What did you do to your Vmax today? Part 2

[dannymax]

I tried to fire up Redbone on Sunday. It turned over fine but would not start, backfiring through the xhaust and intake. I should layout the setup: new-to-me carbs that came from another Vmax that was setup w/ a Morley Jet kit for a elevation of ~600', my elevation is 694". The carbs are clean running 162.5 main jet, A/F 2.5 turns out. Running Marks 4 into 2 and have installed COPS (denso's from a '04 Honda F4vi,"Long") Plugs gapped at .025".
Since this is the first time I had tried to restart since returning the engine to the frame I wondered if I had installed something wrong, there was somthing wrong with the carbs (remember, new to me) or that I had disturbed some connection while either while dismantling, modding while engine was out or something had gone wrong during the install. This is the first time I had ever tackled this extensive of work on a motorcycle so I was learning a great deal as I went through each step.
I was not all that sure I had put everything back together properly when I turned the key to on, listened to it run through the vboost cycle, and the familiar clicking while it frantically tried to fill the bowls. I cycled the on key a couple of times to make sure the bowls were full. I hit the starter and the starter spun, the carb coughed. Being on edge about getting everything "right" my heart jumped out of my chest the first time it backfired out of the exhaust. I'm happy to report that I must have a strong heart! In my mind I going over the entire install, much like one would do when one goes over their entire life while slowly dying on tv. Then it hit me! Bam! I bet I had the front two coils crossed up! I quickly swapped the front two coils around, checked all connections, and hit the starter again. It turned over once...then twice....and sprang to life! While it was a little rough running (gas from November) it seemed to be running fairly well, all things considered. I brought it up to tempeture, burping the cooling system to purge any trapped air. I had some fresh gas which I added to the 1/4 full tank of old gas and Redbone seemed to like this much better.
WHEW! What a relief it is for it to be running this well, I still need to do a carb sync so that should help. It is also acting a little funny returning to idle a little slower than I like but I have also installed new SS throttle cables and when it is idling I twist forward on the grip the idle settles a little. I will go through the cable adjustments. Any suggestions on how to do this?

Very scary post at the beginning Brian, happy to hear it was just crossed coils!

The slow return may be just sync. Does the throttle snap back on seem to bind a little?

There is a pretty good section on cable adjust in the Clymers, if you have that one....I'm sure Haynes covers it well too.

 

[4gasem]

.025 gap on the COPS? Why so tight? I'd have thought they'd be hot enough to open up a bit more than that.

Chris

 

[Rollie]

Plugs at .025 ? Still a little close , try .031 - .035

 

[Redbone]

.025 gap on the COPS? Why so tight? I'd have thought they'd be hot enough to open up a bit more than that.

Chris

I am try a recommendation by Birdoprey to run .022 - .025 gap in this post: http://www.vmaxforum.net/showthread.php?t=10365
I am going with the smaller gap/ hotter spark theory vs the larger gap/ larger spark theory which would let the coil not work so hard trying to overcome the resistance of the large gap. There are other reasons that are laid out in the thread. I will run it this way for a period of time and see how it works. I have some fine tuning to do with my new carbs so it may take a couple weeks to know for sure.
I don't know the science behind it, I'm just following Mark's lead since he has more experiance. :confused2:

 

[Thevmaxrider]

I am try a recommendation by Birdoprey to run .022 - .025 gap in this post: http://www.vmaxforum.net/showthread.php?t=10365
I am going with the smaller gap/ hotter spark theory vs the larger gap/ larger spark theory which would let the coil not work so hard trying to overcome the resistance of the large gap. There are other reasons that are laid out in the thread. I will run it this way for a period of time and see how it works. I have some fine tuning to do with my new carbs so it may take a couple weeks to know for sure.
I don't know the science behind it just following someone with more experiance lead. :confused2:

Maybe the reason behind this is that you need a higher voltage to arc across the gap due to higher resistance. By keeping the gap smaller you reduce the voltage necessary to arc making the coils "work" less to achieve the same thing. Of course with the dimensionally longer the spark the potential exists to get a more thorough burn of the air/fuel mixture. Technically your spark should be "hotter" due to the increase in the cross sectional dimension of the spark, but hey I am no electrical engineer, but instead a health physicist with some nuclear physics thrown in for color. Time to go, I almost sounded like I knew what I was saying.......:confused2:

 

[Redbone]

glad to hear it was something so simple brian. definitely not the first time someone's been caught by that.

as far as your slow return to idle, when you close the throttle can you see the plate linkage close then too or are the cables binding it from closing immediately?

I would consider mine a little 'slow' to return to idle, but not bad. i also have the vista cruise on it which doesn't help but its a lot better if i twist the throttle back to closed instead of letting it snap itself.

Very scary post at the beginning Brian, happy to hear it was just crossed coils!

The slow return may be just sync. Does the throttle snap back on seem to bind a little?

There is a pretty good section on cable adjust in the Clymers, if you have that one....I'm sure Haynes covers it well too.

