Author Topic: CB250RS progress  (Read 641 times)

Offline Oggers

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CB250RS progress
« on: March 22, 2022, 09:53:44 AM »
Things moving nicely. Crankcase halves now split - and no I did not need to remove the clutch. It all "looks" OK in there so I think this is where I will stop engine disassembly. Pic attached. I will though replace the large oil seal behind the drive sprocket and any other seals I currently have in the spares box. 

A few further Qs if I may

Anything else I should at least check whilst at this stage?
Balance chain - now off and awaiting replacement - thanks Dave. Fitting a rivet link - Do I use a rivet tool to deform the hollow pins so they hold the link in place, or is there another method?
I cannot see any discernible gasket material at the mating surface of the halves. Would it be wise to use some - Hondabond?
Ref. refitting the balance chain - I have only pulled off the front balancer weight and noted the marks. Is it then a case of aligning the painted links with the marks on all 3 sprockets and then refitting the front balance weight?

Frame is really nice after a clean. Like new!

Many thanks again

Offline Laverda Dave

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Re: CB250RS progress
« Reply #1 on: March 22, 2022, 10:30:24 AM »
Good progress Mark.
Do you know if the engine has been apart before as there should be traces of the old cement on the cases? Yes, use Hondabond, very sparingly, just a thin smear, you don't want it oozing into places where it shouldn't once the cases are bolted up.
Renew the drive side seal but be careful, use plenty of lube on the lip that fits over the output shaft and make sure the shaft itself is clean with no rust because you need to push the seal over the output shaft from the end and any debris could rip the lip of the seal (dont ask me how I know :().
There are also two seals in the rocker cover (rev counter drive and valve lifter) that will need replacing and asumming you have taken these items out for inspection or cleaning and also the kickstart and gear lever seals in the outer covers.
I had my chain joined by Andy Chain who visits Kempton Park selling...chains.
The Haynes manual explains in some detail about the balance shafts, you need three hands though as the chain passes over one of the balance shafts in the crankcase and you have to hook it over before you join the cases without it slipping from the mark (and trying to avoid touching the Hondabond!). You will need to put three marks on the new chain and these line up with the marks on the balance shafts.
« Last Edit: March 22, 2022, 10:31:55 AM by Laverda Dave »
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Offline Oggers

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Re: CB250RS progress
« Reply #2 on: March 22, 2022, 10:41:41 AM »
Dave

No - don't know if engine has been apart. Given the number of spares I have, and a few opened packets, it seems likely though. Cannot see much trace of cement... if any. Mating surfaces look pretty clean. Drive side seal - well I have 3 spares! Hopefully I will be OK. I have K/S and gearlever seal.

Rivet link - Guess I'll have to buy a tool - and a rivet link.

Balance chain alignment - understood. Pull the chain taut over the rear sprocket whilst rejoing halves perhaps? Yes will mark up new chain....

 

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