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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22749
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 1988 Honda Bros NT400cc which has always run nicely.

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I have a 1988 Honda Bros NT400cc which has always run nicely. The other day I went out on it, running as usual, did about 10 miles, stopped for a coffee, started up O.K. but then it decided to not run as it should. Alright up to about 35 M.P.H, but would not go above that. I struggled to get home, ordered a new air filter and fitted it, but although this improved it a bit it is still not right. Will now go up to about 45 M.P.H. and then strangles itself. Seems like it will start O.K. tick over O.K. and run all day at 45 M.P.H, but doesn't want to go any faster. Having changed the air filter, cleaned the fuel filter, cleaned and adjusted the spark plugs, and cleaned the breather, what the heck do I do now to get it running as it should. Lovely bike to ride, but maintenance is a pain in the A***. Hope that you can help. Regards, John.
Hello John

this sounds like the fuel isn't getting through to all of the carbs

So I'd next check that the float valve inside the lid of each carb is not sticking and so preventing the fuel from flowing freely

while you have the carbs off it would also be a good idea to clean out the galleries and jets with a blast of carb cleaner
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Customer: replied 2 years ago.

Hi Matt, Thanks for your reply. You have actually confirmed what I had already suspected, but hoped not, as the bike is a swine to work on. You have to remove the seat, petrol tank, side panels, air filter, and air filter housing, just to access the carbs. Oh, for good old-fasioned British motorcycles. Regards ***** ***** best wishes, Yours sincerely, John.

No problem John