The throttle seems to operate fairly normal, but I haven't twisted the throttle much since November so that may be just me. The throttle seems to almost snap back but the idle seems a little slow to return (possibly due to the old fuel still in the system or a sync issue as Danny mentioned). I'm thinking that the cable may need a little lube lovin' and some fine tuning as I have new cables on it. I have the Clymers so I'll check that out tonight.
Thanks for the responses! :thumbs up:
Yep, I said lube lovin'!

 

[dannymax]

.025 gap on the COPS? Why so tight? I'd have thought they'd be hot enough to open up a bit more than that.

Chris

Think Birdoprey posted that a tight gap would work better, the theory being the shorter the gap the hotter the spark. I always figured a longer spark (wider gap) would prolly give a more complete burn, and went with .031" instead.

 

[Redbone]

Maybe the reason behind this is that you need a higher voltage to arc across the gap due to higher resistance. By keeping the gap smaller you reduce the voltage necessary to arc making the coils "work" less to achieve the same thing. Of course with the dimensionally longer the spark the potential exists to get a more thorough burn of the air/fuel mixture. Technically your spark should be "hotter" due to the increase in the cross sectional dimension of the spark, but hey I am no electrical engineer, but instead a health physicist with some nuclear physics thrown in for color. Time to go, I almost sounded like I knew what I was saying.......:confused2:

I don't know exactly what you just said Jim, but can I pick up one of those cross sectional spark thingy's when I'm in Canada?:biglaugh:

 

[FREERIDER]

Kids are at there Moms for while. Prepping frame and swingarm for welding and paint.

 

[satariel666]

Maybe the reason behind this is that you need a higher voltage to arc across the gap due to higher resistance. By keeping the gap smaller you reduce the voltage necessary to arc making the coils "work" less to achieve the same thing. Of course with the dimensionally longer the spark the potential exists to get a more thorough burn of the air/fuel mixture. Technically your spark should be "hotter" due to the increase in the cross sectional dimension of the spark, but hey I am no electrical engineer, but instead a health physicist with some nuclear physics thrown in for color. Time to go, I almost sounded like I knew what I was saying.......:confused2:

Well thats trully a good theory.

One but...yeah i know that Im a smart ass LOL :rofl_200:

You reduce not the voltage across the arc but the sprak time.
Arc is smaller and shorter indeed but voltage should be close the same.

IMHO by this we get the gain in the energy supling the ignition, longer life to plug and coil etc.
Thats all IMHO.
I think that modern engines, EFI, high compression etc are more precise and much easier to create the fuel combustion. Newer engines also needs higher octane fuel so again easier to fire the fuel.

V-max is an old engine and in those times its low compression so its needs longer spark to fire properly.

Just my 2 cents, not nessecerly tru.

 

[maxcruiser]

I tried to fire up Redbone on Sunday. It turned over fine but would not start, backfiring through the xhaust and intake. I should layout the setup: new-to-me carbs that came from another Vmax that was setup w/ a Morley Jet kit for a elevation of ~600', my elevation is 694". The carbs are clean running 162.5 main jet, A/F 2.5 turns out. Running Marks 4 into 2 and have installed COPS (denso's from a '04 Honda F4vi,"Long") Plugs gapped at .025".
Since this is the first time I had tried to restart since returning the engine to the frame I wondered if I had installed something wrong, there was somthing wrong with the carbs (remember, new to me) or that I had disturbed some connection while either while dismantling, modding while engine was out or something had gone wrong during the install. This is the first time I had ever tackled this extensive of work on a motorcycle so I was learning a great deal as I went through each step.
I was not all that sure I had put everything back together properly when I turned the key to on, listened to it run through the vboost cycle, and the familiar clicking while it frantically tried to fill the bowls. I cycled the on key a couple of times to make sure the bowls were full. I hit the starter and the starter spun, the carb coughed. Being on edge about getting everything "right" my heart jumped out of my chest the first time it backfired out of the exhaust. I'm happy to report that I must have a strong heart! In my mind I going over the entire install, much like one would do when one goes over their entire life while slowly dying on tv. Then it hit me! Bam! I bet I had the front two coils crossed up! I quickly swapped the front two coils around, checked all connections, and hit the starter again. It turned over once...then twice....and sprang to life! While it was a little rough running (gas from November) it seemed to be running fairly well, all things considered. I brought it up to tempeture, burping the cooling system to purge any trapped air. I had some fresh gas which I added to the 1/4 full tank of old gas and Redbone seemed to like this much better.
WHEW! What a relief it is for it to be running this well, I still need to do a carb sync so that should help. It is also acting a little funny returning to idle a little slower than I like but I have also installed new SS throttle cables and when it is idling I twist forward on the grip the idle settles a little. I will go through the cable adjustments. Any suggestions on how to do this?

Great stuff Brian, glad to hear t hat Redbone lives again! :th_image003:

It always takes a bit to get the bugs out after such major surgery - Redbone will be up and running, better than new soon I'm sure.

Mike

 

[Thevmaxrider]

Well thats trully a good theory.

One but...yeah i know that Im a smart ass LOL :rofl_200:

You reduce not the voltage across the arc but the sprak time.
Arc is smaller and shorter indeed but voltage should be close the same.

