High idle. Throttle sticking?

So it's not just a high idle I'm having, sometimes it's too low, and I can't adjust it to stay the same at all times. Sometimes it'll run ok and then I come to a stop and the thing idles ridiculously high. So I turn the knob down. But it never sticks to where I set it at because I think the throttle is messing with it. I had it idling ok at home and when I gave it gas, the idle went super high and never went back down.

 

I'm trying to upload a video of it but it doesn't seem to be letting me

 

I had similar symptoms when I had a needle diaphragm in the carbs out of place. Depending on it's position, it would let some air and gas in, but probably not at the right mixture and it would run rough. Have you checked those diaphragms for pinholes/tears/improper seating in the carbs yet? Once your carbs are all in one piece (still off the bike), if you manually push the needle valve upward it should fall slowly but smoothly back into place due to the vacuum formed by the diaphragms. If you have one that slams right back down, you aren't keeping enough vacuum above it and it may not be moving the needle properly.

 

Start with the basics and keep it simple, check throttle cable and choke linkage to ensure everything is free and not caught up . that little adjuster by the handlebars can be tweaked for some fine tuning,
Carbenrichment circuit could also add to these symptoms ,

 

Hi, welcome, please, first off, at the top of the site, where you see your name, select your name,a dialogue box appears, select signature and add your bike, ex, 82xj650, that way we all know what you ars taking about, that being said, please read the following links, there is a ton of great info from folks who a really smart with these bikes...do what they say and I promise you, you will not be sorry, here are the links....


http://www.xjbikes.com/forums/threads/in-the-church-of-clean.14692/

http://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/#post-233801

 

I will add that the symptoms are indicative of throttle shaft seals that are in need of replacement.

 

The choke seems okay, any adjustment changes the engine so it's working properly. And the adjustment by the handlebars is ok too we checked that. Another thing is, when I come to a stop sign and it's revving super high.. I can calm it down if I let off the clutch a bit, and pull it back in

 

And thanks I'll look into that

 

does it work when cold and act up when warmed up? if so you want to do a propane test at all the seals and connections (carb to motor manifold , boots to airbox) throttle seals on carbs vacuum ports and lines. engine will rev up when you get to any leaks

 

I think there's a vacuum leak. I heard if you spray beakleen near those boots while the bike is running it will Rev high if there's a leak, which it does. I just didn't see what that had to do with the clutch

 

what problem are you having with your clutch?
you can use propane (unlit) to do that test it is a little safer than brake kleen,
if you are talking about the airbox boots you can coat them with liquid electrical tape to fix untill you can get some new boots.
check your throttle seal s for leaks. sounds like you may have more than one leak

 

Scrubbing the intake boots (both airbox and carb) and coating them with RTV (making sure to fill in the cracks) is essentialy a permanant repair. That's what we had to do before reproduction boots were available.

The key to the propane test is to go slow and try to pinpoint where the leaks actually are.
Again, the changing nature of the symptoms are indicative of the vacuum leak being at the throttle shaft seals, but that does not mean those are the only leaks.

 

I agree there is a vacuum leak(s) somewhere.

Gary H.

 

Yea I assume that's it. I'll get to work this week on it. I can replace the boots, but I've been looking into getting air filter pods to replace the rear boots and ditching the factory air box. Anyone have any experience with that? Idk how hard it is tone adjust the carbs and whatnot after that

 

You are in for an adventure. My best recommendation is to just not do that.

 

+1.

Gary H.

 

That's unfortunate

 

And yes im only having my issue when the bike is warmed up

 

Where does one get liquid electrical tape? I didn't know there was such a thing

 

No it really isn't. Unless you think pods look cool and that is the only reason you desire them.
These bikes were designed very well with an air box.

Not sure about liquid tape, I used RTV and stretched a section of bicycle inner tube over them (carb to engine boots).
http://xjbikes.com/Forums/viewtopic/p=330799.html#330799

 

You will find it in the electrical section of any decent hardware store. I prefer the Gardner Bender brand as it does not dry out during storage, unlike the other brands that I have used. It is great for repairing pinholes in the vacuum diaphragms (and for electrical repairs), but as mentioned earlier RTV is what you want to repair the intake boots. Get black, oil-resistant RTV.

