4500 RPM Dead Spot
Thread Starter
|
Cruiser
Joined: Sep 2011
Posts: 209
Likes: 0
From: Clermont, FL
4500 RPM Dead Spot
I need some guidance to make sure I'm on the right path here. The bike has the stock keihin CV carb. Since I bought it, the bike hits a wall at 4500 RPM, then comes back to life a few hundred RPM later. I replaced the drag pipes with a 2 into 1, replaced the jets (had 45/170) with 46/180, shimmed the stock needle, drilled out the emissions plug and have the screw at 3 turns. I also chopped up a stock airbox and put in a K&N (HD-1390) filter.
I expected the pipes to fix the problem, but there has been no change. Had a friend ride behind me the other night and gave it a blast and he mentioned that there was an orange glow when I hit 4500 RPM (exhaust note changes, it's sort of violent). The current thought is that the main is coming on too late (right around that time). The question is, how do I fix it? As I understand it, changing the needle may help. Should i go with the N65 or the CVP velocity needle? Would a lighter slide spring also help? Basically, I need the slide to move up faster, right?
TIA.
I expected the pipes to fix the problem, but there has been no change. Had a friend ride behind me the other night and gave it a blast and he mentioned that there was an orange glow when I hit 4500 RPM (exhaust note changes, it's sort of violent). The current thought is that the main is coming on too late (right around that time). The question is, how do I fix it? As I understand it, changing the needle may help. Should i go with the N65 or the CVP velocity needle? Would a lighter slide spring also help? Basically, I need the slide to move up faster, right?
TIA.
Thread Starter
|
Cruiser
Joined: Sep 2011
Posts: 209
Likes: 0
From: Clermont, FL
It is a stock (as far as I know) motor. There was a marred up 45 slow jet in it when I first opened up, so somebody had been in it. However, they hadn't drilled out the emissions plug on the mixture screw.
What I mean is that the bike pulls nicely, then at 4500 RPM WAM!, face on the handle bars.. then by 4700 RPM, we're pulling hard again.
What I mean is that the bike pulls nicely, then at 4500 RPM WAM!, face on the handle bars.. then by 4700 RPM, we're pulling hard again.
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
you are in a high humid area and with out the use of a performance kit - you have too much jet and the needle is in the wrong spot being rich < too tall in the clip and OR shimmed to high
kinsler kits < made in japan and the only one i use in my shop 20 years now, when your done installing it most carbs have a 160 main and a 42 low speed and that is with a cam and a compression increase using thinner gaskets -- good fuel mileage - starts in the North east very well late fall - real good plug color - great throttle responce - its what we do in a shop so you dont wash out the piston rings with fuel trying to make a motor that has good VE run on big jets - that is for the guys who ported the heads so they never work correct again - just my take been doing it 2 weeks now
kinsler kits < made in japan and the only one i use in my shop 20 years now, when your done installing it most carbs have a 160 main and a 42 low speed and that is with a cam and a compression increase using thinner gaskets -- good fuel mileage - starts in the North east very well late fall - real good plug color - great throttle responce - its what we do in a shop so you dont wash out the piston rings with fuel trying to make a motor that has good VE run on big jets - that is for the guys who ported the heads so they never work correct again - just my take been doing it 2 weeks now
Trending Topics
Outstanding HDF Member
Joined: Nov 2013
Posts: 2,358
Likes: 34
John I bought a cvp kit to rejet. It had a dynojet emulsion and 180 main when it started doing this. It now had cvp emulsion and 180 main and 45 pilot with the cvp needle and no shims. K&N filter stock airbox. Your saying it's too rich?
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Road Master
Joined: Jan 2008
Posts: 1,187
Likes: 8
From: Montgomery, AL
If I'm not mistaken shimming the needle richens it up across the board and doesn't change when the main comes in. I'd pickup the N65 needle as a start. My Fatboy is stock except for cv mods Sportster needle, 45/175 jetting with a hypercharger. I also run Longshots with no baffles. Not optimal but I like it.
Side note I believe the main comes in around 3500k.
Side note I believe the main comes in around 3500k.