BORE / STROKER KITS
Big Bore/Stroker crank kits are winning races and championships
all over the world. These kits improve the horsepower, mid-range
and overall powerband. Our test riders and pro racers report
increased power that's easier to control, allowing them to get
on the power earlier when exiting corners. This increases straightaway
speed and lowers lap times, while reducing rider fatigue.
offer billet stroker cranks, modified OEM stroker cranks, big
bore cylinders and modifications, as well as complete kits for
to increase engine size:
Changing just the cylinder and piston is easier than splitting
the cases and installing a stroker crankshaft.
Cheaper than a crank, but not by much.
Head is not designed for that diameter cylinder.
Too large bore results in incomplete combustion
Too large bore reduces cooling jacket.
Larger piston adds stress to rod and crank.
Excessive vibration from heavier piston. Still need to remove
crank to rebalance for heavier piston assembly. But if you do
all that work, you might as well use a stroker crank.
Stock Piston sizes are cheaper to replace and
easier to get.
Easier to control
Complete combustion – using head designed for this bore.
Longer stroke breathes “deeper” while valves are
Generally, better power than bore kits
If done poorly, can result in vibration
Very large stroke may require case modifications
Somewhat more expensive than big-bore kits.
Few companies can do it properly.
Bore / Stroker Crank Combinations
Properly done, you get the best power
Overcome design problems with OEM design
Tailor power/reliability to application
Overcomes limitations of just bore or just stroke
Tailored bore/stroke ratio
Adding stoke allows larger bore
Non-drop-in kits can be more work to install.
FOR THE EXPERIENCED ENGINE BUILDER
design these kits for experienced race engine builders. They
do not contain complete "how-to" step-by-step instructions
on building an engine. When the installation is complete, tuning
will be required, including jetting, valve timing, ignition
timing and other issues.
the engine manufacturer will make slight changes to an engine
that could cause interference with our crank, rod or other part.
The engine builder should check all clearances, and modify the
cases to provide proper clearance. Please keep in mind that
we cannot always know if this will be necessary with your cases,
and you should take this into account.
you don't know how to build and properly tune a race engine,
including the installation of a crankshaft, we suggest you contact
a professional engine builder or your dealer.
is not rocket science, but you do need to realize that improper
installation or tuning can ruin your engine.
STEALTH BIG BORE / STROKER KITS AVAILABLE FOR:
** CALL FOR PRODUCT PRICING & KIT DETAILS
450cc Long Rod, 450cc Dirt Track Heavy,
'04/ '05: 531cc, 564cc, NEMESIS 600cc
'06: 526cc, 546cc
MEIMU 1402cc, RONIN 1485cc, SHOGUN 1525cc
650: 629cc, 697cc, 754cc
'05: 513cc, 534cc
RHINO 660: 719cc, 762cc
700 : 779CC
500: 600cc, 636cc
1430cc, 1485cc, 1550cc
STROKER CRANKS AVAILABLE FOR TWIN & FOUR CYLINDER:
These displacement figures
are calculated with standard bores. Oversize pistons will result
in higher displacement
1402cc (+5mm), 1485cc
(+9mm), 1525cc (+11mm)
1081cc (+.4mm), 1108cc
(+2mm), 1178cc (+6.34mm)
665cc (+3.4mm), 685cc
stroker Knife® Connecting Rods available for all billet
** requires special stroker piston (
*** requires special stroker piston (