mikuni carb question
Outstanding HDF Member
Joined: Nov 2010
Posts: 2,250
Likes: 36
From: Montana
stock petcock will work fine. A pingel (sorry if I misspelled that) is always a good idea if your doing high performance work. but carb , cam , ignition, pipes, aircleaner the stock petcock works fine. It wasn't until I got a set of HP heads from branch that I needed a better petcock.
Road Warrior
Joined: Apr 2010
Posts: 1,739
Likes: 10
From: Suffolk, England
The stock petcock on any Harley, no matter how tuned up, is more than able to provide the fuel needed. The sale of after-market petcocks is totally down to salesmanship by petcock makers.
If you have ever had a clear fuel pipe on a bike you will know that the fuel comes through at no more than a dribble at even the highest speed. The stock petcock piping diameter is plenty big enough to keep up with the flow demands.
If you have ever had a clear fuel pipe on a bike you will know that the fuel comes through at no more than a dribble at even the highest speed. The stock petcock piping diameter is plenty big enough to keep up with the flow demands.
Outstanding HDF Member
Joined: Nov 2010
Posts: 2,250
Likes: 36
From: Montana
I have to disagree with foxsters last statement. For the majority of set ups that is true . But when I put a set of high flow heads , cams etc to go with all of the other performance work on my last dyna my stock petcock starved the bike. It would stumble and almost die at higher revs. One new pingel petcock later and I never had the problem again. So sometimes the petcock does need changing.
Supporter
Joined: Sep 2006
Posts: 3,711
Likes: 640
From: San Ramon, Ca
I've had Mikuni's. Older ones. Two HS40's on Shovel's & one on a 93 1200 Sporty. Those all had 3/8 inlet. I'm sure the 42's were too. The fuel tank outlet is 5/16 on a std HD Petcock.
Better to go Pingel (Spl chk) which is 3/8 rather than stretching a 5/16 hose.
My 74 FXE which was an 84" stroker would starve for fuel. The Pingel did fix that.
Better to go Pingel (Spl chk) which is 3/8 rather than stretching a 5/16 hose.
My 74 FXE which was an 84" stroker would starve for fuel. The Pingel did fix that.
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Road Warrior
Joined: Apr 2008
Posts: 1,899
Likes: 8
From: Aurora, IL
I have to disagree with foxsters last statement. For the majority of set ups that is true . But when I put a set of high flow heads , cams etc to go with all of the other performance work on my last dyna my stock petcock starved the bike. It would stumble and almost die at higher revs. One new pingel petcock later and I never had the problem again. So sometimes the petcock does need changing.
Thats odd, My 107" making over 110hp and over 120tq didnt need an aftermarket petcock while using a Mikuni 45mm carb. Never had a single issue of fuel delivery. Always ran perfect.
I did recently change my petcock to a pingle dual outlet but only because one outlet feeds my carb, and the other feeds my fuel pump for the nitrous system. I didnt want my fuel pump to starve the carb. By using seperate lines, I have no worries.
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Road Warrior
Joined: Apr 2010
Posts: 1,739
Likes: 10
From: Suffolk, England
The only two times that I ever saw an aftermarket petcock make any difference was once when the stock petcock's filter was partially blocked and the second time was when the diaphram of the vacuum operated valve was split. In each case a new stock petcock would have made the same difference.
I really think that the only people that see any difference with a non-stock petcock are people with faulty stock ones.
A much more common cause for fuel starvation in my experience is poorly breathing filler caps. Some of the bling caps fitted breath badly and this leads to a partial vacuum in the tank.
I really think that the only people that see any difference with a non-stock petcock are people with faulty stock ones.
A much more common cause for fuel starvation in my experience is poorly breathing filler caps. Some of the bling caps fitted breath badly and this leads to a partial vacuum in the tank.