V7 II Loss of high speed power?

[Dirk_S]

As noted in my previous clutch post, I began to experience some loss of power, noticed it around the time that I smoked my clutch climbing the rock garden with my sidecar in Pennsylvania. The bike is slow getting up to 80mph on the straights, and almost impossible the moment there’s an incline.

I noted that after replacing the clutch, I still experience this missing power. Also noted that I overfilled the oil (twice, sigh). Since then I’ve siphoned some of the oil out from the sump (and air box). I’ve also swapped out the stained air box for a new HiFlo filter.

I just received a compression tester and decided to check my compression on the quick today. That meant not testing the bike warm, but stone cold instead. I know that's not optimal, but I’ve read it could just simply read a little less than it’s true spec when warm.

The gauge read around 195-200 psi for both cylinders. The V7’s compression ratio is listed as 10.4:1 for all models except the Stornello, which gets 10.5 (+ or - 0.5) : 1. I have one of Beetle’s maps installed, a competition map for my high mount dual exhaust. I thought maybe too much fuel might be getting in, but the spark plugs look leaner than that would indicate, right?

200 psi is too high, right? Or no? I live near the seacoast, and we have about average barometric pressure.

I installed new throttle cables just before leaving on this trip a few weeks ago. I thought maybe I didn’t have them adjusted properly, but the butterfly valve appears to open at 90°.

Keep in mind this is unknown territory for me. Any help is appreciated.

Here are a couple pics for your entertainment:













Ask, keep in mind—since cleaning the overflow out from the air box and installing the new filter, I have not yet taken the rig out onto the freeway to see if it’s made any difference.

[Vagrant]

Does it run evenly on both cylinders with no missing? If not, change out the plugs. I've had the resistors fail from too much heat on a Harley while stuck in traffic. Maybe you drowned the sensor in the intake with oil. It might be worth spraying some map air sensor cleaner in while running.
Next time you change oil put 1 1/2 quarts in a bottle and dump it in. Then ride it a bit and check. If you really feel it needs more put in 3 ounces at a time. V7's don't hold 2L like the book says.

[fotoguzzi]

You should take that test ride then ask the question if still slow.

[lucky phil]

What quality compression tester did you buy and have you replaced the fuel filter?

Ciao

[Dirk_S]

Does it run evenly on both cylinders with no missing? If not, change out the plugs.

Thankya, Vagrant. Motor sounds like it’s firing evenly. Will actually be changing them anyways since I’m due for my 50,000 km maintenance service.

Maybe you drowned the sensor in the intake with oil. It might be worth spraying some map air sensor cleaner in while running.

I briefly wondered about possibly drowned sensors, then forgot. Will consider this further if the test ride still yields uninspiring results.

Next time you change oil put 1 1/2 quarts in a bottle and dump it in. Then ride it a bit and check. If you really feel it needs more put in 3 ounces at a time. V7's don't hold 2L like the book says.

Will do. I’ll actually be doing another oil change soon—3rd one in under 2000 miles, but this time adding in the new filter and using the correct amount (I swear!)

These things certainly like to think their camels, no?

You should take that test ride then ask the question if still slow.

Good idear.

What quality compression tester did you buy…

Innova. Link to product:
https://www.autozone.com/test-scan-and-specialty-tools/compression-tester/p/innova-compression-tester-plus-6-piece/273351_0_0
Maybe 190-200 psi is actually OK? I’ve seen different reports, from ~155 up to 200. I have some Gumout that I’ll run through the tank, may do the next few tankfuls.

…and have you replaced the fuel filter?

Not yet, but I do actually have one of those all-metal ones waiting to be installed one day. Might give it a go after the test ride.

[Vagrant]

If you still have the 1/2 plastic it might be cracked just enough to run but not with full power. Just change it now and eliminate it from the equation.

[lucky phil]

Compression is indicating a little high but I'd consider it more a tester issue then an engine one.

