Hopefully I can find some help here. 1988 VMax having some smooth idling issues after motor gets to temp. I have just replaced the battery and did a coolant flush. I have tried different settings with the idle mix screws (from 2 1/4 out to 3 1/2). I bought the bike two years ago with Supertrapps installed. I put a K&N filter in it 4 months ago and had to do a stage 1 jet kit. I did a carb clean/sync at my brother's bike shop at the same time. I did the "crimp" fix as noted on Outlaw VMax's page for better charging. My stator tests perfect. Reg/rectifier is new. I am running out of tests/ideas as to what causes this. I have spark at all 4 plugs. Bike starts fine, I hardly ever have to choke it. After about 5 miles of riding when I get stopped at a light, while idling the rpms want to jump up and down a bit. I have noticed my fuel pump's "ticking" sound to be getting slightly louder/longer when first turning the key to "on". I haven't done an fuel output test yet. I was having a hard time finding the fuel quantity for the test in the service manual. I am wondering if the fuel pump is failing and starts to show it's a** when it gets warm. Anyone else have/had this issue? Any help/suggestions is greatly appreciated. Also want to add that the carb boots are fine, no cracks. I tested for air leaks all around the intake and got nothing.

If it starts without choke, then it's pretty fat. I think once it's warmed up, it's probably too fat at idle..

The people on vmaxforum.net would probably be more help. When I had my gen 1, they helped a lot. Try that forum.

I choke it for about 15-20 seconds when it's cold outside. This time of year in Fla when it's mid 70's in my garage I don't choke it and it starts right up and then I give it about 5-7 good minutes to warm up and let the idle come up before I ride. According to my plugs, it is right where it needs to be, niether rich nor lean. When I installed the K&N a/f I jetted it (stage 1) and after reassembly it was still lean and had a lack of power. I moved the needle c clips one notch towards the jet and it was perfect. I have almost convinced myself that a 24 year old fuel pump with 54k miles on it is the culprit for two reasons. 1. When I first turn the key on, the chattering of the fuel pump priming itself has gotten louder and longer over the past several months, so loud that I can't hear the VBoost's 3 little buzzes over all the chatter. 2. At idle the voltage to the pump is lower than when I am at speed and giving the charging system a little more juice. I appreciate the reply and the advice.

I got on VMaxforum.net today as well and have gotten some good advice there. I received a reply that my pilot jet circuit may be clogged. I just did a full disassemble and clean in an oscillating carb clean tank at my brother's bike shop when I jetted the carbs about 4 months ago. I ride regularly so I don't think old fuel/dirty jets is the issue.

You're probably right about the fuel pump, but that really should affect the idle. If the bowls are full that's not the problem.

That's why I got on these two forums today. It is puzzling both me and my brother and he is a certified tech, been wrenching for 15 years and owns his own bike shop. Fuel pump issues show more at speed when there is a greater need for fuel but I still can't help but to think that's what it is though.

jbVMax wrote:
I had that happen several times with my Gen 1's. Each time it was a clogged jet. It's a lot easier to fix when you know what carb it is.....obvioulsy. The last 2 times I had it happen it would happen only at idle and did it when first started as well. I let the bike run for a minute, then touched all the head pipes.....the cold one is the cylinder with the carb problem. Then it's time to pull the screws squirt cleaner in each orifice and blow out with compressed air. This fixed it each time.

Good Luck!

jb.....Would be interested in knowing what you find out!

My 2002 started doing the same thing about 2 years ago. Said screw it the first year as bike still ran fine at speed. Second year started using StarTron and SeaFoam on every tankful and still got the issue.

If I bump the choke on a tad it clears up...........so I believe the idle circuit is plugged by the ethanol crap.

My snowblower did the same thing...would only run with the choke part way on. Had that carb rebuilt and also found the rubber primer line dissolved where it went into the carb......probably thanks to the wonderful corn fuel!

First, thanks for the advice. On both forums I have heard this remedy the most.
I did a carb clean/sync about 4 months ago when I jetted it. I have also checked to see which header pipe was not hot as to track down a dead cylinder and all seem the same and to be firing properly.
All my plugs look good too.
I will most likely try this "shotgun" remedy next weekend unless in the meantime I can determine it to be something else.
I am in complete agreeance with you, corn belongs on the table, not in my fuel tank!! I do try and run non-ethanol gas in my bike when I get the chance to get up to the one station around here I found with it. I do run Seafoam about every 5th or 6th tank. Firm believer in that stuff! Thanks again for the advice!