Honda CX500 & GL500 Forum

Search Sort Posts:  Oldest to newest Newest to oldest

06-02-2008, 1:47 PM Anonymous Turbo fault Here's a weird one. Following a complete rebuild, powder coat etc the 500 Turbo ran fine for a short while and then refused to idle on the left cylinder. If you rev the engine to 2,500 - 3,000 rpm the left cyl chips in. The engine had a triple bypass which I've done many times on the regular engine and the Turbo is not so different. New stator of course. The coils are correctly connected, anyway the right cyl works fine. New plugs and caps, new coils and HT leads. Fuel is pumping, Sparks are sparking. Injectors are clean and have been Redexed. New fuel filter. Clean new petrol. The computer report NO FAULTS on the LEDs. Connections are good between:- -the spark unit and the coils -the spark unit and the resister unit down by the radiator motor connections -the PIGN plug between the spark unit and the sensor on the intake tube under the left side of the fairing (I assume that although this has two wires, they both do the same thing) The ignition switch is new and works as expected, the kill switch works as expected. I can see no stray wires or tubes disconnected between the connections tray behind the right hand panel and the various ends. Tubes are not kinked. Having exhausted all of the possibilities I can think of from CX experience and the Honda manual, I was thinking that maybe the engine speed sensor has malfunctioned or was damaged during the mechanical seal change. But would this affect just one cylinder? Is there a test I can run for this? How come it worked fine to begin with? Advice is welcomed.

06-02-2008, 1:49 PM Anonymous Re: Turbo fault I don't know why this flagged me as anonymous as I logged in correcctly. Rob Davis, Telford UK

06-02-2008, 6:18 PM HomerRod Joined on 07-21-2006 Posts 69 Re: Turbo fault This sounds like the classic intermittent coil and/or secondary (plug or plug wire) problem. Even though a coil primary and secondary windings measure correctly, they may in reality be shorting out during idle, and at different RPM levels. You could go through all of the time consuming tests, but it's easier just to install a known good coil, plug and plug wire and retest. Check the spark plug for a cracked insulator or poor gap ( they sometimes crack during installation, without you even knowing it). Try swapping right to left, and see if the problem moves to the other cylinder. If that does not solve it, check the resistance on the pick-up coil. At worse case, it may be an ignition module which can be replaced or repaired ( I have a list of websites which show how to repair your own modules). The point is this: NEVER rely on the testing of the coil and wires. Good readings do not mean good running. Always substitute with know good parts. When I worked at the dealer, coils would routinely indicate good, but really were not. Swapping the coil usually solved the problems (strange phenomenom, that they both indicated the same readings!!) Post your results and remember: YOU CAN DO THIS............ PS: If the engine speed sensor tests bad, then it can be removed with the engine in the frame. It is a discontinued part from Honda, but I have repaired it, with no need to try to find another one. The repair details are specific, but basically go the the car junkyard and get a Denso distributor pick-up coil from any Honda,Nissan or Toyota. Then just install it in place of the bad coil (there is a little soldering involved). I can send you a complete write-up on the engine speed sensor. And yes, it can be tested in the bike with the engine off. It's simply a resistance test on each of the two pick-up coils.    Report

06-02-2008, 11:05 PM Anonymous Re: Turbo fault I've substituted the old coil for the new ones and all of them are at the top edge, or slightly over, the 1.1 to 1.7 ohms range between + and -. Swapping to the old coil made no difference. I've tried different plug caps, different HT leads, new plugs, old plugs, without any improvement. Could a new stator highlight a tired spark unit? I'be be grateful for info on testing or repairing the unit, and for what tests can be run on the speed unit. I am familiar with the concept that correct readings don't always mean a part is good, as we've had that with regular CXs. email elsham@blueyonder.co.uk

06-03-2008, 3:41 AM CXTURBOBOOST Joined on 05-03-2007 Posts 99 Re: Turbo fault Try a different ignition unit if you have one laying around or can borrow one. Pete    Report

