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Messages - Oggers
31
« on: March 22, 2022, 06:12:07 PM »
Dave
The balancer chain being pretty light is surely an advantage? Drive chains - final drive to wheel? - even my big Suzuki with a chain the size of the Titanic slip chains has a split link. Surely the balancer chain would not be under undue pulsation/torque ripple, as it is er.. balanced? ....but yes, I would prefer a rivet link, but just cannot find anyone to do it - Mr Oddjob may be an option for sure. Cheers for that.....
32
« on: March 22, 2022, 02:18:35 PM »
Right - I fear I may rock the boat here! I have ordered a new DID balancer (kart) chain and a split link for it. I fully realize that I perhaps ought to use a rivet link, but several problems.
I am not confident or practiced enough to mushroom out a rivet link correctly.
I don't have the right tool.
No-one around here can seemingly do it for me - despite several attempts with the local bike shops.
So, am I asking for trouble using a split link in lieu of a rivet link?
My thinking
Not much torque on a balancer chain - it's not like a drive chain.
Relatively small chain.
Cam chains operate in a similar way, and I have seen cam chains with split links.
Thoughts welcome as ever.
33
« 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....
34
« 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
35
« on: March 16, 2022, 02:33:54 PM »
Dave
All good stuff - many thanks. I have found that simply typing the part number into Google comes up with something! I do have a few parts though. I'll see how it goes. I have decided to take the plunge and split the crankcases. More out of curiosity rather than anything. I guess I should replace the balancer chain if I do - might as well!
Is the balancer chain a rivet link or the spring clip type? or neither!
36
« on: March 16, 2022, 10:05:15 AM »
Yes - thanks for that. I was forgetting the wasted spark CDI system employed. Sensor is on the ATU on crank - I think - so I guess it does fire twice per cycle. Brain fade by me. More used to old Brit bikes with distributors, points and magnetos.
37
« on: March 15, 2022, 02:42:13 PM »
Somebody wake my brain up please! On the 250RS and doubtless many others, I believe valve timing is basically achieved by lining up the marks on the cam sprocket and the head with lobes at 8 and 4 o clock when crank is at the T mark.
However, there could be 2 feasible positions for the crank at the T for this eventuality. Does it matter? Ignition Timing could be 180 deg out - or could it? If not, why not?
38
« on: March 15, 2022, 02:26:52 PM »
Dave
Lobes look OK - honestly!, but yes that rocker pad is a concern. I won't be doing too many miles on it, but it would be nice to get it - or both - right by replacing it/them with the spares. Reading your pins saga it sounds ominous but I'll give it a go. I have new rings and a new piston. Not sure about new gudgeon pin but for sure replace the circlips.
Just adjusted the balancer chain tension as per the book. It was slighly slack. New cam chain now on....
Cheers for the exhaust supplier. I'll think about it. £337 is probabaly fair enough, but on a bike worth 1500 or so? Motad looks almost new.
Tailpiece attached. Bit of a bodge touch up and decal is somewhat marked.
By the by - is there a parts list anywhere please? I have many spares where the number is there but the description isn't.
Many thanks again
39
« on: March 15, 2022, 09:56:03 AM »
Pic of the bore- thoughts welcome. Don't want to rebore
Pic of the rocker pads. Clearly I missed the obvious pit on the RH pad! Those locking pins could be an issue Dave!
40
« on: March 14, 2022, 09:36:07 PM »
Gents
As ever many thanks.
Firstly crankshaft camchain sprocket. Off with the RH cover and ATU and gave it a good looking at - thinking there is no way on Earth I am going to remove it without first removing the shaft. Haynes manual is delightfully optimistic in stating pullers may be used. Aye right as they say up here....So it stays. It doesn't look at all bad, but I will replace the chain - a Morse - and take a closer look at the camshaft sprocket. Tensioner blade/cushion looks fine.
Spare piston and rings are standard Honda parts. Bore again looks OK, and to the best of my knowledge is also standard. Very slight evidence of honing marks. Haynes suggest refitting cylinder and to check tolerances using feelers. I will do so and revert.
Miles are 32K. Rocker pads look OK but I will put up a pic later.
