35HP Kart Build

Status
Not open for further replies.

Stephen115

Member
Messages
382
Reaction score
1
Hello all,

A little history before I get into our current project. When I was 5 my father built a small go kart for the two of us. It had a Tecumseh 5hp engine, and at 5 years old it was a blast. Fast forward to high school and we built a shifter kart with a Yamaha YZ250. We eventually sold it and built a mini drag bike. Fast forward another 10 years and we've decided to tackle an even bigger project for ourselves.

While driving through my neighborhood I came across a Yerfdog chassis for $100. There is some work that needs to be done to the chassis, but that's where the fun comes in (See pictures below)

We initially were looking for a Briggs & Stratton Vanguard V-Twin as our power plant. I had come across a few local 18hp's, but was not crazy about the prices they were asking. My father eventually came across a 35hp that had been sitting outside for $75 bucks. The owner was unsure of the issue that put it there.

Since the MSRP on this engine was originally $2,400, we decided to take on the task of rebuilding it. (See pictures below)

Upon tear down we discovered that the engine had been ran low on oil, causing it to break a rod.

The crank appears to be in good condition, and the other rod and piston seem to be in good condition as well. We're currently researching new pistons and rods, and feel like we can revive this engine.

Thank you, and stay tuned!
 

Attachments

  • 20180803_175437.jpg
    20180803_175437.jpg
    497.7 KB · Views: 59
  • 20180804_094131.jpg
    20180804_094131.jpg
    516.6 KB · Views: 49
  • 20180817_220649.jpg
    20180817_220649.jpg
    191.1 KB · Views: 56
  • 20180825_175616.jpg
    20180825_175616.jpg
    460.7 KB · Views: 51
  • 20180825_182933.jpg
    20180825_182933.jpg
    494.5 KB · Views: 54
  • 20180826_144844.jpg
    20180826_144844.jpg
    467.9 KB · Views: 42

KartFab

Active member
Messages
3,381
Reaction score
9
Location
Dallas, TX
Since it was ran low on oil might want to see about buying two new pistons that are slightly oversize (e.g. .010" over) and takethe shortblock to a mower place or machine shop with those pistons. They can bore it over and get the proper piston to wall clearance and you should be on a good path. IIRC when i have had it done it has cost me $60 per bore. The lawn mower racers like those briggs vanguard engines so im sure you can get some performance parts as well if you are in the rebuild mode.
 

Stephen115

Member
Messages
382
Reaction score
1
Thanks everyone for the feedback!

My father is a C&C Machinist, and will be making a few parts for us. Last night we were able to tear down the motor completely. Unfortunately, we noticed that the cylinder wall of the broken rod, is cracked...

Thankfully my father has the experience, and we'll be replacing that sleeve. He's also going to port-and-polish the heads. It may be a couple weeks before I have a complete update for you guys, but I'll try to keep you entertained!

Thanks,
SJ
 

anderkart

Moderator
Messages
6,382
Reaction score
219
Location
Surprise Arizona USA
Keep in mind that some kart racers claim: That some of these Industrial Engines actually loose performance, when the intake ports are highly ported... They say to do whatever you want to the Exhaust side, but I've heard lots of pro racekart engine builders recommend only cleaning up the intake flashing imperfections a bit on mildly modified engines, and not fully porting & polishing the Intake side of the more commonly raced Industrial engines like the briggs 5hp flatheads...

I've never ran across anyone modding an engine like yours, but you could try researching that at some of the Mower-Racing forums :thumbsup:
 

Stephen115

Member
Messages
382
Reaction score
1
09/02/2018 - Update

Picked up a few parts for the kart this past week. Some parts I grabbed for future projects.

My father has begun working on the engine. We're looking at going .020 over and ordering new rods, pistons, pins, and a gasket set this week.

The starter is in good working conditions, which is surprising after sitting outside for a number of years. One last thing to buy.

Does anyone have a battery they recommend for this build? Autozone sells a $30 one, which seems kind of cheap. We'd like to get the smallest(size) we can, because space is going to be limited.

SJ
 

Attachments

  • IMG_20180901_220845.jpg
    IMG_20180901_220845.jpg
    273.5 KB · Views: 49
  • 20180815_205958.jpg
    20180815_205958.jpg
    153.1 KB · Views: 26
  • 20180815_205912.jpg
    20180815_205912.jpg
    190.6 KB · Views: 30

anderkart

Moderator
Messages
6,382
Reaction score
219
Location
Surprise Arizona USA
Does anyone have a battery they recommend for this build? Autozone sells a $30 one, which seems kind of cheap. We'd like to get the smallest(size) we can, because space is going to be limited.

