Possible cv carb fault?

[mr. pitts]

Hi guys. 96 FLHT fine up to about 60mph. Thereafter, lots of noise but not much go, feels a bit like it's holding back. Bike has aftermarket slip-on's, no idea about air filter as i don't know what to look for. Possibly been stage 1'ed. Might it be a bit weak, or do they normally need a little coaxing after 70mph? Any help gratefully received. Thanks for looking.

Mr. Pitts.

[Foxster]

Good place to look for those symptoms is the diaphram being holed in the top of the carb.

[Tomo.T]

+1 on that diagnosis. Finn Dave has just had exactly that problem on his Dyna. Prepare for a shock when you see the price of a new diaphram !

[banquo]

IIRC the diaphragm is expensive because it's not available separately from H-D, but it is available cheaply from elsewhere. Someone on here 'fixed' a punctured diaphragm as an emergency repair, and it lasted ages.

[FinnDave]

Originally Posted by Tomo8717

+1 on that diagnosis. Finn Dave has just had exactly that problem on his Dyna. Prepare for a shock when you see the price of a new diaphram !

£55 plus delivery was a shock, but the symptoms were different from yours, mine struggles above 40 and was slowing down when the throttle was opened. If you're lucky it'll just be some crap floating about the carb.

[mr. pitts]

Originally Posted by banquo

IIRC the diaphragm is expensive because it's not available separately from H-D, but it is available cheaply from elsewhere. Someone on here 'fixed' a punctured diaphragm as an emergency repair, and it lasted ages.

Hi Banquo, any danger of you telling me where "elsewhere" is? Took the air filter cover off today to check the diaphragm. I think it's basically o.k. If i lift the slide, i can hear it pumping air, & it doesn't just drop down with a bang, so here's hoping. The earth electrode on the plugs was a VERY pale brown, almost white, so think it's a bit lean. The anti-tamper plug has been removed from the carb, so i richened it up a fraction of a turn, but i think it needs more. I'll drop the float bowl this week & check the jets.
It's possible to buy a c.v. carb upgrade kit from Harley Davidson Performance in the USA. I don't know if they are available in the UK, looks like a nifty piece of kit.
There's a video on you-tube of someone mending a diaphragm with something called "Hondabond", available from Honda car dealerships.
More news as it happens.

Mr. Pitts. harley-performance.com oops!

[banquo]

Try giving these people a call. The Harley part includes the slide, but they may be able to supply just the diaphragm (although by the sound of it, you don't need it?).

[Limey_Dave]

From your earlier posts I asume it hasn't always been like this.I would get it sorted with the standard parts before mudying the water with non standard jets and springs.
The CV carb is very forgiving,it will bolt on and run on everything from 1200 to 1450,it may need tweaking,but it will run better than your bike is at the moment.
Plug colour isn't so reliable as it once was with todays fuels,and to get any sort of plug reading,you'd need to do a plug chop.You're not in a position to do that at the moment.
Was there anything you touched or worked on between it running good and bad?

[mr. pitts]

Originally Posted by Limey_Dave

From your earlier posts I asume it hasn't always been like this.I would get it sorted with the standard parts before mudying the water with non standard jets and springs.
The CV carb is very forgiving,it will bolt on and run on everything from 1200 to 1450,it may need tweaking,but it will run better than your bike is at the moment.
Plug colour isn't so reliable as it once was with todays fuels,and to get any sort of plug reading,you'd need to do a plug chop.You're not in a position to do that at the moment.
Was there anything you touched or worked on between it running good and bad?

Ayup Dave,
i've only had the bike a couple of months, & have done nothing to it, i mean NOTHING! The bike is as i bought it, so that's my only yardstick. Regarding the diaphragm, the acid truth would be to take the carb to bits & look at it properly, but i'm loath to do that in the summertime. (WHAT?). Due to me having to work shifts & look after disabled family on me own, riding time is a bit precious, & i need a bit 'o' r n r to keep sane. An hour's ride makes me feel a lot better. Been away from Harley's for about 20 years so it's kinda good to be on one again!
I'll crack the prob one way or the other, but like most folks, i don't know it all. Thanks for the reply.

Mr. Pitts.

[mr. pitts]

Originally Posted by banquo

Try giving these people a call. The Harley part includes the slide, but they may be able to supply just the diaphragm (although by the sound of it, you don't need it?).

Thanks for the tip, Banquo. I'll check them out later.

Mr. Pitts.