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TCI Replacement 2020 It Works

Discussion in 'The Garage' started by Team Junk, May 15, 2020.

  1. RichRide

    RichRide 570Ride

    Installed the GN250 CHI-NA box lastnight on my 1980 xs. I will provide feedback if any issues or thoughts arise! The 40 year old tci let me down and this replacement got me running again.
    Team Junk, MaxPete, gggGary and 2 others like this.
  2. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Thanks Rich.
    MaxPete and gggGary like this.
  3. itschrisb

    itschrisb XS650 Addict

    I’ve been curious about replacing the TCI box on my ‘81 bobber with a GN250 unit just to see the difference. The current box works fine but it would be fun to do a side by side.
    MaxPete, gggGary and Jim like this.
  4. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Yes please. The more input we get, the more we'll understand this conversion.
    MaxPete, gggGary and itschrisb like this.
  5. itschrisb

    itschrisb XS650 Addict

    I will try and setup some tests and see if I can come up with some decent data. My ‘83 with the GN250 VS my friends ‘81 stock bike seemed to be quicker with the gn250 but it’s hard because every bike is different. So on the same bike would be easier to tell.
  6. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    If you still have the original TCI box, you could reinstall it and do an apples to apples against his bike... doesn't matter who's better, just a baseline to do an "after" comparison. Would be interesting to see.
    itschrisb, MaxPete and gggGary like this.
  7. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    do a high gear 30 to 60MPH run off, swap boxes tween the bikes repeat?
  8. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Yeah... that would make a good baseline. I'd remind that the timing needs to be adjusted as required with the GN box to get as close to 35° advance as possible. if you don't do that, I don't think the GN is gonna perform as well as it could.

    Another thing I'm concerned with is fuel consumption. Although I don't think that's a worry for most of us, it's still something that needs looking at. I ran out of summer due to medical issues, but I planned on doing a fixed route back to back with a fill-up and box change in 'tween to compare mileage. Maybe someone else could pick up that baton?
    gggGary and MaxPete like this.
  9. MaxPete

    MaxPete Lucille, Betty, Demi & Gretel: I ask, THEY decide. XS650.com Supporter Top Contributor

    Fuel economy comparisons are notoriously inaccurate unless the distance is really long to wash out the variables like wind, traffic, gear-shifting patterns, etc.

    That is why the auto industry uses standardised road-simulations running on dynamometer cells for fuel consumption or economy testing rather than old "crash-through-plastic-curtain" type of "test" that Shell...or was it Esso....used to do in their TV commercials.
  10. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    I'll be right down to do MPG comparisons on your bike Jim. Hmm down to Bob's and back? Alternating iggy boxes at each fuel stop.
    Last edited: Nov 12, 2020
  11. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    We'll leave the light on for ya... :D

  12. Jan_P

    Jan_P XS650 Addict

    Not sure if I get it right
    the electrical starter has rarely been able to get neither of my two bikes to start.
    for 35 years
    With weak charging and old wiring .. Pushing the button a few times and the battery goes down
    and it wont start with the kick either.
    I have had a job at a major Automotive manufacturer ..With top notch engineers
    The were rarely far off in their designs .Something that can be assumed of Yamaha during those years
    Our fine bikes were manufactured.
    Sometimes the quality or solutions was less than perfect because cost saving but all in all. Working solutions.
    What might be scary on the gonzo if am getting this right is the lesser advance at high rev.

    The combustion takes a certain amount time which is more or less the same if I remember it correctly.
    That is why the advance is there
    To much advance and the ignition can lead to knocking and less performance and engine damage
    To late and the mixture is not fully burnt in relation to Top Dead Center and ,,


    If the spark occurs too retarded relative to the piston position, maximum cylinder pressure will occur after the piston is already traveling too far down the cylinder. This results in lost power, overheating tendencies, high emissions, and unburned fuel.

