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Start, rev 8k+, [Fixed]

Discussion in 'XJ Technical Chat' started by the_bandit, Apr 20, 2009.

  1. the_bandit

    the_bandit Member

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    I had my carbs off the other day, is it possible by moving them around I messed up one of the float heights or knocked loose a jet?
    After putting the carbs back I ran it for a few minutes, everything was fine, and it's been sitting about 4 days since then.

    The bike will start like normal then immediately revs to 6k, reaching 8k before I cut it, everytime. Drained carb bowls and half primed it, it started GREAT then as soon as the bowls had time to fill, revved HIGH again.

    I've checked the throttle cable to make sure its routed right and itsn't switched with the choke. (throttle is the middle one, right? :p )
    I didn't think it could develop problems sitting in the garage by itself a few days, I'll never leave it alone that long again.
     
  2. SinisterStuntz

    SinisterStuntz New Member

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    Re: Start, rev 8k+, don't know why

    LoL Well mine does the same thing sometimes, still haven't figured out the problem. One of my buddies who is a Yamaha certified mechanic, told me to try cleaning out the carbs either by runnin some seafoam through them or by having them professionally cleaned. And if you bumped the idle adjustment nob in between the carbs, that could do it as well. I am by no means a skilled mechanic, but these are just things i've found out by asking around.
     
  3. Thee_oddball

    Thee_oddball Member

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    Re: Start, rev 8k+, don't know why

    sounds like an air leak to me, make sure the carbs are seated correctly in the boots and make sure none of the caps came off the brass sync tubes on the manifold boots. or you have main jet stuck open .

    S!
     
  4. wizard

    wizard Active Member

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    Re: Start, rev 8k+, don't know why

    Back the idle screw right out, if it still won't idle the butterflies are holding open, bench sync' again & make sure the idle screw will allow the butterflies to fully shut.
     
  5. MN-Maxims

    MN-Maxims St. Paul Minnesota

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    Re: Start, rev 8k+, don't know why

    You could have some stuck slides. May be you should pull them off and do the "clunk test" Polish the inside of the carb bores so the slides move freely and clunk when you drop them in.
     
  6. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    Last time I did shim the air filter and move the airbox a bit, if anything I thought it would get less air thus less combustion. So I'll recheck all the boots. Just readjusted #2 and 3 airbox boots. I'm not sure what you mean by caps on the brass sync tubes, I only know of brass sync screws. When I had the carbs off I didn't take anything apart or off them, just machined a drain screw to work again. The butterflies had a perfect tiny sliver of light underneath all of them and appeared to be in sync beautifully. Will they un-synch if not reinstalled carefully?

    Yesterday I backed the idle screw out at least 2 revs, it revved to 8.5k right off and continued to 9k before I killed it. I did turn it (CCW). It was idling great last time it ran though. Today I've turned it out 3 more turns, I'll start it up in a bit here and see what's up.

    I just found that the paper towel "shims" I put in my airbox to keep the filter flush are dry but were soaked with gas, filter is oily.

    Does it mean anything that it started/idled great with the bowls emptied then half primed then took off again to high revs after a few seconds?

    Going to tinker a bit more then try to start again, if not I'll be pulling the carbs again today for the clunk test among other things...

    Edit: just pulled the plugs, 1 and 4 were soaked with gas chamber is wet too, plugs are showing black after being beige days ago

    Edit2: Clunk tested 1 and 4, passed. Given that 2 and 3 plugs didn't show a problem should I bother clunk testing 2 and 3?
     
  7. Thee_oddball

    Thee_oddball Member

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    Re: Start, rev 8k+, don't know why

    1 and 4 are on the same coil, check all the connections to that coil to make sure they are tight and have no corrosion.

    S!
     
  8. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    I just found a small leak in my vacuum line, this can cause flooding I found in another thread. Fixed it.

    No visible corrosion on the outside of the coils.

    Tried to start again, I'm now getting no spark from any plug, did a lot of pulling and swapping and cranking still no sparks anywhere... Maybe both coils bad all of the sudden? I'll have to get a multimeter to check...
     
