Honda Clone weak pulse at full throttle.

Bmeehan19

Hi,
Ive read a ton here over the past 3-4 years and have succesfully swapped a predator 420cc into my G14. It also has a 6” lift, 22” tires, vegas carts carb, pulse fitting on valve cover, shaved rear clutch and plowmans limited slip rear dif insert. I was using the stock g14 muffler that ai drilled a few 1/2” holes in each interior baffle to improve the flow and the cart was simply a joy to drive! Plenty of torque at all rpms, never ran out of fuel like I read could happen at high rpm.

The muffle since cracked and all went down hill. I have the muffler from vegas carts, the round straight thru kind they told me to buy, so I slap it on. Now at full throttle I run out of fuel. I pull the fuel line, rev it up and the pulse goes weak to non existent. So I thought the back pressure wasnt enough, I welded a washer over the exhaust exit with a 1/2” hole and it seemed to help but it would still run out of fuel when wide open, a bit of choke helped limp it along until it caught back up.

Long question is, how do I get the torque back and also not run out of fuel This thing would be able to pick up speed easily up hill with to adults in it.

I do have the offset timing key I have not installed yet. Any help is super appreciated.

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BGW

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raydhd

Why not use the VC recommended pulse fitting by the carb ?

Bmeehan19

I thought about doing that but I am asking here to avoid throwing money at it arbitrarily. I was hesitant due to the fact that it worked perfectly before the new muffler. Was trying to get the “new” muffler to behave as close as possible to the old one. Do you feel the cause of my issue is lack of back pressure or something else?

raydhd

I don't see a new muffler affecting crankcase pressure.

BIKERMIKEYBLACK

Just my two cents on my duromax 420 wen using the intake barb it flooded my carb and had to go to the valve cover....I don’t how less back pressure could affect the pulse but apparently it has as u said welding the washer on helped ...If u have a intake spacer with a barb why not try it maybe mr Shepard could help here

Bmeehan19

I dont have the intake spacer yet. I came here to see if there were different reasons for what im experiencing. Its weird, as soon as the other muffler failed all this started. Did something else get messed up? Up to about 1/2-3/4 throttle it can keep up. If I punch it the bowl will run dry, if I pull the choke it wont stall but I have to slow down considerably for it to catch up. Could it be the motor is seeing higher rpms with the free flowing exhaust and now its finally running out of fuel? Gauging by the seat-of-the-pants-ometer it feels like it has less pull on both flat and hill acceleration now.

chrisr32

If the exhaust is more free flowing you may just need to go with a larger main jet. An adjustable jet make this tuning easier then buying new jets and/or drilling them to get the right size jet.

https://www.eccarburetors.com/169F-4...rb_p_1212.html

Shepard

The pulse from the crankcase is a puff of pressure -- the pulse off the throttle is vacuum. The muffler does not affect either. Sounds more like the pump is the problem. Is the pump original G14? Are the rubber hoses original?
Using the pulse from either source has its limitations. Intake pulse is limited at high rpm -- responses like its running out of fuel. Crankcase pulse causes the carburetor to flood at high rpm.

If it was running well and the muffler had a problem -- the pump was right along side of it.

Bmeehan19

Ive read in another thread that the jet size was the culprit of a very similar problem. And with the hew exhaust I may be running lean with the increased flow. Im going to try the adjustable jet to see if it helps out. I did pull apart my fuel pump and the diaphragm is in good shape and clean. I did replace all my fuel line when I built the cart with the softer rubber hose. Do this theory sound plausible?

chrisr32

If you move away from the stock air cleaner and exhaust on most engines the adjustable jet is required or a lot of trial and error with buying jets.