Bringing Max IV back to life- lack of power issue

I purchased a Max IV about a week ago and have been working hard to get it back running well. The previous owner let it sit a year and I've done the following- Removed and replaced fuel with ethanol free fuel, put seafoam in the fuel, replaced the fuel filter, replaced both plugs, replaced the fuel pump, cleaned the interior of the carburetor (it had yellowish film on the bottom), adjusted the idle and tightened the chains. The clutch belt looks like it working fine, climbs to the top of the top wheel and moves into a tighter radius when the upper moves to a larger radius.

Here's the issue, on flat ground the power is fine, goes about as fast as I'd like it to but as soon as I hit a slight incline (and I hit a ton of those short very steep hills where I hunt) it bogs down and will sometimes die if I don't apply a little choke, and sometimes it dies anyway. It slows to a crawl, I could walk faster that this can get up those hills. I have the B&S Vanguard 18hp engine in it. Am I expecting too much from this? Should I be able to power up hills or is this normal behavior? Any hints as to what to try next would be greatly appreciated.

Needing to apply choke points to a fuel problem. Take the jet(s) out of your carb and clean it, blow some carb cleaner through all the holes in the carb.

I did all of that when I cleaned out the carb today, no change in lack of power.

Here's a thought I had, the fuel line comes out of the body where the upper and lower body meet, the fuel line is long and hangs down almost to the bottom where the fuel filter is located, then the fuel line climbs up a couple feet to where the fuel pump is located. It that too much distance uphill for the standard pump to pump?

What kind of motor do you have, and what fuel pump? I doubt that your pump is having issues, or youd be having more trouble than just climbing hills. Are your clutches working?

B&S Vanguard 18hp. Fuel pump is a brand new B&S one. As far as the clutches working properly, They seem to be, but hard for me to tell as I'm not sure what to look for other then the band expanding and contracting with throttle applied. Would increasing the tightness make sense? It seemed tight when I checked it, but it could be tightened. If that is the suggestion, please let me know how to tighten it as all I've seen is to shim the engine to increase the distance, and I guess that's the only way right?

If you see the primary clutch close in on the belt, and the secondary open up, then it's working. We'll assume it's got the right belt length and tension. Re clean your carb, its easy, won't hurt, and could well be your problem. Currently, can you run the machine at WOT on a reasonably flat surface? Does choking the motor at WOT help or hurt? It'll be an odd situation if it only happens at the base of a hill.

if possible, have the engine cover off the machine and try going up one of the hills. if it's only going as fast as you can walk...have someone looking in on the clutches and belt while you climb, making sure they are functioning properly under load. maybe that will reveal an issue . johnboy va.

When working properly the engine sound should remain constant. Assuming WOT when you hit a hill the machine should slow down but the engine should not bog or reduce in RPM since the gearing changes on the clutch belt so as to maintain power. IDK without seeing a max IV hill climb how fast it should move but it should not stall or even sound slower. This machine should spin all 6 tires and dig into the ground if forward progress is not possible IE a hill too steep to climb. At least I think it should, not sure what the torque limit on a 18HP Max IV is , but my machines with less HP will lose traction before they lose power.

I've been watching videos of max IV climbing hills and mine is nothing like that , engine bogs down and wants to die. It's a bad feeling to be climbing a hill and have it die and start rolling backwards. LOL. On flat ground it's faster but still not running smoothly. I'll dig into the carburetor more and see if it helps.

Something I've found especially with the Briggs on climbs. The fuel pickup in the bowl is in the front and if you get enough angle you cant pickup anymore fuel. Your right its not a good feeling when it dies and you have no option but to roll back down. As for bogging down I've found switching to a red secondary spring greatly helps this. What size tires are you running on your Max IV as this can effect the bogging down.

This sounds like the perpetual issue with cheap mechanical fuel pumps when you also factor in fuel lines going above the fuel tank especially when going up hill. I would try a low pressure electric fuel pump (1-3 psi) which are relatively inexpensive. Tie it into the ignition switch so that it only works when the ignition is on. It won't hurt to also keep the mechanical fuel pump connected. Between the mechanical and the electric pump you should have a good supply of fuel.

I did the above trick on an old classic vehicle and the truck runs so well now it almost seems like it is fuel injected.

What's the compression on the cylinders? The little B&S motors will sometimes wear themselves out quickly when they are abused, and that may have been caused by the prior owner's lack on maintenance.

I have the small 21" tires to fit the tracks that are not installed. Haven't done a compression test yet. I'll grab a low pressure fuel pump and see if that happens. I've heard lots of talk about the red spring. I'll get that ordered.

I have the red spring kit on all my t20 equipped machines, its the best way to keep the machine in the low power band, you will lose some on the top speed though but it's marginal.
Your machine should run well with the small tires and 18hp motor. The 18 is as small an engine that should be in a Max 4 though. If you upgrade ever, I would switch to a Kohler.

Where's the best place to get a red spring?

Just ordered a red spring from max6x6

Verify that you have spark to both plugs

Spent some time today, before eating too much, and found the drive belt was pretty loose (two inches of movement) so I shimmed the engine and brought it to an inch of deflection. What's the proper belt width? This one looks skinny, (measured just over an inch wide)like has some room on each side of the top clutch when engine is off. I reduced the droop in the fuel line and then was messing with the plugs to see if they were both working as suggested and the rear hood shocked me then I noticed is was cracked pretty bad. I fixed that and it seems to be running much smoother now. Taking it hunting tomorrow and that will be the test if I've actually made some headway. Fingers crossed!