  9. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    Just had what I think is some progress, it still won't spark but I accidentally grounded the plug on myself and it did shock me, it will arc to the frame but the plug gap won't spark like it's supposed to. Since there -is- current going to the plugs could it still be the coils? New plugs?

    On my left coil both the forward and rear bolt have a wire attached to it leading nowhere, on the right side there is only a wire from the rear bolt, heading back toward the battery. Is each coil supposed to be grounded?


    EDIT:
    Got it to start again finally, still same problem. Will start, revs to 6k, slowly and steadily climbs RPMs. Throttle works as normal. I really didn't want to have to pull and break the carbs but looks like I'm going to have to unless anyone else has a magical solution...
     
  10. JoeFriday77

    JoeFriday77 Member

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    Re: Start, rev 8k+, don't know why

    Did you try backing out the idle screw like Wiz recommended?

    Have you tied to push the throttle shafts down with your finger to see if that will lower the idle? Any chance you could have dislodged one of the return springs on the throttles when they were off?
     
  11. tommyrhodes

    tommyrhodes Member

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    Re: Start, rev 8k+, don't know why

    I had this exact same problem last summer. I refused to accept that I had an air leak despite all the classic signs. Turned out I had an air leak through the throttle shaft seals. Just my experience though. You should consider backing the idle screw off more. It's a really finely threaded adjustment so it takes a good amount of spinning to make a decent change. Good luck. I know how frustrating it can be.
     
  12. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    Got the carbs back on and after fighting with no spark (again) for another 30 minutes it started and is still revving 6k+ immediately. Butterflies are perfect, slides are not stuck, all boots are properly seated, fixed leak in vacuum line. I removed all the bowls and no parts were loose inside.

    Only two things I didn't know to check were the main jets being stuck open and the caps on the brass manifold sync tubes.

    This is totally distracting me from everything else, every few minutes my mind wanders back to "What's wrong with my bike? Waaaaaaaaah"

    Is the throttle shaft seal the black thing at the top of the carb slide or is that the diaphragm?

    (had the idle screw all the way out at one point, it seemed to actually go 1k higher)
     
  13. wizard

    wizard Active Member

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    Re: Start, rev 8k+, don't know why

    The 2 jets under the plate can be in the wrong holes.
     
  14. JoeFriday77

    JoeFriday77 Member

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    Re: Start, rev 8k+, don't know why

    See the c-clip on the left side in the pic? The throttle shaft seals are behind that and the plastic washer.

    The black thing at the top of the carb slide is the diaphragm.
     

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  15. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    Would an improperly seated slide diaphragm possibly cause an air leak?

    If the jets were switched would it have run great for a while then done this nearly overnight?

    I checked the outside #1 and 4 throttle shaft seals, they look impeccable, When I next have time to pull the carbs I'll check the rest. It looks like if I'm careful I could check them without breaking the rack?

    Chambers 1 and 4 like to flood when trying to start, is it safe to assume it's carb 1 and 4 causing the problem and not 2/3?
     
  16. SLKid

    SLKid Active Member

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    Re: Start, rev 8k+, don't know why

    What about the Idle Adjsutment Screw? The BIG middle one in between carbs 2 and 3?? Have you tried turning it CCW while its revving? How open in your choke whne you're turning her on? If its open and revs up that high, CLOSE IT, even jsut a little. See what it does to your RPMS. If its not that, then check your adjsutment screw
    -SLKid

    Start Simple
     
  17. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    It starts with no choke, I leave it off when it does this. I had the adj screw all the way out (butterflies were actually all the way closed) and that's when it started going to 7k after starting instead of 6.

    How long is it safe to leave it running at 6-8k RPM immediately after a cold start? I've been killing it in no less than 10 sec.
     
  18. SLKid

    SLKid Active Member

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    Re: Start, rev 8k+, don't know why

    Have you tried setting all of your Idle Mixture Screws back down to like, 1 or 1.5 turns?? If not that I'd say its another air leak somewhere.. Is it popping when its revving? From the exhaust?
     
