Backfiring VMax?

[maxed out]

How do I stop My VMax from backfiring? when I try to start the bike, the bike will not start.
Cleaned the carbs twice (jets, diaphragm), drained the tank and bowls.
I can start the bike with using a starting fluid, but have to keep the rpms up high and with a consistent backfiring and will not run when the throttle is backed off. Any advice would be great, thanks.
:ummm:

 

[dannymax]

Have you checked the sync?

 

[alorio1]

I would pull the carbs back off and check float levels, do a bench sync and recheck everything while you have them open. I would also install new spark plugs. If you get it running well enough, resync the carbs using a vaccum gauge to get sync better. I would also adjust A/F screws to 2 1/2 turns out for initial start-up.

 

[maxed out]

Thanks for the help alorio 1,

I am not sure exactly what a (bench sync is), as I do have a vacum sync for the carbs when I get the bike running again, thanks again for your help.

 

[Thevmaxrider]

On the bench flip the carbs upside down. Turn your idle adjustment all the way in counting the number of turns it took, you will need to remember this for later. Using the idle adjustment screw open the butterflies until you can put a small allen wrench (I use a 2mm) between the butterfly, on the cylinder that the idle adjustment opens, and the carb body with the wrench fitting while lightly touching both sides, then adjust the adjustment screws on the other 3 carbs until the wrench fits the same as with the first carb. Close your idle adjustment back down all the way and then back out the number of turns you counted at the beginning. This will get you very close on your synch.

 

[tugla]

pretty easy to bench sync, will be just about perfect after that, can also just do it by eye by holding up to the light and get them showing the same amount, just a tad and then turn up the idle screw as needed to make it run decent.

 

[m-cman]

Sounds like low speed jets are clogged.

 

[LeeMax]

I had same issue on ALL my Max's. 2 things helped my backfiring through the carbs issues.

1. Make sure you have NO vacuum leaks. Look for leaks around carbs and plug them up.
2. Sync the carbs
These 2 above took care of my problems.


3. And lastly, check out different jets, STAGE 1 for instance if you still want to stay semi-stock.

Keep in mind, that generally the carb jets that came from Japan to comlpy with U.S. emissions are way too small and should be swapped out for a richer set.

Hope this helps!:eusa_dance:

 

[94 V-Max Rider]

Sounds like low speed jets are clogged.

I agree with your assessment. I'd take it one step further than just cleaning the slow jets. I'd make sure the entire idle circuit is clear. Another thing worth mentioning is that many tend to overlook the slow speed air jets under the diaphragm covers, myself included. After cleaning my carburetors, the bike was popping through the airbox at idle and low speeds. After cleaning the air jets, it ran flawlessly.

 

[tugla]

also start with a/f turned out 2.5 turns and go from there

 

[rollin thunder]

Mine pops a little bit when I choke it but its fine when warmed up.I put some sea foam in it and it helped .