Your issue with "running fine" on level ground but no power up hill sounded like my recent problem where I discovered one plug wire was "burnt" and no spark. Also could be the belt as well. I am not sure on the MAX IV, but on the MAX II, the belt should be 1 3/16 in wide. Please note, I have spoken with a MAX technician and he states that while the specs call for 1 3/16" width, most belts shipped are undersized, closer 1 2/16". But 1" does sound way too narrow. Hopefully someone with a MAX IV will chime in with correct belt replacement number and correct width.

Great input and yes the belt size and part number for the proper one would be great as I'd like to have a spare handy.

I am not sure if this helps, but from MAX6X6 Site....would be better knowing the year of your machine, clutch type or getting input from another MAX IV owner.
MAX Belt Quick Reference Sheet

https://drive.google.com/file/d/0B6d...VSeG1qakE/view

Well well.... Took it out hunting and it sounded a slight bit different but really no improvement at all. So, took it to a good buddy of mine who wrenches for a living and he tore it down, finding a bent and out of position cam rod that had been in there mucking about. Compression test revealed that cylinder was toast.... Ripped out that engine and buying a new one tomorrow to throw it, 22hp so.that will be nice. Found a rear sprocket on main chain out of alignment and teeth chewed away, ordering some.new parts... Hopefully this will be the beginning of better times for this Max IV.

Hi, I'm in the end struggles of and engine swap from a B&S Vanguard 18hp to a Predator 22hp and everything has gone really smooth until we got to the wiring,.. we're stumped.
Lots of wires that we can't identify what they are are how they are wired in, like the solenoid green/yellow wires that come from near the carb..

I know quite a few of you have done this conversion and I'd really appreciate some guidance on how to wire this thing.

Notes- the holes mounting the engine to the engine stand matched up, putting the clutches at proper distance and alignment. The muffler points forward but we made a pipe to run it to the rear.

So close! Thanks for the help

The fuel solenoid wires have to have 12v applied to open it for fuel flow. I removed mine, just unscrew the solenoid remove needle throw away and reinstall solenoid. No 12V required.

Thanks for the email with the diagram Teddotson!

I am back in business, in a HUGE way... this thing is a beast. The only issue we ran into was the wiring between the Max IV and the Predator, everything else was simple and direct fit although the muffler needed to be modified to point backwards. This thing is now very fast and climbs hills with hour people without issue. Just need to eventually fix a bent axle and replace all the chains and sprockets and this will be perfect.

Great to hear! take some after pics and videos!

What pic/vid host are you guys using to link pics to here? I used photobucket and it doesn't show but an ad for hosting... that site has gone downhill so much with all the pop up adverts..

I just post videos to Youtube, and link.

https://vimeo.com/245122706

Cool.

I use youtube on videos, and post photos in the gallery here on the site.

Here's a vid, she's alive and I put the tracks on. Loving it. https://photos.google.com/share/AF1Q...RFZUVpZjRwM0FB

Awesome job, the machine looks great man! You really got on this project.

Thanks! So... I took it out today and was 'moderately' easy on it but I romped on it going up a hill that has been my nemesis with this machine since day one. Once up top I heard a popping and stopped and found the right rear outside bearing has bitten the dust. No, I don't have bearing extensions on it and the bearings all look like crap. SO.. I've read that Buffalo Bearing is the place to get replacement bearings for it, but where do I find the extensions? I've looked at all the places I know of and haven't found any. On Max6x6 the bearing cage page doesn't even list them. Richard's Relics doesn't list prices and is an annoying page to sift through.

Another question- I have a bent front right axle, my serial number is 10682, and Max6x6 lists one from 10573 and earlier that looks to match, although mine is newer. Here's a pic of the inside end of the axle-
interior and exterior shots of axle from Mav IV #10682 - Amphibious ATV Pictures

and here's one showing the bearing that went bad-
interior and exterior shots of axle from Mav IV #10682 - Amphibious ATV Pictures

What I'm looking to do is replace the bearings when I mount extensions, appreciate the help!

This is the axle that appears, to my untrained eye, to be what I need but the build numbers are off.. mine is slightly newer than indicated on what it will fit.
15516 AXLE, SOLID SN# 10573 & EARLIER - MAX IV

You can hear the bearings go when I got excited about climbing that damn hill... https://vimeo.com/246205011

Just ordered a full set of bearing for all axles from Buffalo Bearing. They were very helpful, but needed some measurements that I luckily had pulled prior to calling them. $145 for all inside/outside (triple seal on outside) bearings. 62mm. The Part numbers were HC206-20 R3 ($12.78 ea) for outside bearing and SA206-20 ($11.40) for the inside bearing.

She's all rebuild with all new parts... took it out today for the first shake down and it did great. Now off to build a custom cage for it.
An Error Has Occurred! click link for pic

Did you ever solve this problem? My max 2 does this while climbing hills as well. It will have plenty of power at first and then bogg down until I hit flat ground again. I'm assuming it has something to do with the float level.