06-03-2008, 11:56 AM Rob-Davis Joined on 03-05-2006 Telford, Shropshire, UK Posts 59 Re: Turbo fault Update Swapping the coils and connections did NOT move the fault to the other cylinder, so it's not the coils, connections, HT leads or plugs.  None of the wires from the engine speed sensor or the three white wires from the alternator have earth returns (it's a new stator).  The battery charges from the three yellow wires from the stator.  The computer still shows no faults. I am forced to conclude that the fault is with either the engine speed sensor in the rear of the water pump area, or is a faulty spark unit.  No spare unit is available.  Is there a simple test to establish this, other than borrowing another spark unit? If the engine speed sensor was at fault, wouldn't this affect both cylinders? =================== Rob Davis Telford, Shropshire UK http://www.cx500.webhop.org now leaving the CX world Skype : rob_davis_cx500    Report

06-03-2008, 4:48 PM CXTURBOBOOST Joined on 05-03-2007 Posts 99 Re: Turbo fault When the speed sensors go out, usually it trips a fault code and sends the computer to "limp" mode. Pete    Report

06-03-2008, 9:40 PM HomerRod Joined on 07-21-2006 Posts 69 Re: Turbo fault You have taken a logical approach to the troubleshooting. I concur with Pete. By process of elimination, I would now be inclined to believe you have a partially shorted ignition module. Swap with a know good one (if available). If you want to attempt a repair, there are some web sites that will show you how to replace internal components (mostly capacitors that have leaked onto the board from years of use & electronic heat). These sites are about Yamaha Virago's, but give good information. One of the has a mail-order rebuilding service. I will post a few here for you to study. It may be easier to just buy one, but maybe repair is an option. Hope this helps... http://members.aol.com/ddenowh/TCI/ http://www.jetav8r.com/Vision/TCIRebuild/TCI_Rebuild.htm  http://www.penguinhosting.net/~bigmac/store/badEcs/badecscomputer.html     ****(this last one is mainly for ECM/ECU's, but gives some good pictures of           leaking capacitors onto a board, and how to identify the culprits).    Report

06-03-2008, 10:19 PM hakko808 Joined on 05-25-2008 Fargo, ND Posts 193 Re: Turbo fault Have you checked compression? It should be possible to use an inductive timing light to verify if your spark is where the problem is at lower RPMs. Should be a way to wire in some LEDs to help isolate issues in the electrical control to spark or fuel injection.    Report

06-08-2008, 6:28 AM Rob-Davis Joined on 03-05-2006 Telford, Shropshire, UK Posts 59 Re: Turbo fault I've tried my spark unit and computer in another Turbo (thanks Tony) and both behaved units perfectly.  However it was suggested that I have the injectors professionally cleaned.  I'll get this done this week. =================== Rob Davis Telford, Shropshire UK http://www.cx500.webhop.org now leaving the CX world Skype : rob_davis_cx500    Report

06-09-2008, 5:59 PM HomerRod Joined on 07-21-2006 Posts 69 Re: Turbo fault Speaking of injectors, make sure the injector winding is not over the resistance spec's. Could be intermittent, due to high resistance in the winding, which does not act up until it's warmed up from use. Check them when cold, then again after the engine has been run a while. Another item to check is the vacuum hose routing. I know some are VERY specific to the proper orifices. Also, check your grounds. Make sure any ground is attached to clean & shiny metal. Use a little dielectric lube on them after securing them. I have seen three or four ignition modules shorted out in quick time, all because poor or corroded grounds not allowing full current path back to frame, which of course caused excessive heat in the ignition unit. Make ground cleaning part of your overall winter maintenance project.    Report

