New guy needing help with engine swap decision - BuggyMasters.Com - An On Line Mini Buggy Forum and Go Kart Forum

georgia mike · #1 09-30-2012, 08:39 PM

Hey guys, I've been going over the site for a day or so, and have searched and searched, but couldn't find any info that pertains to exactly what I'm thinking of doing.

What I have is an old Yerf Dog go cart (I think it's called a Spiderbox). I bought it for my daughter as a project we could tinker with, but since she's only 6, I think I'm going to be doing all the work while she jumps in and out asking "can I ride it yet??"

Anyway, it has the usual 150cc GY-6 style engine on it, but the final drive has been butchered to death by the PO. When I went to look at it, I noticed a complete lack of any lube at all in the gearbox. He was insistant that the final drive wasn't supposed to have oil in it because it had never had any, and it was that way when he bought it, but then he couldn't explain why the bearings had failed in spectacular fashion.

So that being said, I got the buggy back to my shop and got the engine running, but the final drive, I believe, is toast due to his ham-fisted attempts to remove the bearings. That, coupled with the fact that I have a heavy disdain for reassembling things that others have taken apart (and have most likely lost a few important parts), I am really leaning toward yanking this engine and swapping to the HF 6.5 HP Predator engine onto the buggy. It's either that, or buy a used mystery engine that may be no better than what I have, or buy a new GY-6 style engine on eBay for ~$400 shipped. Electric start and lights aren't a major concern for us. I'd just like to make it reliable and rideable for her.

I understand that unless I fab up something, I'll be losing the CVT, and will have to make due with a traditional style centrifugal clutch. Top speed isn't a huge concern because she's only 6 and I'd rather keep it slow for now, and possibly play with sprocket sizes later on if needed. I'd rather lean toward low end torque than higher-RPM horsepower anyway.

I'm a machinist, so fabbing up a jackshaft and welding up a new engine cradle looks like it would be fairly easy and straightforward enough. Has anyone else here ever attempted this, or better yet, successfully done it?

x-bird · #2 09-30-2012, 11:57 PM

I went the opposite route and moved from a lawnmower engine to the gy6. Before you do t he reverse, You may want to look up BMI Karts website and give them a call. They bought up the assets of Yerf and have been selling off all the leftover parts along with used parts from spiderboxes that were recalled--among those were complete engines and rear end assemblies and some engines with some of the components missing. by the time you do the clone motor and related parts to make it all work, you'll be in just as deep. as buying a complete new gy6, if not more so.

georgia mike · #3 10-01-2012, 11:12 AM

Thanks for the tip. I saw their complete engines and sent them an email for a shipping quote.

georgia mike · #4 10-01-2012, 08:25 PM

I got a reply from them and shipping is way crazy, but overall the cost for what I'd be getting doesn't seem so bad if it's all as good as they make it out to be. These engines are from "returned" or "recalled" karts that had the front end issues. So again, I'd be buying a mystery engine, but they say they test them out before sending them out. What that means, well i guess that's up for speculation. It could be a new engine from a dealership's leftover stock, or it could be one from a buggy that was sold and left out in the rain for the last 10 years.

I did also find another alternative over on the Buggy Depot website. It doesn't say whether it's a completely new unit, or rebuilt, but with shipping I'm sure it will be in the same price range as the setup from BMI.

With me being a total newbie with karts, I'll ask what would you guys do? Who would you trust more with your money? I've not read anything bad about Buggy Depot, but have read mixed reviews about BMI.

x-bird · #5 10-01-2012, 10:33 PM

so far i haven't had any negative issues with either company i'vebought a littel off BD and a lot from BMI. Most forums members who've bought the recalled kart engines from BMI have said that they were in as good or better condition than expected. given that you only need the transmission components, you could probably snag one of the incomplete ones that have had some parts removed for the lower price. as you note, the shipping is the real cost. Anther alternative is to consider buying an engine with the external reverse gearbox--you'd have to buy the cable and shifter, but it's a nice feature to have.

georgia mike · #6 10-02-2012, 08:45 AM

Reverse would be nice, but when I was a kid we never had reverse on any karts we had and we got along just fine. Heck, we never had suspension either, so she'll still be one up over what we had as kids.

Thanks for the advice. As for buying an incomplete unit, I believe at this point I'd be better off buying a complete engine and start from there, rather than fix the transmission and then chase other problems with this engine. I'm fairly certain it hasn't been cared for as well as I'd like to think it should have been. Part of the CVT has been damaged by the PO trying to remove it, plus with the very real possibility there will be missing pieces and parts, I think a whole engine assembly will be the way to go. Plus that'll give me more time to focus on other things with the buggy.

bear · #7 10-02-2012, 04:10 PM

Tinkering is half the fun! welcome abaord!

satoys · #8 10-02-2012, 07:16 PM

Quote:

Originally Posted by x-bird

so far i haven't had any negative issues with either company i'vebought a littel off BD and a lot from BMI. Most forums members who've bought the recalled kart engines from BMI have said that they were in as good or better condition than expected. given that you only need the transmission components, you could probably snag one of the incomplete ones that have had some parts removed for the lower price. as you note, the shipping is the real cost. Anther alternative is to consider buying an engine with the external reverse gearbox--you'd have to buy the cable and shifter, but it's a nice feature to have.

I bought a used BMI engine/swingarm delivered for 500$, moved the axle and tires over, had it running in a few hours. I later bought a engine only (from allbmi, alternate ebay name for stevebmi, same as BMI) really cheap, have it running in the old swingarm as my spare. so 2 for 2... bought lots of other stuff from bmi as well.
I've done some of the HF $99 on other yerfs (3203), they work fine on them. I'm more of a "replacer", not a "fabber" tho...

georgia mike · #9 10-05-2012, 09:14 PM

Thanks for your input. That's what I was looking for; first hand experience. I was worried that with the engine being used, and sitting for years, that there may be issues with the carbs and whatnot. I'll keep you all posted on what I decide to do. I may be going to look at another buggy that i may be able to get for less than what a replacement engine will cost.

bandit65 · #10 10-13-2012, 12:12 PM

Quote:

Originally Posted by georgia mike

Reverse would be nice, but when I was a kid we never had reverse on any karts we had and we got along just fine. Heck, we never had suspension either, so she'll still be one up over what we had as kids.

Yea, we didn't have seat belts or helmets either and are only slightly brain damaged.