1982 CM450E Honda

[gdavis211]

Looking for some ideas on what might be wrong with my 1982 Honda CM450E. I have had the carbs rebuilt and it is running fine EXCEPT for when you are cruising about 40MPH and it bucks and cuts out. It sounds like it is LEAN. It has stock pipes and only 6900 miles on it. A friend says I need to raise the high speed needle to let it get more fuel and less air. I have looked at pictures online and I see the clip for the needle. What I need to know are there slots in the needle to raise and or lower it? I am at wits end. I have had the carbs synchronized and the guy said that I have to get it good and hot to run right because it is so lean. Well I have got it good and hot and it gets better but still not right. It idles perfect and runs out great. There is just the point in between where it won't run right. Any help would be GREAT!!
Thanks Gary

[storysunfolding]

Are you using a nonstock airbox or pod filters? I could see running lean as causing you a flat spot but the bucking seems to me like you have crumb in the carb. What do your plugs look like?

After the carbs were cleaned was a fuel filter added between the carbs and the petcocks? If not then some trash in your tank may have flowed down and clogged up part of your carbs.

[gdavis211]

Good thoughts but the carbs have been off and worked on 2 times by this shop and he said the carbs were fine. The tank is clean. Everything is STOCK. Like I say the only thing I can think of is jetting or raising the needle if is is possible to raise it. I need to get a book but I have not got one as of yet
Thanks

[storysunfolding]

Well here's a quick way to be sure. Run the bike up at 35 mph where it's still getting fuel. Hit the engine cut off switch and coast to the side of the road. Pull the spark plug. If it's white, then it's running lean. That way you know for sure.

Otherwise- check out this site for more info about the needle settings. lots of honda guys over there.

http://www.hondabikes.net/forum/

Also- if you haven't already, buy an inline fuel filter between the petcock and teh carbs. Costs about a dollar at the autoparts store and is entirely worth it. Sediment builds up in tanks over time and I still think that's the most likely culprit no matter how many times the carbs have been broken open and cleaned.

You say your tank is clean. Has it literally been professionally cleaned or are you simply not seeing any rust in there?

[BuzZz]

Does it only cut out and lurch at 40 mph, or at any constant, steady state throttle opening?

It could be a vacuum leak or a hole in a carb slide diaphragm causing it.