Yamaha G2 Big Block

[br1ev8]

Thought I'd share my most recent build...maybe it'll assist someone else in the future. I'm near finished now, but I'll catch you up on the progress with a few pics along the way..shoulda taken more in hindsight, though.

My last build was a Marathon with a Yamaha Warrior 350 engine / drivetrain /suspension swap.



I posted the build here, but I think most of the pics' links are broken, as it's a few years old. I still rip on it, but my wife didn't like having to shift, as it's a manual trans. So, I figured I'd do a big blocked cart for her. I hit the ads and bought an EZGO medalist electric roller for $100, then searched for a 4 stroke gas rear end with plans to do a big block has conversion. The day after I bought that EZGO, I saw an ad for a Yamaha G2 for $400 just posted and I was lucky to be the first to contact the guy. So I picked it up and sold the EZGO roller a few days later.



The G2 was rough, no doubt, but it was complete, though somewhat pieced together...eith the unknown model top and rear seat. It also had quite a bit of rust. So I stripped it down to address the issues.





The biggest problem was the left side main frame rail. It was rusted through the bottom in numerous places. So, I cut the rotten section of round tube frame and spliced in a section of 1x2 11 gauge steel tube...a piece I had leftover from when I did the exact repair on my EZGO build.



I finished up cleaning and derusting the frame, then painted it with a quart of rust-oleum with hardener added (no pics, sry). Then, moved to the body...the old paint removal sucked to say the least. Numerous coats were put on over the years and it was latex, which did not come off easy, but I got it done with multiple applications of paint remover and paint scraping. Then I painted it red with more rust-oleum with hardener added, which came out nice and shiny.



More to come later.

[TheNewGuy]

Nice, I'll be watching.

[br1ev8]

I reassembled it all, added some diamond plate to the rockers, recovered the seats, new steering wheel, cut/welded the front roof struts to fit the angle of the nose if the cart and new flooring.







The cart was sold with the original engine, but didn't run. I sourced an oem mikuni carb to replace the Chinese "Mokini" that was on it, put new brushes on the starter generator, new rollers for the drive clutch and a new driven clutch. It ran pretty decent power wise, but the governor was bypassed, so it would hit the rev limiter and backfire like a shotgun going off. It also had an unknown vibration issue going on, and the new driven clutch decided to go after little use. So, I said the heck with it and did some upgrades.

I ordered a Lifan 420 via home depot and it got delivered by UPS somewhat typical UPS fashion (half busted out of the box when dropped in my porch) and found the oil fill casting was busted. So I returned it and bought a Duromax 440 with electric start instead. My plan was to actually use the starter gen on it, but decided against it. I've got small kids that are a bit rambunctious, and I didn't like the possibility of having the key accidentally on and them stepping on the gas pedal and taking off if I wasn't on the cart. So I just used the motor's electric start and removed the factory cart wiring. I also bought a Comet 780 and a new driven clutch.
The cart had a homemade lift kit on it, which gave the motor a little rearward lean, so I built the motor mount plate to counter it (higher in the rear and dropped in the front. I didn't take pics of this, unfortunately. I'm actually missing a lot of pics I should've taken, but can take more if someone would like to see something in particular that could assist them with their build.

So, moving (quite a bit) ahead, I got the motor mounted using new rubber mounts, I had to deal with the typical issues on G2s and G9s with carb clearance to the right rear frame / shock area and how to run the exhaust. A couple shots of the motor installed (again, jumping juuust a little ahead in the process)...

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[br1ev8]

I had to figure out how to mount an air filter in the small space between the carb and the frame, so I made this weird looking manifold out of and exhaust reducer and scrap steel. I cut out the funky pattern to match the inlet of the carb with it's various ports. This allows me to route intake piping to the front of the motor where I mounted the air box and filter.









I didn't want to have to rejet the carb, so I hoped it would flow close to stock and it was low profile so it fit the space perfectly with enough room still to r&r without having to move the motor over. I wanted to use the Duromax's stock filter and airbox for the same reasons of not rejetting, so I made a mount / adapter thing to mount the airbox to which I installed in front of the motor.













Linking the 2 (manifold and airbox adapter / mount thing is a section of thick, flexible poly/plastic unknown material type tube that is around 1.5 inch in diameter. It is high heat stuff that is intended for spa /jacuzzi water plumbing I found at Ace Hardware. It worked perfectly. I got lucky and the engine runs just like stock, no pops, hiccups, etc...starts idles and revs like nothing was touched.

