4k-5k RPM Hesitation in Any Gear

[akronevan2]

First off I'd like to say, WOW what a great forum! I am seriously loving this. I have a beautiful (well getting there) 1982 Yamaha XS400 with 5000 miles. Whenever I ride it, it whatever weather, in anytime of day, there is a hesitation and it loses power in the 4k-5k RPM range. I can bypass this by going downhill, skipping around in the gears, etc. I think it is a jet issue but I have no idea! Any help that I can get would be great. I plan on customizing it over the next year and will post pictures when I can. Thank you all!!

 

[bcware]

Has the bike been modified in any way? Pictures would also be helpful because you might not know something is aftermarket, like exhaust components.

Are there any noises that occur? The hesitation occurs every time you hit the described range?

Before giving any advice we need to know for certain what we are dealing with.

I am assuming there is no hesitation above 5k or below 4k

 

[HoughMade]

If the bike had not been modified, it's not a jetting issue. More likely a dirty carb issue. However, if it had been modified in intake or exhaust, perhaps jetting.

Before I went fiddling with the carbs, though, I would check the timing. You have the electronic ignition, so you don't have to mess with points (personally I like points better, but that's an issue for another day). Check the timing, coils and plugs. If those are OK, then turn to the carbs.

 

[akronevan2]

Thanks Hough, and Bcware,
I will post up pictures when the weather gets better, is their anything in particular that I should be taking pictures of?
Oh, the previous owner said that the original carb had gotten fouled up and he had someone give him another carb. Where did the carb come from, and what off of, I have no idea. I have had the carbs cleaned twice by "pro" shops.
If it were a timing issue wouldn't the bike be hesitating in more RPMs than just 4k-5k? How would I go about checking the timing on the bike? The plugs and coils seem to be fine but I will get in further with the coils to make sure. Thanks for your help.

 

[lhaolpa]

Make sure you have the correct plugs in it.Sometimes,the heat range will make the bike"bang-out"at certain RPMs,then correct themselves after speed increases. lha

 

[akronevan2]

Thought I'd post a link to my video of my bike.

 

[akronevan2]

I tried to post the video in the forum but it didn't work...

 

[g_raff350]

Also check ur valve clearance as well, never hurts to do that and also turn ur petcock to the prime setting while riding to bypass the vacuum opening the petcock just to make sure the carbs are getting enough fuel to keep the bowls full.