is now it won't run long enough to look a vacuum. Maybe I should take a short video so you guys can see what is going on.

davesax36 · Nov 22, 2015

rspauldi1 said:
I'll do the voltage ck today.

as for the sync, I sync'd them up last year when it was running and when I rebuilt the carbs I didn't turn those screws. But as it is now it won't run long enough to look a vacuum. Maybe I should take a short video so you guys can see what is going on.

Yes. This has helped me many times on here.

rspauldi1 · Nov 22, 2015

I am not sure what the pickup coil is but I'll ck the manual and report back.
I will also pull the carbs back off and do as Danny suggested.
I can try putting the airbox back on but I'm pretty sure my other vmax's have run w/o the airbox on. But as it is right now I'm willing to try anything.
thanks for your input, I certainly appreciate the help.

Traumahawk · Nov 22, 2015

rspauldi1 said:
I am not sure what the pickup coil is but I'll ck the manual and report back.
I will also pull the carbs back off and do as Danny suggested.
I can try putting the airbox back on but I'm pretty sure my other vmax's have run w/o the airbox on. But as it is right now I'm willing to try anything.
thanks for your input, I certainly appreciate the help.

Well idling in the garage not having the airbox on, isnt an issue....just dont try to drive it down the road. It will run like crap without the airbox on.

rspauldi1 · Nov 22, 2015

what is the job of the pickup coil? Is it for the charging system or spark?

89 Vmax tries to start be won't

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