  19. Kiwi

    Kiwi Member

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    Re: Start, rev 8k+, don't know why

    You indicate in your first post that you had the carbs off. Did you touch the sync screws? If one of the sync screws has moved, this can hold it's associated throttle butterfly open. You should start by taking the carbs off and carring out a bench sync. Carbs 1 & 2 first, then 3 & 4, then 3 & 2.
     
  20. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    I didn't touch any of the sync screws, all the butterflies are synced still.

    The mixture screws I didn't touch, before all of this all my plugs had a nice beige color, they seemed to be set correct.

    I went out to see if I could hear any popping when running and it's not starting again... It almost started the first time but I didn't choke it so it sputtered and died pretty quick. Now it just turns over and sounds like my battery is getting low from so much trying to start the last few days .. Just confirmed that I'll need a charge before I try to start it again... It wants to fire though, at least one cylinder fired up last time.

    If it is an airleak will there be popping from the exhaust? Would a leak cause the RPM to climb steadily higher after starting?
     
  21. Kiwi

    Kiwi Member

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    Re: Start, rev 8k+, don't know why

    Ok, then there some things you need to check because at 8000 rpm you are definitely pulling fuel from the main jet and for that you need a fair amount of air passing thru the throttle butterflys.

    1. As you've had the carbs off check that the throttle linkage isn't jammed up under the head. This is a common error when installing carbs.

    2. Check (or even better disconnect) the throttle free play in case your throttle cable is binding. Ensure that the chokes for each carb body are seated by pushing down on each (gently) and make sure the linkage is has some free play.

    3. Push down on each carb body throttle linkage arm, occasionally these can bind up in one or more carbs.

    4. No luck with the above then start suspecting an air leak from either the throttle shaft seals, or carb holders. Check the vac fittings on all the carb holders are tight and are not leaking. Theres a method to check for air leaks with propane.

    5. If you take the carbs off, hold them up to a light and with the diaphragm body lifted check that all butterflys are seated properly.
     
  22. TheHound

    TheHound Active Member

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    Re: Start, rev 8k+, don't know why

    This goes for the choke cable to, it could be hanging open.
    Its curious that you say #1 abd #4 seem to not be firing.
    As #1 abd #4 are on the same coil, has nothing to do with reving but..........
     
  23. RickCoMatic

    RickCoMatic Well-Known Member

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    Re: Start, rev 8k+, don't know why

    The Linkage is stuck open.

    If you had the Carbs of ck the Cable end at the Linkage for being jammed under the head.
    Dont pry it.
    Other than that ... something is hanging up
     
  24. wfuglaar

    wfuglaar Member

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    Re: Start, rev 8k+, don't know why

    This has already been suggested, but take another look at how the carbs are seated in the boots. Are you sure they are snug up against the carbs. I experienced the same over-revving situation when I first got my XJ, and after hours of trouble shooting, I loosened up the bands and used Rick's pry bar (a wooden hammer handle), and made sure the carb face was nice and tight against the boots. The problem cleared up immediately.

    I have worked on my bike many times since then, but ran into the over-revving again today after doing some carb work. Despite my past lesson, I had done it again. There was the slightest of gaps, but it was enough to cause a problem Once the carbs were snug on the boots, everything was fine.

    Good Luck
     
  25. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    my #2 and #3 airbox boots are at most 1/2mm from being fully seated on the carb, the rest are perfectly flush. My thinking had ruled this out as the source of a leak, because they do have tightening collars around the rubber, I wonder if hose clamps would be able to make a better seal, all the screws on my collars seem to hit the limit before I think they're tight.

    I'm going to replace the vacuum caps, the old ones were dry and had small cracks. After this I'm going to reinstall the carbs with silicone grease on all boots. New air filter coming too.

    Theoretically, if someone had experienced a stuck slide, would/could it stretch out the diaphragm to the point that it would leak air from under the carb cover? Also, could it unstick itself or would it have to be physically moved?

    The two times I had the carbs off, slide 3 clunked ok, though if put in at a slight angle it would stick. The diaphragm on #3 was stretched and didn't fit in the lip like the others did. Should I switch a few slides and see what happens?

