04 Suzuki Eiger 400 Starting Issues & More

[alexwv1863]

I'm currently working on an 04 Suzuki Eiger 400 and ran into some issues. Main issue being it's really hard to start. Once I get it started, it runs bad. Sounds like it's missing, which I'm pretty sure is an idle issue. It's not my 4 wheeler. I'm working on it for a buddy. Someone started working on the original carb and 2 jets were missing when I got it to work on.

So, I ordered a new carb. To get it to run, I had to adjust the throttle screw on the handle bar almost all of the way out. Even doing that, it still sounds like it's bogging down and missing. 

I did put a gas filter on it, which I'm questioning whether or not that's the issue and it's not getting enough gas like it should. The petcock only has an On, Reserve, and Prime option. It also has 2 ports. I guess I have the hoses hooked up right. There's no way to shut the gas off completely, and also it looks like there's no gas getting thru unless I run it on Prime. Reserve drips gas. I'm going to take it apart today and clean it. I'm also going to take the jets I need out of the new carb and put in the old one. 

I don't know what all this person did you the 4 wheeler before I got it. There's odds and ends missing that I've noticed so far. What else can I try or look for? What could be the gas issue with the carb and petcock? The carb was completely off the bike except hanging onto the throttle cable. The diagram I found for the carb doesn't help me with hose placements. Any help, or questions would be appreciated. I can attach photos if it would be of help.

[TnMtnMn]

Your best bet is going to be to download the  service manual (which I’ve attached Youre Welcome). Should give you all the diagrams that you need. It’s helped me on several occasions. LT-A400F and LT-F400F Service Manual.pdf

As for your problem specifically - Good Luck. Hope that manual helps you out. 

And to me it sounds like you just took over someone else’s headache. Again - Good Luck!!

[Savage3]

The ATV fuel petcock with ON, RES, and PRI (Prime) positions is a vacuum-operated valve that controls fuel flow from the tank to the carburetor. Here's how each setting works:

ON | Fuel flows only when engine vacuum is present | Normal operation | Prevents flooding when engine is off.

RES (Reserve) | Draws fuel from the bottom of the tank | When fuel is low and ON stops supplying | Gives access to remaining fuel before refill.

 PRI (Prime) | Bypasses vacuum system; fuel flows freely | After carb maintenance, dry starts, or vacuum issues | Must be turned off after use to avoid flooding or oil contamination:

- ON is your go-to setting for everyday riding.
- RES is a backup when you're running low—switch to it only when needed.
- PRI should be used sparingly:
  - To fill the carb bowl after it's been drained.
  - If the engine won’t start due to lack of fuel.
  - Never leave it in PRI when the engine is off—it can cause fuel to leak or flood the engine.

 

One things is certain, you don't want to continue making adjustments to carb until you have solved fuel flow issue.

 

Hope this helps sir.

Edited August 10, 2025 by Savage3

[shorty]

Make certain the vacuum hose to the petcock isn't giving you a massive vacuum leak in your induction intake 

[Gwbarm]

Those vacum petcocks go bad with age. Check to make sure you are getting fuel flow in the prime position, if so fill the carb bowl with fuel start it and turn the petcock to the on position and see how long it runs, if it continues to run, good, if it runs for a while starts running bad and dies the petcock is bad. The other problem with these Quads is the magnets on the flywheel come loose they generally stay in place but are continuously moving around in a radial direction  which can also cause running issues.

[alexwv1863]

I have the manual already but so far it hasn't been much help with the issues I'm having. I replaced the petcock with a basic petcock and blocked off the vacuum port on the carb. I also replaced missing jets in the original carb and put it back on. I took apart the original petcock and the gasket in the back felt very soft like it was worn out, so I thought maybe that was one of the issues with fuel not flowing through like it should (why the ATV wouldn't idle). Then I replaced the solenoid as well because I couldn't get the ATV to turn over at all. The solenoid started clicking. 

 

Now, with everything I said I did above, the ATV won't turn over at all. battery is fully charged. My next check will be taking the starter off. I may have burned it up trying to crank it so much. I'm not sure. Hopefully I'll be back working on it tomorrow. 

[alexwv1863]

It's been crazy for the last month but here what I've found out and problems. I replaced some jets from a new carb into the old carb. The new carb would just not run right. It would idle very high and would not adjust right now matter what I tried. So I replaced a couple of the jets that were missing in the old carb and put it back on the bike. It ran for maybe 30 seconds then shut off. I bypassed the vacuum in the carb and put a regular petcock on because the gasket in the back of the petcock was worn out and I figured it wasn't working right. The guy who owns the bike wanted to go with a regular petcock as well. So I taped off the vacuum port on the carb. 

I also put on a new solenoid because I thought it went bad. Turns out the brushes in the starter were completely gone. I just put on a new starter and it starts and idles really good. ...

Now here's where I'm having another issue. It won't take throttle. As soon as I try to give it gas, it dies. It'll start right back up though. So, what could be causing it not to take throttle???

[Gwbarm]

Thats typical running problem of an aftermarket carb. If you put the jets from an aftermarket carb into the original Kei- Hin carb they are not the same as OEM and is probably your problem. Thats good you put a regular petcock on, i did the same to mine, it was bad and i could only run it on prime no gas getting through in the run position. It finally got so bad no gas was getting through in either position.

Mine came with aftermarket on it and ran terrible flooding badly, previous owner said he drilled out the jets because it ran too lean, but he went too far, so i finally found a used OEM and rebuilt it with an ALL BALLS kit supposedly a good kit, but after thinking about it i wish i would have gotten the OEM jets and needle but i needed the gaskets also and went with the kit. A lot of people i know have not had any problems with aftermarket carbs, but i did. Maybe im a perfectionist when it comes to idling and running, expect more than they can supply. The aftermarket carbs fit numerous models spanning numerous years, and the original Kei-Hin for your model was only on it for 2 years 04 and 05 and then Suzuki changed it.

There is another issue with the Eiger that could cause running problems, they were bad for the magnets coming unglued from the flywheel and moving around they dont relly go anywhere but are constantly moving which will also affect running, the new flywheel replacement has internal magnets, i had to replace my flywheel because of this.

All that being said the Eiger is a great machine i have 2 of them, it is a Beast will pull more weight than the Big Bear or the Foreman but the King Quad was the flagship and got all the publicity, the Eiger fell into its shadow and was only produced 4 years. I have often heard it referred to as the King Quads ugly sister, i like it because it looked different. 

[alexwv1863]

I finally fixed the carb issue. Put a letter jet in as suggested. Also, had to find a cap that fit the vacuum port. It wouldn't idle unless that port had zero air getting into it. I ran into a whole other issue that I'm going to make a thread on. It's got me a little scared lol

[shorty]

Keep up the good work 

[alexwv1863]

20 hours ago, alexwv1863 said:

I finally fixed the carb issue. Put a bigger jet in as suggested. Also, had to find a cap that fit the vacuum port. It wouldn't idle unless that port had zero air getting into it. I ran into a whole other issue that I'm going to make a thread on. It's got me a little scared lol