Iso raptpr

If I can build something comparable with a different block I'm good. Let me know what to look for. What blocks will the raptor parts fit in. I'm new to these small engines. I'm just getting frustrated with everyone thinking I want a new in the crate motor. It would be nice to find an old complete one. I got outbid on eBay for one.
 
If I can build something comparable with a different block I'm good. Let me know what to look for. What blocks will the raptor parts fit in. I'm new to these small engines. I'm just getting frustrated with everyone thinking I want a new in the crate motor. It would be nice to find an old complete one. I got outbid on eBay for one.
What I would suggest is letting us know which class and sanction you're running (WKA/NKA/KART etc.). That'll help builders on here better understand what you want :) If you're wanting to take on the adventure of building your own motor that's totally fine and up to you but there is A LOT more involved than you might think. Not saying you can't, but it'll be cheaper to have a builder do it and confidence it'll be done right and pass tech.
The way this was all originally worded, I saw it as you were looking for an "all in one" package which CAN be made from the many businesses on here...but I don't believe they came directly from Briggs and Stratton as such. I hope that makes sense.
We're all here to help and do our best not to bash but sometimes when there's little information given we kind of have to pry at you a little to get the info we're looking for to make recommendations on what to do. No harm or foul was aimed your way...just asking questions to better understand how to help. So if you can get us the class and sanction I think it'll be a great start to getting you where you need to go.
 
The rules for the engine are has to be as it came. I cant modify parts. It needs to be all stock briggs parts. No aftermarket internals. The wks and others are not allowed. I asked they don't allow them. I was told to look for a stock raptor motor. So I thought I would give this forum a shot. So basically the motor needs to be as you would of bought a raptor when you could out of the crate. I hope this makes a little more sence
 

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Streby Speedway Briggs Engine Tech Rules

Posted by strebfest
The class at Streby Speedway is a “BOX STOCK” 5 Horse Power Briggs engine, not Blueprinted engines. Also not to be confused with WKA or IKF “Stock” classes, which could be called Blueprinted or Modified as compared to Box Stock.
Legal Engine Models
130-232
135-232
135-230
Mandatory Engine Spec Numbers
1536 or 1541 – 1991 Model
s 5101 or 5102 – 1992 Model
s 5111 or 5112 – 1993 Models
1011 or 1012 – 1994 Models
7004 – 1995 & 1996 Model Raptor I
7014 – 1997 & 1998 Model Raptor II
7124 – 1999, 2000, 2001 & 2002 Model Raptor III
8124 – 2003 to current
Engines can be “cool bore”, or IC, which is the steel sleeved engine.
If your engines model or spec. #’s are not listed here – engine must be preapproved by Streby Speedway.
“Box Stock” ENGINE RULES
  • The block cannot be decked.
  • The intake port must be untouched and compare visually to a known stock Briggs port.
  • Even though a carburetor bore size is listed, the venturi bore must be untouched. No polishing or machining allowed.
  • A key must be in the flywheel.
  • A stock non-reground, non twisted camshaft must be used. (We reserve the right to confiscate any illegal cams)
  • Aftermarket crankcase breathers are not legal in any class. Aftermarket items that
    positively affix crankcase overflow hose to breather assembly are acceptable, as long as
    they do not modify stock Briggs breather assembly and its operation.

Gaskets


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Any aftermarket gaskets permitted so long as same size and similar material (except
head gasket must be stock Briggs & Stratton #272157, #555066, #555187, and #555236 or metal with .015 pop up). One or two gaskets permitted on intake and on carb to tank. All gaskets will be teched against known stock Briggs & Stratton gaskets. No sealer or paint allowed.
Head Gasket
Head gasket .043″ minimum thickness to be checked in three places 1″ apart. Stock Briggs part or FelPro #FR1004 at .043” minimum thickness.
Cylinder Head
Stock 5 HP head as shipped from factory.
No machining of gasket surface permitted. Three planes of head interior are subject to check by depth gauge to establish their proximity to gasket area surface. The three plane depths are .025″, .408″, .305″. No machining to top of head. Removal of carbon buildup will be allowed for tech inspection purposes. No polishing of head allowed.
Cylinder Block
Block must be as produced, with no alterations or reworking. Block may not be machined on intake or exhaust ports gasket surface or on head gasket surface.
Cylinder Bore/Piston
2.5625″ is stock bore. Beginning in 2013 you may run a +.020” stock briggs and stratton piston. No circular or machined grooving of cylinder allowed in any position of cylinder. Angle boring not permitted.
Stroke
2.437″ (+/- .010″) for wear is stock stroke. Minimum crank journal diameter is .990″. To check stroke, push piston down to take up play of rod clearance. Check stroke from BDC to TDC.
Deck to Piston Clearance
This dimension cannot exceed .015″ above block (see corresponding head gasket rule listed above). Machining of deck surface is not permitted. When measuring piston pop- up, it should be done with bar stock on a parallel with the piston wrist pin in center of piston.
Crankshaft
Stock factory crankshaft per engine model. Lightening, polishing of counterweights, addition of material is not permitted. PTO bearing must be stock as supplied from factory and installed in original position. Offset cranks are illegal. No hardening (except for stock Raptor crank).