Ciao 

[Dirk_S]

Compression is indicating a little high but I'd consider it more a tester issue then an engine one.

Ciao

I had read that a compression tester doesn’t need to be high end priced to work well, but to also avoid the lowest price point (Harbor Freight). That said, I don’t think it seems all that surprising (to my amateur brain at least) to have high pressure if I’ve overfilled on oil a couple times and have had a habit in the past of filling with the lowest octane fuel (something I’m trying to remind myself more often to NOT do).

[Dirk_S]

Just to follow up on progress. I’ve had the rig at my welder’s shop for the past few weeks to get work done before my Newfoundland trip.

I did a compression test with a hot engine before t dropping it off at the welder’s, and both cylinders gave a reading of about 185 psi. lucky phil mentioned a concern that my cold reading was too high. I checked with Hamlin, and Jim said that 185 when hot seems pretty healthy.

Today I’ll swap out the fuel filter, clean the injectors, and do my valve clearance checks, which are overdue by about 50 miles.

I also bought a leakdown test kit, and plan to perform that test tomorrow (living in a small apartment, you’d think my brain would jump to renting from stores first, but nope).

[Dirk_S]

UPDATE: SOLVED!

When I replaced the fuel filter (pic attached), I found no cracks or other signs of leaking. However, when I tipped the fuel filter upside down, a good bit of dirty fuel spilled out. I also found that my fuel port to the injectors had some rust flaking on it, so I assume some water had sat in the tank for some time, possibly over a winter? After installing the metal Deutsche filter, I took it for a quick drive around town, and it seemed zippier. Wasn’t able to tell for sure until my riding mate and I set out for our Canada trip.

On those highways, I found I was finally able to do 70 mph and then some on the straights with a full sidecar, which was wishful thinking on my Pennsylvania trip. On the long hill climbs, I just needed to pop it down a gear or two, and I could still do 70. I guess the fuel filter had become blocked with enough dirt, not giving the injectors what they needed when the throttle was opened wide in the higher gears.

Additionally, on our Canada trip (that was unfortunately abbreviated due to a suspect charging issue on my bike…probably another post to come from that), I found some time to clean out my injectors, and found just a little more smoothness and oomph, which I think makes sense if rust particles had made their way down the injectors.

With the new, lighter sidecar connected to the V7 and the power returned, 70 mph on the freeways is finally a doable thing. I still have a minor amount of stuttering/hesitation in a couple spots of the throttle positioning—I wonder if this might be more due to the custom map that’s installed, or maybe I just need to do one more cleaning of the injectors. Besides that, I’m a happy camper, and can subside that creeping desire to upgrade to a V7 III…for now.









Now to figure out this charging issue.

[Alfetta]

recently i had a fuel issue with my tractor.  i had some rust crumbs show up in the glass bowl.  I was a bit shocked because i have recently replaced the entire gas tank with a new unit, and my gas cans are plastic.  I don't know about your area, but i think I'm getting "dirty" fuel straight out of the pump. i'm going to have to start filtering fuel and see if i can determine what station is feeding me grit-bit fuel...

[mechanicsavant]

Alpheta on your tractor . I’ve run into a few instances where the “crumbles “ in the fuel system are from old fuel lines detiorating internally (possibly an older hose ) that doesn’t like the alcohol content of newer fuels ? Chased this on an older airhead & a small excavator. I hope this 411 helps .

[SmithSwede]

I’m happy for you that this problem got solved.  And in a way that makes sense. 

Thanks for posting the solution to the forum.  There is nothing worse than a thread talking about a problem and it never culminates with a solution !!!

[larrys]

I’ve run into a few instances where the “crumbles “ in the fuel system are from old fuel lines deteriorating internally (possibly an older hose ) that doesn’t like the alcohol content of newer fuels ? Chased this on an older airhead & a small excavator. I hope this 411 helps .

^^^^^This. Was a big problem in boats in the years following alcohol being added to gasoline.
Larry