I have an old Maxx 2 1976
, the 2 stroke motor is seized up and want to replace it with a 4 stroke. Any suggestions on what I should put in.
I have an old Maxx 2 1976
, the 2 stroke motor is seized up and want to replace it with a 4 stroke. Any suggestions on what I should put in.
depending on space for fitting it in ... some have been happy with the harbor freight predator motor . 23 h.p. i believe . can't beat a briggs vanguard 18 h.p. to 23 h.p. either . need to check clutch shaft size for matching also or buy new clutch . others will make good suggestions also, have fun ....johnboy va.
I agree with John, less one thing. Stay away from the B&S 23hp, in my opinion its not a reliable engine and is plagued with over heating, and fuel starvation issues.
I prefer Kohler and Honda engines in general and have several that are over twenty years old, and are still going strong.
Noel, do you still have the 23 in your Max II or did you replace it?Originally Posted by Noel Woods
I'm wondering if your machine had the air intake duct that was on the flat top machines? I had a 23 in the II I rode in Tennessee that seemed fine until I sucked some garbage into the bowl, it was a big hood body that I put a fan in the body to aid in cooling, it did not have the intake duct either. The guy who had it before me went 23, internal muffler with someone else after I had internal mufflered his 18 b&s and then he swamped. Just before I got it he also cut every other slat out of the hood similar to John boys for the large can muffler to dicipate some of the heat. It seemed to work good until the carb clogged one jet, I then rode it 2 hours like that.
I ended up with that machine after his passing, nephew Jon has the machine less the engine which I plan on putting in my II but I plan on a different carb, the briggs carb that is on it has a funky float jet system i believe is for stationary and i dont like it.
Last edited by ARGOJIM; 01-14-2022 at 11:07 AM.
My new beer holder spilled some on the trails - in it's hair and down it's throat.
Joe Camel never does that.
Advice is free, it's the application that costs.
Many 4 strokes will fit in the engine bay no problem.
However there are many things to consider such as,
Exhaust will probably need modifications
Engine mount will need modifications and or replacement/reengineering
New drive clutch
Engine will need a 1" or 1-1/8" straight keyed crankshaft
Throttle cable may need changing
Wiring will need adaption/alteration
Body will most likely need to be altered due to the deck height of the cargo area and the small hood access hole
For a few pointers, but not to scare you. 4 stroke is the way to go for trailability and reliability.
My new beer holder spilled some on the trails - in it's hair and down it's throat.
Joe Camel never does that.
Advice is free, it's the application that costs.
I just replaced the Tecumseh motor in my 1983 max ll with a 25hp Kohler command. This is my first machine. It was fairly straightforward. I had to modify the engine mounts,that wasn't no more than drilling some holes. I used my old clutches and had a friend to mill down the crankshaft. I believe that you can get the motor with a 1 inch shaft. Long story short. It wasn't too big a deal.
even my 21 h.p. b and s vanguard overheats some on long rides ..hot days . cooling fan took care of that . but you can't beat a kohler .. they run kooler . j.s.
The two machines that had B&S 23 engines went thru bilge fans, expanded metal coverings, and multiple fuel pumps. They each had air intake tubes vented to draw in cool air from the exterior of the machine. The worst offender was in an Argo 6x6 and I finally solved that problem by selling the machine. The Max had the other 23 B&S and I swapped it to a Kohler 23 and guess what, no problems whatsoever. I think the Briggs 14,16, 18, and 21 hp engines are fine, and I've owned and still own B&S big block motors and without issues. The two 23 hp motors I've owned and several other in friend's machines have all been dogs though.
I hope that others steer clear from this particular engine as well.
Tagging along on this topic, as I also have to replace my engine.
I keep seeing back-and-forth comments about Vanguard 23 engines. Works fine for some, overheats a little but fans can beat it for some, for others they quit like a dog and are destined to fail. Is it possible that all three of these are true? If I am a user in the reasonably cool but variably-sloped Pacific NW US, and I use a couple of six inch 80CFM radiator fans with temp control to pull air through the engine cavity, an external muffler, and a heat shield over the exhaust side of the engine, can I beat the heat?
I hope to believe good treatment is rewarded with good performance. I think I'd like to stick with the same since I learned a lot about this engine in rebuilding it, before its camshaft exploded. I now know about abating heat on various components (especially the fuel pump). I have plenty of spare parts to draw from the old engine, some of them new replacements. I plan to use a pair of 80CFM fans with temp control to switch between OFF/Series (half speed)/Parallel (full speed), in push-pull configuration straddling the engine. It's really hard to walk away from planning to buy a new Vanguard 23. Those who feel this invites more trouble, please try to convince me a Kohler swap is worth it. I'm open to consideration, but my short-term wallet and oil-stained service manual have got me sticking to Vanguard.
For my '94 Max II, I have to replace a 2012 Vanguard 23 that came to me dirt-caked, heat-fatigued heads, spraying oil from seals, poorly breathing and poorly pulling fuel, just in bad shape like they say. I would like to believe it was poor treatment and bad maintenance, and overworked disrespect that caused the reliability issues. As for the camshaft explosion, in sleuthing through the fragments, I think the connecting rod initially exploded from a bolt failure after my rebuild, although I'm pretty sure I followed assembly specs.
If I spend a few hundred more on a Kohler, I also have to replace the 1" I.D. keywayed Salsbury engine clutch with a larger bored one that fits the Kohler ($$how much), and I have to chop/reconfig the exhaust piping to reuse from Briggs. Depending on the new clutch profile and how the engine sits, I might have to switch my Dayco HP3003 belt for something else. What else would I have to do?
Noel Woods: What was the combined airflow CFM of the bilge fans, and what does "went through" mean, are they failing or wearable parts? For hot/melty fuel pumps, totally agree it needs special abatement and I saw it caused many behaviors that looked a lot like vapor lock.
Last edited by neveroddoreven; 01-18-2022 at 01:30 AM.
Hello:A
Sorry, I can't recall the cfm from the bilge fans. The 12" electric fan from Amazon was 1750 cfm though, and I used one of each on my Argo, and a 7" electric on the Max which was around 1100cfm. The fans were mounted on to an expanded metal hood to get the heat out faster. The bilge fans were mounted to pull cooler air through the body into the engine bay. I actually mounted the Argo with a three way switch to reverse the air flow in cold weather to get heat into the passenger area, but never needed to use this feature as the heat radiating through the firewall provided plenty if not too much heat, even on cold days.
I "went through" multiple fuel pumps for both the Max and Argo. Each machine melted the back side of the plastic fuel pumps which lead to having to replace several. I even mounted the fuel pumps from each machine in alternate locations to get more air flow, and rigged up "stand off brackets" to move the pumps away from hot metal surfaces, but that only prolonged the time it took to melt the replacement. I actually met a B&S field rep at a friend of mine's air cooled engine repair facility, the tech told me that these engines were not designed to me worked in the hull of an amphibious vehicle and that they were better suited for log splitters and ZTR mowers and such where they were not encased and restricted for airflow. In fact, he just shook his head while looking at my Argo and told me I would be lucky to get 100 hours before engine failure. I reported that back to Argo as this was a new machine at the time. I know both Argo and MuddOx (that were building Max at the time) got away from B&S engines and went with other motors only.
Many things may have changed with B&S since then. They may have designed better cooling into the 23hps. Knowing how most companies have a tendency to cut costs though, I sincerely doubt that Briggs has made a better 23hp since then.
If you go with the B&S 23, let us know what your findings are. For me, I learned my lesson and will not have another of those motors.
I wish you the best of luck and hope you don't have problems with the 23.
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