Top end rebuild (Stuttering, Elec. Issues Prior) (Pic heavy)

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Good deal. That's a better way too look at it too -- preventative. Then you can avoid ten page threads that conclude with something you should have checked in the very first place. :lol:

Honestly though, I learned so much from this whole thing and if someone else got something from it, superb.

Starting a new thread for the rebuild.

 

Throttle shaft seals can really fool you. Quite often you won't be able to detect any sort of vacuum leak, because they're only leaking when the shaft is at certain degrees of rotation, not constantly.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

For that reason, I think I'm going to strip the rack again this winter and replace mine. They were new a year ago, but I have a bad feeling I used petroleum-based lube when installing instead of the stuff I got from Chacal.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

I agree, sign me up for doing the carbs realllly soon.
Not to mention the soda blasting..

 

So I just read this ENTIRE thread. Started about two hours ago, and just finished. At the end of page 9 I was about to suggest removing the mufflers and checking that you didn't have a plugged exhaust header.. it seemed like the only thing that hadn't been checked, double checked, and completely eliminated.

Glad to hear you finally figured it out! Congrats on learning your bike inside and out, and thank you for sharing the journey with the community here! I think I have learned a great deal from your discussion and repair that will help me in the future if (knock on wood) I ever run into such a problem with my own XJ.

Speaking of your problems, I should probably pull apart and rebuild my carbs soon, including gasket replacements...

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

I am going to be re-doing my carbs in the winter months here, and definitely want to ensure everything is good from a preventative perspective.

I've done some looking, and "throttle shaft seals" turned up inconclusive as to exactly what part of the carbs these are. If you could explain, or show a pic of where these seals are so I can examine mine, that would be appreciated.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

They're on the outside of each carb body, one on either side of the butterfly shaft. They're covered up by a c-clip and a washer.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

AHA! Thanks for the image, Andrew.

The far right circle in the image with the C-clip is typically slightly moist with fuel on my bike, and drips slightly onto the pan below the carbs.

I am DEFINITELY going to be re-working my throttle shaft seals.

Thanks again for the perfect image.

 

It seems like a more invasive procedure -- which it IS -- but if you can handle normal carb cleaning dis/reassembly, you can do the shaft seals.

Just work slowly, carefully. Make sure you look and see how the shaft springs are coiled and how everything works. It will help with putting it back together.

Also keep everything organized on your workspace so you don't mix up which bits go on which side of which carb and yadda yadda squared.

 

Im definitely up for the challenge, but where do I get the replacement seals?

Any other bits I should be replacing/examining while I'm in the carbs? I replaced the float bowl gasket, O-rings, float needle & seat this spring.

 

Message member Chacal here on the forums, or click the "XJ 4Ever" link at the top of the page. He'll have everything you need.

The only other thing you should look at when you have the bodies separated is the fuel rail between the carbs. Just like the shaft seals, the rubber on the fuel connectors starts to disintegrate.

 

XJ 4 ever .... Len has the seals, just click the logo at the top for a catalog and go shopping. Good prices, fast shipping, he'll see you right and knows these machines inside out. You'll learn a heap just from reading his Information Overload Hour.

These seals are not hard to replace but it does involve completely dismantling everything and there's alot going on in there so use your digital camera and some sort of storage system. I use clear see-through plastic take-out containers with clip on lids. You can see what bits are in them and write on the top with a Nikko marker what carb number they came from.

Don't even think about a carb rebuild without doing these.

 

The pilot screw o-rings, "beanie" screens, and float valve seat o-rings (if you didn't already.) Also check the condition of the rubber seals in the bottoms of the enrichment plungers.

http://xjbikes.com/Forums/viewtopic/t=31061.html

Plus, as Andrew pointed out, "fuel rail" components as needed (o-rings, plastic "tee" fitting, etc.)

MAJOR CONSIDERATION REGARDING MIKUNI THROTTLE SHAFTS:

Unlike the Hitachis, the Mikunis butterfly plate screws are peened on the backside to keep them from coming loose. You will need to carefully (VERY carefully) file the peened-over part off the back of the screws in order for them to be removed without chewing up the shaft. You need a small sharp precision file for this.

I also strongly suggest investing in the correct JIS screwdriver (Japanese phillips screws AREN'T phillips screws) for removing the butterfly screws. REPLACE the screws, and be sure to use Loctite when installing the new ones.