bike is acting very strange (JET HELP)

I was trying color tune but the bike kept acting really weird. At first it ran OK but would slowly stall with out choke. When i took it for a little ride to warm it up it ran great although i had to take off with choke on then i could shut it off. Then when i came back the engine would ra e up to about 3000 - 5000 rpm with choke on and stall with it off. I reset the mixture screws a few times to make sure that wasnt the problem and turned the idol way down the brought it back up to get the bike to a point where it would run. Later it was racing with our with out choke. Im gonna try getti g a better sync today and if that doesnt work, pull the carbs again and check to make sure the butterflys arnt sticking. Anywhere else i should look?

 

Re: bike is acting very strange

Classic sign of vacuum leak. Get a can of starter fluid and spray around the throttle shaft seals when it is running, if the idle speed goes up then you have found it. If the carbs are way out of sync that can also cause your problems.

 

Re: bike is acting very strange

I tried testing with a propane torch didn't get any out of the "ordinary". Got the carbs off right now. Going to go through them make sure nothing is plugged and really bench sync.

 

Re: bike is acting very strange

Be sure to "wet-verify" the float levels; that could also be part of your problem.

 

Re: bike is acting very strange

I did set the floats steady but will double check when I take the carbs off the bike.... again. Using starter fluid I found a very small vacuum leak. Will have to change boots and throttle shaft seals.

 

I was reading another memebers post and some one said something about stock jet size. This made me wonder if mine were stock or not. I looked it up and found that I should have a 110 main fuel jet and a 40 pilot fuel jet. For the air jets it should be 50 main and 195 pilot. What I have in mine is 107 for main fuel and 45 for pilot and 55 for main air and 195 for the pilot. The only one that is right is the pilot air and the rest seem out of wack to me from what I read on what they should be at. This could be a big part of problems.

These bikes are tuned low to meet emission standards right? When I order new jets, should I maybe order a size up? Or should I just go with stock?

Im 1257 feet above sea level if that matters at all too.

 

Go back to original settings. Once I cleaned, bench synced, and all the other fun stuff according to the book. I also had larger jets. Went back to stock, I ride from the 3500 ft level down to the 1500 ft level. Mine runs 42 MPG. I have it stock except a jardine 4 into 1, I only run my pilots at 2 3/4 to 3 turns out. I have been fighting this carb set-up for months. Good Luck . Be patient and most of all go back to stock settings and start there.

 

Check ALL your AIR Jets:

Air Jets are OPPOSITE from Fuel Jets.

Main = Smaller [o]
Pilot = Larger [O]

This Illustration is 750 Maxim:


When you make any adjustments:
Seal the Manifolds to the Head.
Bench Sync with the Throttles as CLOSED as Possible:
3X5 Card Strip, Business Card Strip, Resume' Paper Strip or Thin Strips of 35mm Film Negative.

Attend to any possible Manifold Leaks
Fill with Black Epoxy • Coat with several applications of Liquid Elect Tape • Shine with Black Nail Polish.

Vacuum Nipples seated & Air Tight

 

Cool thanks guys. Back to stock it is then. Im hoping changing the jets will solve most of my problems. gotta get that vac leak fixed too though.

 

Got the jets changed, throttle shaft seals replaced, carb boots repaired and it starts. Now it is only running on two cylinders (1 and 2). Before I pull the carbs to clean them.... AGAIN. Could this be caused by the sync being off? With the number 3 carb being the main one that you sync everything to, I figure that would be one that is running.

 

anyone?

 

Did 2 & 4 fire prior to carb cleaning? Are they sparking? Well -- What does color tune tell you is going on in there (2 & 4?????? )

? OT from your question, but someone will ask if you've done valve gaps

Stock jets should be #110 main and #40 pilot for the 650

Generally cold cylindres would be an electrical issue -- even way out of synch carbs should allow the bike toi run although poorly...

Unless you are providing NO fuel

So, use the color tune to see if 2 and 4 are sparking?

 

It was running on all four before I changed the jets back to stock. Put them all back together and on the bike and its not wanting to start and only running on 1 and 2 when it does start. I did check for spark too and it is sparking. Yes I did my valves and the floats and cleaned the carbs multiple times and rebuilt them. Im stummped.

