long write on my almost year long tuning problem

[65fury]

Okay... where to begin... umm lets see almost a year ago i bought my vmax and had it about 3 weeks when i decided to paint and clean and fix it up a bit, new bearings, brakes......ect ect ect i also pulled the carburetors to clean them since it had been sitting a while and ever since then... it HAS NOT RUN RIGHT EVER!!! it started out as a mid range issue, stumbleing, choking flat out just not running in the mids at all when WOT... and ive cleaned the carbs 3 times personally and even sent them to Fargo who soaked them and rebuilt them with new gaskets and such. The carbs are definfinitly clean and after every cleaning it still runs like crap!

So with all these issues ive literally done every carb setup i think possible betweeen different main jets and needles and shimming and PAJ2 jets and everything inbetween... Ive Sync'd the carbs a million times with a mercury gauge and a morgan carbtune which i just bought. Im running COPS so it not coils or wires that are causing this problem.

The only thing that seemed to ever make a difference towards success was me covering the intake with tape or rags... wierd yes but ive been running around with my intake taped half off for about 2 weeks now since my bike is MY ONLY MODE OF TRANSPORTATION right now. With the tape i can run into my mids with less stumbling and actually ride at highway sppeds 60-70mph when before it would die out after 55mph.

So Sean has offered to send some carbs to try on my bike to see if they will make it run better.... in the mean time ive just been riding it like it is, but ave noticed more problems coming about. It now likes to back fire and pop when starting it cold(after its been sitting for a whole) also itll pop and run rough at idle after riding for a while... but not all the time. And way to many times it has been idleing fine, i just sync'd it and then boom! its idleing rough and one carb isnt feeding it at idle, rev it and its fine but my idle is choppy and rough. So ill do the pee shooter and the shotgun and its good.... until about an hour later after i road around town and then came home and let it sit. I got out start it and my idle is off again!

And today... it ran "fine" to work and back... but 4hrs after im home i go to leave and itll only run on two cylinders!!!!!! so i let it idle and i rev it a bit and it clears.. go down the street about 1/4mile and it wont run on atleast 2 cylinders again! no matter the rpm even reving up it wont fire on more than two cylinders:bang head::bang head: So i get it home... barely and go through the carbs that seemed to bee giving me the trouble #4 and #2 i did the pee shooter and shotgun them for the third time this week! I even check my fuel filter and its good. So i start the bike and it seems to be idleing rough still but i can tell its atleast on all four cylinders... but wait..... is that smoke coming outa my exhaust?? yep!!! smells a bit like oil too...:bang head: so now its burning oil?? at this point i dont care and decide to take a test drive... but nooooo after about 1000' its running on 2cylinders again... come home and i notice no more white smoke but still not running right at ALL!

Basically im done.... i know ive been told to dyno it... but at this point i cant even get it to one. Ill wait for Morelys carbs and see if there is a difference... Ive racked my brain and have been getting all kinds of help on here, but after trying almost every combo on my carbs... im not sure what else to try... and yes ive checked ALL rubber boots the carbs touch or are even near... spraying brake clean, carb cleaner or any other flammable liquid on or around hasnt changed anything... so no air leaks that i can find.

ANY SUGGESTIONS ARE ALWAYS WELCOME

 

[firefly]

Okay... where to begin... umm lets see almost a year ago i bought my vmax and had it about 3 weeks when i decided to paint and clean and fix it up a bit, new bearings, brakes......ect ect ect i also pulled the carburetors to clean them since it had been sitting a while and ever since then... it HAS NOT RUN RIGHT EVER!!! it started out as a mid range issue, stumbleing, choking flat out just not running in the mids at all when WOT... and ive cleaned the carbs 3 times personally and even sent them to Fargo who soaked them and rebuilt them with new gaskets and such. The carbs are definfinitly clean and after every cleaning it still runs like crap!

