Gummed up piston rings

[hawkeye]

I have old 1983 CM250 Honda, i noticed that it was hard to start cold. I checked compression and got 125 psi on both cylinders. I put a squirt of oil on both cylinders and got a reading of 150 psi on both cylinder and it started instantly. To me this is rings not leaking valve seats.

I started to strip the engine down but two of the eight head bolts are seized up in the upper crankcase, these bolts are at least 8 inches long so there is plenty of twist going on and i don't want a sheared bolt in ally.

I have decided to re assemble the engine and add additive direct down the plug hole to try and free the gummed rings. I think the bike has sat for a long time causing the problem as it only has 19k miles on it.

I have already tried Reddex for a couple of day but to no effect. 

Has anyone ever tried a mixture of Acetone and Reddex if so what quantities should i use, i'm thinking 50/50

Acetone is good for breaking down varnish so i have read.

 

Would like to pick someone's brain on this

[Ian Frog]

Just erring on the cautious side I would first check out some of the injector cleaners that claim to break down varnish deposits first.

At the very worst try reading labels in Halfords see if any of the active ingredients are listed.

Cheers

Ian

[Mississippi Bullfrog]

You could try some diesel, any lightweight oil with detergents can work 

 

One product I've had success with is a marine cleaner, Quicksilver Powertune. Available from boatyards or eBay. I have used it on gummed engines where nothing else worked. 

 

Johnson's and other marine companies do similar products that work just as well. 

[hawkeye]

I will look into these for sure, i have also been told Acetone is goods as it break down varnish (millions of women use it lol)

Certainly given me some things to try

 

cheers

 

[hawkeye]

Well i have used a 50/50 mix of Acetone and Reddex, i have done it for two days and have to say that it now start first stab on the button.  Ran the bike till it was hot then put it away to cool down. 

Will do another day then leave for a week (this was when it got hard to start) and do a compression test. More to follow later/

[hawkeye]

Just a quick update, using the the 50/50 mix did not help much. The bike does start if left for three to four days but the compression rato is no better.

Top end will have to come off. remove engine from frame, drill the heads off the bolts. Remove head and barrels allowing me to get the the base of the two stuck bolts. 

Will heat crank cases and use my cam stud extractor, but that in the new year.

 

Happy Christmas tom everyone.

 

[Tinkicker]

Here.  Just pour it dwn the plug hole and let it stand a week.

 

https://www.ebay.co.uk/itm/Marvel-Mystery-Oil-and-Fuel-Additive-Engine-and-Valve-Treatment-32-fl-oz-bottle/281448134413?hash=item41879db70d:g:zA0AAOSwGvhUEDe7&amdata=enc:AQAHAAAA4Ctpnq57NIy5sccu/wakx4mcL+9dfIO/PejIK3m5MyCHJxJODca+tOvofCgIovL2eojkCv2+oFu5/Hx0eerGjrr1trFSbRqC5yzRyJcaX1dEVFeU4e2fucBf3XXvueL6KgrHT4XbdnPy3I4idgj6uShDJfxMSPiEjEbN0AsEpNzg1cc88Jxyug1YK6ebJKS9NbjK3N3pjGAYpEI4s96KzG4t0TwK/SDMgDBJtVubT7ococL8KCkGj51MElFo8vYeyghdk1BYxvka95p+ReRpGmmv6VmBznXMD+la9ZIGJEUr|tkp:BFBMmo79oKBh&pageci=383b065d-17a8-46d9-b70f-9f93f5b35f45&redirect=mobile

Edited December 11, 2022 by Tinkicker