Thread: 3 pulse fittings?
11-10-2009, 05:54 PM #1
3 pulse fittings?
I heard that tuners put 3 pulse fitting on the crankcase for a ski with a triple carb!? would that really help or is it a HP thing with high output engines or would the mod help the average triple fuel pump and a stock 750?
11-10-2009, 06:02 PM #2
3 pulse fittings would only be required for 3 fuel pumps. The 785 has 2 pulse fittings because it is using 2 physical fuel pumps (which is strange, I know, but it does). A single triple outlet pump only required 1 pulse fitting.
11-10-2009, 06:07 PM #3
So If I went with 3 external pumps, I would need 3 pulse fittings then? Would that improve anything ?
11-10-2009, 06:13 PM #4
On a stock 750? If you already have a triple output fuel pump, then probably won't improve anything. The carbs will only take the fuel they need and the rest is sent back to the tank via the return line. Adding more flow to the carbs will just send more back to the tank. If you had a single crappy 1 outlet pump and wanted to add 2 more single crappy pumps, then it would help as each pump would only have to feed a single carb which would lessen the odds of running lean on fuel due to the crappy pump not keeping up. Performance wise, unless you are leaning out due to 'crappy pump sydrome', it won't make a difference.
This is a crappy pump:
...and the little 'mini-me' is the evil Auto-Cock that needs to be thrown away if you happen to have one. But I don't think yours would have it.
11-10-2009, 06:27 PM #5
- Join Date
- Aug 2006
- Homer Glen Il.
theres no need for three pulse lines i run 46 Novi's on my 785 with 2 Mikuni 60 l pumps and some guys run 1 pump with 46's they use the Novi pump
11-10-2009, 06:41 PM #6
They are really used for when you have some aftermarket carbs that have their own internal fuel pump...such as Black Jack carbs. Then you will have a pulse line for each carb.
11-10-2009, 08:50 PM #7
thanks 32, lugs, that explains it! I have the triple outlet on the slt as per Beerdarts diagram! works fine.
When adding dual or triple carburetors, it's customary to add additional "pulse" fittings. Most tuners will tell you that an individual crankcase pulse for each carburetor will yield the best performance. This kit includes the correct size drill bit and 1 pulse fitting.
I was reading this off the Watcon website. Thats why I asked.
11-10-2009, 08:56 PM #8
My ski has triple fuel pumps. Should I need a pulse line for each carb?
11-10-2009, 08:57 PM #9
Or will 2 be sufficent? I dont know if it has 2 or three.
11-11-2009, 12:01 AM #10
- Join Date
- Oct 2006
- Cleveland OH
If you have external fuel pumps (single, double, or triple outlet), 2 fuel pumps may be enough depending on output.
1 mikuni round pump (single, double or triple outlet) will put out 35L per hr.
1 Mikuni pentagon pump (double or triple outlet) will put out 65L per hr.
You can also "T" 2 double outputs together on 1 cyl, when used with a triple cyl.
So 2 double outlet rounds would = 70L per hr when "T" together using 2 pulse fittings.
And 2 double outlet pentagons would = 130L per hr when "T" together using 2 pulse fittings.
If your carbs are using internal fuel pumps, (one inside each invidual carb) then you should have a pulse fitting for each.
Red Tops, just like OEM 44's on a PRO 785, have an internal fuel pump on the PTO and MAG carb. They then feed the CEN carb together, and use it as the return with the restrictor installed creating the fuel pressure.
Hope this helps.
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