Popping, spluttering and cutting out when hot. Embarrassing!

[Pittnathan]

Hi. I've recently bought a vmax and today was the first time I've really gone any distance. It was fine whilst moving but as soon as I hit heavy traffic it started popping like hell at low revs and wouldn't hold idle.

It's rarely been used for the last few years by its previous owner and needs an oil service. It also has straight through pipes and as far as i'm aware standard jets.

Please help as I look a right prat sat at the traffic lights revving the ass out of it, so it doesn't cut out!:bang head:

 

[alorio1]

You could have a weak/bad battery or the charging system is not putting out enough to provide igniter box enough voltage to make the coils fire.
Check the battery for fluid level if it is a wet cell and read thru this thread...

http://www.vmaxforum.net/showthread.php?t=19108

 

[Pittnathan]

It's only just had a new battery fitted. Wouldn't it do it all the time if it was a case of a weak spark? I've been thinking along the lines of breaking down sparkplug, wrong jets or maybe carb balancing?

 

[alorio1]

Usually in heavy traffic the cooling fan comes on and taxes the charging system even more, thats when the popping and misfiring starts. Have you noticed this ?

 

[Pittnathan]

To be honest I've never heard the cooling system kick in. It almost reaches the red and still no fan!

 

[alorio1]

New plugs and a fuel additive like Seafoam would not hurt also, might be a good idea.

 

[alorio1]

You will have to get it in a quiet place and either run it until temp gets high enough to switch fan on or jump temp switch to operate fan, but you should feel hot air blowing when the fan does come on in traffic. If you have a volt meter check your voltage just for the hell of it and post back. If I can't get you on the right track there are other members on here that will chime in and help that know a lot more than me.

 

[Thevmaxrider]

Also check your ground wire from the battery to the engine block at both ends just to be sure. If the bike has sat for an extended period of time without running I would also put some fuel system cleaner (seafoam, start your engines, et al) into a tank of fuel and see if it gets better. Got to be electrical or fuel start there. A good way to see if the fan is the culprit would be to remove the right scoop and disconnect the fan wiring from the fan sensor on the bottom of the coolant fill housing. Use a piece of wire to jumper the connection and the fan should start. With the bike running jumper the connector, if the sputtering starts then you have narrowed the search to a charging/grounding issue. If it still purrs along then you have to look elsewhere. One thing you didn't mention is if it does it only when the bike is hot or if it is constant no matter what the water temp is. To check if it is a fuel issue when it starts to spit and sputter give it a little choke (not full open but just start actuating it) and if it improves you have idle circuit issues in the carbs and need to synch and shotgun/peashooter them.

 

[Pittnathan]

Wow! Thanks for all the helpfull advice. Just to clarify, it only does it when hot. It runs perfectly from cold for about 15mins then starts spluttering, even whilst moving at low revs in any gear.

 

[Rhoy Carter]

Get a volt meter and check voltage across the battery while idleing and at 3000 rpm, the voltage should be above13.5 at both speeds when at operating temp. This is one of the main things to cause what you are describing,

 

[Pittnathan]

I'll try all the things suggested at the weekend. Also booked it to have the carbs balanced just for good measure on sat morning

 

[tugla]

if I were you id give it a hole tune up. change plugs, check wires/coils, chg oil and filter. air filter if needed, sync carbs, check all a/f screws are set close to the same amount. voltage check as mentioned and do "crimp fix"(can find post if you look in the search) just basic stuff to get familiar with the bike and go from there.

 

[Fastatv]

Hi. I've recently bought a vmax and today was the first time I've really gone any distance. It was fine whilst moving but as soon as I hit heavy traffic it started popping like hell at low revs and wouldn't hold idle.

It's rarely been used for the last few years by its previous owner and needs an oil service. It also has straight through pipes and as far as i'm aware standard jets.

Please help as I look a right prat sat at the traffic lights revving the ass out of it, so it doesn't cut out!:bang head:

Had a similar problem with my 95. Synced and adjusted carbs and this really helped but....the crimp fix completly resolved the issue. Sputtering, missing, dying, hot starting....all went away. So far, the best thing I've done to my bike. Check the thread that Alorio ( hope I spelled that correctly ) provided. Rick