 

Check float levels -- WITH THE CLEAR TUBE METHOD WHILE ON THE BIKE -- got fuel in those bowls? So, it's a fuel issue somewhere? -- go slowly, think carefully, and it sounds like you need to validate fuel level. But, regardless you'll have to pull em and double check all...

Maybe not - it may be weak spark, but I agree seems unlikely however, there is a way to test the strength of the "spark" -- got a manual?

 

I have the haynes manual. and the XJ CD. I opened up the drain screw on all four and there is gas in them. I really hope its not the floats. I had a hell of a time setting them the first time.

 

Check float levels -- PLEASE __ WITH THE CLEAR TUBE METHOD WHILE CARBS ON THE BIKE

 

Will do. I forgot to do it when I was replacing jets and throttle shaft seals. Im guessing I should do it with the bike on the center stand. Anything else it could be?

 

Carbs off the bike. You want then level, not close to it.

 

doing it with them on the bike would gibe me a ball park idea of if they are off or not wouldn't it?

 

There's a +/- 1mm tolerance, so no. Do them off the bike and that way you won't have to do them again.

 

I don't know if you saw this or not but it's informative.

http://www.xj4ever.com/setting%20fuel%20levels.pdf

 

Ya I saw that. Im getting really f***ing sick of these carbs... Abandon all hope ye who enter here..... Im pretty determined though.

 

So do it right and you won't have to re-do it. Again. And again.

The carbs have to be level in all directions, side to side and front to back.

If the levels are off, AT ALL, then they have to come back off anyway.

If you "forgot" to wet-set them, just pull them and do it right.

While they're off, do a nice, careful, precise bench sync. And if you "forgot" anything else (like the pilot screw o-rings) do that NOW too.

Or continue to be frustrated. Every shortcut sets you up for another go-around. How long you wanna fight with this anyway?

 

I wanted them on the bike -- as level as poss. on center stand and chock up front wheel so rear wheel is on ground -- wanted to see if you were getting good flow and good levels to all four from your tank -- but if already off, then check them level obviously -- those tabs are real sensitive so very little pressure required --- ensure all floats are right way up -- ensure all float needles are installed same orientation -- if levels are OK then (and we are sure we do not have a spark issue and you didn't mix plug wires to cylinders) then is your pilot circuit clear? Is the pilot hole in the bowl clear -- is the pilot sink in the bowl clear -- do the squirting clean test, etc. all of this documented ad naseum in the Church post and others... Did you have pilot screws all same out? Like 2 1/2 turns each -- make sure you haven't "overtightened" the pilot screw you can jam it down into the alu too easily -- everything easy and careful please

If you're PO'd -- STOP

Go have a drink, think because sometimes doing nothing but thinking after being away from the bike will give you an "ah ha" moment on what you did wrong...

Come back tomorrow fresh -- do not rush

 

If you only knew how many times I pulled off the carbs on my bike to get to where it is today. Only a little patience will get it done. I read the book over & over. And a how to from a parts place on how to set them up. Now I get to enjoy the fun pf all them days & days of pulling these carbs off to adjust just small amounts. Now It hits & I have all my setting written down so next time it wont be as bad...

 

I understand... FWIW they should come off quickly - like in 10 minutes -- not sure what ur doing

 

First, check to see if that Coil is firing.
Just take a Spare Plug and Plug it into a Plug Cap that is missing.
Ground it to the Head.

Keeping one of these Old Girls running means fighting stuff that age and die.
Fuse Panel.
Alternator Brushes.
Coils and Wires.

The Coils fire 1 & 4 :: 2 & 3.
If a paring are suspected of not firing; SWAP the Coil Plug-ins to the Harness.
If the missing switches cylinders ... the Coil crapped the bed.

Were at the point where buying a used coil could be buying one about to die of old age.

 

Ok guys I appreciate all the info, but I've been through all this already, and will go through it all again.

Fitz, at the start I was cutting corners and ran into problems and said "oh crap, I didn't do this or that that was on that list I read on XJBikes.com in that post that said 'don't cut any corners'. DUH". I learned my lesson from that.

Here is a list of what I have done so far.

When I got the bike (should mention that this is my first bike and I know there were thing I should have done before I bought it, but I didn't), I made it run with gas sprayed in the carbs, all four cylinders fired, not well, but fired.

