Loading... Please wait...

Tech Department


Customer service has always been a core value at JR Race Car. We are here to support the junior community with advice and suggestions about all makes and models. Our tech line is open Mon - Thu 8am-5pm and Fri 8am-noon; e-mail tech_support@jrracecar.com

Check back often for new and updated tech articls.  Don't forget to print them off and take them to the track.

engine-tech-bg.jpg clutch-tech-bg.jpg


Engine Break-in Guide

Carb Tuning

Round Fuel Pump Routing Diagram

Timing 101

Kill Switch Wiring

Titan Exploded Parts

Shockwave Maintenance Guide

Reverse Driven Maintenance Guide

Alignment Guide

Clutch Vocabulary Sheet

Hercules Axle Assembly Guide

Hercules Brake Assembly Guide

Beadlock Installation Instructions

Center Pull Motor Plate Guide

Engine Rebuild Instructions

Engine Tuning Guides


ZR (Stage 8&9)

ZR4 (all bores)

Titan (all bores)

Shockwave Tuning Chart

C-4 Flyweight

C-14 Flyweight

H-1 Flyweight

C-15 Flyweight

C-2 Flyweight

Ballast Guide

Tire Comparison Guide


A few FAQ's:

Q: How do I send my engine in to JR Race Car for a rebuild?

A:All you need to do is complete the new Refresh Information Sheet and send us your Info Sheet, engine and other accesories you would like us to refresh.  Please call with any questions.


Q: Does JR Race Car use a key to time the flywheel?

A: No, we do not use flywheel keys.  Our Timing 101 artical details how to set your engine timing.  Remember to use red locktight on the flywheel taper.


Q: How do I tell if my coil is bad?

A: JR Hot coils will test between 4 and 5 Kilaohms.  Other coils (including Stock Briggs) should test over 3 Kilahoms.


Q: How do I tell if I have a 3HP or 5HP coil?

A:The only difference between the 3 and 5 HP coils is the bolt pattern on the coil legs.  The 3HP coil has a wide bolt pattern with very little material on the outer edge of the bolt holes.  The 5HP coil has bolts in the center of the legs.


Q: Do I need to brake-in my rebuild motor?

A: Yes, the brake-in process is very important to how your motor will run.  Proper brake in will set piston rings for maximum HP!! See the JR Race Car brake-in guide.


Q: How do I set belt tension on the Shockwave Clutch?

A: You should be able to grab the belt with your left hand and not easly rotate the driven with your right hand, see shockwave installation video. If your belt is squeeling, it is too tight.  If you car will not roll forward at idle, your belt is too lose.


Q: How often should I change my clutch belt?

A: We recommend changing your clutch belt every 50-75 passes.


Q: How many spider shims should my shockwave have?

A: Each flyweight profile has different spider shims.  The flyweight profiles (C-4, H-1, C-14, C-15) for the appropriate shim package.




Still have a questions, we would love to here from you!!!

   Full Name:
*  Email Address:
   Company Name:
   Phone Number:
   Order Number:
   RMA Number:
*  Details:
*  Captcha Check: