Author Topic: CB250RS Rebuild Progress  (Read 12776 times)

Offline K2-K6

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Re: CB250RS Rebuild Progress
« Reply #135 on: February 11, 2019, 10:44:15 PM »
Cautious optimism then, hope it's going to run without issue this time.

To be ultra cautious regarding running hot if that's the case. Worth considering the plug temp grade given that it holed a piston in one of it's previous builds.
Overheating the plug tip can lead to pre-ignition which puts the piston crown at risk.  I wouldn't run the lower range 7 NGK choice but either 8 or even 9 if that's in the manual for this engine.  Don't know what you've got in it but the higher numbers will give you more safety margin if they run ok.

Offline Laverda Dave

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Re: CB250RS Rebuild Progress
« Reply #136 on: February 12, 2019, 12:49:14 PM »
I have an 8 fitted at present Nigel but may go up to a 9. What I am making sure of doing is planning my route where I don't sit in traffic. I'll stick to riding around the Chalfont/Amersham and Aylesbury areas until the engine is properly run in.
James, I'm using mineral oil, I don't think I'll run this engine on a semi synthetic. As the engine only holds 1.5litres of oil, runs hot and works hard I'll change the oil every 750 miles to give it (and its owner!) an easier life.
1976 Honda 400/4
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1978 Honda CB400/4 'Rat' bike
1982 Laverda 120 Jota

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: CB250RS Rebuild Progress
« Reply #137 on: February 12, 2019, 02:03:04 PM »
You deserve for it to be OK, you have persevered above and beyond. I hope it keeps going well for you.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Laverda Dave

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Re: CB250RS Rebuild Progress
« Reply #138 on: February 12, 2019, 02:50:21 PM »
Thanks Julie. My fingers and toes are crossed this time!
I cannot belive how much quieter the engine is though following the latest rebore, its a different bike!
I'm sitting on a train on my way to Westenhanger now to collect the fairing. I think I'll be sending it to Menno for a respray to match the tank etc he painted last year. Just wish I could find the engine bar.
1976 Honda 400/4
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1978 Honda CB400/4 'Rat' bike
1982 Laverda 120 Jota

 

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