Vboost cuttin in/out

[Fire-medic]

desert_max is correct, I stand corrected. The secondary circuit in a distributor circuit is from the distributor to the high-tension coil, the coil sends a high-tension signal to the distributor (the center wire in the middle of the distributor cap) which sends the high-voltage to each cylinder in-turn. In an electronic distributorless-ignition system, that's done by the ignition control module.

PRIMARY IGNITION (autoditex.com)

The classical or conventional ignition system consists of the following components: ignition coil, distributor, spark plugs, high-voltage wires and some means of controlling the primary ignition circuit. The primary circuit of the ignition coil can contain: points, points controlling a transistor, the transistor being controlled by some other means. In point-type ignition systems the current in the primary circuit is controlled by a mechanical switch (or breaker). The mechanical points may control a switching transistor which opens and closes the primary circuit of the ignition coil.

 

[85vmax]

Air filter is super clean, I have never checked the fuel filter, Could the fuel filter really make it run bad at high rpms, but not low rpms?

Yes sir......

 

[Fire-medic]

Air filter is super clean, I have never checked the fuel filter, Could the fuel filter really make it run bad at high rpms, but not low rpms?

Think of the fuel filter as a strainer.

Now, think of a colander, the thing you use to dump pasta into after boiling to drain the water. The bigger the holes in the colander, the quicker the boiled water drains.

Your gas filter is the colander. When contaminants encounter the gas filter media it captures them, which obstructs gas flow where those contaminants are. The filter media is designed with enough surface area to allow sufficient flow even-when 'dirty.' However, at a point where the demand of the engine for fuel exceeds the ability of the filter to allow the free-flow of sufficient passage of gasoline, fuel starvation occurs. Thus, a 'dirty' filter cannot pass fuel at a volume to allow normal operation. Remove/replace the fuel filter.

And go boil some pasta for dinner. Prego!

 

[desert_max]

I thought we already did that. If not, that's job one! That filter shown looks like carp. (the politically correct form of crap)

 

[Fire-medic]

I thought we already did that. If not, that's job one! That filter shown looks like carp. (the politically correct form of crap)

 

[02GF74]

.
However, to FM's point, if your coil-to-plug wire broke off inside the tower, that very likely is your problem.

The high voltage is able to jump across the gap in the spark plug (intended) so if the piece broken off has wire running inside it, once the lead is butted up against it, the voltage may well be able to jump across the smaller gap but not every time so ignition is intermittent.

Removing the broken off piece and inserting the lead fully may well fix the problem.... but it doesn't explain the problems on the primary side, namely erratic tacho/vboost issues.

Incidentally how is it possible to break the HT lead - they are usually quite flexible/rubbery, has it hardened and become brittle with age?

Also is the affected coil the one the tacho/vboost take the signal from?

 

[MotoLife]

Hey guys there was no piece in there like I thought, but i trimmed it put it back, I figured it out it only cuts out when im riding it hard like a dirt bike, when im cruising and rolling on and off throttle everything works... And I was wrong the tach does slowly go up when its cutting in and out...

 

[MotoLife]

Im at a loss, it idles and rides fine...But when i start riding it violently it just starts cutting out at high rpm...

 

[Fire-medic]

Did you drain the carbs 1 at a time, to see what's in the float bowls?

OK, basics. Spark plugs are cheap, change 'em.

 

[Fire-medic]

Gas tank looked great! I think I could see all the way down the to fuel pump? Put a new fuel filter in and it still stutters at high rpm...

Yes sir, the rpm needle stutters when the bike does!

The fuel pump is not in the tank, it's by the seat latch mechanism, under the faux gas tank. What's bolted-through the bottom of the gas tank is the low fuel electrical sensor, it has 1 wire.

 

[Woody]

Did you drain the carbs 1 at a time, to see what's in the float bowls?

OK, basics. Spark plugs are cheap, change 'em.

Like FM said.
"DRAIN THE BOWLS"

 

[MotoLife]

Here is a pic of the champion plug I pulled, it was getting spark... I’m about to drain carbs

 

[MaxMidnight]

If it performs as expected when using the throttle 'normally' then IMO it is not an ignition problem particularly as it has been confirmed that the rev counter still operates when the motor misbehaves. I'd also be surprised if it was V Boost related.

The comment 'it only cuts out when I'm riding it hard like a dirt bike' which I assume means rapid changes from closed to open throttle still make me think it is a fueling condition.

Whilst we can all make guesses as to what is causing the issue getting hard facts with which to base a diagnosis isn't so easy.
Whilst that plug suggests a rich mixture we don't know how the motor was being operated before the motor was cut. On that basis I wouldn't suggest a jet change at the moment.

Call me a cracked record and slap me with a haddock but rather than play 'Guess the problem' my standard advice is that you would waste far less time by getting a dyno baseline run.
That will give you the facts to decide what the next step should be.

 

[dannymax]

Disconnect the fuel line from the carbs and cycle some gas into a glass container...look for foreign particles.
Clean and apply di-electric grease to all your electric connections including fuses. Suggest doing this sooner than later.
Take Mr Midnight's excellent advice and get a dyno run.

 

[MotoLife]

Disconnect the fuel line from the carbs and cycle some gas into a glass container...look for foreign particles.
Clean and apply di-electric grease to all your electric connections including fuses. Suggest doing this sooner than later.
Take Mr Midnight's excellent advice and get a dyno run.

Ok im going to buy spark plugs, dielectric grease and ill go drain the bowls now... thanks guys

 

[02GF74]

What is the gap in that spark plug, it looks a bit large to me.

 

[MotoLife]

Hey guys I put 4 new ngk dpr8ea-9 spark plugs in with dielectric grease in boots, and drained the bowls, two of the carbs had some sediment (ill upload pics later). Its running good but it still cuts out under hard acceleration, im started to think Main jets are gunked or something else in the carbs. If it was electrical related it wouldnt only show up under high rpm right?? Runs and idles excellent until you start hammering it, wheelies in 1st and 2nd gear. Can I just take the whole set of carbs off and buy a stage 2 jet kit and send them off? Super frustrated, but I still ride it everyday.

 

[VMAXXIMUM]

Pull the rack, buy Sean's kit and send them to Dannymax, Capt.Kyle or Sean. Oh, don't bother with a jet kit if your running the stock header pipes, it won't do much.

 

[Fire-medic]

No to the Stage 2 jet kit. OEM exhaust, just clean the carbs and run it stock.

Sean has his own jet kit/induction parts, and choose an aftermarket exhaust (ask Sean Morley for recommendations) if you want some extra oomph. That's gonna run you probably $1K for the carb kit and an exhaust. The guys who sell parts may have a deccent used aftermarket full exhaust, you need that to make a jet kit work properly. Slip-ons change the noise, they look different, but you get no performance boost.

If I were in your position, I'd just get it running well stock, and ride it.

After a season or two, think about the carb kit and full exhaust.

 

[MotoLife]

If i take the whole carb set off, about how much to have cleaned? Gotta be at least one jet or something thats clogged making her starve for fuel under hard acceleration....right?