Stripped bike down to frame and painted and put it back together.
Half a** cleaning and rebuilding of carbs, bench sync and mixture screws at 2.5 turns.

Got valves in spec.

Put carbs on bike and it ran like crap.

Pulled carbs, cleaned more, bench sync, mixture screws at 2.5

Put carbs on bike and it ran like crap.

Pulled carbs, cleaned more, changed O-rings in pilot screw, got enrichment plunger out and cleaned in there as well, bench sync, mixture screws at 2.5, wet set floats. (This is where the cutting corners thing really started to pound me on the head)

Put carbs back on bike and it ran decently but couldn't get a good sync or mixture screw to really do anything.

Found out jets weren't stock and I had a vacumm leak.

Pulled carbs replaced 107 main fuel and 45 pilot with 110 main and 40 pilot, and 55 main air with 50. Pilot air was correct at 195. Changed throttle shaft seals, repaired cracked (not cracked all the way through that I could see) intake boots. Bench sync and set mixture screws. This is when I forgot to check the floats.

I just went and checked to make sure my coils were wired properly and they are. I checked for spark on the ones that aren't firing and they are.

Put carbs back on bike and now I'm where I'm at now. Cylinders 3 and 4 are not running, and the bike is very hard to start (but it will) I will go through cleaning, verifying floats, bench sync, and set mixture screws again.

Like I said I've been through it all. Im thinking that maybe the floats were knocked off a little when I was changing the jets and throttle shaft seals. I just hope that they are right because setting the floats was half the battle.

 

Oh and of course I did all the safety stuff too brakes and such.

 

I would think its fuel related. Try this, take a propane touch and flood the area around the carbs and see if the cylinder fire. If not just flood the air box with it running and see if the cylinders fire.
If they do you can concentrate on the idle circuits in the carbs. Dried gas and crud gets in to the smallest places and is very hard to get out. It almost is like cement in some cases. If the passage is clogged the carb cleaner only works on each end of the clog. Guitar stings work well as probes to push into the passes.
Let us know what you find.

 

Do your carbs pass the clunk Test? Also replace the vac caps and spring clamps on the tubes that you hook up to for the vacuum sync. If the are original they are most likely hard and leaking. DO NOT buy ones from a automotive shop. They will no stand to the heat from the engine. I know I was told on here they would work just fine they did not. After a few trips they were cracking and one even sucked the top off the damn thing. Buy proper replacements! Remember the jets on the Canadian XJ's are lager the on the American XJ's.

 

Attach some vacuum lines to the Vacuum Ports on the two holes that are not firing.

Plug the Hoses with Golf Tees.
One at a time, ...
Pull the Tee, ... block the end of the hose with your finger ... using a small syringe ... let a few drops of gas get sucked into the hose when you lift your finger ...

If the Hole FIRES when the Test Gas is let into the Intake Stream ... the Carb has a Fuel Delivery issue to work out.
• Bowl not filling
• Wrong placement of AIR Jets.
• Torn or unseated Diaphragm Rubber.
• Beenie Screens clogged

+++
Un-vented Fuel Bowl.
There might be places on the Bowl Gaskets that require perforations that didn't get cut-out on the Gasket, ... or are stamped and were left unplugged.

 

••• How did this work-out?

 

Ok so I've almost finished setting my floats. I've got them set, checked, and I'm at the double checked part but one of them wont shut properly unless I hit it with the handle of a skrew driver. Kinda sounds to me like a sticky float rather than it being something getting in the way of the seal or being set to high to me. Correct me if I'm wrong.

What I've done since my last post is: bead blasted all the painted parts (minus the gold hats), lemon boiled and cleaned, polished the slide bore, float needle seat, float pins, and the holes in the float towers. Bench synced and put them back together and now as I stated earlier am setting the floats.

So maybe the needle seat and needle in that carb need to be polished more?

 

I just noticed this post Rick. What do you mean un-vented fuel bowl? where are the vents on it. And can you explain a little more about the gaskets. Im prett sure I know what you mean but I want to make sure.\

Thanks
Bob

 

Well I finally got the floats set and the bike is running quite nicely. Started the sync and colortune yesterday.