Buying my first Vmax.

[Saml01]

Holy crap these vac gauges are teeeny. If they suck im gonna turn them into some really baller cufflinks.

 

[Saml01]

If the lines are new, I wouldn't worry too much about it. Is it the fuel line that's smooth and shiny, or the more flat, rubbery kind? The shiny kind tends to get pretty stiff when it gets cool.

The fuel lines running to the pump are gray, shiny, rubbery they stay pliable.

The black rubber lines from autozone that run to the carb from the pump and between the carbs become rock hard.

I am worried the fuel inside is drying them or something. They werent sold as fuel rated hose, which I just assume means its made to withstand high pressure. But this was just called vacuum hose. I dont see this pump reaching the same fuel pressures like an automotive pump so I assumed its fine.

 

[The Beekeeper]

Never use anything not rated for fuel in a fuel system!..............Cycle or automotive.................

 

[Saml01]

Never use anything not rated for fuel in a fuel system!..............Cycle or automotive.................

They dont sell fuel rated hose in this size. Neither does advance auto.

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[RaWarrior]

He's right, fuel line is tough to find in smaller sizes. Dennis Kirk sells it in diameters all the way down to 1/8" however, and some powersports dealers/ speed shops may also (if they're a dealer for Parts Unlimited).

I've found the clear vinyl tubing to work well for fuel also, but it's also sold as "highly petrochemical resistant". You can get that at Home Depot or someplace similar by the foot. I've made gas gauges out of it, running a length of the tubing along the outside of a tank vertically.

If it used to be pliable and isn't anymore, time to lose it. Hard lines are brittle, and brittle lines crack and leak. Leaky fuel = bad news.

 

[Saml01]

Ill keep an eye on the lines.

 

[Saml01]

OK. Here we go.Last time I posted I screwed up the carb sync so bad that the bike didnt run afterwards. I came to bitch and moan that I should have bought a dedicated tool to begin with. I decided to edit the post sit down calmly and reread the shop manual; I realized what I did wrong and tried again. Second time around it was a success.

I took the advice of someone in the thread I made about home made sync gauges and just pinched the line to reduce the intake pulses affects on the gauge. it worked.

If you compare this to the first video I posted you will notice the bike returns to idle quicker and also revs faster.

http://www.youtube.com/watch?v=QKcsheCo9IA

 

[BIGMO]

Nice guages. Looks like they work well.

 

[Saml01]

OK. Now that I got most of the obvious stuff squared away I can start troubleshooting less obvious stuff. I was experiencing a hesitation when accelerating from 4 - 6k. I pulled the plugs and they were white as snow. Too lean for sure. I dropped the needle 1 clip position and the bike runs TONS bette from 4 - 6k. Smack it open anywhere between those two points and it hauls ass. However, now I have a backfire occasionally when snapping the throttle closed after a WOT pull.

My car does this because I have tuned the boosted cells to pull down to 12.5:1 afr at full spool so it too is a rare occurrence but does sometimes happen.

The bike though I am unsure, since it also has an over run circuit or something I imagine its contributing to the occurrence.

The carbs have a stage 7 kit. 165 main, 170 paj2, 45 paj1(I think), needle clip in 5th position from the top.

I am waiting for the bike to cool off so I can check the plugs but in the meantime I thought id get some background.

Normal or not normal?


P.S. Bike is dangerous. I took it from 10 - 85 and its just stupid fast.

 

[gamorg02]

OK. Now that I got most of the obvious stuff squared away I can start troubleshooting less obvious stuff. I was experiencing a hesitation when accelerating from 4 - 6k. I pulled the plugs and they were white as snow. Too lean for sure. I dropped the needle 1 clip position and the bike runs TONS bette from 4 - 6k. Smack it open anywhere between those two points and it hauls ass. However, now I have a backfire occasionally when snapping the throttle closed after a WOT pull.

