One million Questions. Ballsy 5 horse

[woncamaro]

Well, this is my first post and believe me, I have done my homework before posting. I still have some questions although. I am building an engine for a fun kart with no regulations and am attempting to make max hp on a budget without blowing anything up are constantly repairing/maintaining. Here's my breakdown so far on parts: raptor piston, billet raptor rod, "medium lift" mr. velocity cam, raptor carb, k&n filter, polished valves, head yet to be milled, ported and polished eyebrow, mucho ported intake and exhaust, 3 stage header, stock crank, lightweight version cast iron flywheel.

Flywheels: Some say 7 grand some say 6 on cast iron. Well, I want a 3 horse aluminum on my motor and am curious to know how well it will fair. Is the acceleration gain worth the hassle of collecting a 3 horse aluminum flywheel, coil and coil adapter bracket?

Cams: I have taken an interest in a 94-ss cam, but have purchased a motor which apparently alread has a medium mr. velocity cam. Will it be worth my while to spend the extra money on a bit larger cam? Does anyone know if anything needs to be done as far as lifter bore reinforcement for the 94-ss cam?
Is it even a good choice of cam for someone who is basically building a motor to run their go kart "dukes of hazzard style"?

Head: How many thousandths can I mill my head without needed to increase valve clearance for the .262 lift 94-ss cam?

Head Gasket: Copper? Regular stock?

Spark plug: Stock, medium or hot?

Coil: stocker or hot coil? does it matter?

 

[Kenny_McCormic]

Do not mill head, it kills flow. Hot coils=scam. make sure you build it on a cast iron lined block (chrome plated pistons and rings for aluminum bore engines are a ***** to find). DO NOT EXCEED 3600 RPM WITH A CAST ALUMINUM FLYWHEEL!!! 6K MAX ON THE CAST AND THATS PUSHING IT!!! Billet recommended! And I wouldnt take that rod past 5 or so best to get a billet one.

 

[newrider3]

I believe he said billet rod. Those aluminum mower flywheels they sell on Ebay are absolutely dangerous. They WILL explode if used at anything over stock RPM and on anything other than the mower it came on.

 

[oscaryu1]

Well, this is my first post and believe me, I have done my homework before posting. I still have some questions although. I am building an engine for a fun kart with no regulations and am attempting to make max hp on a budget without blowing anything up are constantly repairing/maintaining. Here's my breakdown so far on parts: raptor piston, billet raptor rod, "medium lift" mr. velocity cam, raptor carb, k&n filter, polished valves, head yet to be milled, ported and polished eyebrow, mucho ported intake and exhaust, 3 stage header, stock crank, lightweight version cast iron flywheel.

Flywheels: Some say 7 grand some say 6 on cast iron. Well, I want a 3 horse aluminum on my motor and am curious to know how well it will fair. Is the acceleration gain worth the hassle of collecting a 3 horse aluminum flywheel, coil and coil adapter bracket?

Cams: I have taken an interest in a 94-ss cam, but have purchased a motor which apparently alread has a medium mr. velocity cam. Will it be worth my while to spend the extra money on a bit larger cam? Does anyone know if anything needs to be done as far as lifter bore reinforcement for the 94-ss cam?
Is it even a good choice of cam for someone who is basically building a motor to run their go kart "dukes of hazzard style"?

Head: How many thousandths can I mill my head without needed to increase valve clearance for the .262 lift 94-ss cam?

Head Gasket: Copper? Regular stock?

Spark plug: Stock, medium or hot?

Coil: stocker or hot coil? does it matter?

Raptor carburetor does squat. Get a Tillotson adapter or Mikuni adapter. Heck, theres a Mikuni adapter on eBay right now.

Do not hog out the intake ports. Fuel dropoff, ect... It's like shooting a pea through a 1/2" tubing. A lost cause.

Go to Turk Bros's online store, and buy a billet 5HP flywheel. Have fun spinning 10,000+, or until you blow the head.

Head - Do not mill over .030 for any reason. After that, it kills flow. 4HP heads and crankshafts are a scam. Fireslots are a myth.

Head gasket - "Tru Seal" head gaskets are just sticky. Coppers are reusable. Coppers also seal well, if you're going to mill your head, get the thickest copper gasket (or other type) for your engine.

Go down a few heat ranges for the plug. I prefer gapless.

Coil - HOT coils are nothing IMO. Stock coils are fine.

Do not mill head, it kills flow. Hot coils=scam. make sure you build it on a cast iron lined block (chrome plated pistons and rings for aluminum bore engines are a ***** to find). DO NOT EXCEED 3600 RPM WITH A CAST ALUMINUM FLYWHEEL!!! 6K MAX ON THE CAST AND THATS PUSHING IT!!! Billet recommended! And I wouldnt take that rod past 5 or so best to get a billet one.

It will indeed kill flow if you mill .070 or some outrageous number. Chrome plated pistons are NOT hard to find. I found 3 a few days ago. They all went for about $5 because no one knew what they were.

Just so you know, people have spun 5HP's 7000+ and nothing has happened. However, they were risking their necks. People are brave enough to spin 9000-10,000 on stock flywheels. A few didn't live to tell the story.

5k for that rod is pushing it. You'll also need valve springs. Do not take a bushing crankshaft and spin over 6000 or so. Buy the EZ Bore kit for the bushing. Single bearing and dual bearing blocks are fine.

I believe he said billet rod. Those aluminum mower flywheels they sell on Ebay are absolutely dangerous. They WILL explode if used at anything over stock RPM and on anything other than the mower it came on.

Correct. They were not casted [that well], or in any case to exceed their specified RPMs, which is 3600RPM.

 

[crazycart]

Ive spun a pushmower with a aluminum flywheel over 4500, mowing down cat tails....

 

[woncamaro]

Carb adapter out of the question for me. Too much $ for just a fun kart. I hear some say that milling cuts down flow, well, I have cut the eyebrow clear out. I hear some say 7 grand max on the stock cast iron flywheel, some say 3600 max, what did the raptor racing engines with cast iron flywheels run as far as rpm? I ran my last briggs to 4500 with everything stock but valve springs, exhaust and some porting. What's the stock head gasket thickness .050? I see some .036 coppers available. Maybe I could run the thinner gasket and save on milling costs? I bought a raptor .010 oversize piston a while back. Is this chrome plated? My block is single bearing cool bore

 

[Russ2251]

I have been eliminating head gaskets by lapping heads and blocks using valve grinding compound then sealing with Permatex Super “300” Form-A-Gasket Sealant. Eliminated need for milling. Check for any clearance issues before attempting this (duh).

 

[jr dragster T]

How do you lap a head? Like I know when lapping valves you spin it aroud the make the seat and valve smooth. But how do you create friction between the head and the block?

 

[Kenny_McCormic]

You get a thick piece of glass (perfectly smooth/level) put some lapping compound on the head and rub it.

 

[Russ2251]

I am fortunate to work for the company that I do.
I have access to scrapped prober machines that use a platen that is absolutely flat. Tolerances to just a few millionths of an inch.
I apply some valve grinding paste to head and work in a random figure 8 pattern. I check surface of head for uniformity. Turns a solid grayish color from edge to edge.
Block is a little more difficult because of it's bulk.
Takes about 20 minutes for each surface or about 40 minutes total depending on roughness or warp of surfaces.
There is a noticeable increase in overall power.