So with all these issues ive literally done every carb setup i think possible betweeen different main jets and needles and shimming and PAJ2 jets and everything inbetween... Ive Sync'd the carbs a million times with a mercury gauge and a morgan carbtune which i just bought. Im running COPS so it not coils or wires that are causing this problem.

The only thing that seemed to ever make a difference towards success was me covering the intake with tape or rags... wierd yes but ive been running around with my intake taped half off for about 2 weeks now since my bike is MY ONLY MODE OF TRANSPORTATION right now. With the tape i can run into my mids with less stumbling and actually ride at highway sppeds 60-70mph when before it would die out after 55mph.

So Sean has offered to send some carbs to try on my bike to see if they will make it run better.... in the mean time ive just been riding it like it is, but ave noticed more problems coming about. It now likes to back fire and pop when starting it cold(after its been sitting for a whole) also itll pop and run rough at idle after riding for a while... but not all the time. And way to many times it has been idleing fine, i just sync'd it and then boom! its idleing rough and one carb isnt feeding it at idle, rev it and its fine but my idle is choppy and rough. So ill do the pee shooter and the shotgun and its good.... until about an hour later after i road around town and then came home and let it sit. I got out start it and my idle is off again!

And today... it ran "fine" to work and back... but 4hrs after im home i go to leave and itll only run on two cylinders!!!!!! so i let it idle and i rev it a bit and it clears.. go down the street about 1/4mile and it wont run on atleast 2 cylinders again! no matter the rpm even reving up it wont fire on more than two cylinders:bang head::bang head: So i get it home... barely and go through the carbs that seemed to bee giving me the trouble #4 and #2 i did the pee shooter and shotgun them for the third time this week! I even check my fuel filter and its good. So i start the bike and it seems to be idleing rough still but i can tell its atleast on all four cylinders... but wait..... is that smoke coming outa my exhaust?? yep!!! smells a bit like oil too...:bang head: so now its burning oil?? at this point i dont care and decide to take a test drive... but nooooo after about 1000' its running on 2cylinders again... come home and i notice no more white smoke but still not running right at ALL!

Basically im done.... i know ive been told to dyno it... but at this point i cant even get it to one. Ill wait for Morelys carbs and see if there is a difference... Ive racked my brain and have been getting all kinds of help on here, but after trying almost every combo on my carbs... im not sure what else to try... and yes ive checked ALL rubber boots the carbs touch or are even near... spraying brake clean, carb cleaner or any other flammable liquid on or around hasnt changed anything... so no air leaks that i can find.

ANY SUGGESTIONS ARE ALWAYS WELCOME

It sounds like an electrical problem, what voltage do you have at the battery terminals? did you check spark plug wires? spark plugs? does it have a healthy spark from each coil?:ummm:

 

[06VMAXIMUS]

Problems like you are having are absolute nightmares! The bike is 25 years old, so perhaps starting with the simple basics would help. Have you ever done a compression/leakdown test on it? It doesn't hurt to know exactly what your engine condition is, and low compression or a valve hanging slightly open will drive a person nuts. (you would always have the problem though, it wouldn't come and go). I agree with firefly, it does sound like an intermittent spark issue to me. I think some people here have good luck with the cops, while others have not. I would be tempted to return to the original coil setup, at least until you get the issue sorted out.

 

[Miles Long]

It sounds like an electrical problem, what voltage do you have at the battery terminals? did you check spark plug wires? spark plugs? does it have a healthy spark from each coil?:ummm:

By your description, it appears as if your bike's problems are caused by an inconsistant operating state - sometimes it runs well, other times it runs like crap, sometimes so-so.
Is your '86 a higher-mileage bike? The dyno, as suggested, would be the best way of determining the state of motor health. If that's not available, have you performed a compression test?
In any event, let's assume the motor itself is in good shape -
Consistant good operation then depends on two factors - consistant fuel delivery and consistant high-voltage spark at each plug.
Then assume that your carbs themselves are functioning properly - after all, youv'e been over them with a fine tooth comb - but what about consistant fuel delivery to the carbs? Have you checked this system?( pump itself, filter, air lock problems, etc.) The "bottom line" test would be to disconnect the fuel line and check for sufficent delivery with the pump running - I think this is about 1/2 gallon per minute? (others chime in please)
If all this checks out, assume (I love that word, it makes for good joke fodder) that fuel delivery is not the problem. So go on to the electrical end.
Numerous posts in the electrical section of this forum indicate that the early V-max electronics are not as reliable as later models - hence all the changes that have been made over the years.
Do the easy things first, as Mr. Firefly has suggested above (check for arcing at the plugs by running the bike at night - in the open, of course)
Your bike may have a good spark (healthy voltage) at idle, or when cold, etc, but this doesn't guarantee it is sufficient at higher rpms, at normal operating temps, or after extended running times, etc.
Perhaps acomponent(s) of the electrical system is failing, or insufficient, at certain times or conditions.
A healthy spark is dependant on operating voltage, which initially begins with a healthy stator-RR-battery system. From here, part of that healthy voltage(at this stage,I like to think of it in terms of amperage), is channeled to the ignition box, then to the coils(converted to mega-voltage), then to the plugs.
But again the "bottom line" is the intial voltage, which has to be consistant and at a least minimal level( 13.5- 15 volts, with the bike running) If not, the spark may be too weak.
The easiest way to check this would by using an on-board voltmeter, mounted on the handlebars. If you notice that poor performance is directly related to low voltage, that would point the way to examining the electrical components on an individual basis.
Hope this helps, and good luck. Miles

 

[jfeagins]

Carb problems seldom just come & go at will. A carb problem will persist, and only vary slightly depending upon engine operating temp and/or overall daily weather factors - not what you describe.


If you have a rubber part improperly fitted to either the top or bottom of one or more carbs, it could cause significant fuel mix problems & the symptoms might vary greatly with engine temp and/or outside weather conditions. HAVE YOU CLOSELY INSPECTED ALL RUBBER BOOTS FOR CRACKING?

Aside from that possibility, my best guess is a bad CDI box. Corrosion in there would come and go and play tricks galore. Most often, low voltage is the first cause of CDI box problems, and then - usually first appears at the times when the fan kicks on, but might not be the reason. Yours may be completely going south. On mine, when the fan kicked on and the CDI began screwing off, I could usually see spark jumping from the plug wires onto the frame or valve covers someplace (Don't ask me why). I tuned up all my electrical connections - especially the grounding where the R/R bolts up to the bike, and did the big battery box mod. My low voltage went away and so did my CDI box screwups.

Perhaps someone has a loner that you can swap out for comparison?

 

[65fury]

Thanks for the replies, ill start with what ive checked and have found.

-i always seem to have spark(ill pull the plug and run the bike with the sparkplug against the head and i always have spark)

-Voltage is always is 13.5+ at idle and will spike to 16v when revved, but it wont stay that high, just a quick spike. I have ridin with a voltage reader hooked up to it though... might have to try that.

-I dont have my original coils any more, I was having spark plug boot and wire arcing with my old ones and i upgraded but still seemed to have issues with how the bike ran. NOTE the bike never ran any better or worse when swapping to COPS, so id like to assume they arent the issue as of now

-Also i have checked the fuel filter, pressure and all the above, if i unhook the pump itll freely spew gas into a bottle(it does stop and then start after a few seconds of pumping... but i think thats how it suppose to work?)

-Ive also replaced fuel lines just incase i had a cracked one.

-My bike has low miles... about 16k when i bought it and ive put another 5k on it(i rode it to Texas and Colorado last year)

-Stator is grounded well, altho it wouldnt hurt to run a ground wire from it to the battery i guess.

