Hor start issues, please help
Thread Starter
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Novice
Joined: May 2022
Posts: 19
Likes: 8
From: Waterbury, Ct
Since it started with the new muffler the first thing I would do is remove the Cobra Slip-Ons and put back the old mufflers and see if that fixes it.
You mentioned you put on a high flow filter and now upgraded the exhaust without any mods to the carb.
You may need to re-jet the carb just like you have to tune an EFI bike when changing the air intake and exhaust.
Nice looking bike BTW
You mentioned you put on a high flow filter and now upgraded the exhaust without any mods to the carb.
You may need to re-jet the carb just like you have to tune an EFI bike when changing the air intake and exhaust.
Nice looking bike BTW
I haven't tried swapping exhaust yet, but that may be a final step if I can't resolve this.
From what I've read, it seems the stock carb setup is ok with a high flow filter and slips-ons. I only had to tweak the mixture screw. I think if I did a full exhaust I would have to rejet.
Tourer
Joined: May 2011
Posts: 469
Likes: 158
From: Alberta
Put an old spark plug in your pocket. When it acts up, pull a wire and put that plug on it then lay it on the head. See if it's getting spark at crankover speed. Do that and get back to us....
That year doesn't have a VOES - it uses a MAP sensor on the intake manifold that does (basically) the same thing but in a different way.
That year doesn't have a VOES - it uses a MAP sensor on the intake manifold that does (basically) the same thing but in a different way.
Thread Starter
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Novice
Joined: May 2022
Posts: 19
Likes: 8
From: Waterbury, Ct
Carb models still had the MAP sensor, they just did less with the data.
Last edited by BrianCMM; Feb 10, 2023 at 09:29 AM. Reason: spelling
Tourer
Joined: May 2011
Posts: 469
Likes: 158
From: Alberta
The carb has been completely taken apart and cleaned, float level verified, everything in great shape and clean. I don't where I would look for a vapor lock issue. There really are no vacuum lines on this carb. Maybe I should try shutting off my fuel pet **** when I stop to refuel... although I've never had an issue before and I did test the vacuum line on the pet **** and it works as it should.
I was also leaning towards a bad/weak coil when hot. I have checked the resistance when cold and it's all in spec but I have yet to test the resistance when hot.
Thank for the help!
I was also leaning towards a bad/weak coil when hot. I have checked the resistance when cold and it's all in spec but I have yet to test the resistance when hot.
Thank for the help!
Yes coils act up when hot and if you let the bike sit for awhile, so they cool down, then the bike will start fine. If it is continually doing that type of thing then I too would suspect the coil or the ignition pickup or module.
Tourer
Joined: May 2011
Posts: 469
Likes: 158
From: Alberta
With all the sensors on that year of bike, it likely is one of them that is causing his issues.
HDF Community Team
Joined: Dec 2005
Posts: 5,421
Likes: 2,621
From: NC USA
I was also wondering about the vacuum petcock as a possible culprit but thought a simple spark check would be quicker and more simple to check.
Remember - just because a coil ohms out good is no guarantee it will produce spark cold or continue to spark when hot. Ohm test only tells you whether it's open or shorted for certain.
Remember - just because a coil ohms out good is no guarantee it will produce spark cold or continue to spark when hot. Ohm test only tells you whether it's open or shorted for certain.
Thread Starter
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Novice
Joined: May 2022
Posts: 19
Likes: 8
From: Waterbury, Ct
So is this a stock cv40 carb or an aftermarket one. On the CV40 carbs the vacuum port is at the rear of the carb, just before it goes into the intake gasket. If you don't have any vacuum lines, how is the vacuum petcock working? If you take the air filter breather off you can just see the vacuum line at the rear of the carb. It can be a pain to hook up again when reinstalling the carb. That vacuum line if you have a VOES, goes to the VOES and then its T'd off to the vacuum petcock.
Yes coils act up when hot and if you let the bike sit for awhile, so they cool down, then the bike will start fine. If it is continually doing that type of thing then I too would suspect the coil or the ignition pickup or module.
Yes coils act up when hot and if you let the bike sit for awhile, so they cool down, then the bike will start fine. If it is continually doing that type of thing then I too would suspect the coil or the ignition pickup or module.
Thread Starter
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Novice
Joined: May 2022
Posts: 19
Likes: 8
From: Waterbury, Ct
I also just noticed the manual shows a Vapor valve. I don't remember every seeing that on my bike (and I've had the tank off and such so you think I would've seen it). I'll check and see if that is working as well.
I wish it was riding season so I could test out a few of these suggestions. All though it is hitting 55 today in CT, I'm still waiting for my rims to come back from chroming so I have no way to ride right now.
I wish it was riding season so I could test out a few of these suggestions. All though it is hitting 55 today in CT, I'm still waiting for my rims to come back from chroming so I have no way to ride right now.
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Tourer
Joined: May 2011
Posts: 469
Likes: 158
From: Alberta
If it is the vapour valve it would tend to cause you more problems running down the highway. As you were travelling along the bike would start to loose power and eventually run like crap. If you cracked open the gas cap the symptoms would go away. On my 98 Classic, that valve was missing on my bike and I just extend the vent line to down under the bike.