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Post by davidchef on Jul 24, 2024 8:30:23 GMT
Hi, I have purchased a CB250N A, it has a dream tank and panels with a single clock. It is not running properly (only getting 50mph and then bogs down) and I am trying to get to grips with the issue(s). My first steps have been to ride it, clean it, take the carbs apart (90 and 110 jets, no o rings or washers!), buy a cheap set of clocks and refurb them, adjust valves, check timing and advance, fit indicators. It is enjoyable journey so far and I intend to replace the chain as the existing is worn and buy a carb kit to sort out that situation. If anyone knows a good source for a carb kit other than David Silver I would be grateful. And any pointers you might have in setting up would be good.
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bazzer
Full Member
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Post by bazzer on Jul 24, 2024 18:54:37 GMT
Hi David, welcome. Everyone loves lots of pics on here and will also give some fantastic advice mate. Good luck with the rebuild. 😀👍
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stevegbr
Administrator
ADMIN
BIRMINGHAM
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Post by stevegbr on Jul 24, 2024 19:22:35 GMT
hello and welcome to the forum.
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ian
Member Of The Year 2019
Isle of Man
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Post by ian on Jul 24, 2024 19:25:47 GMT
Hi David welcome, and good luck with the project. When I had a 250, I found NRP had a good selection of SD carb bits of decent quality, including Keyster kits. I've only got my 400 now & they don't have much trouble with carbs - it's usually the CDi with them. nrp-carbs.co.uk/shop/index.php?route=common/home
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Post by tucksie on Jul 25, 2024 6:03:17 GMT
Hello and welcome.
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Post by davidchef on Jul 26, 2024 20:02:33 GMT
So far I have cleaned and replaced o rings, jets etc in the carbs. The front sprocket and chain hàs been replaced. I found a set of clocks on eBay, bit of a mess and full of spider eggs and general rubbish, amazingly all the bulbs were fine! I've dismantled and cleaned and put back together and they are now on the bike. In striping down and cleaning up the rear wheel and hub I realised the nut holding the rear brake rod in place is just a nut and bolt not the normal captive bolt , nut and split pin! I've put a lock washer and lock nut as a temp measure whilst I wait for new bolt, nut and split pin to arrive.
A quick run up the road this evening and straight up to 60moh at about 4,000 revs no problem, does that seem about right?
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Post by na44superdream on Jul 26, 2024 22:30:06 GMT
Check your gearing, 15T front 41T rear?
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Post by alfie on Jul 28, 2024 14:49:36 GMT
Something wrong there, either speedo reading too fast or rev counter reading slow.....checked today 4krpm is about 38mph and 60mph is 6.5krpm, currently using 15/42 final drive ratio, about 2.5% overall lower ratio than standard.
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Post by davidchef on Jul 28, 2024 22:35:18 GMT
I have checked my ratio and they are correct. Rode round and put fuel in tank and rode up the local dual carriageway for 20 miles and the bike pulled okay up to 70mph, settled back to 60 and the rpm was about 6.5k. I can only assume the short ride with newly cleaned and fitted clocks did not have rev counter working properly. Bike still missing from time to time at steady 60, I am guessing ignition advance not right or old coils playing up, would that be right?
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