    But still, would a stuck slide in #3 have caused the flooding in chamber 1 and 4 (or was that me over cranking it because I was getting no spark)? Would it cause the accelerating RPMs with no throttle and the butterflies/idle screw all the way closed?
    Linkages/cables are correct and not jammed on anything. There is no play on the butterfly adjustment screws, though I'll push on them next time its running just for good measure.

    I don't want to turn my mixture screws yet, being that I didn't touch them and it ran beautifully before I took the carbs off.

    It sounds like all 4 cylinders are having the problem, not just one. Would a colortune plug help to confirm or deny this?

    If it is a leak, will the propane method still work even though RPMs are already high and getting higher? What kind of jump would it make from 6k if it started sucking in propane? (I assume this would depend on the size of the leak though)

    How do I check for a jet stuck open? I thought jets were little threaded metal pieces with a hole, no moving parts.

    I'm starting to get really annoyed with myself, I didn't even need to take those carbs off, I just wanted to fix a stripped drain screw which I wouldn't need to use for a looooong time but now that it's not running I'm draining the bowls after everytime I mess with it.

    If it ain't broke don't fix it? Grrrr I should have listened.
     
  26. RickCoMatic

    RickCoMatic Well-Known Member

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    Re: Start, rev 8k+, don't know why

    The AirBox Boots might line-up if you ROTATE the Boots or MOVE the AirBox closet to the Carbs.
    Rotating the Boots under ideal conditions is difficult.

    First, I prep the AirBox.
    I SAND the AirBox Hole with 800 Grit to ever-so-lightly enlarge the Opening.
    Then, I smear the LOCATING CHANNEL on the Boots with some Synthetic Waterproof Grease.
    You will need a TOOLS to assist the fitment.
    An old CB Radio Antenna.
    Cut to 2.5 feet, Heat-fabricate right angle on end 3/8" long. Heat; flatten-out end to make "Shoe horn". Sand; dull edges to prevent ripping rubber Boots.
    Tool. Long, skinny "Pursuader" Long, thin, Phillips, Screwdriver, End grinded to DULL POINT -- 45-Degree angled added after heating and bending.
    DULL --> But ... sharp enough to get purchase on the Boot to ROTATE it.

    Use the TOOLS to reposition the Boots.
    Eyeball the Carb end ROTATE BOOT until Line-up Tabs at Airbox end are at 12 Oclock.
    No Line-up Tabs ...?
    Pull all Boots; eyeball.
    Straight ones. Middle
    Bent ones. Outside Carbs.

    Move AirBox Closer to Carbs.
    File or Grind additional travel in Mounting Points to allow Box to be moved closer to Carbs.

    Pull Diaphragm Piston Assemblies.
    Polish Bores with ScotshBrite Pad (Gray)
    Remove AlumaOxidation
    Further Polish Bores to mirror finish with Dremel Tool
    Experiment moving Pistons to different Carbs for best performance.
    [​IMG]

    Polished:
    [​IMG]

    Seat the Diaphragm Rubbers by PASTING them in place with Waterproog Grease.
    Smear waterproof grease in diaphragm locating channel.
    Position Diaghragm rubber and seal.
    Wipe Diaphragm Rubber clean with alcohol.
    Seal Diaphragm to Body with Toothpick and TINY Bead of Elmers Glue.
     
  27. tumbleweed_biff

    tumbleweed_biff Active Member

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    Re: Start, rev 8k+, don't know why

    Rick, a question. I thought that alcohol was bad for the diaphrams?
     
  28. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    Polished all slides and bores, they clunk much better than before. I also replaced 2 intake manifold clamps with regular hose clamps, replaced the vacuum tube caps, and used silicone grease to install the carbs this time.

    It was a little sluggish to start but it did. With the idle adjustment all the way out, it wanted to idle around 4k rpm, less if I turned the handlebars all the way left (throttle routing problem?).

    Oil was nearly pouring out of the head and got onto the #1 header, started smoking, though oil level is fine. Huge backfire from left exhaust when I cut the motor (maybe because I was spraying starter fluid around to find more leaks).
    In 2 spots I got about a 300rpm jump from the starter fluid. I'm hoping replacing the clamps will fix it and I won't have to pull the carbs again to replace throttle shaft seals.