Engine ran fine. No discernable smoke but I didn't go far. Paint is indeed good and I have a spare tank in even better condition! The rack has been junked, but has revealed a tailpiece which could do with a wee paint touch up in some areas at least. Stonechips mainly. Paint recommendations welcome - maybe I could stretch to a complete repaint as the rest of the bike does seem to deserve it, failing that, touch up paint carefully applied and rubbed down?
Exhaust - in two minds about that. How much is a pattern pair?
Not got to balancer chain just yet......Forks just removed at the moment. I intend to replace the seals and the oil but that's about it. I do have a spare complete fork assembly for R/H side. No idea why! Guess I could use it, but would have to replace the spring in the L/H side perhaps?
I intend to give head/barrel and cover a repaint - thinking about vapour blasting then a good rattle can of satin black. Suggestions welcome. Upper crankcase half could also do with similar. Someone has done a DIY on all of these and it lets the side down. Don't intend to split the crankcases though!
Many thanks again...stand by for further questions as I progress - or not as the case may be!
Mark
41
« on: March 14, 2022, 02:56:01 PM »
Chaps
Managed to take a photo of my new steed. A 1980 CB250RS in very decent nick - well on the outside anyways. Hopefully an attachment at the end of the post.... Nice round headlamp - which I actually prefer, and I may even replace the square indicators with round to match....such heresy!
It is now all apart, engine out, head and barrel off, and now awaits my tender mercies to replace worn bits with the myriad of spares that came with it. Good news is that rockers, cam lobes and bore all look OK. Nothing too shocking I don't think. I'll just replace things as I go....A few Qs if I may
I have a camshaft sprocket and a new cam chain. it would seem sensible to replace them along with the crankshaft sprocket. Any clues as to how to pull off and replace the latter woiuld be appreciated. Haynes manual is a bit vague.
I actually have new IN and EX rockers in my pile of bits. Given Dave's troubles with the locating pins I wonder if it is worth replacing them? The existing ones look fine.
I also have both new final drive sprockets, but no new final drive chain. Dave Silver I guess, anywhere else?
Whilst the engine is in bits, is there anything else worth checking or replacing? I'll look at the balancer chain.
I also have a new piston and rings. Is is worth replacing the existing with these?
Many thanks
Mark
42
« on: March 03, 2022, 10:27:58 AM »
Dragon
Appreciate that - thanks. I really don't want to spend the money though. Good bike though it is, a CB250RS is never going to justify the outlay on things like a rebore and subsequent new piston/rings as you would never recover the costs. I appreciate that may not be the point for some folk, but at present it is for me. When I get it, I'll take a proper look inside and think some more, but PO seems to believe it runs well with no smoke or loss of power, so perhaps a philosophy of if it ain't broke then don't fix it may be in order here. Reading Dave's posts, cams and rockers would seem to fall into the same difficult to justify pot. I'll take the risk if they are not too bad, and definitely clean the mesh and replace the oil. Replacing bearings may be worth it, as would most consumables and chains, but that would be about it for me at least.
43
« on: February 28, 2022, 05:25:18 PM »
Bought it.....pics when it lands from the courier.....
Dave - stand by for some questions over the weeks! Intention is to strip it fully, fit all the (new OEM) consumables that come with it, and fix whatever needs to be fixed. May fit SS fastenings just because I like the look of them. I also want to delve into the engine. Cam chain and balancer chain would seem due for replacement, and I want to check out any potential for worn bearings.
Has a round headlight - which I prefer, and a Motad exhaust - which may or may not survive my aesthetically critical eye.
44
« on: February 25, 2022, 04:57:13 PM »
Dave
Once again many thanks. All advice is useful I feel. I haven't acquired the bike just yet, but if I do, for sure I'll check it out as you suggest. My problem with a rebore is cost and who does it. Up here in the wilds of Aberdeenshire you may appreciate that such delicate machining is something of a rarity amongst the tractor fraternity and the lump hammer appoach taken by the oil boys' machinists is not particularly encouraging- I should know as I am one of them....I'll give it some thought when I look down the bore for those tell tale wear marks!
45
« on: February 24, 2022, 01:54:05 PM »
Dave
Many thanks for this - much appreciated. If the cam bearings are gone are we talking new head? As for rebore I don't really want to go there as it simply is not worth the cost. If things have worn between rings and bore would it be worth simply replacing the rings?
Renewing balance chain - Was this easy or a pig?
I assume renewing cam chain and tensioner is easy enough?
Cheers
Mark
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