Over all this problem seems toi have been slowly getting worse since i first started having problems... and when its missing on 1 or 2 cylinders and i pull the plugs and still got spark then its a carb issue... but other times itll start running rough and it seems more like an electrical issue.. its like im chasing two issues, but i cant pin point either one. Sean i think may be letting me test one of his CDIs so ill have his carbs and CDI to test with. Im really hoping i get some awnsers with these parts:confused2:

Ill do a compression test today... anyone have suggestions on teh best way to do it? ive never done it on a bike.. Thanks


Jason

 

[06VMAXIMUS]

They make an inline spark tool that actually plugs into the plug and boot, and has a small light that illuminates with each spark. You might be able to install one of these and go for a ride while keeping an eye on it when it acts up. As far as the compression test, remove your plugs and ground them out on the engine, install the tester, then crank it over while holding the throttle wide open. Once the needle on the gauge stops rising, that's your compression for that cylinder. Do all four and record the results.

 

[Rhoy Carter]

There are all kinds of safety'sconnected to the tci and we traced one that was acting sort of what you are describing down to the sidestand relay (located left front under the tci ). You might try replacing the relay or by-passing the relay and see if that helps.

 

[65fury]

They make an inline spark tool that actually plugs into the plug and boot, and has a small light that illuminates with each spark. You might be able to install one of these and go for a ride while keeping an eye on it when it acts up. As far as the compression test, remove your plugs and ground them out on the engine, install the tester, then crank it over while holding the throttle wide open. Once the needle on the gauge stops rising, that's your compression for that cylinder. Do all four and record the results.

Thanks, ill go get some readings and let yall now. I dont know anyone with teh spark plug light deals.... although that is very cool.

Jason

 

[65fury]

There are all kinds of safety'sconnected to the tci and we traced one that was acting sort of what you are describing down to the sidestand relay (located left front under the tci ). You might try replacing the relay or by-passing the relay and see if that helps.

Hey thanks, ill check that out too, i wouldnt be supprised if i was having just electrical issues at this point.

Jason

 

[06VMAXIMUS]

This isn't the exact tester that I have, but you get the idea. They cost about $20 at napa, autozone, or advance. Very handy to have when checking for spark!

 

[65fury]

This isn't the exact tester that I have, but you get the idea. They cost about $20 at napa, autozone, or advance. Very handy to have when checking for spark!

But since i have COPS.... would that still work??

 

[65fury]

oops nevermind... i see how it works now:bang head::rofl_200:

 

[wood1]

get Sean to ship you a known used CDI with the carbs to try it out

 

[65fury]

get Sean to ship you a known used CDI with the carbs to try it out

Thats the plan:biglaugh: He had some loaners out but i think he's getting them back before he sends the carbs out to me.

Jason

 

[wood1]

http://www.vmaxoutlaw.com/tech/cv_carb_tuning.htm

not sure if you have seen this

 

[65fury]

http://www.vmaxoutlaw.com/tech/cv_carb_tuning.htm

not sure if you have seen this

yup sure have, read it and tried it on my bike more times than i can count. Ive been thru almost every carb thread on here:rofl_200: Thanks anyways

Jason

 

[wood1]

crap... it just makes me think it's either your ignition or the fuel pump. Isn't there a thread on rebuilding the fuel pump somewhere? Couldn't hurt.

 

[65fury]

crap... it just makes me think it's either your ignition or the fuel pump. Isn't there a thread on rebuilding the fuel pump somewhere? Couldn't hurt.

Yup with all these random issues Im starting to think something electrical is bad. But the fuel pump seems to pump fine. I can run 115mph for as much road as i have and i doesn't run outa fuel so i cant imagine its bad.

Jason

 

[one2dmax]

Carbs should be shipping out tomorrow. I did find another error on a customer carb set here last night that I haven't even thought to ask. I don't think this applies to your situation though. WARNING - DO NOT USE KEYSTER CARB REBUILD KITS

You can use some of the kit but the main brass emulsion tubes are incorrect and I don't like the jet block gaskets (too rubbery).

Sean