    Taking a lunch break now, I'll either edit this post or make another one tonight with any progress.
     
  29. Thee_oddball

    Thee_oddball Member

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    Re: Start, rev 8k+, don't know why

    you could see il running from the front of the head near the header?? you might have as blown head gasket which could explain some of your idle problem (i think) but the idle is of little concern if you have a blown had gasket..could you post a pic of the area please.
     
  30. tumbleweed_biff

    tumbleweed_biff Active Member

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    Re: Start, rev 8k+, don't know why

    Rather than using starter fluid, use a propane torch. Safer that way.

    You definitely have some carb issues, but of grave concern is the oil "pouring out"

    Finally, where are you located (city/state)?

    Mike
     
  31. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    Biff, I live near King City, CA
    Looking back, "pouring out" sounds a little too dramatic, I think I should have said steady drip. Definitely more than the usual oozing I used to get because PO overfilled the oil.

    I really hope this might have been caused by the unique conditions of me trying to start it, running it in the garage at 8k rpm for a minute at a time, letting it sit for a month, then starting it again. I'll be watchful of it.

    I just came back in from putting the last 2 clamps on, I seem to have solved the original problem of this thread (air leaks from reinstallation of the intake manifolds). The original clamps weren't holding the boots tight enough to the carbs, and I don't doubt the silicone grease helped.

    As of now it idles great ~12-1400 rpm handlebars center, drops to nearly 800 hard left, and bars hard right causes it to throttle to over 4k.

    Back when I was riding it it revved really high a few times and sacred the piss outta me, until I figured out it was turning the bars right that was doing it. It did it one time in my driveway as some people were walking by on the sidewalk, they looked at me like I was such an a-hole, haha.

    I watched the travel of the throttle cable while moving the bars through the full range, it pulls less than 1/8th of an inch when turned right.

    Anyone know what length the cable is supposed to be? Mine loops around before going under the tank, looks like it could be 4-6 inches too long.

    Going to attempt to ride it, being careful of it getting away in right turns (and the new trick my clutch learned in the other thread).
    Hopefully I can just install a new throttle cable, do my shims and be done (for the summer at least)...

    Edit: Just remembered I have to install and bleed the front brake before I go riding >.<

    Edit 2: Well, how disappointing. I bled the brake and was ready to go. Started it, went immediately to 8k rpm and climbed to 9k within ten seconds. I'm right back where I started. I think when I tested for leaks with the starter fluid I melted some silicone where I had sealed another leak. I reapplied the silicone. Tomorrow if it doesn't start properly I'm officially throwing in the towel, taking it to a mechanic. I hate to admit defeat, but I want to ride sometime this season.
     
  32. tumbleweed_biff

    tumbleweed_biff Active Member

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    Re: Start, rev 8k+, don't know why

    Well, I wont be able to offer the engine from my 750 ...
     
  33. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    I think whatever my problem is won't be fixed with new motor or new carbs. I hadn't thought yet about an all new set of boots, I'll look at the price on that...
    I know whatever is wrong with it has been looking me right in the face the whole time, for it to start and behave for a little while today and then to go berserk again, I must have done something right.
    I've got the silicone drying and my fingers crossed it was the starter fluid that melted my old patch job.
    I've decided it won't behave for me tomorrow I'm going to seek professional help.
     
  34. AndrewM

    AndrewM Member

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    Re: Start, rev 8k+, don't know why

    Bandit,

    When you say the revs change when you move the handlebars to the right and left, I can't but help think that you have a cable problem? You shouldn't have any change in engine revs when you turn the bars.
     
  35. RickCoMatic

    RickCoMatic Well-Known Member

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    Re: Start, rev 8k+, don't know why

    To get over 6,000 RPM's, ... the THROTTLE PLATES ARE OPENING.

    Secure the Throttle Cable.
    Use Duct Tape. I use Gorilla Tape. Gorilla is textured and waterproof.