 

http://www.xjbikes.com/forums/threa...-pods-and-4-into-1-exhaust.29381/#post-251972
It's called "Success stories of pods and 4 into 1 exhaust", but it kinda dissolves into arguement here and there... Seems you need to get into rejetting the carbs to make it work. or not work. or blow up the engine. or have the best XJ on the block. Seems risky to me...

 

Auto parts might have it too. AutoZone sells it. It's in a can similar to purple primer near the shrink sleeves in the electrical section.

Gary H.

 

Pods = nothing but problems......keep your intake stock.....advanced warning....

 

Ok, I wanted to eventually do a 4 into 1 exhaust with rejetting the carbs but if that's that difficult to do.. maybe I'll bring it somewhere. Any experience with exhausts?

And I'll try the RTV tonight thanks

 

You might be able to do a 4-1 exhaust without re-jetting. Putting pods on the air intake side of the carbs will cause all the problems.

Gary H.

 

I guess that's not important right now. Getting it to run right first is, but it will definitely need a new exhaust down the road. Needs some sound

 

Guess I won't be doing pods

 

I've never done a carb cleaning on this bike yet so I'm sure it needs it. I'll be doing that eventually, maybe hiring someone to tune it with a new exhaust. Just not sure if I should rejet the carbs while I'm at it? This is a bobber project so I'm not keeping much factory. Altho if pods are as difficult as you say then I'll leave those alone

 

1. Do your own tuning. You can look far and wide before yuo will find a shop that is actually good at working on 30 year old machines, and if they really are good you will be charged accordingly.

2. Go ahead and clean the carbs now. You may find some responsiveness and HP that was missing from them being dirty.

3. The carbs will be coming off several times if you find that you need to rejet with a 4-1 system.

4. There aren't many choices for aftermarket exhausts that are of any decent quality (by decent I mean at least as good as OEM in terms of materials).

5. Everyone with a hacksaw is doing a bobber (and mostly not paying attention to what a real bobber actualy looked like). Why not consider doing a period-correct race themed build. That will get you far more looks and questions than a bobber will.

This is a (mostly) period correct XJ750 Suzuka endurance replica (sort of. it actualy uses a later engine, but this is very much like what the endurance bikes looked like at the time).

 

That's a sick bike man. I guess I shouldn't have said bobber because im not rly doing the bobber seat. Just want it not factory that's all. Here's what I got so far. Nothin too crazy. Redone rear, some changes to the front, still needs a round headlight. I'm satisfied for now..
It just needs to sound good

 

.

 

Oh that's nice. Tasteful mods.

 

K-moe, are those PODS on your picture??
Also, where the heck can I get a rear end like that? Disk brake with shaft? Sweeeet! And those rims!! Pretty unusual to have a rear tire that skinny on a bike of that style. And the exhaust!! Titanium? Just guessing based on the way they made the curves in sections. I have serious parts envy!
Now, back to reality.
Shanesajda, that's an decent looking set of mods. I have tons of questions! What gages are those? Did you relocate the warning lights? If so, where? Can I see a picture of the rear? Wanna see how it looks without the plastic tail section.
Thanks
Matt5

 

Thanks guys.

@MattiThundrrr so the gauges came off a 79 honda cb350. It was a pain in the butt. There's a diagram on here somewhere that explains how to wire it, I'll try and find it. The tach can't work cause it's mechanical so I only use that side for the neutral light and blinker light. Altho my neutral light never goes off... (need to figure that one out still) the warning lights / fuel lights are gone, removed

 

Trying to upload pics.. always have issues with the uploading on this. I'd like to make a build page for my bike but idk how to figure that out either

 

I'll take some more Tomorrow. But yea I think it's better without that car bumper... and square signals. Got these off ebay. Doesn't look like a while lot but I had to make brackets for everything. Even the headlight which I lowered a couple inches to look right with the gauges.
The rear, I just flipped the signal brackets upside down, new lights went right in. Made a bracket to mount that light/plate bracket

 

Thanks for the pics and info. So is there still some of the rear fender under there, or did it all come off? I'm trying to figure out what to do with my rear section... and headlight... and gauges... and turn signals... and mirrors... and... and... and...
So much to do, so little CA$H.

 

The entire rear came off. No fender

 

All in all it wasn't too costly. The bars were the priciest at 80 bucks, bought from biltwell.