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Connecting Rod
Stock connecting rod only. No under sizes or resizing of undersize rods allowed. New type Briggs & Stratton connecting rod legal with oil hole in back rather than on side of rod. Oil hole on old and new rod will be .177″ NO-GO. Old type may be drilled to spec. Minimum stock rod length is 3.1233″, and maximum is 3.1333, measured from the bottom of the wrist pin to top of crank journal. Briggs rod with built in dipper is legal, part #555207.
Dippers
Stock Briggs dipper is mandatory in the Box Stock class. #555207 rod with built in dipper is legal – Briggs & Stratton.
Piston – Pin – Rings
Old style stock unaltered Briggs & Stratton piston with minimum measurement of .937″ from top of piston to top of wrist pin. Minimum piston length is 1.869″. Pinhole may not be altered or relocated. Deck above top ring may not be altered. No machining allowed on piston. Pin must not be altered and maximum I.D. of pin is .290″, maximum OD is .490″. Raptor III piston has a .937” minimum dimension from the top of the piston to the top of the wrist pin. Minimum piston length is 1.671”. The top two ring piston land width is .0603” – .0612”, and the oil ring land width is .1020” – .1032”.Stock Briggs & Stratton unaltered rings in stock location only. Only end gapping and deburring of rings allowed. No machining of rings allowed. Three rings required. Expanders under rings not permitted.
Ring dimensions:
Old style piston top and second ring – 2.390″ minimum I.D., .115″ minimum width for wear.
Old style oil ring – 2.420″ minimum I.D., .095″ minimum width for wear. Groove must be present on oil ring. Groove must measure .093″ regardless of condition of ring.
Raptor III rings, .090” minimum width top two rings & .058” +/- .005” thickness. Oil ring .070” minimum width & .100” +/- .005” thickness.
Ends of ring must remain flat. Rings must fall on tech gauge without spreading or using force. No excessive end gap allowed. End gap with ring compressed cannot exceed .500″.
Camshaft
Stock Briggs factory camshaft with alignment as shipped from factory. Visual tech on camshaft lobes “lifter surface”, and lobes must remain flat and of original width. No ground cams allowed.
Lifters
No extended or adjustable lifters allowed. Head of lifter .985″ minimum, 1.005″ maximum. .985″ minimum with -0.003″ allowance for out-of-round. Lifter must measure .985″ at some point.
Valves
Must be one angle only on valves and seats. Intake 30°, exhaust 45°. Intake valve minimum diameter 1.115″ intake seat I.D. 1.004″ NO-GO. Exhaust valve minimum diameter .990″, exhaust seat I.D . . . 880″ NO-GO. Stock valves only. Cannot be polished or lightened. No refacing of valves allowed. No replacing of valve seats allowed. Stock Briggs guides allowed in exhaust and intake. Any valve setting permitted.
Valve Seats
Must remain stock.
Valve Springs
Stock valve springs and stock keepers, or stock exhaust springs on both intake and exhaust allowed. Valve spring lengths – intake 1.240″, exhaust 1.410″ maximum, or both 1.410”.
Exhaust spring must be on exhaust. Intake spring must be on intake. Springs must be unaltered as supplied from factory. No ground aftermarket springs allowed.
Maximum wire diameters – intake .087″, exhaust .091″, or both .091”, and/or minimum wire size .088” both sides.
Upper Valve Spring Retainers
Must be Briggs Part #23184 and #555147.
Crankcase Valve Breather
Crankcase valve chamber stock breather #294178 or #555073 must be used with unaltered valve. Breather will be teched up to and including grommet. Two valve chamber gaskets allowed. Breather tube must be removed from carburetor; tube may or may not be used, and may be shortened. Aftermarket items that improve securing tube and stock grommet to breather will be allowed as long as they don’t alter performance of the stock Briggs breather assembly.
Ports, Intake and Exhaust
No cutting or metal work allowed. Port must have .050″ material below seat.
Flywheel
Stock 5 HP flywheel only. No addition or removal of material allowed. Weight on flywheel is 6-lbs. 4 oz. minimum.
Ignition
No battery ignition allowed. Stock coil must be used in unaltered form. No aftermarket ‘Red’ coils allowed. No slotting of attaching holes or machining of attaching bolts
allowed. Resistance from plug wire must be 2,000-OHMS minimum and 3,200 OHMS maximum as run regardless of temperature factor. New composite ignition legal. There must be resistance from ground to plug wire. Spark plug connector must be factory type. Rubber boot is allowed. Coil air vane must be installed. Coil must retard.
Carburetor
Only carburetor #397135 and #555129 may be used (the Chinese replacement carb that became available in 2006 is not legal).
These part number carburetors must have a casting #5, no other number allowed
Butterfly with cast in #8 is only one legal. #555111.
Jets must have stock recess on backside.
No flat back jets allowed.
No recessing of holes from backside.
No funneling of hole allowed.
No oblonging of hole allowed.
Diaphragm side cannot be used to create a pressure fuel feed.
No modification to throttle shaft, butterfly, screw, or any portion of the air passageway.
No drilling of holes anywhere in carburetor.
Diaphragm side of carburetor must be installed as supplied from factory. Diaphragm cover plate cannot be surfaced to insure seal. Silicon or other material may not be applied to diaphragm side of gaskets.
No long brass pickup tube allowed.
A tab to reinforce a broken bolt ear on the carburetor is permitted.
Choke stub subject to removal in tech.
Felt washer must be on carb under lever. New rubber O-ring allowed.
A washer or coin may be crimped or glued on mixture needle.
Rubber band or spring may be used to hold choke open.
Stop arm on throttle shaft is not a tech item. Arm may be bent, filed, or cut. Remainder of throttle shaft must be unaltered. Minimum throttle shaft thickness is .093″.
Carburetor linkage tech stops at the throttle shaft. Bellcrank and shaft link are non-tech.
Choke can be removed in its entirety. If left, it must remain stock and complete. Choke stub subject to removal in tech.
With choke plug removed: .691″ NO-GO may not reach butterfly at full throttle.
Swirl optional. If installed, must be in stock position and must be unaltered. Subject to be removed during tech inspection.
Visual tech on carb bore. .691″ maximum I.D. Remainder of carb will be teched against known stock carb. Air horn and all other parts of carb must remain stock. Air horn measurement 1.011″ NO-GO.
Main metering hole must be under .062″. Idle hole must be under .028″
Cam Profile
Intake

