How To Set Cam Timing

When it comes to rebuilding four-stroke engines, getting the minor details right tin frequently mean the difference between a long-lasting, powerful engine and an engine destined to have a short life. JE Pistons has decades of experience designing, technology, and testing pistons for high-performance four-stroke engines. Though there are many technical details in a 4-stroke's performance, cam timing is i of the most disquisitional points to become correct afterwards freshening upward your pinnacle end. We'll walk through all the of import details that should exist considered when timing the engine, and provide helpful tips to ensure that you get the job done correct.

Later installing a new piston in your four-stroke motorcycle, setting the cam timing is critical for right operation and damage prevention. Notice JE pistons for your cycle.

Every bit the name implies, the root of all cam timing related engine build problems typically stems from one central relationship, which is the position of the crankshaft relative to the position of the camshaft(s). Deviations from the factory prescribed positions can event in lost engine performance, which is a minor issue compared to the possibility of catastrophic engine failures, which are a possibility, since improperly timed cams tin event in valve to piston contact.

To tackle setting the cam timing correctly, the manufactory service manual must be utilized. The service manual is the only place you'll notice detailed information prescribing the correct process. Before starting the chore, take some fourth dimension to thoroughly review the steps outlined in your transmission.

All cam timing procedures usually beginning with rotating the crankshaft to a prescribed position. The specific steps to exercise this will vary depending on the engine, however, the importance of getting this part right cannot be stressed enough. Often times, small markings volition have to exist aligned with features internal to the engine, or on one of its covers. Be sure to use aplenty lite when aligning the crankshaft. Also, make sure that you're looking squarely at the alignment characteristic. Viewing the alignment features at an bending can lead to an inaccurate positioning of the crankshaft.

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With the crankshaft positioned, the next step on engines utilizing cam chains is to wrap the concatenation around the cam, or cams, while simultaneously ensuring the cams are in the correct position. While doing this, the crankshaft must likewise stay in its original position! Engines with gear driven cams are typically a little easier to work with because ensuring the gears are correctly aligned is the merely concern.

While maintaing the alignment of the crank marks, install the timing chain on the camshaft(southward), start with the side furthest from the concatenation tensioner and keeping the chain taught.

The cam gears will feature some type of alignment mark, such equally a scribed line or dimpled dot. Depending on the engine, these features volition demand to exist aligned with a mating feature on the engine. For example, information technology is not uncommon to align the cam gear mating feature with the cylinder head cover plane.

In single cam configurations such as this, there will be a notch on either side of the cam gear to line upward when installing the cam chain.  In many dual-cam configurations, in that location will be notches on each cam gear to line upwards with the cylinder head aeroplane. Ever cheque your owner'southward transmission for exact recommendations.

On engines utilizing a cam chain, the way in which the chain is wrapped effectually the cam gear(due south) is important. Ensuring there is no slack in the chain when information technology is wrapped effectually the cam gear is critical. We want all the chain slack to be on the side of the engine where the chain tensioner resides. That being said, on engines utilizing 2 cams, it is best to install the cam furthest from the chain tensioner first. Pull the concatenation taught from the crankshaft, then advisedly slip the cam gear into position, ensuring both the creepo position and cam gear position are aligned with their corresponding mating features. On dual cam engines, once the showtime cam has been installed, the chain tin can exist pulled taught from the first cam, and the second cam and gear can exist slipped into position and oriented correctly.

At this signal, the position of the cam(southward) and crank should be double checked. On engines utilizing cam chains and two cams, some service manuals will specify a chain link or chain pin count between the indexing characteristic of the intake and frazzle cam, in addition to the alignment features on the cam gears themselves. On gear driven engines, this will simply exist a matter of checking the alignment features of all the gears in the organization.

One time the cams have been correctly positioned, the cam cap can exist reinstalled, and the valve clearances can exist checked. After any valve clearance adjustments have been carried out, the concluding pace on engines utilizing a cam chain is to set the chain tension.

A couple different types of chain tensioners are commonly used, notwithstanding, regardless of type, installing the chain tensioner in its retracted position is incredibly important. Consult your service manual for specific instructions on retracting the chain tensioner. Go on to install the chain tensioner on the engine. One time installed, follow whatever necessary steps required to extend the chain tensioner and tension the concatenation.

With the chain tensioner extended, the cam concatenation will have some tension on it, however, information technology may not exist in its optimal position. Proceed to rotate the engine through 4 crankshaft revolutions. Rotating the engine over will allow the chain tensioner to further tension the concatenation. Information technology will also serve as an opportunity to confirm that everything has been prepare and then that at a minimum, there are no mechanical interferences. If you lot're unable to rotate the engine through all four of its strokes, there is a strong possibility that the timing has been set incorrectly and that the valves are interfering with the piston.

Assuming the initial spin over of the engine went without consequence, ostend i terminal fourth dimension that all key relationships have been maintained. Reposition the crankshaft in accordance with its alignment feature. Double check that the cam(s) are aligned with their respective features. Once this has been done, the hard part of the chore is complete, and nosotros can walk away with confidence that the cam timing has been set correctly.

Source: https://powersports.jepistons.com/blog/setting-cam-timing-four-stroke-motorcycle

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