HD 883 Custom top speed 100kpm?!

[Ddonovan]

I'm hoping someone can give me some insight as to why my 2007 HD 883 Custom is topping out at 100kph I don't have a tach but after much experimentation I know to shift gears when he engine begins to give a low kind of grinding growl. This us happening lately at about 103kph in 5th gear! It never did go high but I used to be able to push it to 110-120kph...now I'm afraid the engine will blow up if I push it past 105 I can't even do the speed limit on some local highways at this rate HELP!

[Gummiente]

It's always difficult to diagnose any problem over the internet, but I'll give it a try. I'm missing some info, though, such as the mileage, what modifications have been done and when the last tuneup/service was performed.

I'm not sure what you mean by a low growling noise, but you may be shifting at too high an RPM. If you consult the owners manual it will tell you at what speed to shift for every gear, this is what you should go by. Eventually you will be able to shift "by ear" as you get used to it.

As of the limited top speed, the first two places I would check would be the air filter and the fuel filter. A dirty air filter will restrict airflow to the point that it will limit the available power on tap, especially at higher speeds. A plugged fuel filter screen (located inside the tank) or a plugged inline filter (I don't think the 07's have this) can limit fuel flow and affect acceleration and top speed.

Other things you can check for are the condition of the spark plugs (which should be changed every 12,000mi or whatever the manual recommends) and that you are using the proper fuel rating. Air cooled motors like the Harleys need a high octane fuel, low octane like 87 will affect performance and, eventually, engine life.

If none of these points fix the problem, you should get the bike to a shop and let them diagnose what is wrong.

[GS_in_CO]

Is it running smoothly when it's topped out?
Is this the same road location as previous? (i.e. - you didn't move to a higher altitude in the meantime did you?)
Did you add a fairing?
Checked tire pressure?
Same tires as before? (i.e. didn't change tire size thus throwing the speedo off...)
How many miles on the engine since it would go fast? (i.e. could it be worn?)

That's six questions. It might take 14 more before a conclusion can be reached.

[Ddonovan]

The bike has about 7500kms on it - 7000 of those are mine. No mods. No dealer service (I have only had it a year) but regular oil changes. Shift points by feel and sound are about the same as the manual in lower gears but if I shift it according to manual at higher gears it lugs. (manual shift points kph: 1st to 2nd= 25; 2nd to 3rd=40; 3rd to 4th=55; 4th to 5th=75. My shift points kph: 1st to 2nd=25; 2nd to 3rd=45; 3rd to 4th=65; 4th to 5th=85).

It runs smoothly when topped out - same as it does at the top of the other gears.
Same road type as always; more or less same elevations on all highways I have travelled.
No mods at all - tires are spec, good shape, and properly inflated.
I know that speedo is on point as I have ridden with others and checked in with them.
Engine should not be worn at such low kms. I don't know how many kms since I noticed it being slow (I do a lot of winding back road riding where over 80 is flying!) but I bought the bike with less than 500 and it's now at about 7500.

The air filter was pretty clean but I cleaned it anyway - will try the fuel filter tomorrow.....

???

[Gummiente]

Harleys do not come with reusable air filters, so just tapping the dirt out isn't sufficient. Washing the filter will further damage the pleats and actually reduce airflow. Best thing to do is get a new air filter or go for the more expensive K&N oiled filter, which can be washed and reused indefinitely.

However, from your description I'm starting to think it may be a fuel delivery problem, possibly even vapour lock. Check the routing of the gas line and make sure it is not kinked or touching any hot engine part. Then drain the fuel tank and remove the fuel tap. Clean the filter screen and reinstall. Remove the float bowl from the carb and check it for sediment. If there is a lot of it, the jets may be plugged and the carb will require disassembly and cleaning.

[GS_in_CO]

Seems to me that if were fuel delivery that the mixture would be leaning out and it would run badly - at least for carbureted engines. Fuel injection with ECU control might behave well up to the limit of fuel delivery. (I don't know which is on this machine)


New air filter is about the easiest thing to try other than a different grade of gasoline.

[Gummiente]

Seems to me that if were fuel delivery that the mixture would be leaning out and it would run badly - at least for carbureted engines. Fuel injection with ECU control might behave well up to the limit of fuel delivery. (I don't know which is on this machine)

His bike is carbed. I suspect fuel flow issues because I had a similar situation on my 95 Triumph Thunderbird that turned out to be a collapsed filter screen inside the tank. Also had several customers with Urals who had plugged fuel filters that reported the same symptoms, so I'm just making an educated guess here.

[Ddonovan]

Gummiente: the manual says to rinse the air filter with "warm soapy water" so I am assuming it can be done. I did see in another place that the stock air filter can be reused once. I am looking into a K&N one for next time though. 2007 is fuel injected - no carb - but that would have been my first guess if it were possible.

I looked into doing fuel filter but from all I have been able to find out it is a huge job and one that may be beyond my skills to do with security that I won't screw it up...although I have only seen info for Dynas and one Sportster where the guy said the tank had to be removed completely! Unless anyone knows better, J might have to pay the shop

[GS_in_CO]

Seems to me that if were fuel delivery that the mixture would be leaning out and it would run badly - at least for carbureted engines. Fuel injection with ECU control might behave well up to the limit of fuel delivery. (I don't know which is on this machine)

His bike is carbed. I suspect fuel flow issues because I had a similar situation on my 95 Triumph Thunderbird that turned out to be a collapsed filter screen inside the tank. Also had several customers with Urals who had plugged fuel filters that reported the same symptoms, so I'm just making an educated guess here.

Theory yields to experience.

It just seems to me that mixture would go lean at wide open throttle if fuel isn't being supplied.
But I haven't had fuel supply issues other than the car electric fuel pump that melted internally and the plastic solidified so the pump would never turn again......

Air filter is simple and cheap to do. Owner can do.
Fuel delivery - shop job.

[Gummiente]

Gummiente: the manual says to rinse the air filter with "warm soapy water" so I am assuming it can be done. I did see in another place that the stock air filter can be reused once. I am looking into a K&N one for next time though. 2007 is fuel injected - no carb - but that would have been my first guess if it were possible.

I looked into doing fuel filter but from all I have been able to find out it is a huge job and one that may be beyond my skills to do with security that I won't screw it up...although I have only seen info for Dynas and one Sportster where the guy said the tank had to be removed completely! Unless anyone knows better, J might have to pay the shop

Ok, my bad. I thought EFI wasn't standard on Sportsters until 2009. Ignore all my previous recommendations, save for the air filter, and get the bike to a shop. The EFI doesn't have many user serviceable parts and a diagnostic machine is necessary to trouble shoot the system. My apologies for steering you in the wrong direction.