IMHO by this we get the gain in the energy supling the ignition, longer life to plug and coil etc.
Thats all IMHO.
I think that modern engines, EFI, high compression etc are more precise and much easier to create the fuel combustion. Newer engines also needs higher octane fuel so again easier to fire the fuel.

V-max is an old engine and in those times its low compression so its needs longer spark to fire properly.

Just my 2 cents, not nessecerly tru.

Hmmmmm, interesting theory. I would think that the spark "time" would be determined by the ignition and not spark plug gap. If I close up the gap it takes less voltage to arc across it so theoretically the spark should take less time to form and should last longer for any incident pulse from the ignition....... whoa that hurt my brain time to go now:rofl_200:

 

[one2dmax]

Brain, Make sure to send pics and a review (of the trans and anything else) so I can add it to the site.

Sean

 

[Redbone]

Brain, Make sure to send pics and a review (of the trans and anything else) so I can add it to the site.

Sean

Will do Sean. I still have to bleed the brakes/ clutch and couple of other bits to get Redbone "picture worthy" but I should have all that done by tonight or tommorow.
I am crawling up the walls here at work because I want to finish the work and go for a ride!

 

[one2dmax]

Getting your other stuff out today hopefully by the way. Was the engine as shiny as you hoped for? I thought it turned out very nice.

Sean

 

[Redbone]

Getting your other stuff out today hopefully by the way. Was the engine as shiny as you hoped for? I thought it turned out very nice.

Sean

Yes, I expected shiny from your picture but in person it is way better. I'll try to get some great pictures but I just have a cheap digital camera to use. I had some buddies over and they could not believe that it was the same engine! I 'm here to tell everyone that it looks better than showroom new!
It should be nice here for the next week so I'll be able to get some great pics for you. Thanks again Sean! :thumbs up:

 

[nd4topspd]

sounds awesome!!! shoot those pics lol

 

[satariel666]

Hmmmmm, interesting theory. I would think that the spark "time" would be determined by the ignition and not spark plug gap. If I close up the gap it takes less voltage to arc across it so theoretically the spark should take less time to form and should last longer for any incident pulse from the ignition....... whoa that hurt my brain time to go now:rofl_200:

Dwell is determined by the ignition, time(how fast the arc travels beteween the electrodes) is determined by many factors.

Ignition coil will produce determined voltage, determined by manufacter, it will be still close the same voltage no matter what you will do.
Another thingy is how the spark plug transform that voltage into arc.
Arc can be created with 50V and 25,000V. Current is the factor that determines the power of ark arc. Something like welding.

So lets say that voltage is constat, about 25,000V.
This is the specific voltage to break the gap beteween the electrodes.
This voltage is determined by the kind of material that electodes are made, the size of that electrodes and the atmosphere around the whole fenomena.
When arc fires, gases beteween electrodes transforms into "plasma". The temperature of plasma is determined by current.
Another factor that determines the temp. of plasma is the gases pressure.
If pressure is higher then the plasma is hotter.

So more compression ratio means hotter plasma, more current nedded and by that - no need to have that big gap like the modern engines have.
If you will keep wide gap then most defo the plug will toastet shortly by overheating.

I hope that i made myself clear, my english is not that good to talk in
that kind of technical level.
Sorry for eventualy misunderstandings.

Thats mine thoery, not nessecerly tru, i could be wrong, im not taking the responsiblity of mine thoeries so please dont do that at home
:rofl_200:


Now thats a real brain damage...did i say brain?
What is brain? LOL :rofl_200:

 

[Blujay]

I rode my baby for the first time today. I got my 85 offa ebay in November. I drove from Sacto Ca to El Monte Ca to pick her up, after I loaded her on the trailer and tried to leave, my trusty old PU refused to start. I spent the next four hours changing the trucks intank fuel pump. It ended up being a twenty hour day. I've been sorting things out since I coasted her off the trailer once we got home. I"ve done a bunch of upgrades, progressive springs, fork seal kits, welded the air holes closed, steering head bearings (The old ones were notchy like a 3/4" ratchet) Busa front brakes, Galfer rear pads, Shinko tires, Pulled the fuel tank for derusting and sealing and the list goes on. The clutch M/C sight glass had popped out and the front brake one was barely hanging in there so I made two new ones out of an old piece of plexiglass and expoxied them into place, so far so good. Anyway once I had brakes and a clutch I had to take her out for a short spin, there are still some carburetor issues but I think I may be falling in love,..... again. I do have one question though is it normal to feel engine vibration in the handle bars? When I first felt it I thought maybe I'd screwed up changing the front wheel bearings but I coasted down a hill with the clutch in and the engine off and she was smooth as silk. I've still got a ways to go but I think she'll be ready for our vacation tour in September. Jay

 

[Nicki66]

Hey Redbone, Congrats on getting her running again. I just recently installed the COP's in my max and initially had the plug gap at .022 and I was not impressed with how she ran. I regapped the plugs to .030 and was pleased with the performance.
To bleed your clutch you may want to try the method that I used in this thread: http://www.vmaxforum.net/showthread.php?t=12103. This worked quite well for me and is without a mess or waste of fluid.