Hi All!
I got an MP 7.5 Sport kit for my birthday last year.
It ran great for awhile but I think I cooked my engine.
Yes I did follow new engine break in procedures.
I never took apart a glow fuel engine before, but it didn't
look too complicated so I gave it a shot. The engine
with this buggy was the GS21R.
After blowing my engine, upon inspection I came upon
some startling results. The first was that the recoil
was only affixed with one screw to the crank case body!
(The engine came preassembled in the kit mind you.)
The screw that it was affixed with wasn't even a metric
hex head screw as referenced in the instructions.
It appeared to me that the recoil assembly was not fitting right, so when I opened up the engine I found the reason:
The crankshaft was too long, by about 1/16th of an inch!
The flywheel on MY crankshaft was more triangle shaped
with no holes, while the flywheel in the manual for the GS21R is circular with multiple holes. If I tried to put a second screw into
the recoil starter, it would be so tight against the crankshaft that
it was impossible to pull.
So now I figured out why I blew the engine. Someone gave
me the wrong crankshaft. It looks more like a GX21 crankshaft.
I examined the connecting rod, piston, and cylinder and all seem to be damaged. (Rough metal as opposed to burns) In addition, this engine had no head gasket! I have come to surmise that the RC shop where it was bought from either screwed me over or
someone at Kyosho was asleep when assembling this engine.
I'm hoping to repair this engine, because most of it is intact.
Also seems like a fun little project -- reviving a dead engine.
If it doesn't repair, I'm going to buy a new one anyway and
keep the old one around for parts.
Now I've bought the corresponding repair parts as well as a few hop ups: Head Gasket, Cylinder/Piston, Connecting Rod, Screw Set, Crankshaft.
So at first glance I was not all impressed with my MP 7.5 Sport.
Technically, It's a miracle the engine would even run at all.
I am hoping that with the repair parts the engine will run
a whole lot better. It had virtually no accelleration from stop
and my friends with electric cars were laughing at it
It
would eventually get up to an impressive speed but it often
would stall.
So this winter it is my mission to outfit this beast to the max, but only with parts that actually do something
I've ordered the following hop ups:
3-Piece Flywheel/Clutch/Spring Set -- for acceleration from stop.
Foam air filter replacements -- old one was dirty.
Adjustable Upper Rear/Front and Tie rods -- I can tell by the wear on the wheels that the non adjustable stock ones suck.
Front and Rear Stabilizer Rods -- for driving on rougher terrain.
New tires and foam inserts for them -- driving off curbs at high speed.
Now I ask you my friends -- is there anything worthwhile
that I would need that would noticably improve performance?
What about shocks? A non-Kyosho engine?
I got an MP 7.5 Sport kit for my birthday last year.
It ran great for awhile but I think I cooked my engine.
Yes I did follow new engine break in procedures.
I never took apart a glow fuel engine before, but it didn't
look too complicated so I gave it a shot. The engine
with this buggy was the GS21R.
After blowing my engine, upon inspection I came upon
some startling results. The first was that the recoil
was only affixed with one screw to the crank case body!
(The engine came preassembled in the kit mind you.)
The screw that it was affixed with wasn't even a metric
hex head screw as referenced in the instructions.
It appeared to me that the recoil assembly was not fitting right, so when I opened up the engine I found the reason:
The crankshaft was too long, by about 1/16th of an inch!
The flywheel on MY crankshaft was more triangle shaped
with no holes, while the flywheel in the manual for the GS21R is circular with multiple holes. If I tried to put a second screw into
the recoil starter, it would be so tight against the crankshaft that
it was impossible to pull.
So now I figured out why I blew the engine. Someone gave
me the wrong crankshaft. It looks more like a GX21 crankshaft.
I examined the connecting rod, piston, and cylinder and all seem to be damaged. (Rough metal as opposed to burns) In addition, this engine had no head gasket! I have come to surmise that the RC shop where it was bought from either screwed me over or
someone at Kyosho was asleep when assembling this engine.
I'm hoping to repair this engine, because most of it is intact.
Also seems like a fun little project -- reviving a dead engine.
If it doesn't repair, I'm going to buy a new one anyway and
keep the old one around for parts.
Now I've bought the corresponding repair parts as well as a few hop ups: Head Gasket, Cylinder/Piston, Connecting Rod, Screw Set, Crankshaft.
So at first glance I was not all impressed with my MP 7.5 Sport.
Technically, It's a miracle the engine would even run at all.
I am hoping that with the repair parts the engine will run
a whole lot better. It had virtually no accelleration from stop
and my friends with electric cars were laughing at it
It would eventually get up to an impressive speed but it often
would stall.
So this winter it is my mission to outfit this beast to the max, but only with parts that actually do something
I've ordered the following hop ups:
3-Piece Flywheel/Clutch/Spring Set -- for acceleration from stop.
Foam air filter replacements -- old one was dirty.
Adjustable Upper Rear/Front and Tie rods -- I can tell by the wear on the wheels that the non adjustable stock ones suck.
Front and Rear Stabilizer Rods -- for driving on rougher terrain.
New tires and foam inserts for them -- driving off curbs at high speed.
Now I ask you my friends -- is there anything worthwhile
that I would need that would noticably improve performance?
What about shocks? A non-Kyosho engine?
