when i throttle it dies

Hi guys-

So I just finished cleaning my carbs for the first time. Wow, that was not too bad. You guys are great. Every detail, even the oring in the pilot mixture screw. I got it on the bike and I got her to idle (although it starts low and then after awhile jumps really high- when choke is open). When I close the choke, the rpm drops below 1000 and it dies. Whats up with that? I am just about to finish building the YICS tool. So I will synch the cabs with that. I also purchased a colortune (still in the mai) and as soon as that arrives I can tune. I dd have this issue that concerns me. When I turn the throttle, the bike just dies. Did I do something wrong when cleaning?

thanks xj-brain---

seca550_sf

 

I'm guessing a carb sync is required. Did you bench sync before you put the carbs back on. Screw the mixture screws right in(gently) and back out two and a half turns as a good setting before your coulortune arrives.

Then sync the carbs. Screw the idle up a bit to keep it running long enooough to adjust it. If it runs smoothly on choke then the enrichment circuit in the carbs is clean so your half way there.

Keep at it.

 

Glad to hear of your success so far. I have to echo Goon here, I'm deducing that insufficient clearance was set on the butterfly valves. You can adjust them with the sync screws. Set all of them with a standard, either a small 0.020 or thereabouts drill bit or similar, wire gauge. I think that would be helpful as well.

 

If it runs better with the choke out , what does that tell you? It needs fuel! Some of your mixture screws are too lean so when you colortune it you will find that some are hitting intermittently. Open these up for a nice blue color and it will start to run. Once it does be certain to drop the master idle screw, (back of the carbs in the center) back down to around 1000 to 1100 RPM. Then colortune the rest of the carbs. I usually hook up the carb sync tool while colortuning at a carb clinic. This way I can moniter the changes. If you don't hook up the sync remember to plug the vacuum hose to the petcock or your YICS tool will be canceled out on #3 cylinder.

 

Hi-

I'm almost done. Thanks for all the encouragement. I want to make sure I do this right. I am trying to correlate the parts that you mentioned with the diagram below. Wow.. how noobish am i? BTW... sorry for these vary basic questions.

mixture screw = pilot screw
Screw the idle means the throttle stop screw

When I cleaned the carbs, the butterfly valves (i didnt know what this was for the longest time i do now though) were not completely closed. These valves are not suppose to be fully closed when the throttle is closed right? I did see some light through it when the throttle was fully closed. However, it wasn't much (i could not run a naked twisty tie wire through the valve gaps when the throttle was closed). I dont have the exact measure. I did eye synch the valves. Should I just play around with the idle screw or should I break down the carbs and use the feeler gauge? If I do take the carbs down, I would measure that there is .02 mm space between the valves and the throat when the throttle is closed, right?

HG mentioned I should turn the mixture screws in and then 2.5 turns out. When I turn it in, how do I know that I have turned it in enough? I am afraid I might break that pilot screw. BTW, I can reach these screws w/o having to take the carb apart right? It seems so delicate? Hopefully the XJ cd will tell me what needs to be done when using the colortune and the yics tool. When using the colortune, I will be adjusting the combination of the mixture screw and idle screw. When using the YICs, that will involve using the synchronizing tool.

Just as a little anecdote, after getting the carbs back on that bike and having it fire up (although not to well ) i was dancin for joy in the garage... unfortunately, the garage door was not closed so all my neighbors must think Im crazy now

 

How do you get these pictures to show up so clearly and large but I can't get a picture to appear larger than a postage stamp? Secret code or are you greasing the right palms?

 

ah.. something i can possibly answer...

well there is that insert image widget which creates those [ img ] ...[ / img ] tags... Which im sure you already know. The image that is attached to the post retains the properties of the source image. The image I posted comes from this link:

http://sweb.cz/xj550/Mikuni_BS28a.jpg

which has the width 909 px, height 1235 px and file size 89KB. So the image file is relatively big.

lemme try:

here is a small image 246 x 165 pixels- 34k


here is a LARGE image 1813 x 1177 pixels - 169k

 

I'm sorry, I'm not computer savy. I keep getting my posts kicked back and a message that says I can't post anything larger than 600X800 pixels. How do I get around this if I'm posting a jpg. or gif. ?

 

Just my opinion, I don't like them that large, throws off the whole thread so you have to scroll right and left to be able to read stuff.

 

Draggin us bqack on topic :wink: , It sounds like you have done a bench sync so it should be running better. Sounds like time to remove the carbs again and reclean the pilot jet circuit.

And recheck float levels
And suck on the petcock vacuum line to see if fuel flows. (damn that sounds rude)

That's a top pic showing how a carb works. Study it carefully and use it to make sure you are getting all those galleries clean. Blow some air through them all and make sure you can feel air coming out the other end.

Idle and mixture terminology. Yup, we're on the same page there. 8)

 

Hey robert-

r u uploading the image.. or do you have a url where the image exist. If you are uploading then i am sure there is a limit on how big an image can be added. If the image is already hosted somewhere else (and thus you have a url for it) then you can embedded it to your post. You can use yahoo (photos.yahoo.com), snapfish, ofoto to upload the file and get the url for that image and then embedded it to the post. I'll PM you my email and perhaps I can figure out where to upload you photo so you can attach it here.

Back to carb issue, so I turned the mixture screws in (until i cant turn it anymore) and then turned it out 2.5 turns. I also turned the idle screw in a few turns. Bike would not start.. I spent about 2 hours playing around with different combinations of adjusting the mixture screws and idle screw. Came down to taking the carb back out. I will set the butterfly valve to .02 SAE using the feeler gauge and turn all the mixture screws to 2.5 turns out. Back to square one. BTW when the throttle is closed you are suppose to be able to see the pilot outlet and bypass hole.

 

Rodger that, you should see the holes. I thank you for the PM Seca550, I'll get back to you on this issue. All of my photos are uploaded from my desktop file. I'm not sure how to publish to a website and rely upon the information of my more enlightened brethren on how to post those pictures. I'll try some experiments here shortly, see how it goes. Thanks again.