[slonomo]

Cool build.

Very cool solution to the air intake issue. I've done a few Yamaha's and that rear frame section just really gets in the way. If you could mass produce those you might sell a bunch

[br1ev8]

Thanks Slo. If I had a jig of some sort, it would be totally doable, but I did the cut/fit, cut/fit process... tedious, but very cheap if you've got the time and resources.

Regarding fuel supply, I read a post SHO305 made regarding tapping into the rocker cover for the fuel pump's pulse line. It has worked flawlessly. I used the stock G2 pump, just moved it to a location closer to the carb...made a simple bracket to mount it on top of the motor where the engine's stock fuel tank used to be..u can see it in a few of the above pics.

For the exhaust, I couldn't use the engine's stock manifold, it wouldn't clear the cart's upper frame cross member when the suspension squatted. So I made a header that would direct exhaust rear and down. I used double stacked 3/8" steel plate for the flange and steel pipe / exhaust tube bend scrap I had from another project. I coupled that to a piece of exhaust flex pipe from Autozone, then clamped it to a Walker car muffler, which I suspended with exhaust hangers hooked to mounts welded to the swingarm. This way the exhaust moves with the motor, as everything is mounted to the swingarm...the flex pipe isn't necessarily even needed, since the muffler will move around on the rubber hangers as needed when the motor moves on its rubber motor mounts, but the flex pipe was an extra safeguard.

[br1ev8]

Since I removed the s/g, I needed charging capabilities, so I installed an alternator. It's a mini Denso 1 wire alternator rated at 35 amps... available all over ebay and Amazon for around $60. It's small, which fits the bill perfectly. I mounted it in the area where the factory airbox used to be. Since most alternators are designed to spin clockwise, I mounted it inverse of the motor, so the pulley faces the motor. Using scrap metal / materials of course, I made a bracket, adjustable for belt tension with a long threaded bolt. The cross piece is also adjustable for proper belt alignment. It's a bit ugly, but gets er done.
It was advertised as a "1 wire", but that wasn't the case unfortunately. I could not get it to "excite" / charge no matter the trick I used. Through some reading, I found it probably wasn't a 1 wire and would need the 2 spade connectors wired up to keyed power in order to start charging. So, I ran the 2 spade connectors in the 2 prong socket in the back of the alternator to keyed power, with 1 of them (left side prong) having a 100k ohm resistor soldered inline. This was the ticket and now charges at a steady 14.5 volts directly from idle. It's enough amps to power whatever is needed, really. I also couldn't detect any engine power loss from spinning the alternator vs not, despite what I read could be the case.
Of course in order to have "keyed power" to the alternator, I had to get a keyed switch that had an accessory circuit and one that would also ground out the engine coil to kill the engine when I turned the key to off, so I found a 5 prong keyed switch at AutoZone, that had exactly what I needed for like $14...off/accessory/start. You could alternatively wire the alternator to a separate toggle switch to give it the switched power from the battery, but I wanted to keep it clean and simple...turn the key and go...turn off and done.

[br1ev8]

These clone motors don't like to start without the choke, even when warmed up...i guess if I jetted it richer, it would crank without it, but I'd rather it not be too rich. I had to figure out how to run a cable and a choke knob or lever somehow. So, I made a lever type actuator mounted behind the seat wall that connected to a shaft that went throigh the wall and mounted a golf ball to it...pull out for choke on, in for choke off. Not the best pic of the actuator.






I also made a ground distribution block and bought a power distribution block...I didn't want to have a bunch of cables connected to the battery.



The original fuel inlet door didn't come with the cart, so I made one out of diamond plate aluminum...with a magnetic latch (cabinet door latch from Lowes)...used diamond plate to match the section of diamond plate I used across the top, rear of the body to cover up a massive hole cut out of it at some point in it's previous life.






Made a cup holder out of an old cutting board as well

[br1ev8]

Then, decided to build a brush guard. I bought a harbor freight pipe bender off facebook and then some 1 inch pipe and went to work. After some modifications to the bender, I was real happy with the beds it made...near perfect by my standards

[TheNewGuy]

You have skills ! Very nice work...Great looking cart