HF rpm Confusion

[budd0413]

So after spending a whole afternoon searching this forum I am more confused than I started. Everyone has their own opinion of what a hf motor can handle with or without mods.

Some people say just yank off the governor and you can run 5200rpm on stock internals. Some people say throw in 18# valve springs and you can break 6000 if you are not scared of being torn apart by your exploding flywheel. So the purpose of this is to spark someone to make an end all be all, perhaps a sticky about what the real,safe working limits are of a hf 6.5 hp motor.

so heres what I would do to my hf motor if I had one. Basically performance basics from agk.

Remove the governor
install 18# or better valve springs
less restrictive exhaust and intake
tune the carb, they suggest a #90 main jet
aluminum flywheel
aluminum connecting rod

So assuming all of this is done, is this motor going to last running wot or at like 6 grand for any extended amount of time, or does this just ready the motor for the occasional 6 grand bump?

 

[sayre315]

if you get one of the honda aluminun flywheel and ARC rod then it should hold up to around 7-8000

 

[Pa and Corby]

I am doing the same mods to my clone, minus the aluminum flywheel and rod. and I ve done a bunch of homework on it, the engine will handle the rpms no problem, just keep the oil changed. Ive been told it will rev to 5200 rpm's but the exact rpm isnt that important is it? you will have to but a stiffer spring in your tav so it engages at a higher rpm thats all. P.S. Ive done averything except removeing the gov and adding the 18# springs but thats next! also there are a few web sites that specialive in clone hop ups, i have them somewhere here? let me know if ya need them, I spoke to them they are real helpfull!

 

[jr dragster T]

IF its stock dont mess with it. If you have ARC stuff rip the guts outa it(7000 rpm+)

 

[oscaryu1]

Some people say just yank off the governor and you can run 5200rpm on stock internals. Some people say throw in 18# valve springs and you can break 6000 if you are not scared of being torn apart by your exploding flywheel. So the purpose of this is to spark someone to make an end all be all, perhaps a sticky about what the real,safe working limits are of a hf 6.5 hp motor.

A guy running a Clone shattered a flywheel at less than 6,000. And they retorqued everything before doing this. Lucky it was running on a stand at that time.

Remove the governor
install 18# or better valve springs
less restrictive exhaust and intake
tune the carb, they suggest a #90 main jet
aluminum flywheel
aluminum connecting rod

Flywheel and rod first, then come the other mods. If you're a safer like me.

 

[Scout]

Anyone have anything new to add? After running mine a couple times I realized the governor sucks and is in no way smooth.

 

[Russ2251]

Surging?

 

[Kenny_McCormic]

BILLET flywheel before anything. $100 is a lot less than a funeral.

Then tear it down, remove the gov and oil sensor, add a billet rod if your running it with stiffer springs. The gov/oil sensor removal has a youtube video. http://video.google.com/videoplay?d...519&ei=eeBDScqZCoXE-wG3ycXXDA&q=Box+stock+6.5

The stock muffler is a choke point, get a header.

USE A TORQUE WRENCH

 

[Scout]

Surging?

Yeah, you could call it that.

 

[Russ2251]

Adjust low speed mixture screw to a richer setting.

 

[Scout]

Wait, the surging comes at WOT. Idle is fine. When I drove down the street the other day it would rev up and die, rev up and die, etc. Last night I disabled the governor and next week I will order a flywheel and maybe some other goodies. (More money... )

 

[Russ2251]

Clean the carb and check float level. High speed jet is possibly partially blocked/clogged or is wrong size.
Engine should run perfectly in stock configuration first before making any mods such as flywheel and other goodies.
You would't buy new windshield wipers for a broken windshield, would you?

 

[Kenny_McCormic]

File out the jet, while muttering, "**** EPA idiots".

 

[Russ2251]

File out the jet

OUCH!!! Wire gauge drills would be a better choice.

"**** EPA idiots"

I found one or two

.

 

[Kenny_McCormic]

Wire guage drills=$$$ I have a torch jet file kit. Guitar string also works.

 

[Russ2251]

Every bit you'll ever need!

 

[jr dragster T]

They sell numberred bits for under $20 here.

 

[Russ2251]

You get what you pay for.
Precision ain't cheap.

 

[crazycart]

Russ, are those bits from northern any good? I got a big kit of like ryobi ones and they all are snapped/dull already.

 

[Russ2251]

I ordered my original kit from Amazon 2 years ago. Unknown if these are the same but were roughly the same cost. Haven't had any problems.