    If the Engine changes RPM's when the Handlebars are turned, ... the Cable is routed incorrectly.

    8,000 RPM's means you are bringing-in Main Jet Fuel.
    That don't happen unless the Throttle Plates are Opened and the Diaphragms cause the Needles to rise.

    Bench Sync the Carbs usuing --> 3/8ths Inch wide strips of 3 X 5 Card.
    Using the 3X5 Card Strips will Mechanically Sync the Throttle Plates "Virtually" closed.

    Make a Depth Gauge out of a Glass Barrel Fuse -OR- a Drill SHANK taped at the end.
    Mark 9/32nds (Nine thirty-seconds) from the end.

    Set the Depth Guage on the Top of the Pilot Mixture Screw and Pre-set the DEPTH of the TOP of the SCREW at 9/32nds deep.

    (Seal the Mating surfaces of the INTAKE MANIFOLDS to the CYLINDER HEAD.
    Use a Popsicle Stick and INSURE that the Manifold to Head Joint DOES NOT LEAK AIR.)
     
  36. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    How is the throttle opening if I can push down on the sync screws and they don't move? The throttle linkage will not move when pushed down. I get the same result starting it when both choke and throttle cables are disconnected.

    The carbs are synced the butterflies are all but closed. Judging by my plugs my mixture screws are good.

    I haven't resorted to using aquarium sealant on the boots to carbs yet... That'll be real messy..

    And to me, the handlebars turning making it throttle is not a big deal, I rode it with it doing that for 2 months.

    the big problem is that it wants to idle at 8k... Yesterday I had it fixed for a matter of minutes

    People left and right are getting mad at ME because I can't fix this, I doubt its helping...

    Later:
    Well I've just been outside and it's still not behaving so I'm done, thanks for trying your best to help, guys...
     
  37. ktcubed

    ktcubed Member

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    Re: Start, rev 8k+, don't know why

    Don't give up. All problems (except seizure) are solvable. Take some time off, a deep breath, and step away from the bike...

    Then try again.

    Where are you located? Perhaps there is someone nearby willing to take a look at it with you.
     
  38. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    I found that my plugs were fouled, pic attached... Went and got new ones, met a guy in the store who's going to come over tonight to look at it.

    Just about the only thing I haven't tried is replacing all 8 carb boots for $247. I hope this guy doesn't just tell me to get new ones and charge me...
     
  39. ktcubed

    ktcubed Member

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    Re: Start, rev 8k+, don't know why

    Perhaps the new plugs will do it. There are stop-gap measures you can try on the boots before buying new ones (or in place of). People on here have advocated things like parts dip, liquid electrical tape, etc. If you just looking for vaccuum leaks as the cause, you could wrap them in celophane for the time being (don't leave on long if it starts to run as I'm sure it would eventually melt, but as a diagnostic tool...).
     
  40. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    I've read that the intake manifolds are quite thick and it takes deep crack to make them leak, I've got one starting to crack but I sealed it with aquarium silicone and still have the problem. It's not in a spot that I could innertube it. The manifolds and clamps all seem to seal great to the carbs.

    As for the airbox boots, it's an extremely difficult time to get them onto the carbs and tightly clamped. I was prying the airbox as far forward as I could with a piece of wood and still the bottom of the # 2 and 3 boots won't go all the way onto the throat. I was able to tightly clamp the rubber that did overlap.

    Thinking through this again has given me new hope, thanks ktcubed.

    Plan of action:
    I'll talk to this guy tonight, see what he says and probably order replacement airbox boots.
    If that doesn't work I'll replace the intake manifolds and gaskets.
    If that doesn't work I'm going for 4 new slides and diaphragms.
    Still nothing and I'm literally going to drop it off somewhere and say "Make it work, I'll pay whatever."
     
  41. RickCoMatic

    RickCoMatic Well-Known Member

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    Re: Start, rev 8k+, don't know why

    The places you want to check for Manifold Leaks are:

    Where the Clamp surrounds the opening for the Carb Neck.

    At the Mating Surface between the Manifold and Head.

