1994 Vmax dying under load

[Thestrugglebike]

Hi. I’ve been reading these thread for a while. I got a new to me Vmax 1994 and have been trying to get it up and running properly. I have cleaned and synchronized the carburetor, got a new battery, put new spark plugs in, and put a new fuel filter on. At this point the bike will idle and rev in neutral but when releasing the clutch in gear the bike bogs down and dies. I’m looking for a direction to figure out where to search next.

 

[MaxMidnight]

Has the bike always had this problem under your ownership or did it start after you 'fixed' it?
Are the plugs showing signs of a weak or rich mixture?
Are all of the throttle slides lifting in concert?

 

[Fire-medic]

Put it on the centerstand, get it in 5th gear, with the sparkplugs out, and try to turn the engine over by hand with the rear wheel. If you can do that OK, then I think I'd try a compression test and a leak-down test.

Something else you might try is to remove the clutch cover, and see that the clutch plates are able to be separated. Pull in the lever, fasten it down, and try to get the plates apart. You should be able to use a screwdriver to easily pry-apart the tabs of the friction discs in the clutch basket. If they're stuck-together, remove the pressure plate, the diaphragm spring, and all the friction discs, and the 'steelies,' use some sandpaper to roughen the 'steelies,' and throw the friction discs into a shallow pan with fresh oil, and oil them good. Let them soak in the oil for awhile, and reassemble. You'll probably need a new clutch cover gasket.

Sometimes bikes sitting for extended periods have the clutch plates stick together.

 

[sdt354]

Kick stand switch?

 

[MaxMidnight]

Assuming that when Mr Thestrugglebike says 'the bogs down and dies' he means the revs drop and the motor stops rather than a sudden cut out e.g. you flick the kill switch then I wouldn't be looking at either the clutch or side stand interlocks.
Nor would I be looking at the clutch pack as you would expect the bike to jump forward before it died.

It would be helpful if he could elaborate further on how the motor cuts out?

 

[Thestrugglebike]

The bike will start great, idle great and rev in neutral. I can pull in the clutch and switch to first gear and be fine. As I’m letting out the clutch and giving gas the bike rpm’s stumble hard and it dies unless I pull the clutch back in. I’ve made it down the street and it died and I eventually made it back. I started from scratch here as I bought it as a project. It was last tagged in 2009. Originally the bike would only start with choke and die after warming up before the carb clean and rebuild. Now it idles perfectly fine and revs. Everything appears to be stock. I will dig into it more based on your suggestions when it’s not over 100f.

 

[Fire-medic]

OK, a weird one but what could be happening is the star selector on the shift drum has come-apart. You think it's in 1st, but it's in a higher gear to start. I dunno if that's it, I kinda doubt it, but it could be. Think of trying to start out in 3rd or 4th on a manual transmission C10 truck, you're only gonna get underway slipping the clutch a lot.

Can you get it into 1st gear OK, and then toe it through each gear until 5th? Engine running & engine not running. If you can easily 'catch' each gear going up/down, then it's not the star segment & its pins on the shift drum.

 

[Thestrugglebike]

I’ll do compression checks when I get a chance. It is stumping me. I can shift through the gears fine. Maybe some type of binding when in gear with the clutch out? I do a little wrenching here and there but most in-depth stuff is a learning experience.

 

[DocDoom]

The bike will start great, idle great and rev in neutral. I can pull in the clutch and switch to first gear and be fine. As I’m letting out the clutch and giving gas the bike rpm’s stumble hard and it dies unless I pull the clutch back in. I’ve made it down the street and it died and I eventually made it back. I started from scratch here as I bought it as a project. It was last tagged in 2009. Originally the bike would only start with choke and die after warming up before the carb clean and rebuild. Now it idles perfectly fine and revs. Everything appears to be stock. I will dig into it more based on your suggestions when it’s not over 100f.

This happened to me for a different reason. I did rebuild and clean the carbs as well, but there was super fine rust particulate making it through the fuel filter (and the second one I added) that would mess up the carbs and apparently not affect the pilot jets: causing as described stumbling and dying under load once it was moving. It's fun rebuilding carbs to muck them up instantly. An external tank was how I figured it out eventually. The first thing I did was bypass the kickstand switch though, I know it would probably cut-off more violently if that was in the (normally open?) position but electrical things can be mysterious.

 

[Radioguylogs]

Can you roll the bike freely in neutral and with the clutch pulled in?

 

[Jack Hammer]

This sounds like a carb problem to me. Main jets plugged up. What size are they? Fuel filter? Fuel pump? Inside of tank?

 

[gentsvmax]

This happened to me for a different reason. I did rebuild and clean the carbs as well, but there was super fine rust particulate making it through the fuel filter (and the second one I added) that would mess up the carbs and apparently not affect the pilot jets: causing as described stumbling and dying under load once it was moving. It's fun rebuilding carbs to muck them up instantly. An external tank was how I figured it out eventually. The first thing I did was bypass the kickstand switch though, I know it would probably cut-off more violently if that was in the (normally open?) position but electrical things can be mysterious.

Dont know how you "cleaned" the carbs, but after sitting as long as you say, I would send Ultra Sonic to the rescue.
As yiu said "new to you" you'll find out these carbs have micro circuits that spay carb clean and wire wont touch.
And yes that rust can cause alot of headache .

 

[DocDoom]

Dont know how you "cleaned" the carbs, but after sitting as long as you say, I would send Ultra Sonic to the rescue.
As yiu said "new to you" you'll find out these carbs have micro circuits that spay carb clean and wire wont touch.
And yes that rust can cause alot of headache .

