SportsterDoc
New member
A minor vacuum leak will cause rough idle / rough low RPM operation.
When throttle is opened, the % increase in air is neglible.
When throttle is opened, the % increase in air is neglible.
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08 Spyder GS SM5 misfire/stumble when riding at steady speed
- Thread starter bwbarnes
- Start date
BajaRon
Well-known member
In general. I would completely agree with you. However, the Spyder already runs pretty lean (after warm-up). Some Spyders seem to have a problem with the rear cylinder running leaner than the front. In a situation where you're already borderline. And considering that at cruise you get your highest vacuum (other than decel). It could be that a normally insignificant vacuum leak could be the straw that breaks the camel's back.
This is why I thought it worth a look. Can't hurt.
SportsterDoc
New member
Motorcycledave
Active member
I am just going to toss this out and see if it sticks.....
I had a customer who had the same problem, the dealer in
Lodi CA. ( now defunct )could not find the problem so just on
a whim the owner went to NAPA auto and bought some fuel injector
cleaner and put it in the gas tank.... guess what it worked .
I had a customer who had the same problem, the dealer in
Lodi CA. ( now defunct )could not find the problem so just on
a whim the owner went to NAPA auto and bought some fuel injector
cleaner and put it in the gas tank.... guess what it worked .
Oldtimer51
Member
Just wondering if you did a catalitic converter removal (cat-delete) Some owners do that and that could change the mixture being put into the intake by the computer and injectors since they dont get the same signals originally programed for. Just somethig to consider. not an expert here but a friedn did that and her F3 goes from limp mode to limp mode now. Don't know what else she messed up with. I heard she sold it last week!
Mikey
Well-known member
Seafoams worked also for me a few times!
jayallday01
New member
Hey there, I know this thread is old and you may not even own your Spyder, but I found that with my 08, the throttle body gaskets were causing the issue. They were old, dry rotted and cracked. I changed them out and my Spyder runs perfectly now.
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That's interesting. How did you know that your throttle body gaskets were bad? Did you have the same symptoms or more? Do you mean you replace the rubber flanges between the throttle body and cylinder head?
Thanks,
Bruce
Thanks,
Bruce
BajaRon
Well-known member
It's pretty easy to check for vacuum leaks, once you get all of the upper engine components exposed. You want to do it on a cold engine. Because minor vacuum leaks can be reduced, or go away completely as the engine warms up. You can use several things. Water, starter fluid, carburetor cleaner, brake cleaner and even WD40 or propane.
Water is safest. But also not very good. Small to medium leaks will not show up with water. WD-40 is pretty safe, but a little messy. I do not like to use propane. It has too many negatives for me. And starter fluid is not specific enough to be sure. It disperses quickly and could be getting sucked into so many places, including the proper intake location, that you really don't know what's leaking.
Carb or brake cleaner works well for me. They come with a directional nozzle which helps pinpoint the leak and also dry completely clean. There is a fire hazard because they are flammable. But it is very minor if done correctly. Work in an open area away from the wind.
Start by identifying all the possible vacuum problem areas before you start so you're not hunting around for them with the engine running and warming up your leak. Start the engine and spray directly on the possible problem areas one at a time. Listen for a sudden RPM change. When you hit the sweet spot, you should get a noticeable RPM increase.
Once you find a leak. Shut the engine off and correct the leak. But don't stop there. You may have more than 1. And, you want to check that your fix was successful. Start the engine again and start at the problem you found to be sure it's fixed. Then proceed on to all the other possible issue areas to be sure everything is tight.
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jayallday01
New member
I saw a post on a Spyder Facebook page of someone mentioning the same symptoms. The fix for them was the throttle body gasket. Also their Spyder is the same age as mine and that compelled me to check. I am glad I did as mine were rock hard and cracked to the point where light could seen through. I guess you could call it a vacuum leak of sorts, but I know it was wreaking havoc on my ride.
I'm going to pull the body work off this weekend and try some brake clean to check for vacuum leaks at the rubber flanges (and other locations) as BajaRon suggests. Hopefully I will be able to track down the issue and be able to fix this annoying issue.
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BajaRon
Well-known member
There is one other possible source for a vacuum leak that this method will not find. And that is PCV Valve which is attached to the Evap Canister. If it is sticking open or not sealing properly, it will give the same symptoms. I recommend getting rid of the canister system altogether. It is poorly designed and can be quite problematic. It's not very hard to do and very inexpensive. It not only solves any potential PVC issues. It also eliminates the possibility of your Spyder catching fire from a malfunctioning system. A rare occurrence, to be sure. But it only has to happen once to get your attention.
obiwanbill
New member
I had a 2008 SE5 GS, bought new in spring 2009. After 13 yrs, she developed transmission and Brake issues. Many parts especially plastic and rubber had cracked and leaking brake fluid. Had it in to my dealer of last 30 yrs and told me a repair figure twice the book value. Additionally, parts were slow in coming and some parts might not be available for a bike that old. Sold it to a friend of a friend looking for a Spring project. Bought a slightly used 2020 RT LTD that the bank owns 70/72's of. Hey, I own 2/70's so far!
Repairing a bike that old, hope you have better luck
Repairing a bike that old, hope you have better luck
Look at the photos you posted about vac hoses just below the hoses is the throttle body gasket, (rubber base of the throttle body is the gasket).
Claire
New member
I have a friend who likes to tinker and very talented working on engines. Cost me more for parts than labor. I just replaced 02 sensor, spark plugs, fuel filter and small fuel line that leads to filter, throttle body hoses, evap + purge valve mod. Its my only ride so its worth it for me to maintain properly.
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