Sick VMAX Makes Me Want to Cry!

[drdrewdown]

ok, so i'm sure many of you that attended the Topeka Dyno Run last weekend got to hear my sickly VMAX. It seems that i'm missing out on about 40 horsepower and i believe its been doing this since purchase. I've had it for 2 months and the PO had it sitting outside under a cover. I believe this problem i'm having has been going on since i bought it, but its more noticeable now with the louder exhaust i've installed. We also installed 147.5 main jets at the time of exhaust installation, had to replace a couple of the slide diaphragms with rips in them.

You'll be able to see what happens on the Dyno printout but the symptoms are cutting out in WOT scenarios. It sounded really bad on the DYNO. It sounds like a sportbike hitting the rev limiter.

ran it another time after changing the coils & plugs

seems to have made the graph a little less noisy but the problem is still quite apparent.

I need suggestions from you wizards.

Things i'm going to check & report back are:

Voltages on battery just to make sure its charging right. (havent had any problems with it, just wanna make sure)

I want to look at the fuel filter & perhaps the fuel pump ( i've read about strange things with them)

I also want to look at the plug boots & see if there is any arcing going on.

As well as making sure the motor is properly grounded.

I'm sure I'll need the help of Sean Morley ( good thing he lives 20 minutes away) and anyone else who can chime in for things to check.

Any other obvious things i'm missing or need to check?

Thanks in advance

 

[Rand-5107]

Wet and dry compression test and or leak down test.

 

[Thevmaxrider]

I would also start looking for an air leak. Check and make sure the airbox is down tight on the carbs, the carbs are down tight on the manifolds, and that the Vboost manifolds look good. Judging by the way that thing is all over the map something seriously not right. Also check carb synch, make sure the vacuum port covers are good and that the vacuum line on the #2 cylinder, left front, is in good shape. Have you had the airbox open? Have seen mouse nests in them before and if you have a nest in there it could cause you some serious grief. After you have done that you might want to see if Sean will loan you a CDI box just to rule out ignition issues. Do these to start and I will keep mulling it over.

 

[drdrewdown]

I would also start looking for an air leak. Check and make sure the airbox is down tight on the carbs, the carbs are down tight on the manifolds, and that the Vboost manifolds look good. Judging by the way that thing is all over the map something seriously not right. Also check carb synch, make sure the vacuum port covers are good and that the vacuum line on the #2 cylinder, left front, is in good shape. Have you had the airbox open? Have seen mouse nests in them before and if you have a nest in there it could cause you some serious grief. After you have done that you might want to see if Sean will loan you a CDI box just to rule out ignition issues. Do these to start and I will keep mulling it over.

i've had the airbox open/off a couple times now & it all looks really good. We didn't have any issues stabbing the carbs down either. I will check the vacuum stuff you mention

Carbs have been synced a couple times now, once before we pulled them off & then once after cleaning/rejetting.

i would be curious to try a different CDI box, i think i just gotta do the process of elimination.

I will def keep everyone posted!

 

[Rand-5107]

Low compression = low torque and horsepower. If it's low, I would suspect sticky rings.

 

[drdrewdown]

Low compression = low torque and horsepower. If it's low, I would suspect sticky rings.

but this would only rear its ugly head under WOT?

 

[Rand-5107]

I can't say for sure about that. I had a motor in the past that ran ok, but when I tested it, the compression was low dry but came up wet. So I used a sticky ring treatment. You know you add it to your oil and let it idle 5 or 10 minutes then drain. Compression came back up and it ran really good after that. Pull your plugs and borrow a tester it doesn't really cost you anything and you can rule it out.

 

[drdrewdown]

i'll add it to the list!

 

[drdrewdown]

tested the electrical stuff tonight. it was showing 13v at the battery terminals with 1v being lost in the rats nest of wires. My buddy Paul is an electrical wizard & wanted to mod it, bypassing all the connectors going straight to the terminals & now she's getting 14v at the battery. We tried the "crimp fix" but only increased voltage slightly & he said screw this hahaha.

as you will probably guess, the problem still exists & i've made plans to look at the carbs again on wednesday. i hope to get a new fuel filter tomorrow if i'm lucky.

 

[Rollie]

Look closely at the plugs for a small crack when checking the plug boots.

 

[drdrewdown]

Look closely at the plugs for a small crack when checking the plug boots.

the plugs are one day old & i will check the boots for arcing tomorrow evening, its too late now, i'd wake my 80 year old neighbors. haha

 

[SpecOps13]

Wow, best of luck narrowing this down and getting it corrected....I'll keep an eye on the thread in case I can think of anything that might help....

 

[Elimax]

Hi all:

Not to get too much off-subject here, but Rand, you mentioned a "sticky ring treatment"....is that a chemical additive? And where did you get it from (Autoshop? Or ordered it online?)

Thank you.

Elimax

 

[drdrewdown]

well everyone, i know you all have been on the edge of your seat to hear how this has progressed so here is the story.

after seeing what Maleko was having to do with the plug wires & coils i decided it would best to just redo the ignition system with the COPs style. Got a set of the COPs harnesses(Gannon's harness) from Sean. Installed them with the new coils in the kit & man what a difference.

No more does it sound like a sportbike on the rev limiter, it pulls strong! There is a couple spots of stuttering at 7k & 9k RPMs but this is a whole new bike.

The old spark plug wires were corroded as you can tell by the pics in this post i made in wdydt thread.

http://www.vmaxforum.net/showpost.php?p=214227&postcount=3690

thanks everyone for your help!

Any idea what i should look at for the stuttering at 7k & 9k? It powers right thru it (now, thankfully) but short of putting it on a dyno what would you guys look at? it ONLY happens at WOT, if i'm less than WOT it just pulls like a beast.

Testing a lean theory i put the stock size 152 mains back in this evening just to see if there is any difference from the 147.5s that i had put in a few weeks back.. just "feeling" it, it seems better but its hard to say.

p.s. Gannon's COP harness kits are amazing! i'd highly recommend them to anyone looking to update/upgrade their ignition, really a very nice well put together kit. bravo!

 

[drdrewdown]

It's been a really long time since I last posted here but I wanted to update the thread in case anyone else runs across this same problem

Long story short I tore the carbs apart and found one of the rubber plugs in the third hole instead of the first. Fixed that, synced the carbs and now it's running like a beast! Thanks everyone who gave their input and helped me last year in Topeka. See you all in a few weeks!

-???τ √?? ??M???Ģ Ģ?L?X? ??X??-

 

[mattmullins]

You might want to find out if the dyno wheel is 900 lbs or more pounds there's a guy up her that's has one and it will show 10-15 hp loss different from one that is 4-600 lbs

 

[drdrewdown]

You might want to find out if the dyno wheel is 900 lbs or more pounds there's a guy up her that's has one and it will show 10-15 hp loss different from one that is 4-600 lbs

as long as it shows more than the 80hp i had last year i'll be just fine :bang head:

 

[naughtyG]

as long as it shows more than the 80hp i had last year i'll be just fine :bang head:

LOL I'm sure you'll be pleasantly surprised!

One thing's stumping me: you say you're 20mns from Sean's but your location says 'Land of Oz'. Where are you?

 

[drdrewdown]

LOL I'm sure you'll be pleasantly surprised!

One thing's stumping me: you say you're 20mns from Sean's but your location says 'Land of Oz'. Where are you?

The OZ is from Kansas.. you know The Wizard & all.

I live in Wichita, sorry i see how that would confuse you Aussies