Trouble above 7K rpms

[HDKILA]

Just bought my 85 today and the bike is hesitating in the upper rpms. I disconnected the vboost but I am unsure if I did it correctly. How can I be sure the Vboost is fully open? I did the key in the ignition a few times and then it all together stopped working (cycle open and shut)!

All i did so far to disconnect the vboost was disconnect the round 5 prong under the left side cover. It seemed to drop the idle down 100-200 rpms but I am still having the same problem.

Where should I start next...Is seafoam a good idea? The previous owner insisted the carbs were serviced and balanced 1 year ago.

How about the valves...the bike has 30K and I am unsure if the valves have ever been dealt with.

 

[maleko89]

Are your float bowl vents kinked and in the right position? What's your float level? I would check sync, plug wires, fuel filter, boots and air filter. When all that checks out then dig into vboost.

 

[HDKILA]

Are your float bowl vents kinked and in the right position? What's your float level? I would check sync, plug wires, fuel filter, boots and air filter. When all that checks out then dig into vboost.

I don't have a manuel yet. Can you guide me to the float bowl procedure...I looked through severl links already and did not find it.

 

[maxcruiser]

I don't have a manuel yet. Can you guide me to the float bowl procedure...I looked through severl links already and did not find it.

Check out Vmaxoutlaw in the VMF links icon above - they have the shop manual that you can download.

Also check the front left intake manifold, there's a rubber hose that goes to the vboost sensor - check for cracks and such

Mike

 

[lankeeyankee]

Dude direct him with the simple stuff first. You guys and your float bowl adjustments...


Look at your airbox under the faux/tank

Do you have the Y Piece? Is it modified in anyway?

When the Y piece is modified and the carbs arent tuned for it you will get the upper RPM break up..

 

[HDKILA]

Dude direct him with the simple stuff first. You guys and your float bowl adjustments...


Look at your airbox under the faux/tank

Do you have the Y Piece? Is it modified in anyway?

When the Y piece is modified and the carbs arent tuned for it you will get the upper RPM break up..

Y piece is good and not modded...

 

[lankeeyankee]

Tell us a little more info about your bike besides its an 85:ummm:


Exhaust type?
Mileage?
Carb work? Stock, airbox, individual filters, jet kit?:confused2:

The more info you provide us the easier and quicker the guys can pin point your problem.

Just bought my 85 today and the bike is hesitating in the upper rpms. I disconnected the vboost but I am unsure if I did it correctly. How can I be sure the Vboost is fully open? I did the key in the ignition a few times and then it all together stopped working (cycle open and shut)!

All i did so far to disconnect the vboost was disconnect the round 5 prong under the left side cover. It seemed to drop the idle down 100-200 rpms but I am still having the same problem.

Where should I start next...Is seafoam a good idea? The previous owner insisted the carbs were serviced and balanced 1 year ago.

How about the valves...the bike has 30K and I am unsure if the valves have ever been dealt with.

 

[HDKILA]

Tell us a little more info about your bike besides its an 85:ummm:


Exhaust type?
Mileage?
Carb work? Stock, airbox, individual filters, jet kit?:confused2:

The more info you provide us the easier and quicker the guys can pin point your problem.

Supertrapp exhaust with stock airbox, carb was supposedly tuned 1 year ago. 30K on the odo and.

I opened up the airbox and found a bunch of dead mice in there...

I also noticed tonite that on full throttle occasionaly my oil light comes. It stays on for a second or two then goes off...

 

[HDKILA]

I checked the hose that goes from the vboost sensor to the intake manifold and that DEFINETLY has cracks in it. I am going to go to napa tommorrow and get a new hose. I saw that there is a plastic tab with an arrow on it right before the rubber hose goes into the manifold. Can I bypass that with just a one piece hose or should I get two pieces and keep that piece intact.

I also got my vboost sensor working again. It would seem that the connector was loose. It still seems like it binds a little when it cycles on/off.

 

[maleko89]

I would keep the piece in between the pressure sensor hoses. Not sure if it serves a function or not.

 

[m-cman]

Also be sure to keep the arrow pointed in the same direction...

The oil light comes on occasionally under full acceleration since the oil level sensor is at the front of the pan. The oil shifts toward the back in that situation. The oil pickup is near the back of the pan so there is no problem with oil starvation. ie; nothing to worry about.

What was done a year ago has no bearing on the current condition of the carbs. If the bike sat for any length of time, the carbs will require a good cleaning even if the PO drained the float bowls and fuel tank (which he probably did not). There may also be rust in the tank. Have you replaced the fuel filter yet?

 

[lankeeyankee]

Well since the age of the bike is an 85 and you already found rubber dry rotted, I am steering towards the rubber boots that connect from the carb to the intake / vboost runner and also the boots from the carbs to the intake.
These arent cheap to replace but if they are dry rotted and leaking they will kill HP on the top end.

If I were you....

Pull your airbox completly off..
Pull the carbs.

Inspect all the rubber boots, ANY sign of dry rot cracks , replace them. Also check the rubber diaphrams that are used to control the slides.
It doesnt sound like an ignition problem breaking up to me, more so leaning out on the top end due to sucking air through a crack...... I have a similiar problem after eating burritos but thats usually blowing air out of a crack.:rofl_200:

 

[Storloc]

After finding dead critters in the airbox I would be checking all the rubber and electrical wiring for gnawing cuz those little bastards love to eat shit they shouldn't! You may want to run the "shotgun" at least initially and of course make sure all the boots aren't splitting. I would do an initial inspection/cleaning before getting into the harder stuff.

 

[HDKILA]

Thanks for all the advice so far gang. I did not end up replacing the hose as it was just a little scarred and actually in pretty new condition.

I am going to check the fuel filter next. And then I will pull the carbs and clean them.

I put seafoam in last night...how long until I assume that did not work? Is that an instant fix normally?


Btw the bike idles perfect at 1100 and starts right up.

Thanks,
Abe

 

[HDKILA]

Where is the fuel filter located? I see the pump but no filter.

 

[maleko89]

It's back from that. Above and on the right side of battery inside a rubber sleeve. Follow the fuel line.

 

[HDKILA]

It's back from that. Above and on the right side of battery inside a rubber sleeve. Follow the fuel line.

Thanks! Found it. It looks like I just slide it forward out of the rubber sleever towards the headlight? Do I have to use a yamaha fuel filter? It looks like a chinsy little mower fuel filter...


I looked in the fuel tank and it looks a little crumby/rusty on the bottom. I don't know if it's scarred or actual gunk. Should I take a screwdriver down there and rub it to see if it comes off?

Also I noticed today the bike seems to get nutty right at 6k...should I look more into the vboost? I have noticed it seems to bind when it cycles on the way back up..Also I can see the slack in the adjustment line. Do I need to take the carbs off to adjust that vboost cable?

Thanks,
Abe

 

[maleko89]

To remove, detach rear line and then slide forward for easy access.

Use a clear one from a local auto parts store. Get the one for 3/8 inch fuel line. It's a Purlator 806. The cores are replaceable and cheap. I believe I got 3 cores for $5.

I would remove carbs and check your vboost. There are three adjustments. Adjuster clearance, cable tension and sync clearance.

 

[HDKILA]

To remove, detach rear line and then slide forward for easy access.

Use a clear one from a local auto parts store. Get the one for 3/8 inch fuel line. It's a Purlator 806. The cores are replaceable and cheap. I believe I got 3 cores for $5.

I would remove carbs and check your vboost. There are three adjustments. Adjuster clearance, cable tension and sync clearance.

went to yamaha and got the stock filter and he gave me one that had a smaller diameter!

I am going to post pics up of my old fuel filter...it has chunks of shit all inside of it and is dark yellow. It HAS TO BE the original...

off to napa now for the right filter...

 

[HDKILA]

Can someone guide me on how to pull the carbs. Odviously take the airbox off and loosen the rubber boots but what about the fuel line...is there any special care that needs to be taken?


I put the new fuel filter in and it still acted up. I can rev the bike freely in neutral with no problems btw.

Thanks,
Abe