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Post by szabgab on Mar 16, 2017 15:47:31 GMT
what colour was the smoke was all ways taught black smoke= rings,white smoke =valves now its stripped you may as well do the lot and make sure bikeman It was mostly white smoke, after the bike cooled down completely. People suggested worn oil rings, as the piston shrinks whilst cold, also for the smoke to develop it needed a 20-30 seconds, or a good rev. Also the biggest smoke was coming from the right side, sure enough, right piston was the one gummed up (but again it was the right side of the head, that had gold discolouration in the cam area too) |
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Post by Deleted on Mar 16, 2017 16:23:56 GMT
Silvers have the 250 standard ring sets at £14.00 pattern and £29.00 Honda? Hi, sorry, do you mean davidsilverspares.com? They stock the 400n rings for 51 USD (about the same, as cmsnl)... Them being a US supplier would ship forever though  David Silver may have expanded into America- but he is a Brit. I also now know we are on about a 400 not a 250! £30 from his UK site:- www.davidsilverspares.co.uk/parts/by-part-number/partnumber_13011413025/Pistons have to be measured across the skirt- not the top as the diameter is normally reduced above the top ring. Standard 400 pistons were 70.47-70.49mm with a wear limit of 70.40mm. But you would hit the piston/bore clearance service limit way before that. You have to measure rather than work blind.... |
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Post by szabgab on Mar 16, 2017 16:33:31 GMT
Hi, sorry, do you mean davidsilverspares.com? They stock the 400n rings for 51 USD (about the same, as cmsnl)... Them being a US supplier would ship forever though David Silver may have expanded into America- but he is a Brit. I also now know we are on about a 400 not a 250! £30 from his UK site:- www.davidsilverspares.co.uk/parts/by-part-number/partnumber_13011413025/Pistons have to be measured across the skirt- not the top as the diameter is normally reduced above the top ring. Standard 400 pistons were 70.47-70.49mm with a wear limit of 70.40mm. But you would hit the piston/bore clearance service limit way before that. You have to measure rather than work blind.... Well, mine is 70.39, so I guess, it is really ready for a honing. Is there any point of replacing the rings? Also, if only the rings are to be changed, do you have to change the bearings too? I have been told, the compression gets too high for the old bearings... |
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Post by szabgab on Mar 16, 2017 16:37:01 GMT
Also thanks crouchy for the info. I have spoken to them, the guy on the phone definitely sounded British (also the +44 number gave them away  ) ) |
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Post by Deleted on Mar 16, 2017 18:45:22 GMT
We always called blindly replacing the rings as a "Poor Man's Rebore"- much favoured by dodgy bike dealers to cure a smokey engine as cheaply as possible! I am afraid there is no hard and fast answer as what to do now. Probably new standard rings only, will sort the bike out for a few hundred sunny day miles each year. I would always put new rings in anyway even if the engine was ok and all the measurements were within spec. For Honda- they gave a service limit for the bore as 70.60mm. And a service limit for the piston as we said of 70.40mm. So you would think you could go to the limits of both and have a maximum piston/bore clearance of 70.60-70.40 =0.20mm. But the catch is Honda state that the piston/bore clearance wear limit is only 0.10mm- because both piston and bore wear- piston gets smaller- bore gets bigger. So your piston is just under the piston wear limit- but we don't know what the bore measurement is. You could have an enormous gap- does the engine burn oil at all?  If it makes you feel any better- very few people actually take any measurements and just bung in new rings.... |
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Post by Deleted on Mar 16, 2017 18:47:04 GMT
As to the direction I would go- check out the price that Silvers is banging out brand new 400 cylinders?....
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Post by wazzbo on Mar 16, 2017 18:54:40 GMT
Hells bells, I`ll take 4 at that price..
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Post by Deleted on Mar 16, 2017 18:55:43 GMT
I reckon a mistake.....
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Post by wazzbo on Mar 16, 2017 18:55:55 GMT
cms want 638 euro +vat
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Post by wazzbo on Mar 16, 2017 18:58:53 GMT
I see he`s selling usa parts over here now, we couldnt buy them from his usa site when he first set it up could we
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Post by szabgab on Mar 16, 2017 19:16:38 GMT
Hah, yes, I would take one of the new cylinders, plus some pistons... I reckon, if correctly priced, they would cost more, than the cylinder  Bearing wise - do they not to be changed, if only the rings are swapped? But again, this poor machine is getting trashed around Budapest by me all summer and winter long, probably would deserve a new bore. I love it to bits, even if a scoot would serve me better |
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Post by Deleted on Mar 17, 2017 7:33:47 GMT
Which bearings? There is no connection between compression and whether the bearings can handle it. I suppose if an engine is clapped out enough to need a re-bore, high mileage, bad history, low oil pressure, rumbling noise, etc. To. Then the bearings may need looking at- but if all seems well most people leave the bottom end alone unless they have to.....
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Post by Deleted on Mar 17, 2017 11:40:21 GMT
will be buying myself some rings very shortly
bikeman
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Post by szabgab on Mar 17, 2017 11:43:43 GMT
Which bearings? There is no connection between compression and whether the bearings can handle it. I suppose if an engine is clapped out enough to need a re-bore, high mileage, bad history, low oil pressure, rumbling noise, etc. To. Then the bearings may need looking at- but if all seems well most people leave the bottom end alone unless they have to..... Oh I'm glad to hear that. This robber disguissed as THE local classic bike repairman was claiming, that if rings were to be swapped, the bearings would have to be changed too, lots of money for him obviously. What is the situation, if the whole cylinder, rings, pistons, the whole lot are changed? The bottom can stin stay the same? Thanks! |
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Post by srx600 on Mar 17, 2017 18:41:53 GMT
I'd consider taking it to a rebore place as they can get rings for just about anything, takes all the worry out of it. In the past rebore guy knew a company that made rings so me would measure up and make them fit.
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) ) 
