Honda ATV Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter · #1 ·
Yeah, I know about the Goki kits, but they're out of business and the parts are hard to get and expensive. I'm wondering if anyone has tried using factory (300 Fourtrax, 300ex, etc) engine parts to create an electric start version of a 350x.

I've got a 350x project that's been sitting around for a while, time to either get going on it or sell it. I'm 55, getting a little old to be jumping up and down on a kick starter all the time. I've also got a 300 Fourtrax that has electric start (and kick start backup), the engines are basically the same basic design, with some minor differences (the Fourtrax is shaft drive, and has the 90 degree bevel drive output shaft instead of a splined shaft for a chain sprocket), but it sure looks like I could use the left side outer case section from a Fourtrax 300 or 300ex engine on the 350x case to add the factory starter drive unit, plus a flywheel with a ring gear. Anyone try this? Are there any major reasons why the parts can't be mixed and matched? I know well how modular Honda engines are, I've built 125's, 185/200m/200x, etc.
 

·
Registered
Joined
·
307 Posts
yes i have. You can use a 300ex motor. It fits in but does not bolt in. There is a differance. It's not hard but I have custom spacers needed to do it 3 spacers will be different. 400ex also works, however i can not confirm as I have no 400ex motors. It's not super easy however as there is no room on the 350x frame but if you follow my write up it is simple. I placed 300ex stuff in locations just as they are on a 300ex.....if you have 2007-2009 trx300ex/300x its a tad easier as the reverse cdi is included into the normal cdi unit. I'd be suprize if anyone else on here can even help you on this topic. I'm currently build my daughter a 300ex from 350x spares.

I ended up passing mine off to a kid who was going to finished it. I had too many atvs i needed to finish. in 20 years hearing about this mod i have never seen anyone do a write up or photos so I said i'd do it.

 

·
Registered
Joined
·
12 Posts
Discussion Starter · #3 ·
yes i have. You can use a 300ex motor. It fits in but does not bolt in. There is a differance. It's not hard but I have custom spacers needed to do it 3 spacers will be different. 400ex also works, however i can not confirm as I have no 400ex motors. It's not super easy however as there is no room on the 350x frame but if you follow my write up it is simple. I placed 300ex stuff in locations just as they are on a 300ex.....if you have 2007-2009 trx300ex/300x its a tad easier as the reverse cdi is included into the normal cdi unit. I'd be suprize if anyone else on here can even help you on this topic. I'm currently build my daughter a 300ex from 350x spares.

I ended up passing mine off to a kid who was going to finished it. I had too many atvs i needed to finish. in 20 years hearing about this mod i have never seen anyone do a write up or photos so I said i'd do it.


I thought about just swapping in a 300ex engine, but then I'd lose the kick start option and 6th gear. I'm hoping to use the case, internals, cylinder, and head of the 350x, but use the left side case cover of the 300ex engine that has the casting for the starter drive, along with a flywheel with ring gear from a 300ex so the starter gears can engage it.

That would give me a 350x engine with both electric start, the original kick start option, and the 6 gears of a 350x.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #5 ·
Isn’t a 250sx shaft drive? With electric starter drive in the left case cover, and kick start on the right? That would be just like a 300 fourtrax engine. Can’t use a shaft drive case in a 350x.

I’ve got two 350x engines sitting on the work table, and a running, driving 300 Fourtrax to compare them with. I’ll locate another starter drive unit from a 300ex, a 250sx, or a 300 Fourtrax, left case cover from a 300ex, and a flywheel with a starter drive ring gear and see if I can’t bolt them onto a 350x engine.
 

·
Registered
Joined
·
307 Posts
no a 250x was what the 300ex was from 1987-1992. kick start stroke 4 stroke, 300ex is electric start nearly 100% the same

I have 2 motors in parts for 300ex's literately every part to build one.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #7 ·
no a 250x was what the 300ex was from 1987-1992. kick start stroke 4 stroke, 300ex is electric start nearly 100% the same

I have 2 motors in parts for 300ex's literately every part to build one.
OK, that clears up some confusion on my part.

Is it possible to use the left case half of a 300ex engine (with the correct offset for the flywheel and electric starter drive area) with the right case half of a 350x (with the kick start drive) to end up with a 6 speed, electric AND kick start, manual clutch, chain drive output 350cc engine?
 
1 - 8 of 8 Posts
Top