Can't rev bike

[Kesher Simonelli]

Hello all,

So far the information here on this forum has been everything I need to do just about everything on my bike however I've hit a wall. I picked up a 99 vmax a few months back and it was running on 3 cylinders and wouldn't idle off choke. I pulled the carbs cleaned them and found that they weren't even assembled correctly from previous owner. I put them back together to spec and put them back on. After that the bike ran good but had an inconsistent idle. I tried syncing and adjust af ratio couldn't fix it. I pulled the carbs and bought a full rebuild kit and took a very long time to rebuild them to the specs of the manual and with help from the forum. I put them back on and it was idling almost perfect. But when I would give it any throttle it falls on it's face. I thought maybe it's too rich since I was running 152.5 jets so I pulled the carbs and jetted to a 150. It still idles fine I've synced all the carbs but it won't rev at all. The airbox is on I've checked for vacuum leaks and I'm at my wits end I don't know what could be causing this. It makes no difference wether the bike is warm or choked or anything it won't rev past 3000 it just falls on it's face. Any help would be massively appreciated.

 

[Fire-medic]

I dunno, sounds like either a massive vacuum leak, or a lack of fuel.

 

[user 16790]

is the fuel pump working correctly

 

[MaxMidnight]

Have you checked to see if the throttle slides aren't lifting? Have you looked with the airbox lid off to see what is happening.
Is the vacuum advance connected and working?
One last thought, you haven't connected the air vent hoses to the inlet manifold stubs?
(No, I have no idea what would happen either but when you are desperate it's surprising what goes through your mind )

 

[Kesher Simonelli]

Update.
I thought I had it figured out I checked the wet float levels and two of them where pretty low even though I set them on the bench dry. I pulled the carbs again and readjusted the wet level and verified they were all at the 17mm below the carb mark. That had almost no change.

The fuel pump has been checked and is good.

Inlet stubs are connected to my sync gauges.

I can't verify if the throttle slides are moving correctly because any throttle kills the motor. They should be working correctly they are brand new and operate perfectly with my fingers.

I checked all around for vacuum leaks with propane and didn't find any.

 

[Fire-medic]

You might want to try either/or a cyl compression test, and a leak-down test. That's a good indicator of the overall health of the engine.

 

[digin150]

I would try to give it a little choke and see if it increases rpm, if it helps I would think you still have a fuel issue,good luck.

 

[one2dmax]

Are you doing this testing with the airbox in place?

 

[user 16790]

what type of carb rebuild kits did you use, I've read on this forum that some people have had bad troubles with some aftermarket rebuild kits

 

[one2dmax]

Don't use Keyster kits! Junk with a capital JUNK. AND, regardless of the aftermarket brand do not use any of the Brass parts. Clean and reuse your originals or get OEM brass.