    The Mating Surface os quite often the culprit. It is here where Yamaha placed an O-Ring and a Paper Gasket.
    When the O-Ring gets brittle ... it LEAKS ... Bad ... Mostly under LOAD!

    Test the Manifolds with a Vacuum Gauges.
    If you can't get the Vacuum to change ... the O-Ring is leaking.

    The BEST way to rectify the Leak is to Seal it up EXTERNALLY.
    If you try to remove the Manifold you might break a Bolt.
    Use RTV and tuck the sealant into the Gap between the Manifold and Head like you are glazing a window.

    Retest for leaks.
     
  42. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    if I hook a vacuum gauge onto each intake vacuum tube would it clue me into the bad one? What should they read normally?
     
  43. RickCoMatic

    RickCoMatic Well-Known Member

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    Re: Start, rev 8k+, don't know why

    It's NOT about what it reads "Normally" ...

    It's about what is Reads and your ability to change it.

    If you hook-up the Gauge ... (and you MUST use a Restricter to quiet-down fluctuations) ... and the Value is LOW and won't respond to having the Sync Screw adjusted.

    If the Value remains "Flat" ... there's a leak.
     
  44. Thee_oddball

    Thee_oddball Member

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    Re: Start, rev 8k+, don't know why

    like ric said at 6k the throttle plates are coming open, I would lift up the slides one at a time and use a pen to see if the throttle plates push open with little or no resistance...if so they are not hooked up correctly.
     
  45. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    *sigh of defeat*

    I'm dropping it off to a independent shop tomorrow @ $60/h...

    -.-;
     
  46. ktcubed

    ktcubed Member

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    Re: Start, rev 8k+, don't know why

    Hope they find it fast...
     
  47. Jeepin_CJ7

    Jeepin_CJ7 New Member

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    Re: Start, rev 8k+, don't know why

    Any updates on this? Mine's doing it too. <- Nevermind, fixed it.
     
  48. tumbleweed_biff

    tumbleweed_biff Active Member

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    Re: Start, rev 8k+, don't know why

    You can replace the 4 intake boots with new ones from Chacal for something around $50.

    Or you can do what some have reported doing and going to Home Depot/Lowes and picking up a 1&1/2 x 1&1/2 in plumbing coupler for something like $3 ea. With a little bit of knife work you can cut it down to fit quite well.
     
  49. Jeepin_CJ7

    Jeepin_CJ7 New Member

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    Re: Start, rev 8k+, don't know why

    It was crazy how this thread was the same damn thing that was happening to me. I fixed a float bowl problem over the weekend and polished the slides. When I put everything back together I was getting 6k rpm starts. I thought I may have broke the silicon fix on the manifold boot, so I fixed it. That still didn't do anything but I'm glad I got the boot fixed permanently. The problem was from the hose clamps on the manifold boots. I was trying to keep everything nice and tucked in and the end of the hose clamp was pushing up the throttle linkage on the two end carbs. Make sure you keep those hose clamps away form the linkage no matter how ugly they are!!! :p

    Pushing up on the linkage:
    [​IMG]

    Side view - DO NOT DO IT LIKE THIS:
    [​IMG]

    How it should look:
    [​IMG]
     
  50. the_bandit

    the_bandit Member

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    Re: Start, rev 8k+, don't know why

    Things I learned today:

    The mechanic indicated that a leak on the airbox side of the carbs wouldn't do much harm (other than the air not being filtered). This was where I replaced the clamps in an effort to get a tighter seal.

    I was also informed today that my handlebars are not stock, and that's why all my cables and wires to the controls seem 6 inches too long, go figure. That's why it revs 4k when I turn the bars hard right and drops 200rpm when I turn them left. (this is not the thread topic problem)

    When I was fiddling with the bike myself, I checked checked and rechecked the throttle linkage, nothing was interfering with it fully closing.

    I'll definitely make a post when I get this resolved. Hopefully he'll tell me the recipe to fix it and no XJ rider will ever have this problem for as long as I did.
    I'm supposed to call him Wed if I don't hear anything.
    (There's a lot of potential $60 hours between now and then, goodbye paycheck...)
     

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