My car does this because I have tuned the boosted cells to pull down to 12.5:1 afr at full spool so it too is a rare occurrence but does sometimes happen.

The bike though I am unsure, since it also has an over run circuit or something I imagine its contributing to the occurrence.

The carbs have a stage 7 kit. 165 main, 170 paj2, 45 paj1(I think), needle clip in 5th position from the top.

I am waiting for the bike to cool off so I can check the plugs but in the meantime I thought id get some background.

Normal or not normal?


P.S. Bike is dangerous. I took it from 10 - 85 and its just stupid fast.

try using a shim to put the needle a half clip or open your a/f screws 1/4 turns at a time.

 

[Saml01]

I don't like shimming needles.

I will try the AF screws. Though I doubt richer pilots will cure the problem. Its not spitting through the carb, its firing in the exhaust that means unburned fuel is making its way into it.

My best educated guess for the cause or contributing to the cause is the timing. This bike has a MAP sensor for timing advance. Slam the throttle closed and the timing ******* from where it was causing the combustion stroke to happen much later. Further contributing to the backfire.

Its cool a **** to listen to, but I dont know if its necessary.

 

[gamorg02]

when my pilot screws were lean, it was causing backfiring through the exhaust when the throttle was snapped closed.

 

[Saml01]

when my pilot screws were lean, it was causing backfiring through the exhaust when the throttle was snapped closed.

I will give it a try, thanks for speaking from experience.

 

[gamorg02]

I will give it a try, thanks for speaking from experience.

no prob. easy way to tell is to throw the choke on and see if that specific symptom goes away.

also part of my pilot circuit was blocked so i had to clear it as well.

hopefully this helps!

 

[Saml01]

Damnit, I think I found the culprit of the backfire. A misfiring cylinder...still. Same number 2 cylinder as before. Sit at any RPM long enough and it will start cutting out. That unburned fuel makes its way into the exhaust at higher RPM's and ignites.

While letting the bike idle I can grab the header, rev the motor and feel it getting hotter presumably from extra fuel getting ignited in those rare events where it does fire, but while the rest are beyond even poking at, this one you can cuddle up against.

I got home after a ride and was able to grab and hold the number 2 header; thats how bad it is.

How bad can it be?
Coil? Pickup? TSI?

 

[Saml01]

I FIGURED IT OUT. HAR HAR HAR

Findings incoming.

 

[Saml01]

I decided to look into the shop manual for the resistance figures of the coils. So I started checking them. I was happy to discover the coils checked out fine. BUT.... the spark plug cap on the problematic cylinder had 500kohm vs 10kohm resistance. AWESOME. No need to order new coils now, just a cap.

I looked over the cap very carefully and noticed the spark plug end has a flat head groove in it. Can it possibly be user serviceable? Its garbage anyway, why not take it apart. Turns out it is serviceable.



This is what the breakdown looks like.


These are the innards. From left to right.
1. It has the business end which screws into the body to hold the rest of the pieces in and the cap on the plug.
2. Ceramic resistor.
3. A spring which pushes the resistor against number 1 and connects the cap to it.
4. A small insulator. Presumably to prevent the spring from welding to the end inside the cap.


Why was the resistance 10 times greater than normal and the cap pretty much useless?
Pictures speak for themselves.


I whipped out my dremel with a wire wheel and cleaned the ends of every piece to a shine. Then re-assembled.

Guess what, cap is as good as new. 10kohm.

I checked the rest to be safe and all had some form of burning on the ends and even though they were working I bet it was hurting spark none the less.

 

[Saml01]

How come I cant find 10kohm NGK straight spark plug caps?
I can find 5kohm on bikebandit, but thats not what the bike requires.

At $4 each, I dont know if the above is worth the hassle to anyone.

 

[gamorg02]

so did that def solve it bro?

 

[Saml01]

so did that def solve it bro?

I cant tell you lol, it was too late to start the bike.

But it cant be anything else. :ummm:

Ill report back tomorrow.