Plan of attack, please advise

[Decayism]

1997 V-Max 1200

I've had ongoing carb issues for a few years and have taken it to a couple different motorcycle shops to have it fixed ($$$) and issues still persist and are the worst they've ever been this year.

A several years ago, when I purchased the bike, the airbox was modified, carbs were jetted, with supertrapp's installed, it ran fine, but then started to backfire / pop at idle and deceleration..

A couple years ago, the airbox was put back to stock, the carb / jets / needles were put back to stock and the supertrapps remained.... still intermittently backfired and popped with a slight cutting out right before v-boost would kick in.

This year.... my fuel mileage has taken a crap (usually would get 170KM per tank, which has dropped off to 120KM per tank). I smell fuel coming from the exhaust and when I come on to the throttle, cuts out; is sluggish and doesn't have the get up and go you would expect under pressure.

I'm going to attempt to sort this out myself because I've had zero luck bringing to shops and frankly, don't have the cash to waste on a big question mark.

As it stands, the airbox is stock, the carb and innards are stock and the supertrapps have five discs installed.

P.S. there is a substantial amount of black soot / carbon on the exhaust tips and I do smell fuel when starting and revving.

Can anyone suggest a way forward to get it running properly?

What a mess.... :bang head:

TIA,
Geary.

 

[blaxmax]

You are rich---
Try 147.5 main jets and turn your a/f mixtures screws to 2 1/2 turns out. Probably wouldn't hurt you to put a set of cops on.
6 to 8 discs in the supertrapp.

 

[marsmax85]

Maybe check your sync also along with your cops !!

 

[Traumahawk]

Start with the basics......sync, and do a shotgun to make certain that the pilot jets are clean.

http://vmax.lvlhead.com/tips/shotgun.htm

Cops work....but only if you have bad electrical issues, bad coils, etc. Even then, they are a replacement for stock, not really an improvement.

 

[Zeus36]

Since it ran fine before you put everything back to stock, the problem may not have been in the fuel delivery system. Sounds like you've done a lot to put to the fuel system in order by going stock. It may have been ignition related when it started acting up. (coils) I second the COPs mod to eliminate potential shorting coils.
Even though I only had 14K miles on my 1997, switching to COPs got rid of some gremlins.

 

[D-Max2012]

I've had ongoing carb issues for a few years and have taken it to a couple different motorcycle shops to have it fixed ($$$) and issues still persist

several years ago, when I purchased the bike, the airbox was modified, carbs were jetted, with supertrapp's installed, it ran fine, but then started to backfire / pop at idle and deceleration..

So the problem started while you had the upgrades in-place and got worse over time.

A couple years ago, the airbox was put back to stock, the carb / jets / needles were put back to stock and the supertrapps remained.... still intermittently backfired and popped with a slight cutting out right before v-boost would kick in.

So going back to stock did not help the situation.

You could have FM blocking your jets.. Too many of these older tanks were not designed to handle water that is being drawn in because of Ethanol in the fuel. It creates rust that makes it to your jets.

Hope my problem / fix, helps you out..
91 , Previous owner neglected it.
Had a problem when I would get to around 4K RPM the bike started dying out. If I pushed past 5K, it would kick in strong. Broke down the carbs multiple times and washed all parts in an Ultra-Sonic cleaner from Harbor Freight. Replaced cracked boots and V-Boost boots. Removed, cleaned and coated my tank, cleaned pump, and all hoses. Put 1/2 bottle of Seafoam in a full tank. then at next fill up, put the other half in. On 1-1/2 tank fulls with Seafoam,, I did not feel any stumble. It's been great since.

 

[[email protected]]

My first step would be to pull the carbs. Thoroughly clean them. Inspect and verify all jets are correct. Check the needles, slides, diaphragms, and coasting enricheners. Replace any damaged o-rings and gaskets. Double check the pilot jets.

Put it back together. Adjust idle and synch. Then see where you are at.

If multiple people have been in there it's hard to say what you have going on in there.

Sent from my SM-G900V using Tapatalk

 

[blaxmax]

Almost every Vmax I've ever read about has had electrical issues and the stock coils are going to crack. Read up on the cops replacement as they have done many members here a world of improvement.
http://www.vmaxforum.net/showthread.php?t=40699

 

[caseyjones955]

The COPs sure made mine easier to tune and smoother running. I definitely had some serious tuning issues, pig rich with a stage 1 jet kit and im sure the issues that made it difficult to deal with were exacarbated by an aging, weak, obsolete ignition system.

If someone gave me a badly tuned vmax today I would heed the above advice and if that doesnt work I would pull the carbs and check cleanliness, dry float levels, check ALL jet sizes, I was fighting a PAJ2 (air jet behind diaphragm) sized way small until Traumahawk caught it but it stumped me for a long time and it was a real problem until I put them back to OE. It wasnt only my main jets way out of whack. If other ppl did the work it may be worth looking inside to see whats there if it becomes necessary to pull the carbs for cleaning.

 

[Decayism]

Thanks for all the info guys.

I'll start with:

1. Shotgun & inspection
2. Confirm the a/f are 2 1/2 turns out
3. Replace the cops and plugs
4. Check air filter
5. increase to 8 discs on the supertrapps
6. Sync carbs
7. run "another" can of seafoam through her...

i'm also considering replacing the boots...

I'll let you know how it turn out!

 

[caseyjones955]

Sounds like.a reasonable plan to me. if that doesnt make it run like a top pulling the carbs for cleaning and inspection/jetting is straight forward and relatively quick.

If it comes to that do you still have other jets and stuff from the before time?

 

[Decayism]

Unfortunately they're long gone...

 

[sdt354]

Do a compression test and see where you stand. Then check the spark at each plug.Harbor Freight sells cheap spark checkers. You can crank the engine and hold a plug to ground also. Cops do eliminate a lot of problems, but I'd find the issue first. Then like Mike mentioned, take the carbs off and go through them. Or send the rack to Danny and you'll be assured of a good running Vmax.
Steve-o

 

[Decayism]

Do a compression test and see where you stand. Then check the spark at each plug.Harbor Freight sells cheap spark checkers. You can crank the engine and hold a plug to ground also. Cops do eliminate a lot of problems, but I'd find the issue first. Then like Mike mentioned, take the carbs off and go through them. Or send the rack to Danny and you'll be assured of a good running Vmax.
Steve-o

noted, thanks.

 

[TheTwistedNomad]

Where are you in Ontario?

 

[Decayism]

Where are you in Ontario?

Out Trenton, Ontario way.

 

[Rollie]

+1

do a compression test and see where you stand. Then check the spark at each plug.harbor freight sells cheap spark checkers. You can crank the engine and hold a plug to ground also. Cops do eliminate a lot of problems, but i'd find the issue first. Then like mike mentioned, take the carbs off and go through them. Or send the rack to danny and you'll be assured of a good running vmax.
Steve-o

 

[95spfldmax]

Add a float level check to your list of carb adjustments. Especially having a rich condition. It's amazing how much just a little off affects the situation.

 

[caseyjones955]

Morley has a great picture guide for dry float level but I couldnt find it. I used the Factory Pro website which has one thats about the same thing, its very simple and very good. I thought mine were right before but I rechecked recently with a different manual caliper. I cant link with my phone but its easy to find. Mine looked exactly like the before and after pics there when I opened them again and after I set them to 1.125". IMHO to important of a step to skip. Before this I never realized how important float levels are for CV carbs. They were all a bit rich in factory guise.

 

[caseyjones955]

Edit, sorry, double post