SJ

I bought one of those $30 batterys from Autozone for an old riding mower I was selling. They have a super-low Cold Cranking Amp rating, It barely cranked over my 16hp. Briggs with a (fully charged) hydrometer reading of 1260. Mine didn't list the CCA rating, but I'll bet they're only like 60 or something...

I think the best smaller sized Battery's are made by a company named Odyssey. They make serveral smaller sized battery's with some serious CCA ratings.

I bought their PC925 model for my old racekart starter. It cranked my ultra-high compression/radical-cam'd/Methanol-fueled 357cc engine over super fast for 3 years. Then I swapped the same battery over to one of my riding mowers, where it lasted another 5 years no problem... The're pricey, but mine lasted a long long time...

Might find a lower price shopping around, but I bought my Odyssey from my local Battery Plus store: http://www.odysseybattery.com/extreme_battery_specs.aspx
 

Stephen115

Member
Messages
382
Reaction score
1
Pistons came in today! We've decided to go .020 since we've gone this far, and the price is the same as a Std. Bore.

I also grabbed a SuperStart battery from a friend. I do thank Anders for the Odessy tip though.

Next step is to get the rear end reinforced and welded up, and get the cylinders bored.

Also, I'll be making an order this week for more parts.

Stay tuned!
SJ


Sent from my SM-N960U using Tapatalk
 

Stephen115

Member
Messages
382
Reaction score
1
Update: 10/15/2018

The last few weeks have been really busy, but now I have sometime to provide you guys with an update. Most of this time has been spent waiting on parts.

First off, we ordered the metal for the sleeves from a metal supplier in Montana. It is 80-55-06 Ductile Iron As Cast. We should be pressing the sleeves in within the next couple of weeks.

I ordered new springs for the "mysterious" clutch that I received from Anderkart. I spoke with Noram, and narrowed it down to the Noram Titan and Mini-cup. Although they don't make a 1 1/8" slutch anymore, the parts still fit. We've gone from the green springs that are rated for 3600 rpm, to the light red springs that are rated at 1800 rpm. (Those are the engagement points.)

We have also completed the main components of the frame. We rebuilt the rear Yerfdog swing arm, and flipped it over to lower the frame. I'm envisioning an older indy/formula 1 race car if you will.

We also completed the suspension and gas tank mount. (I'll have to take a picture later.) I also went around and welded up any open spaces in the frame.

We had to ended up scraping the original Yerfdog axle. It was too rusted, and nearly impossible to get anything off. We cut the axle into pieces, which allowed us to get the drum brake and sprocket off. The right wheel and axle are seized together. We're going to have to press it out. New axle and bearings should be here this week.

I hope I'm still keeping you guys entertained. There's a lot more work that needs to be done.

Thank you!
SJ
 

Attachments

  • 20181013_095100.jpg
    20181013_095100.jpg
    608.9 KB · Views: 44
  • 20181011_183954.jpg
    20181011_183954.jpg
    442.3 KB · Views: 24
  • 20181008_171446.jpg
    20181008_171446.jpg
    271.9 KB · Views: 23

Stephen115

Member
Messages
382
Reaction score
1
Quick question for you all.

I'm starting to plan out the rear brake setup on the kart. The original Yerfdog frame came with a single drum brake on the axle. I'd like to ditch that because, well, its not going to stop this thing.

I've been looking around at some used motorcycle/atv rear calipers and have come across a lot of replacement calipers on Ebay. At around $25-30 I'm worried about the quality. I'm not looking to spend hundreds of dollars because we already have front brakes. Just need a little more stopping power in the rear. Any thoughts/recommendations?

Thank you all for your help!
SJ
 

Tpdingo

Member
Messages
903
Reaction score
1
Location
Bellmore, NY
Well depends on how fast you are going. Those brakes are usually much more powerful than the tires grip. If you just want pure bloody fast acceleration with a low gear ratio and incredibly sticky tires, the stock brakes should stop no problem. Consider hydraulic brake kit too. Just remember you are limited by your tire's grip, not your brake limit. Also note that when you are going 40-60mph and you try to stop, you can get those brake calipers to put out a lot of stopping power with a little something called ADRENALINE. It's power brakes for your go kart :thumbsup:
 
Status
Not open for further replies.
Top