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Post by jr1 on Jul 13, 2022 21:57:11 GMT
Hi all
so my 2,750m 250 delux runs excellent takes a bit of starting from cold but that’s all, it also smells and sounds right and when I measure the temps on the headers it’s 76deg on both sides.
now my 400nb starts really easily hot or cold, idles well and rides fairly well. I have stripped the carbs and gone through the bike as it’s only done 1650m from new, so it’s stood most of its life.
I went to work on it yesterday and it just isn’t quite as crisp as I think it should be and it doesn’t sound or smell like my 250.
mixture is set standard at 1.5 turns
new plugs fitted and carbs cleaned and balanced. New o rings fitted on the inlet rubbers and new copper seal in the exhaust headers.
i noticed yesterday that it appears to be running a little hot and there is the start of some yellow discolouration on the right hand header following a recent re chrome nothing on the left header.
I checked the header temps the right was 96deg and the left 86deg. When compared to the 250 having completed the same journey the temps were 76deg, so the 400 is running much higher.
both bikes are absolutely standard specification.
hope the above makes sense.
any Ideas appreciated.
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Post by buster on Jul 14, 2022 8:33:24 GMT
the 400's will likely run hotter than a 250 (when honda took them out to 450 they fitted an oil cooler) if it starts easily I'd rule out stator/cdi/coil (for now), it sounds like it may just need a little tweak to one of the mixture screws, if they are 'right' ie all components in the right order, pilot circuit nice and clean (easy starting suggests its good) then 1.5 turns is a safe starting point, tiny adjustments can make quite big differences, some can do it by ear, on a twin I use plug colour as an indicator
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Post by jr1 on Jul 18, 2022 7:07:37 GMT
Thanks for the reply.
Good point that the 400 runs hotter. The temperature difference between the cylinders temperatures is the main concern, so I will go back through the carbs to double check.
I have a colour tune so I will try that out to check the mixture, in fact I’m probably best to do that prior to any other work as a bench mark.
I’ll brave the heat tonight and have a look that should sweat some kgs off !!!
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Post by dick on Jul 18, 2022 8:21:11 GMT
apparently measuring the header temps is done from the exhaust collar, not the pipes themselves, as they will reflect false readings info sourced from mr.hillyards various videos.. and one side note, if the bike has been stood most of its life...use it !
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