238cc Tillotson race motor build

[Flyinhillbilly]

I’ve been putting off building this because I’ve been waiting on a head from a guy that I’m pretty sure has screwed me out of my $650 that I paid him six months ago. I’m trying to resolve that situation one more time, but I’ve decided to move on with the build since my daughter had to race with a motor I built from spare parts last weekend. She was up to 5th when her chain broke, but I know she can do a lot better if I turn up the woopow, so I’m turning it up to 11. She has a great deal of natural talent, and it’s time that I put her on something that doesn’t rely so much on momentum.

The foundation is a studded 2.835 Tillotson block, the rotating assembly consists of a 2.3 ARC super alloy stroker crank, 3.525 ARC billet connecting rod, and a Wiseco 2 ring forged piston that comes in at a .640 compression height. The cam is yet to be determined, and instead of the fully welded 34mm port Warhead that I was going to put on it i’ll Use the 96cfm Tillotson 32/28 head that Laid Back Racing built for me. The carb will be a 28mm flat slide on a mixture of 25% nitromethane and 75% VP M5. The flywheel will be ARC, and the coil will be genuine Honda. This will be topped by 1.3 rockers, and chromemoly pushrods, and it’ll all be closed up with an ARC billet side cover, and a custom billet valve cover from Mr. Valve cover.

I’ll post pics as I build it, and let you guys know how it runs. I’m hoping it’ll be pretty fast.

In this first set of pics, you can see that I’m going to have to clearance the block a little on the top side of the bore for the rod, it’s a little too close for my liking, you can also see the Cometic head gasket, studded Tillotson block, and all of that shiny ARC and Wiseco goodness. I threw a pic of the head in because I like it so much.
I’ll post more pics as I progess.

 

[BigWes]

So she got up to 5th with your spare parts build before it shredded the chain... I'm assuming that's the one you put in the video right?

Don't let this dude fool you guys...his parts engines would eat most our good engines alive!!! That thing sounded wicked...other people's parts!!! Lol!!!

I know it was disappointing for her to have a chain fail. But she must know she has an awesome dad in her corner!

I can't wait to see how this engine builds out!

 

[Karts of Kaos]

are the valves in the head the same size? i have never seen that before.

 

[Flyinhillbilly]

So she got up to 5th with your spare parts build before it shredded the chain... I'm assuming that's the one you put in the video right?

Don't let this dude fool you guys...his parts engines would eat most our good engines alive!!! That thing sounded wicked...other people's parts!!! Lol!!!

I know it was disappointing for her to have a chain fail. But she must know she has an awesome dad in her corner!

I can't wait to see how this engine builds out!

That’s the one, it ran pretty good for what it was. This one should be way faster.

---------- Post added at 09:04 PM ---------- Previous post was at 09:03 PM ----------

are the valves in the head the same size? i have never seen that before.

It has a 32mm intake and a 28mm exhaust valve set.
That head works crazy good.

 

[karl]

I’ve been putting off building this because I’ve been waiting on a head from a guy that I’m pretty sure has screwed me

That blows, but I like what I see.

Especially the "trimmed" sidecover, might need to make me one of them, super helpful for checking clearance !

 

[Flyinhillbilly]

That blows, but I like what I see.

Especially the "trimmed" sidecover, might need to make me one of them, super helpful for checking clearance !

That thing is invaluable if you’re going very big with anything in those engines. You run out of room fast.

 

[BigWes]

That thing is invaluable if you’re going very big with anything in those engines. You run out of room fast.

Did you make that one or buy it? Looks great.

 

[Flyinhillbilly]

Did you make that one or buy it? Looks great.

I made it from an old side cover that the chain guard bolts had stripped in. It’s nothing to sophisticated, I just kind of trimmed it along the internal bracing and left the two dowel holes for alignment.

 

[Flyinhillbilly]

We need more clearance Clarence.
I took the block to work today and used some of my high falootin’ tools to clearance it where the rod was hitting. Although the rod no longer hits, I still don’t have the clearance that I like to see in that area.

 

[BigWes]

We need more clearance Clarence.
I took the block to work today and used some of my high falootin’ tools to clearance it where the rod was hitting. Although the rod no longer hits, I still don’t have the clearance that I like to see in that area.

That's too close. Your cut is clean and tidy. My aircraft mechanic OCD approves!

Are you going to radius a bit off the corner of the rod?

 

[Flyinhillbilly]

That's too close. Your cut is clean and tidy. My aircraft mechanic OCD approves!

Are you going to radius a bit off the corner of the rod?

Thank you.
I’m going to take a little more off the block, it extra thick right there.

 

[Flyinhillbilly]

I swiped my daughters kart last night and took it racing with a couple of buddies, and the spare parts motor got it done, even if just barely.
Hopefully I’ll have this new one together before this weekends race at our regular track.

 

[Flyinhillbilly]

Digging hard into the corner in practice.
I didn’t have my fire suit on, shorts and a t shirt aren’t really appropriate safety equipment, but fortunately I didn’t need any.

 

[BigWes]

Cool

 

[Budget GoKart]

Imagine how fast you could go if this engine was geared super fast on a mini bike

 

[Flyinhillbilly]

Imagine how fast you could go if this engine was geared super fast on a mini bike

I actually started out with mini bikes and transitioned into karts.
I doubt that I would want to ride a mini bike as fast as it would go with one of these engines.

 

[BigWes]

Oh no, I seen some vids off the board...those crazy Latinos and black guys in the city running their bikes down back alleys over 100 mph wearing shorts and flip-flops and their hats on backwards. I'm surprised they ain't killed themselves. Some of those guys have awesome bikes. Some have awesome engines on sketchy frames. Either way. Those mini bikes don't look very stable too me. I'll stick to my Harley. It's comfortable and has antilock brakes!

 

[Flyinhillbilly]

Oh no, I seen some vids off the board...those crazy Latinos and black guys in the city running their bikes down back alleys over 100 mph wearing shorts and flip-flops and their hats on backwards. I'm surprised they ain't killed themselves. Some of those guys have awesome bikes. Some have awesome engines on sketchy frames. Either way. Those mini bikes don't look very stable too me. I'll stick to my Harley. It's comfortable and has antilock brakes!

Yeah, shorts and a t shirt with a helmet and neck brace is a whole different situation than 100mph on pavement on a mini bike.
I used to 50+ on my mini with no gear at all, but I’m not as dumb as I once was.

 

[Flyinhillbilly]

Well, it looks like the spare parts motor gets raced again this weekend since I’m not going to have a cam in time. I’m going with a custom ground tool steel billet cam, and since that’s not on anyone’s shelves, I have to wait. It’ll be worth it though.
I set out to make this a no compromise engine, so if it puts it off one more race, then so be it.

 

[BigWes]

So be it!!! I'm still waiting on a delivery truck myself...