Take em apart, replace all seals and rubber, remove and soak anything metal or anything soak tolerant in caustic solution, compressed air. After the first time they took a dump and refilled with rust back on the bike... like on the order of seconds to minutes, doing the same again and firing on an external tank had it purring. After tank replacement haven't bothered me again. The PSA was it may not always be obvious but if your fuel filter is leaving like fine glitter on your hand when you touch it, you could theoretically do a lot to make different parts of your bike new to chase the problem but rusty tank gonna get you down every time. Carburetors are beautiful things, and like most beautiful things expect a lot from you, confuse you, get worked up over what seem to you to be small things, and make you wait when you're ready to leave. So... Treat em well and listen to the little things.

 

[Fire-medic]

I've made this observation before, I agree with DocDoom and gentsvmax about the importance of a clean gas tank. My friend at Riva Yamaha, Pompano Beach FL, Bill Boyce, has worked as a Yamaha mechanic since his teens. He was here (there) for the release of the VMax Gen. 1 and made many a Dynojet Stage 7/Kerker 4/1 full exhaust conversions, and has maintained Vmaxes ever since.

He told me, "you have to just buy a new gas tank, if yours is badly rusted. If you don't, you will continue to have obstructed carburetor passages. It's not worth it for us to pull a gas tank, treat it and re-install it. The labor $ makes it cost-effective to buy and install a new tank." That's where DocDoom got his new gas tank.

Now, if you're doing this for yourself, and if you follow the instructions exactly you can remove, treat, and replace your own gas tank. Many people get antsy, and fail to follow the instructions. They end up with a crummy-interior gas tank, and still have rust and now, gas tank liner plugging things.

If you use a liner product, clean the entire gas tank to shiny metal. Follow the coating instructions (be sure to remove the gas level sender) exactly and re-install it. CaptainKyle has good luck with cleaning/sealing, he's done many. Use the search function and see what he says about which product he recommends.

I've had good luck with cleaning vinegar 6% concentration, it will make your interior shiny-clean, but you have to dry it inside immediately, or it will flash-rust in a half-hour. If you cannot coat it immediately, throw some used motor oil in there and coat the interior, and cap it off. Use some acetone to remove the coating when you're ready to coat it.

 

[gentsvmax]

I've made this observation before, I agree with DocDoom and gentsvmax about the importance of a clean gas tank. My friend at Riva Yamaha, Pompano Beach FL, Bill Boyce, has worked as a Yamaha mechanic since his teens. He was here (there) for the release of the VMax Gen. 1 and made many a Dynojet Stage 7/Kerker 4/1 full exhaust conversions, and has maintained Vmaxes ever since.

He told me, "you have to just buy a new gas tank, if yours is badly rusted. If you don't, you will continue to have obstructed carburetor passages. It's not worth it for us to pull a gas tank, treat it and re-install it. The labor $ makes it cost-effective to buy and install a new tank." That's where DocDoom got his new gas tank.

Now, if you're doing this for yourself, and if you follow the instructions exactly you can remove, treat, and replace your own gas tank. Many people get antsy, and fail to follow the instructions. They end up with a crummy-interior gas tank, and still have rust and now, gas tank liner plugging things.

If you use a liner product, clean the entire gas tank to shiny metal. Follow the coating instructions (be sure to remove the gas level sender) exactly and re-install it. CaptainKyle has good luck with cleaning/sealing, he's done many. Use the search function and see what he says about which product he recommends.

I've had good luck with cleaning vinegar 6% concentration, it will make your interior shiny-clean, but you have to dry it inside immediately, or it will flash-rust in a half-hour. If you cannot coat it immediately, throw some used motor oil in there and coat the interior, and cap it off. Use some acetone to remove the coating when you're ready to coat it.

Agreed, go now, go quickly to EXACTREP! Get the plastic 5 Gal.. While your at it pop a sending unit in, grab a matching gas gauge and your set!

 

[DocDoom]

Agreed, go now, go quickly to EXACTREP! Get the plastic 5 Gal.. While your at it pop a sending unit in, grab a matching gas gauge and your set!
View attachment 91376

I dig the gas gauge, I've been brainstorming ways to integrate one so that it isn't fugly. The light is fine but ethanol-free fuel is hard to find here so I'm often topping up with gas cans etc. Nice setup.

 

[gentsvmax]

I dig the gas gauge, I've been brainstorming ways to integrate one so that it isn't fugly. The light is fine but ethanol-free fuel is hard to find here so I'm often topping up with gas cans etc. Nice setup.

Thank you sir! Yea , there are off the shelf sending units available now that make it alot easier to do than the frakinstien creation inside my tank LOL.
A well known member (Gannon) just did one that looks great, works well with such sender. Pics Gannon, Pics!

 

[F 18 Driver]

Hi,

I'm new to the board but pretty experienced with motorcycle carburetors I have owned 5 Honda Valkyries that are six-cylinder, 6 carburetor machines

It appears to me you missed something when you cleaned the carburetors.

Please describe the method used in detail…

Just spraying carburetor cleaner will not do.

 

[DocDoom]

Hi,

I'm new to the board but pretty experienced with motorcycle carburetors I have owned 5 Honda Valkyries that are six-cylinder, 6 carburetor machines

It appears to me you missed something when you cleaned the carburetors.

Please describe the method used in detail…

Just spraying carburetor cleaner will not do.

I didn't. If it could come apart and get soaked or if it could get replaced it was; there was no further breakdown possible without a hydraulic press.
The repeat offender was the rust particulate, which is why an external tank worked consistently and the primary worked for about fifteen minutes before it clogged something. Severely rusted tanks and carburetors don't mix well.