I Love my Stelvio - But! ...

[DanPez]

I had the same issue with the paint bubbling, Guzzi finally sent the piece after making a fuss about it. Also they said "we" only replace this once.

That said, I found a couple of issues that caused the problem:

1. The tip over valve (it sounds like you have this sorted out)
2. The hose coming from the overflow (hole under the cap on the left side of the bike) was more of a vacuum hose consistancy of hose and the fuel had gotten to it and melted the hose and caused it to kink. I replaced the hose from the tip over valve and the fuel over flow with 3/16" fuel line and this has solved the problem. I also removed the charcoal canister and all associated plumbing, bike runs a whole lot better without it. BTW, there is a one way valve (check valve) located between the TB's, mine was stuck closed, this is another reason the tip over valve didn't work properly.

My Aprilia Caponord had the same type of check valve and it was standard operating procedure to remove the valve and install a barbed fitting in its place so the fuel tank would not pressurize.

Removing all this plumbing ... charcoal canister .... wouldn't it affect the ECU mapping?
In your case ..... for the better!
The one way check valve that you are talking about would it be the lines going to the TB for the Vacumeters?

 

[kwn306]

No, the line with the one way check valve comes from the tip over valve in the fuel tank and runs to the charcoal canister. The line starts at the top of the fuel tank, runs down between the TB's (that is were the check valve is located) and than back up to the charcoal canister under the speedo.

By removing the charcoal canister and associated plumbing, it reduced the amount of air going in to the TB's and that was causing a lean condition, yes the bike runs a lot better. You need to cap off the two ports on the intake runners if you remove all the plumbing, I used allen cap screws with flat and lock washers.

 

[guzziben47]

I tried capping off the two ports on the intake runners, but left the plumbing in place (capped off the two plumbing lines too) to see if I'd notice much of a difference. And I didn't notice much of a difference. So I didn't go further and remove all the plumbing.

Was there a flaw in my method for trying out this mod to see if it is worth doing?

 

[kwn306]

I tried capping off the two ports on the intake runners, but left the plumbing in place (capped off the two plumbing lines too) to see if I'd notice much of a difference. And I didn't notice much of a difference. So I didn't go further and remove all the plumbing.

Was there a flaw in my method for trying out this mod to see if it is worth doing?

If you still have the ports "capped off", gut the tip over valve under the fuel cap and replace the hose under the fuel cap on the tip over valve side and run it down along the frame to breath underneath the bike. What this will do is by-pass the other line that runs from the tip over valve down between the TB's, through the check valve and back up to the charcoal canister. My check valve was stuck closed and pressurizing the tank. I found that by letting the tank breath the bike ran much better and the throttle was not as touchy.

 

[guzziben47]

I put this question in a separate post, but I want to also ask it here too. Are you saying you can leave the can in there and[/quote]replace the hose under the fuel cap on the tip over valve side and run it down along the frame to breath underneath the bike

? In other words, would it work o.k. to plug the hose where the check valve is, and run the line from the side of the tank to the ground (in addition to what I have already done)? I haven't yet figured out how to get the plastic surrounding the tank off, so that would make this much easier for me. The way the bike runs at steady throttle is the my primary issue with the Stelvio; I'd like to do everything I can to help with that issue....

 

[kwn306]

I put this question in a separate post, but I want to also ask it here too. Are you saying you can leave the can in there and

replace the hose under the fuel cap on the tip over valve side and run it down along the frame to breath underneath the bike

? In other words, would it work o.k. to plug the hose where the check valve is, and run the line from the side of the tank to the ground (in addition to what I have already done)? I haven't yet figured out how to get the plastic surrounding the tank off, so that would make this much easier for me. The way the bike runs at steady throttle is the my primary issue with the Stelvio; I'd like to do everything I can to help with that issue....

Yes, just add the additional hose (leave the charcoal canister in place) and remove the other hose and plug it, this only works though if you gut the tip over valve.

To remove the plastic, you don't really need to remove it, just loosen.

Remove both seats, remove the gray plastic peice near the front of the drivers seat (either 4 or 6 allens). Remove the gas cap, remove the 4 little allens under the cap, there will be 2 little allens at the rear of the tank cover and 4 little allens at the front of the tank cover. Start to remove center section of tank cover and you need to take the rubber part of the fuel tank that was under the gas cap and push it through the hole.

Now you can get to the hose in question, while your at it replace the hose on the other side as well before it melts from gas fumes.

BTW, I forgot to mention you need to rebalance the TB's after doing this mod because now there is alot less air flowing through the TB's.

 

[guzziben47]

O.k., thanks. I have a twin max but I don't have the tool that let's you re-set the tps, so I guess I wait until I get that (I know they sell it here for two or three hundred dollars), and then take a shot at it....

 

[guzziben47]

One more quick question. If all you do is remove the tipover valve (to deal with the pealing paint issue), and don't touch anything else, you don't have to then synch the throttle bodies, do you? It sounds like the tipover valve is connected to the line that goes to the charcoal can, so that's what has me confused....

 

[kwn306]

One more quick question. If all you do is remove the tipover valve (to deal with the pealing paint issue), and don't touch anything else, you don't have to then synch the throttle bodies, do you? It sounds like the tipover valve is connected to the line that goes to the charcoal can, so that's what has me confused....

Yes tip over valve is connected to the charcoal canister, you also have that one way check valve in that line as well. That line run down between the TB's, has check valve installed and then up to the charcoal canister.

By removing the other line and capping the holes in the TB runners you have changed the air flow through the TB's, that's why you need the rebalance.

 

[guzziben47]

I reconnected the TB runners after I read that you have to rebalance, so now the only thing that is different is the tipover valve is removed. Do I have to rebalance if all I did is remove the tipover valve?

