Name

Use

Where Available

Part #, Links

GASKET DRESSING  HYLOMAR

Highly recommended for all fiber/paper gasket surfaces.  Extremely easy to work with, will not clog passages like RTV sealant.

Permatex used to distribute this, but it is now available exclusively from the mfr.

www.hylomar-usa.com

METAL-TO-METAL DRESSING

YAMABOND 4

For metal to metal contact, sealing between carb and head, etc.

Yamaha dealers

More Information

THREAD LOCKING

LOCTITE

Use Red for nuts & bolts you don't EVER want to come loose.  Use Blue for nuts and bolts you may need to remove.  Use lubricant or Loctite on ALL threads - don't ever install any nut or bolt dry.

Local Auto Parts Stores

More Information

CLUTCH HUB AND OIL FILTER SOCKET

Works for XR/CRF 50 & 70, most pre-78 CB, CL, CT, SL & XL models, XR200 80-84, XR200R 81-94, XR250L 91-94, XR250R 86-94.

POWROLL

#18541

$9.95

IMPACT DRIVER

Works like an air wrench, but with a hammer.  Removes stubborn bolts and screws.

HARBOR FREIGHT,

SEARS

# ITEM 90881-0VGA

#00947641000

DIGITAL CALIPER

A must-have for accurate measurements

HARBOR FREIGHT

ITEM 47257-5VGA

FLYWHEEL PULLER

Different rotor designs require unique pullers.

CHECK WITH YOUR LOCAL DEALER

Kawasaki/Suzuki

TORQUE WRENCH

Absolute necessity for leak-proof engine builds!

SEARS,

HARBOR FREIGHT

#00944690000

ITEM 807-0VGA

CASE SEPARATOR

The easy way to split cases - works for 2 & 4 stroke applications.

MOTION PRO

08-0245

COMPRESSION TESTER

Easy check for engine health

MOTION PRO

08-0188

DEGREE WHEEL

For fine tuning cam and ignition timing.

MOTION PRO

08-0092

Application

Formula

Example

Engine Displacement

Bore (in centimeters) x Bore  (in centimeters) x Stroke  (in centimeters) x .7854 = Displacement of one cylinder. For multi-cylinder engines, x the sum by the amount of cylinders.

Honda XR 200 has 65.5mm BORE and 57.8mm STROKE:

First, turn mm to cm by moving decimal point one place to the left, then:

6.55 x 6.55 x 5.78 x .7854 = 194.476 cc's

Ducati Monster 620 has 80mm BORE and 61.5 mm STROKE:

8.00 x 8.00 x 6.15 x .7854 = 309.133 x 2 (cylinders) = 618.266cc's

Once you have the number, plug it into this formula:

Displacement in cc's

+ Chamber Volume in cc's

Divide the Sum by Chamber Volume = Compression Ratio

Honda XR200 with our 12:1 Piston: 198cc Engine, 18cc Chamber Volume:

198

+18

=216, Divided by 18  = 12

You will need the Open and Closing measurements for the cam, these can be obtained from the manufacturer (Powroll cam specs are here). You will see something like this:

From these numbers, you will plug in this formula:

Intake Open + Intake Close + 180 = Intake Duration

Exhaust Open + Exhaust Close + 180 = Exhaust Duration

Using the numbers shown (from our #12714 cam for the XR200):

18 + 43 + 180 =

   241° Intake Duration

41 + 20 + 180 =

   241° Exhaust Duration

Honda XR200R Claimed Horsepower from the factory (measured at crank) = 18 hp

Good estimate for a number at the rear wheel would be about 15 hp

Generally, well-tuned engines can reach (but not exceed) the following rule of thumb:

Single Cylinder Four Stroke - 1 hp per 10cc's

Nascar Engine - 2 hp per Cubic Inch

Formula 1 Engine - 3 hp per Cubic Inch

If you see dyno numbers for a thumper that are exceeding 2hp per 10cc, there's something wrong with the dyno.

Using that trusty XR200 again, at 198cc's a very well-tuned XR will crank out about 18 hp at the rear wheel. This is within the rule of thumb, and believable.

27 hp from that same 198cc engine is into the realms of Nascar,  heading towards F1, and outside of the realms of believability.