06-17-2008, 11:50 AM Rob-Davis Joined on 03-05-2006 Telford, Shropshire, UK Posts 59 Re: Turbo fault The injectors have now been professionally cleaned and this has made absolutely no difference at all.  Right cylinder works fine but there is no idle on the left cylinder until the revs hit 2,000 or 2,100 and then the cylinder fires normally.  No difference whether the engine is cold or warm.  To recap:- Swapped coils and associated wiring, no change.  New coil and HT lead on the affected side.  Tested computer and spark unit in another Turbo, both ran perfectly.  No errors on computer LEDs. Plugs are sparking well and so are the spare plugs.  Different plug caps made no difference. New fuel filter and the petrol squirts out comprehensively from both the fuel feed and the fuel return pipe, if these are disconnected.  No leaks when the engine is running. I've been round the freshly powder coated frame with a flying earth lead, one end on the battery negative and touching everything I can find with the other end.  No improvement. If I wind up the idle speed to over 2,100 rpm the engine then picks up and climbs to 2,500.  Very gradually decreasing the idle back down again works as expected and after a short while the engine slows and then goes onto one as it drops under 2,100 rpm. I've looked at the routing of the various vacuum pipes and not found any of them crimped or impeded; also I've unplugged, clean and reconnected all the connections on the electrics plate behind the RH side panel and jiggled averything reachable to see if there's a loose connection, no improvement. This bike is rapidly heading for the spares pile as I am running out of patience with it, the only saving grace is that it's worth more as dismantled spares than as a non runner. =================== Rob Davis Telford, Shropshire UK http://www.cx500.webhop.org now leaving the CX world Skype : rob_davis_cx500    Report

06-17-2008, 12:25 PM Timothy_D Joined on 04-22-2006 Santa Rosa, CA Posts 691 Re: Turbo fault I'll try sending this to my turbo mechanic.  Maybe he'll have an idea. Two '82 Turbos, GL650I, CX650C Why do I own four bikes? Because I'm not married. DUH!    Report

06-21-2008, 5:14 PM Anonymous Re: Turbo fault I am a motorcycle mechanic and have seen a similar problem on many bikes. It can be caused by an air leak around the inlet rubber / manifold to that particular cylinder. It can be replicated on any bike by removing one of the rubber plugs that close of the spiggot used for carb balancing. Then that particular cylinder will display identical symptoms to those which you describe. Of course, the CXT is fuel injected, but an air leak in the inlet area will still display these symptoms. It is possible that the inlet rubber is either split or perished, causing the problem. I have a cx500tc as a matter of interest. I can't say that this is the answer but it is worth investigating as you seem to have exhausted all other possibilities. Good luck. Andy.

06-23-2008, 11:23 PM Rob-Davis Joined on 03-05-2006 Telford, Shropshire, UK Posts 59 Re: Turbo fault Guys thanks for the various inputs. Compression is good and equal on both sides.  No 'conventional' air leaks - I've fitted new o-rings to the inlet tracts and the air feed.  What I am thinking now is that some residual dust from the shot blasting (despite careful cleaning) has entered the left hand reed valve and jammed it open.  At idle speeds, too much air gets in, but at 2,100+ rpm, the throttle butterflies are open enough for the engine to run normally.  I'll take the unit off and examine / clean it, along with the piping. =================== Rob Davis Telford, Shropshire UK http://www.cx500.webhop.org now leaving the CX world Skype : rob_davis_cx500    Report

06-25-2008, 10:54 PM Rob-Davis Joined on 03-05-2006 Telford, Shropshire, UK Posts 59 Re: Turbo fault The reed valve and air bypass units were not particularly dirty inside, and the reed valves were operating correctly; I dismantled and cleaned everything.  But I did find that the thick short hose connecting the two mechanisms was badly cracked on the exterior.  It was so well stuck to the units that in removing it, it was destroyed, but I can't see if the cracks had penetrated all the way through. However I've obtained replacements pipes for the thick length and the two shorter connecting pieces which feed the inlet tracts, I'll fit these soon and try the engine again.  I imagine that a crack in the thick pipe would affect both cylinders as it's common to both air feeds - but you never know. =================== Rob Davis Telford, Shropshire UK http://www.cx500.webhop.org now leaving the CX world Skype : rob_davis_cx500    Report

