Idle "lopes" after motor reaches temp

[jbVMax]

Hopefully I will find some help here. My 1988 VMax doesn't want to idle smooth after motor reaches operating temp. Here's what I have/have done. I bought the bike 2 years ago with Supertrapps installed. I put a K&N filter and thus had to do a stage 1 kit. I cleaned and sync'd the carbs at the same time at my brother's bike shop. I did a new battery and coolant flush yesterday. Stator tests fine. Reg/rectifier is new. No air leaks at boots or around intake. I did the "crimp fix" as noted on Outlaw VMax's page to improve charging. I have spark at all four cylinders and plugs look good. Bike runs fine, all the power I want, just after reaching temp and stopping at a light, the idle wants to be erratic and dip a little, up and down. I have noticed my fuel pump's "ticking" to be getting louder/longer lately when I first turn the key to "on" after sitting for a length of time and am wondering if this might be a fuel pump issue, although most fuel pump issues are at speed rather than idle and my bike rides at speed smoothly. I haven't done a fuel output test yet as I haven't been able to find a fuel quantity amount for the test in the manual. Anybody else had a similar issue? Any help is greatly appreciated.

 

[naughtyG]

Hi and welcome to the best Max site on the InterWeb.

With slip-ons and K&N you did not need a Stage I - rejetting is usually only useful when changing to a full exhaust system.

Your issue is well-known - your pilot jet circuits are clogged up. You need to do the 'shotgun' cleaning method. Here's how to do it:http://vmax.lvlhead.com/tips/shotgun.htm

If that doesn't completely clear it up, you will need to tear down your carbs for a proper cleanup and possibly swap any worn rubber parts.

Being in FL you are lucky - if you need any help there are plenty of Max users there, especially CaptainKyle who regularly holds 'Tech Days' at his place in Tampa.

 

[jbVMax]

Thanks for the reply. After installing the K&N I had a very lean condition and significant loss of power therefore I installed a stage 1 kit. My brother owns a motorcycle service shop and has a carb clean tank. I did a proper clean/inspection on the carbs (I also do some carb cleans for him at the shop when he gets backed up so I am familiar with the process). Diaphrams and all components looked good. After reassembling I could tell I wasn't at full power so I pulled the slides out and moved the clips 1 notch closer to the needle tips and then rode it. I had full power. I forgot to mention that the bike has 54k miles on it. So does the fuel pump. Any thoughts as to whether it can be a failing fuel pump or not? I do appreciate the advice and the link to the pilot jet clean process. I may try that as well.

 

[ninjaneer]

I think I have the same prob. Started noticing it after I installed my marks exhaust last December. I have been wondering for months. The symptoms will come and go, but the absence and presence of the symptoms I attribute to the fact that I am currently messing around with the jetting, needle clipping, and pilot screws. I havent actively paid much attention, waiting until I dial in the setup and stop changing the variables.

During the last Tech Day that naughty's talking about, SpecOps13 told me that my prob sounds like a too-lean idle condition. This seems to line up with your hypothesis that the fuel pump isn't delivering enough fuel, but I would hazard a guess that the fuel pump is either a go or no go system, not a go or a no go during certain throttle positions. But what do I know.

With out all the facts, I would experiment and see if opening up the afr screws a 1/4 at a time resolves the issues and then base the next step to find the root cause using the results.

Good luck! Am on the phone, so can't really tell if your new to the forum. If so, welcome! Also where abouts in FL are you?

I also submit that are carb gurus here more qualified than myself, who will undoubtedly be chiming in if they haven't already.

Sent from my Tapatalking Hercules Android

 

[naughtyG]

It's normal for the fuel pump to click for a longer time after the bike's been sitting: the pump runs until the fuel bowls are full. When the bike's been sitting, the bowls are emptier due to fuel evaporation.

A couple of things for you to check: what's your float wet levels? Very easy to check, bike must be level, attach a piece of clear hose to the fuel bowl drain hoses and hold against carb bodies. There's a horizontal mark in the middle of the slides' enclosure, proper fuel level is 16mm +-1mm under the mark. That way you can check your pump's working right.

Also Kyle in Tampa is breaking a few Maxes and has lots of spares, so you could always take a trip over and replace your pump to make sure it's all good. I don't really think that's your prob though, but of course I could be wrong.

 

[jbVMax]

Thanks for the reply. Yes I'm new to the forum. Joined specifically to help resolve this issue. I live in Apopka, central Fla, 20 min north of Orlando. My theory that the fuel pump may be the culprit is two things: 1. As rpms go up so does the power to the electrical system therefore giving the pump more power. 2. The "tick tick ticking" sound the pump make priming itself when first turning the key on has steadily gotten louder and longer over time. It's to a point that I can no longer hear the VBoost's 3 little buzzes over the fuel pump's chattering. I may be way off, I suppose that's why I jumped on this forum. I'm willing to try the "shotgun" clean, but I just did a full disassemble and clean (in an oscillating carb clean tank) about 3 months ago.