.020 — 18-13 BTDC
.050 — 7 BT-0 TDC
.100 — 10-17 ATDC
.150 — 29-36 ATDC
.200 — 55-64 ATDC
MAX LIFT — 0.231″
.200 — 43-33 BBDC
.150 — 13-6 BBDC
.100 — 6-13 ABDC
.050 — 23-31 ABDC
.020 — 40-45 ABDC
Exhaust
.020 — 51-46 BBDC
.050 — 38-33 BBDC
.100 — 21-16 BBDC
.150 — 2BB-3 ABDC
.200 — 21-31 ABDC
MAX LIFT — 0.231″
.200 — 76-65 BTDC
.150 — 48-40 BTDC
.100 — 28-21 BTDC
.050 — 10-4 BTDC
.020 — 2-7 ATDC
E-Z spin start 45-60 ABDC.
E-Z spin lift .013″ minimum, .019″ maximum with .001″ maximum travel during the 40° duration time. At no time can the E-Z spin or its .001″ travel go below .013″ or above .019″.
E-Z spin duration 40° minimum.
NOTE: All cam profile readings must be taken with zero valve lash.
When checking cam profile, rotate engine in direction of rotation only. (Valves should have no clearance and no spring tension when checked).
Fuel
Pump Gasoline Only!

 
Now we're talking!! The guys on here can absolutely help you out now with this!

Note: Some builders may have a couple "clarification" questions here and there for you that might require some more investigating but it's only to make sure they can or can't do something. :)
Happy Racing Gkh!!
 
I believe bare blocks are still actually available, #555669. If not there is one on e-bay. Looks like they are trying to make an affordable flatty class. Would have worked great 20 years ago.
 
I believe bare blocks are still actually available, #555669. If not there is one on e-bay. Looks like they are trying to make an affordable flatty class. Would have worked great 20 years ago.
They have been doing this for a long time. It's the motor they know.
 
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