07-11-2008, 10:15 PM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 307 Re: Turbo fault Rob,  I'll bet your bike comes good with replacement of the THREE hoses that route the air to that warm-up valve and to the respective inlet manifolds - it's a thing I've seen on about 6 turbos in Oz - cracked and leaking hoses.  You might even think of removing that warm-up valve entirely - Oz bob's turbo starts and runs just like new, and it hasn't got the warm-up valve installed (I saw it hanging up in his garage the last time I visited him).  Of course it might be necessary for you to have it in there - Bob's temperatures rarely fall below about 4 C.      Report

07-12-2008, 6:54 AM CXTURBOBOOST Joined on 05-03-2007 Posts 99 Re: Turbo fault Don't remove the valve in the US unless you are in extreme high temperature areas....... The bike won't start right at all. Pete    Report

07-13-2008, 11:23 PM Rob-Davis Joined on 03-05-2006 Telford, Shropshire, UK Posts 59 Re: Turbo fault I've dismantled and cleaned the warm-air unit, replaced all the hoses and clips, and this has made no difference at all.  I can try running the engine with the twin feed hoses disconnected and closed off to the engine end. So my feeling now is that the new stator is faulty.  Does anyone have the readings that I should get via a multimeter for the stator connections?  I am familiar with the regular CX stator readings, but not what the Turbo ones should give me. =================== Rob Davis Telford, Shropshire UK http://www.cx500.webhop.org now leaving the CX world Skype : rob_davis_cx500    Report

07-14-2008, 3:41 AM Brian FORD Joined on 08-25-2007 Chicagoland, Illinois, USA Posts 7 Re: Turbo fault Rob, Perhaps your left injector has a higher resistance in the triggering windings or connections that require the higher voltage from the alternator in order to activate it that doesn't occur until the engine reaches 2100 RPM. You could try: 1-Remove the left spark plug and dry it off. Replace it and start the bike at only idle. Let it run for 30 seconds on one cylinder, (wiggle the connectors to the left injector), stop the engine and remove the spark plug and see if it's wet. You can do that for both plugs for comparison. (If the cylinder fires wiggling the wires, there was some slight corrosion on the connectors that failed to allow the injector to fire until greater vibration or voltage caused it to overcome the resistance. Unlikely since you've moved these connectors when you removed the injectors for cleaning.) 2-swapping injectors to opposite sides If either or both of these tests confirm that the left cylinder isn't firing at idle due to a lack of fuel being injected at idle, then: 3-check & compare electrical resistance across both unplugged injectors. 4-check & compare the electrical voltages being sent to each injector to fire them at idle and again at higher RPMs when the left one is firing. As for the stator readings, all the yellow wires should read 0 ohms (direct short) among them, and infinite ohms (open circuit) between any of them and ground/earth. You can check for DC voltages across the battery terminals at idle (~12.5V-13.0V) and again at 3000+ RPMs (~14.5V). (If an insufficient voltage from the alternator was affecting the left injector's function, I'd expect it to do the same for the right one as well.) If the problem is determined to be from the lack of fuel at idle, then the trouble points to the left injector's electrical circuitry. You can try the same kind of elimination tests to ensure that the spark plug is firing at idle.    Report

07-14-2008, 4:32 AM RichNCT Joined on 03-02-2006 Posts 2,079 Re: Turbo fault Rob, to give you a little piece of mind, the T stator is the same as in the carbureted TI bikes, except for a difference in the wiring harness fastening attachments. It only does charging duty. TI stators can be modified slightly and will work fine. Dan over here sells T stators modified and ready to install. Born to be relatively wild    Report

07-14-2008, 11:18 AM Rob-Davis Joined on 03-05-2006 Telford, Shropshire, UK Posts 59 Re: Turbo fault