Predator 670 Carb Adjustment

Stock carburetor tuning from the factory was not stable at idle. Did some research online and found that the stock Predator 670 carburetor IS adjustable after removing the caps. Remove the caps and they are then available to adjust. ENJOY!

[@mandersontx1116]

It might start easier if you crank it longer than half a second. Good tips and thanks for sharing.

[@thepauldixonOC]

I installed and tested mine with the original pump still inline. I was told to remove the original pump and it works even better. I will have to try it out.

[@kartguy]

Welch plugs my good sir nice video! Yes they are on a lot of motorcycle carbs as well sealed for EPA emissions. Thanks buddy I had to do the same to mine.

[@davidgarrison7709]

What brand and specs of electric fuel pump did you use? Also what was the adjustments you made on carb? 1/4 turn ccw on both?

[@Quentin60isthenew40]

You’re on the right track. But after removing idle SCREW caps (they are not exactly a jet) do this: Turn each screw IN/clockwise, slowly, gently, carefully until it is seated all the way. Then turn each screw one OUT one + a quarter turns. That’s a typical starting point for idle screws on most old-school carbs. One, two or four barrels. Final adjustment with engine warm, 15-1600 RPM idle & everything else right should be 1.25 - 1.50 turns out. You will be able to hear/feel engine slow a bit when it’s turned too far IN, just back it OUT/off a tad, a quarter turn at most.

[@IneffablePanther]

i believe this help thanks

[@colbybuckheit9206]

What mud motor kit do you have on it ?

[@kerrynew1969]

The choke linkage was too short on mine so it would not start when cold , it looked closed but it was not all the way closed, i had to bend it longer to get the choke plate to close completely.

[@tracktorred7570]

They make kits to put dual mikuni style carbs on those engines it would help you out a lot on a mud motor being those carbs have accelerator pumps built in

[@thepauldixonOC]

Hey C Price...is the R side related to the high speed jet

[@cdp50359]

Got mine done! Thanks, runs great

[@bradstandish3106]

when replacing the fuel pump with an electric pump do you need a pressure regulator after the pump? or can you just use the electric pump? ours is having severe issues getting fuel

[@theoriginalpauly]

I'm sure you're past this problem by now, but I'm answering for others. I use a basic electric fuel pump with no pressure regulator. I removed the pulse pump completely. It works perfectly.

[@rickrascon6487]

Good video mines doing the same I never put the altitude adjustments in there did you? I live in New Mexico 5000 ft above sea level

[@thepauldixonOC]

I am on the east coast, pretty much sea level in most areas, so no never needed to try those jets. But, if you are higher in elevation then you have less oxygen to burn, so those jets would cause a lean condition where I live. For you it sounds like you must install those and then install the electric fuel pump.

[@sandrasolger4267]

I have the same Twister 4 on a gutted 17' bass tracker for bay fishing. I was having all the same problems mentioned. I went to 6Sigma and bought there rejetting kit. I removed the plugs from the enrichment screws with a drill and screw, I did not want to beat on the carb. I was thinking there was a screw for each side of carb. I backed off both screws 1/4 turn and it ran much better. It will know crank with out the choke once engine is warm. How fast will your boat go? I also believe that fuel pump on the engine is a problem, I like the idea of bypassing with an electric pump.

[@cdp50359]

Mine is hard to crank in cold weather and I have to use the choke with every crank. But I'm not 100% sure of what your talking about on the 1/4 adjustment. I need to fix mine like you said.

[@briansolger2027]

Once you uncover the caps on the fuel mixture screws take a screw driver and turn both screws to the CCW 1/4 turn. I have since opened up a 1/2 turn and it is fine. I have not had a chance to put it in the water and test.

[@noworriesmate5903]

The electric pump is a good idea. Amazon ( of course ) has low pressure electric fuel pumps. He didn't bypass the original pump bit he should.

[@dougpoteet3846]

Can you show me where you hooked up the kill switch to that motor. I'm in the process of installing a 670 on a Backwater LT kit and haven't seen anywhere online where I should install the black and red wires.

[@thepauldixonOC]

Take the yellow wire from the low oil shut off and wire the red lead of your kill switch to that and black to ground on the engine. I will verify this afternoon. Hopefully post a small vid.

[@thepauldixonOC]

Posted the vid: kzbin.info/www/bejne/lWiymomfpp2KrLM

[@thepauldixonOC]

Thanks

[@nolanbull1]

What did you use to replace the caps??

[@thepauldixonOC]

Nothing at all, Its just like any other small engine carb.

[@dougpoteet3846]

@@thepauldixonOC I think the caps are there to satisfy the California Nazis regarding emissions, from what I've been told.

[@ryoungatlmidotnet]

@@dougpoteet3846 HF doesn't sell this engine in California, so you can throw the blame elsewhere.

[@SC-dw3jz]

Full choke to start a small engine is the norm and throttle it so it sucks fuel upon start.... and crank it more than a second at a time 🥴

[@sandrasolger4267]

By the way, get rid of the twist grip and go with throttle lever speed control you will be much happier

[@tonystone936]

Hi, you must use a mikuni carb

[@thepauldixonOC]

So far i have reached 18 mph, this is before the carb adjustments

[@thepauldixonOC]

Your right it is terrible....i have a plan for that!

[@kenzeigler5307]

Do a 670 in a gator! What type of fuel pump did you use? Thanks! You boat sounds awesome

[@thepauldixonOC]

Use a low pressure fuel pump. I got mine off of Amazon: www.amazon.com/Doyes-Electric-Transfer-Universal-Carburetor/dp/B07K7J25GJ/ref=sr_1_3?crid=2EY9RHD8VHGUK&keywords=low%2Bpressure%2Bfuel%2Bpump%2B12v%2B1-3%2Bpsi&qid=1648294230&sprefix=low%2Bpressure%2Bfuel%2Bpump%2Caps%2C90&sr=8-3&th=1

[@Chris72401]

fwiw, the main jets that you're adjusting isn't the proper circuit. The low speed jet is what you need to adjust. It's below the security screw/cap between the two hoses on the top of the carburetor.

[@cdp50359]

I removed my pneumatic fuel pump after I installed my electric one. It did much better

[@thepauldixonOC]

I will go ahead and do that then

[@cdp50359]

@@thepauldixonOC the diaphragm inside the pump was leaking gas to the overflow on mine. That's initially why I did it

[@abundantblessings3555]

is the pneumatic fuel pump the one that came on the engine

[@cdp50359]

@@abundantblessings3555 yes

[@rickrascon6487]

Mine starts fine when it's warmed up but today in the morning won't start I think it flooded I installed an electric fuel pump

[@thepauldixonOC]

You engine will make less power in high altitude so maybe you don't need the electric fuel pump , definitely swap out those jets for the other set

[@c.r.angeconeb6009]

In the manual he says 😂 ... maybe it's the bolt on outside the muffler.... tap it

[@c.r.angeconeb6009]

Nicely executed... looking into getting them ... anyone try twin mudders????