RPM Surge

Hi guys,

I am hoping for a little help with my XJ650 maxim 1981

The issue I'm having is that after it sits for a couple days, when I go to start the bike it revs up extremely high (as if the bike was full throttle). I do this a few times, and the bike idles normally.

I was cleaned the carb, everything seems to be fine in there. It was leaking gas into the air box & draining out of the over flow in the air box. But now its not leaking (even when i turn the petcock to "pri" or "on" it doesn't leak). So I am assuming that float needles are now working fine since the leak has stopped, but I am still unsure of why this is happening.

Thanks guys,

 

You should leave in ON position if you have stock vacuum petcock and it is in good shape, fuel will only flow with engine running. I your float valves are leaking the fuel in float bowl can overflow into airbox or worse into the engine and into the oil sump. You state you cleaned carbs, did you check the float needle valve ...were they replaced? or if rubber tip was there a ring at top , or were they hard? are you running a filter? Were your carbs synched ? Inquiring minds want to know.

 

I cleaned everything that was there,
The float needles were quite off, 3 without rubber 1 with rubber... I assumed that this meant they were changed. But perhaps just warn off.
I will order 4 new carb rebuild kits & change out all of this. This is what I thought was the issue, glad I have a second opinion.

Have a bran new air filter, with the stock filter box.

Carbs were bench set, but once I get this dealt with ill hook up the manometer to them so it's perfect.

Thanks for the help! I'll keep you posted!

 

Good man ,glad I could help recommend xj4ever for the float needles I went with the metal tip ,as the crap fuel we use breaks down the rubber over time.

 

Check that the throttle cable is clean, lubricated, and seated/ routed correctly. Also check that the throttle tube is also clean and lubricated with graphite, or a dry-film lubricant.

 

Had this same problem on my 82XJ650 Maxim... Bench Synched Carbs, Got Carb rebuild kits, Clunk Tested O.K., Only thing I didn't do is replace fuel mix screws or o-rings because they were sealed with that brass cap. Was just going to sell her, but after reading this, I think it's back to the church of clean and setting the float levels correctly. One person had this same issue back in 2012 and said something about backing up an e-Clip or something I haven't heard of yet. If you have figured out what caused your issue yet, please let me know. I'm new to working on Motorcycles and have read a lot on these forums that really helps. Here's a video of what happens with mine.

 

Michael, welcome aboard. Best to start your own thread, easier to reference.
Where did you get your carb rebuild kit from? Did you break the rack completely apart?
Does the idle stay elevated at that 6k mark?
Valve clearances checked? (dang I miss BigFitz)

You need to get yourself a small sheet metal screw, carefully - really carefully, drill a small hole into those brass caps above the adjustment screws, don't drill too deep, just deep enough so that you can get the sheet metal screw to grab purchase of that brass cap. You will then use the head of said screw as a handle for pulling the cap out. They come our relatively easy (at least mine did). In fact using an appropriate tool with a sharp edge you could see if any of those caps are raised a tad and try prying them up prior to the drilling thing.

Church is a good place to go.

 

e clip is what holds the throttle shaft seals in you can see them on the outer carbs

 

hey it looks like this thread has been dead a while. Anyone figure out the issue to michael’s problem? Having the same issue right now and I cant crack it

 

Nick,
Have you done a “complete” carb rebuild? Broke the rack and replaced all rubber bits and pieces?
You can’t do a half-arsed job of rebuilding the carbs and they DO need to be rebuilt.

Check your valve clearance lately?

Not knowing anything about your history here I’m gonna throw this at you and say “good luck, keep asking questions until you get the answer you understand.”

read this: https://www.xjbikes.com/forums/threads/in-the-church-of-clean.14692/
The this:
https://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/