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    Tru-Tension - Chain Monkey

       (0 reviews)
      Brand: Tru-Tension
      Price: £19.99
      Retailer: Tru-Tension (Direct) Www.tru-Tension.com
      Value: 7
      Quality: 8
      Performance: 9
      Ease of Use: 8
      Kart Review Score: 8.0


    Correct chain tension is crucial to achieve maximum performance from your engine and minimal energy loss in the drivetrain.

    In the case of having the chain too tight, you will not only zap your engines power but you will increase the wear on the engine crank and bearings. This can be costly if it's a regular occurrence.

    Having the chain too loose on the other hand, can often see the chain being thrown from the sprocket, usually causing damage to the sprocket, sprocket carrier, chain, engine or a combination of all. In the case of Rotax Max, it can damage the radiator, resulting in more expenditure.

    Worst of all, it will leave you angry and frustrated as you watch the remainder of the race from the sidelines!

    First impressions

    At £19.99 the Chain Monkey is similarly priced to other tools for specific tasks in karting. We think it's at the top end of what you would expect to pay for a tool which is relatively simple in design and construction.

    Clearly, a lot of time and effort has gone into the branding and marketing of this product. Everything from the monkey cartoon character to the Tru-Tension website is well presented and polished.

    The Chain Monkey comes in a plastic bag with the usual cardboard hanger.



    Inside, we find the instructions and a chain monkey sticker. Everyone loves stickers, don't they?


    On one side of the instructions we find how to set-up the Chain Monkey.


    On the reverse, it explains how to use the Chain Monkey for day to day use.


    Chain Monkey Sticker

    The actual Chain Monkey comes pre-assembled ready to go.






    The chain monkey fits all karting chains from the standard 219 pitch direct drive chains found on Rotax Max, Honda/IAME Cadets and TKM all the way through to the HD 428 pitch chains found on KZ and 250 gearbox karts.

    General Usage/Observations

    The important and most time consuming element of the Chain Monkey is setting the Chain Monkey to the correct tension.

    To do this you need to mount your engine and tension the chain to your ideal tension.

    Once this is completed, you need to fit the chain monkey, wind in the main spindle/screw until you take up all the slack in the chain and then wind up the lock nuts to the orange nut.

    In practice, we found it hard to lock the two locking nuts together as they are low profile nuts which means you cannot get a standard spanner on the middle nut when they are wound all the way up to the orange nut.

    We found it was actually easier to wind up the two locking nuts to the orange nut and lock them together by hand.

    We then carefully wound the main spindle out, removing the Chain Monkey and making sure the lock nuts did not move. We then tightened the two lock nuts properly.

    If the middle lock nut was replaced with a standard profile nut, we think you would be able to lock the two together whilst they are hard up against the orange nut.

    Below is a quick video tutorial produced by Tru-Tension on how to setup the Chain Monkey.


    Below are some images of the Chain Monkey in use on a KZ kart. The engine was tight and we were setting the Chain Monkey to the correct tension.


    Hooking on the Chain Monkey


    Tightening the main spindle to take up slack on pre-tensioned chain



    Tightening the lock nuts. We found this easier to do after removing the Chain Monkey.

    Once setup is complete, the Chain Monkey is ready to be used in anger.

    When you have changed a sprocket or any other work that requires the engine to be moved it's time to take out the Chain Monkey.

    Hang the chain Monkey on the chain, tighten the main spindle until the lock nuts reach the orange nut, slide the engine forwards until the chain is tight then tighten the engine.

    Remove the Chain Monkey by winding down the main spindle and hey presto! The chain is set to your pre-set tension.

    We found the chain monkey really helped when making large changes to gearing which meant the engine was moving a significant distance. We could simply attach the Chain Monkey and push the engine forwards without worrying about the tension.

    Once the Chain Monkey was removed, we were left with the correct tension. It's worth noting that the tension had great repeatability and we were always left with the correct tension. It can be frustrating when you think the tension is OK and tighten the engine, only to find it's actually too tight or too loose. After all, nobody enjoys squatting down to tighten or loosen engine clamps!

    We all agreed that this handy little device helps achieve a consistent chain tension. It also takes about the same time as winding out the engine stop on the kart. 

    The design could be tweaked a little so that the main spindle is not required to be would out quite so far to un-hook the Chain Monkey, thus saving time. The “hook” part of the Chain Monkey could possibly be reduced in depth to aid with this.

    If you have a kart with an ill fitting engine mount or engine clamps you will still have the issue of the chain going tight when you tighten the front clamp or loose when you tighten the rear clamp. You need to make sure you engine is sitting properly on the chassis rails with no rocking.


    A great idea which takes the guess work out of chain tensioning. Ideal for the novice who is unsure of the correct tension and an aid to the experienced mechanic who wants excellent repeatability time after time.

    With a tweak or two, the Chain Monkey could be even faster to set-up and use. That said, the product is new to the market and the manufacturers are open to constructive feedback from customers.

    Edited by Heyhoe

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