 

[kwn306]

I reconnected the TB runners after I read that you have to rebalance, so now the only thing that is different is the tipover valve is removed. Do I have to rebalance if all I did is remove the tipover valve?

Nope, but all you have done is letting the tank breath. You have not helped the running issues.

 

[guzziben47]

I just tried disconnecting the check valve (one way valve) leading to the charcoal canister (in addition to removing the tipover valve), and that has a noticeable positive effect on the running of the bike. I'll have to check to see if the sync is okay....

 

[DanPez]

I just tried disconnecting the check valve (one way valve) leading to the charcoal canister (in addition to removing the tipover valve), and that has a noticeable positive effect on the running of the bike. I'll have to check to see if the sync is okay....

Looking under the gas cap at the tip-over mechanism I saw the size of holes that were drilled ......one exhaust to atmosphere (small) and another (little larger) running down from the tip-over valve to the check valve towards the charcoal canister and back to the TBs.

I took a look at this check valve running down from the tip-over valve to see if it works. (in my case it does)
I found that this check valve tubing was kinking the wires of my TPS. :evil:

I'm figuring the idea behind this messy tubing is to collect the vapors from the gas tank and sent them back to the TBs. (No waste of gas fumes)
Doing so you inject a richer air/fuel composition. (The Lambda probe will reajust anyway)

The problem I see with this check valve is that it needs lots of pressure before it releases.
How do I know this ..... I blew into it :whistle:

That why it runs better when you remove the check valve...... you cause less restriction of gas fumes going to the TBs. (Richer faster)
But in my opinion removing charcoal canister and plugging the TBs should not be done ...... because your changing the air volume and the fuel mixture to the TBs.
The ECU has no way to compensate unless you remap.

 

[guzziben47]

I'm going to give it a try both ways. Removing the tipover valve and the check valve were definite improvements. I'll try it with and without the evap system (i.e. the tank vent line hooked up to the coal can and the throttle bodies), and report back. There is a lot of conflicting information about what works and what doesn't (and its often not clear if everyone is talking about the same issue); plus some of the people on the list are guzzi mechanics and others have no mechanical training or experience (like me), so it's hard to make definitive conclusions. But, like I said, I'll give it a try and tell you what my seat of the pants evaluation is....

 

[kwn306]

Just remember everyone has an opinion, that makes the world go around.

I am an old skool mechanic, stopped wrenching in 1980 before the EPA and the Federallies got ahold of motorcycles.

I gutted the tip over valve and couldn't blow air through the line to the canister, my decal on the tank cover didn't show the check valve, hence me tearing the bike apart to find the problem. While the bike was apart I decided to remove all the stuff.

The reason the check valve is there is to keep the fuel away from the hot motor in case the bike falls over. The fuel passes through the tip over valve, through the check valve, into the canister and then down the relief hose in front of the motor. The fuel can not come back through the check valve and back into the tank when the bike is back up right. My Aprilia Caponord had the same check valve and it was removed because the tank would pressurize itself in the hot weather to the point of blowing fuel back on you when you opened the cap when the tank was over 1/2 full.

The Stelvio is a fuel injected bike, I know enough about engines and the way they work to know that the fuel injection system will compensate for me riching up the mixture by closing off the two ports on the TB runners. The 02 sensor or Lambada as the Italians call it has the duty of providing this service to the ECU once the bike is at operating temps.

We have all beat this to death at this point, you started off with a paint pealing issue or trying not to have one and by doing a few other items your bike runs better, now we have at least two threads on this forum deadicated to this. As long as the LEO's and the Feds in your area don't stick a sniffer up your tail pipe your good to go.

 

[guzziben47]

Thanks for taking the time to explain all this Kurt. If it wasn't for guys like you going through all this over and over, guys like me would never figure this out. In my case, I'd probably be getting rid of the bike if I hadn't made these changes. So I appreciate the info.

 

[kwn306]

Thanks for taking the time to explain all this Kurt. If it wasn't for guys like you going through all this over and over, guys like me would never figure this out. In my case, I'd probably be getting rid of the bike if I hadn't made these changes. So I appreciate the info.

Your welcome Now go out and ride this weekend and enjoy your bike with the new throttle response.

I have never owned a Guzzi before this Stelvio, I love the bike, it appears the motor / gear box / final drive is built proof unlike the BMW GS.

The Italians need to refine their FI system though, HD used to use the same system or one very close (Italian made) and ditched it because of the twitchyness of the throttle and went to the Delphi System. Trouble is with HD is that their bikes run sooooooooooooo lean the computer is smart enough to shut the bike off before it overheats, I spent many an afternoon sitting on the side of the highway waiting for my Ultra to cool off. My Stelvio does not have that issue, the Italians have a much better oiling system to cool the motor that's why I purchased the bike.

Just came back from the VA State MG Rally, talked to a lot of people, I had the only Stelvio. I explained some of the issues I had with the bike and all the owners claimed that it was "Italian Character" and smiled and said that's why we love the brand. Not sure I love the brand but I do love the bike, it gets under your skin.

There is a vast amount of knowledge on this board, some good and some...... :lol: The owner (Todd) and the moderators (Wayne, John, etc.) are great sources of knowledge, they have taught me a bunch in the last year. Just become a sponge and soak up as much as you can, pretty soon your BS meter will kick in and you will know what to throw away.

 

[GTM®]

I found out on Wednesday when I picked mine up, there had been only 38 total Stelvio sold in the US to date.

 

[kwn306]

I found out on Wednesday when I picked mine up, there had been only 38 total Stelvio sold in the US to date.

What.........is that one per dealer or something like that :lol: :lol: :lol:

 

[mohawkeye]

Congrats Todd!