The Old Lawnmower Club
Collection, Preservation and Display of Old Lawn Mowers

JP Mini Mower - Chain Adjustment

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RansomesRob

Hi folks.

Getting my JP Mini Mower ready for the lawn cutting season today and have come across an issue that I need help with please.

When I was moving the mower forward and backwards it was occasionally seizing and would not move forward.

I removed the Chain Cover and noticed the centre sprocket was loose and could be moved backwards and forwards and up and down.

On the inside of the side frame is the sprocket stud nut that when loosened slightly allows the chain to be raised to tighten the chains and lowered to loosen them.

I cannot seem to be able to tighten the sprocket stud so it stays securely tightened? 

When the nut is tightened it stops the mower being able to move forwards, slacking it off allows the mower to move but the centre sprocket can be moved backwards and forwards again.

Hoping someone can tell me what either I am doing wrong or tell me what I need to remedy the issue.

As always, thanks for any help you can offer.

Cheers.

Rob

Forums

RansomesRob Sun, 06/04/2025

Hi folks. After further tinkering this afternoon,  I think the problem is the chain has maybe stretched over the years?? It is too long and is either coming off the cog teeth or, the cog teeth are missing the gap in the chain links and are hitting the edge of the chain therefore jamming. I have tried multiple adjustments on the chain adjuster to no avail.I have been able to tighten the adjuster nut now so it does not spin around rather than fully tighten.

Photos to follow. Cheers. Rob

RansomesRob Sun, 06/04/2025

Hi folks.

Photos showing what I think is causing the issue with my Mini Mower.

I am assuming that over time that the chain has maybe stretched?? and is now too long. I intend to get a link removed to see if this helps matters? 

The removed chain measures 16 and 7/16".

chirpy999 Sun, 06/04/2025

Certainly could be a worn chain . Remove it by taking off the split link and measure it. Try Ebay or a bearing supplier/ motorbike shop for a new length of chain , it wont be more than a feew pounds.

Clive1997 Mon, 07/04/2025

Hi Rob

Will check our bits as we did have a mini mower in bits & scrapped the parts, I usually keep chains but not sure. Also have a complet  mini mower which has had little use,  can check chain measurement on that. Will be in touch.

RansomesRob Mon, 07/04/2025

Hiya Chirpy. Thanks for your comments. Took the chain off yesterday and it measures 16 and 7/16' long. A mate has offered me a loan of a chain breaker to remove a link and Clive has kindly offered to see if he has a chain available from a dismantled machine. Cheers. Rob

RansomesRob Mon, 07/04/2025

Hiya Clive. Thanks for your reply. The chain measures 16 and 7/16". A mate has offered me the loan of a chain breaker to remove a link BUT if you should have one available I much prefer to do that in case removing 1 link is not enough and removing 2 might be too much.

Cheers. 

Rob