My review of the GT5_A Superhawk

6MM studs can still be decent if they're made from good, strength rated steel.
Furthermore, the heads on these kits are pretty awful even on the lower compression kits. I keep advocating the use of the puch heads, as they have a couple hundred percent more cooling area, and good squish bands.

If you want to lower compression a bit and cool down your motor, here's what you do. Raise the exhaust port 1mm, by using a slightly thicker base gasket, or port it. This will lower your compression 2 ways: The trapped volume will be less and your head will be 1MM higher. lap the head and top end of the jug flat and use just one head gasket. If it's still too hot, get a variable timing magnet and retard the ignition 1 degree.

Replace those studs! Get grade 5 or 8 threaded rod from mcmaster, and loc tite them in their holes. The chineese studs strip if you look at them crosseyed because they're unrated. Sometimes you'll get lucky, mostly you will not.

like he said, 6mm studs aren't the problem, it's the cheap quality of them. i replace mine with allthread with a higher strength rating and never had a problem.

morini's run 6mm studs, i'm pretty sure.

the engines i've had with 8mm studs are no better. i think they're actually worse. they're soft, and i've had them stripped right out of the box due to them hammering the acorn nuts on at the factory.

personally, i replace the 6mm studs, washers, and nuts. in fact, i'm gonna go buy some more right now...

Got It!
So what about the Super Rat head on the new Super Hawk Gt5-A Engines that has hardly the fins compared to the 2011 GT5 engine? How do you keep it cool?

i can't.

the engine i built for a friend keeps blowing head gaskets, and the plug, while looking good at the electrode, is bluing on the outside from the excessive heat.

the only way i've been able to keep these engines from blowing head gaskets and keeping them cool is by leaving them in the box in a dark corner of my workshed.

after i move into a new place with a garage on the first, i'm gonna build one for myself and see what i need to do to make it work.

for now, i'll just keep repairing my buddies bike till we either give up and buy an older kit, or it blows up.

i think these engines are failures on many levels, and i'd personally like to tell Don Grubee that he's single-handedly destroying motorbicycling as we know it...

So!
I brain stormed on it for a while and came up with this Idea to try a different Head!
I had a GT5 Slant Head and I used 3 gaskets, next time I work on it I will try 2 or 1 gaskets.
Anyhow!!! It runs better with a different Head it does not over heat.

(So The Super Rat Thin Heads w/ Small and Not enough Fins is the problem)!

Cold plug!
Run it rich!
Permatex Copper High Temp Gasket Sealer Spray Can!
Another issue solved!

Man I impress myself sometimes!
You See, I used the motor so I was like, stuck with it. I had to make it work.
One more thing?
I found that if you use a muffler clamp on the front mount around the bike frame and drill two holes threw the bracket and threw the top of the front mount on the engine and tap it. It holds the engine very nice and stiff, eliminates the vibration a high %. You can rev it all the way in 1st gear and hardly feel the vibration. So the front of the engine has to be stiff mounted on the frame real good, this was proven to myself through several of my MB Builds w/ a shift kit and custom fitted and welded expansion chamber set-up. And of course port the intake and exhaust manifolds. If you want your engine to breathe the best it can to get the most power and mpg out of it.
Hope this helps someone!
I wish you good times, fun and safety.

bairdco said:

my buddy brought the bike back sunday, same problems, blown head gasket.

head was warped again, and the spark plug was loose...

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Question.. how does your buddy treat the machine overall when using it? If he runs it with the throttle only off or wide open, with little or no use of the low and mid range it might be a factor.

he's a pretty conservative rider. he mostly just rides it to work and back everyday, maybe 5-6 miles a day.

i, on the other hand, have a starfire GT4 that i beat the heck out of everyday, constantly run it at full throttle for hours at a time, and it's two and a half years old.

there's a HUGE difference in quality between the starfire and the skyhawk factories. i don't know why Grubee decided to go with the crappier one.

You're very welcome richirich

Best wishes on whatever you end up doing this winter.....

Peace, map

richirich said:

And hey Mapbike, i just got the motor now that i can practice on this winter. Even though i would not use it , it would be good to try the porting, transfer ports ,piston skirting. it would give me a good idea how the metal grinds and reacts. and who knows if it works out maby ill just buy a new case and try the motor again.
Anyway thanks for the tool info.
its raining here today so its reading no riding.... bummer

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