 

[naughtyG]

Well there are a couple more issues with fuel - being in FL you get at least 10% ethanol in your gas. Whenever you let the bike sit, the alcohol (ethanol) absorbs water that sits at the bottom of fuel tank, pump, bowls etc. Not good.

Your bike being an '88, I would strongly recommend you take a good look inside your fuel tank with a bright flash light. Do you see any rust? If so that's your problem. Also drain your bowls quickly into a clear container to make sure all gas is clean - eliminates the guesswork.

As you know your bike best, if you've noticed the pump getting noticeably louder it's very possible it's on its way out - they can fail like any other component. As previously mentioned, contact Kyle in Tampa (captainkyle here) he's parting out an '05 and I'm fairly sure he still has the fuel pump. Stand-up bloke too, you'll get an honest price. I used to live in Tampa then O-town so I know Kyle and the neighborly Maxxers. Top dudes all round.

 

[jbVMax]

Today, along with doing the "crimp fix" at the shop, I set the air mixture screws in from 3 turns to 2 turns out and then 1/4 incriments to 3 1/2 out where they are now. Didn't seem to help.

 

[naughtyG]

If your PAJ circuits have any crap in them at all, adjusting A/F screws won't help with your stumbling issue..
Also do you have an O2 sniffer at the shop? That's the only way to really adjust those accurately. Here most people set them to 2.5 turns out and go from there.

 

[jbVMax]

Thanks again for the advice. I do try and run ethanol free fuel in it whenever I can. Harris Fuels in Mt. Dora. Yes, ethanol is the devil!!! I've seen clean carbs go bad in as little as 5 weeks if not being run regularly. I tell people too, when storing your bike, use a fuel stabilizer then ride for 5 or 10 miles, and "DON'T DRAIN YOUR CARBS!" Fuel goes bad quicker in small amounts and that drop that gets left in your jet will go bad faster than if the system is full.

 

[jbVMax]

Tank is clean. Even if rust was an issue, I think that would affect performance at all temps and throughout rpm range. All good advice though, thanks to you for your suggestions. Ride safe!!

 

[naughtyG]

No problem - sounds like you know what you're doing so you should be good. Do try the shotgun though, it's pretty quick 'n' easy and can make a world of difference if there's any crap in your pilot jets circuits. When I did it to my '86 it fixed the conking out when hot problem I had at traffic lights real good. But it started again after a while, so I tore right through my carbs for a good cleanup and rebuild. It ran fine for about year then all went shit again. That's when I realized my fuel tank was full of rust... Joy oh joy. Swapped it for a treated one (lucky me I had a spare), cleaned up everything again and it ran like a champ 'til I sold it!

 

[wildweasel_pt]

I think the problem may be electrical due to much heat on the bike. One of my bikes has the same issue. When it gets hot in traffic it starts to stumble and it stalls many times. Then its a pain to get it to start again without letting it cool a bit...

 

[jfeagins]

Check the charging voltage when hot. If the voltage drops off too far, the black box gets finicky and will start doing strange things, including stumbling at lower RPMs, and especially while sitting in traffic or at a stop light, and increasingly so, if you are running blinkers and/or brake lighting while stopped. Often, this stumbing will cause the bike to die.

I finally updated to the new style R/R, added solder to the stator wiring connections, and also did the battery box mod and went with the larger battery. Have not had any grief from running hot again. (knock on wood)

 

[RaWarrior]

With a clean tank and fresh carbs I'm also going to lean toward an electrical issue. When my bike had a low voltage problem it would sometimes have a funny idle that would waver between maybe 750-1250 rpm. It went away after I replaced the stator, r/r, and rewired the charging circuit. Had to do all of that until I had normal voltage at the battery, as in around 13v hot idle fan on, and 14.4 from around 1500rpm on up. When the idle was wacky it had around 12 at idle and peaked at 12.5 or so.

See my tutorial in the how-to section for more on this. I redid the wiring(bypassing the crimp entirely) and replaced the R/R, had great voltage cold but it fell back down to like 12 when the motor got hot. Replaced the stator with a Ricks Electrics one, fixed. Statics can short under heat, load, or both.

An '88 has the old analog ignition box as well, which are known to be unreliable and it getting hot(it sits right above the engine) sometimes causes it to wig out.

 

[CaptainKyle]

I am leaning towars electrical to . Check all electrical components when the bike is hot they seem to break down with heat. I have seen plenty of people check RR's & stators cold & think there fine & in reality they are not.