    Loss off power might not be a problem given that very few use it for racing
    Emissions ..not a large engine small engine
    Unburnt fuel perhaps not either a big issue
    But what about exhaust valve temperature in warmer climate ... ?

    From 78 on should have advance around 40 degrees before top dead center
    I admit that I am skeptical about DIY solutions .After 35 years I have seen many of those a few resulting in engine damage
    Mostly with the carburetor

    Please take this the right way .. I am not just Complaining and Whining about other peoples efforts.
    One word spoken before can save burnt valves for perhaps many owners
    I am a " By the Book " man if the spec says 41.4 or 40 degrees There should be something
    clearly saying 35 can also work. In the long run
    Which I am Skeptical about given the competence of them designing the machine from the start
    Without that analysis I would not install it .. given the consequences possible.
    MaxPete and Jim like this.
  13. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    A contrarian view would be that if we all went "by the book," we'd never discover other ways forward. There's been an ongoing discussion on iggy timing. You can read about it here. The upshot is that most knowledgeable folk here agree that 35 to 38° is plenty of advance for these motors and modern fuels... in fact some claim the motor runs better at 35°. Having run it at 35° for about 500 miles now, I'm convinced that 35° works just fine.

    At the least... it's not hurting anything.
    Last edited: Nov 12, 2020
  14. Jan_P

    Jan_P XS650 Addict

    Yes Sir
    I know that a machine runs smother with a less advance ..especially if the piston pins play and bottom are a bit sloppy
    I set it a bit late myself. Because i like a quiet old machine.
    500 miles is Nothing ..If it comes down to overheating the valves.
    One season is 5000 ... 6000 miles here with sometimes 7 months to cold.
    I appreciate that evolution and New fresh thinking by necessity means testing something new.
    And dumb questions from the rigid non changing persons .
    Sometimes it leads to development and in this case better more running machines Cheaper.
    But I have been doing this for many years and pretty much had the interest all my life.

    The list is long of people trying something different an new
    Whit sometimes major engine damage as consequence.
    In the 70 ies the tuners of already worn machines that not made it out of the city limits before it was over.
    For XS 650 s the carburetor And exhausts setup most common. Goes wrong.
    I have not read about this sufficiently to evaluate the level of the solution
    But from, a logical point of view
    If factory says 40 degrees ( for post 78 ) Why install something with 35 instead and why not 20 as well and so on.
    Again I admit I prefer factory stock as much as possible :This may well be a very good well thought through solution.
    I also appreciate that anyone does what he wants with his motorcycle
    But again I have seen many people over the years trying new things on Their Motorcycles
    getting it wrong.
    Again I am not entirely Anti .. This Input can lead to some clever extra electronics that can give the extra
    5 -6.5 degrees at high rev. If not already thought over. But i believe it is a difficult task getting it right with cam overlap and so on.
    Perhaps a Oil temperature gauge.
    Personally I would not install it at this point in time with the little I know so far.
    Most likely 35 or 40 degrees does not matter for most riders .and most outdoors temperatures .right jetting and filters
    But again I have seen many people over the years . Not many if any later admitting I made a Mistake.
    Again .. This is not an attempt to talk down -- trash talk the solution . The development process also involves incorporate earlier experiences as input as those I mention I have seen over the years.
    If a young man is planning to ride the bike dynamically perhaps this is not the solution for him. I don't Know.
    MaxPete and Jim like this.
  15. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Jan_P Perhaps you should do the maintenance so you can use your electric starter. XS's I work on quickly start with the button before I'm done.
    Lots of engineering involved in "ideal" timing and it's a moving number depending on many variables and end uses.
    Ultimate performance vs everyday useful power and smooth operation meant compromise before the days of sensors, computer mapped timing, and fuel injection. XS John was famous for his lowered compression, retarded timing "Smoothmobile"
    A minor data point; GM retarded the timing on the Geo Metro 10 degrees when NOx regulations came out. It cost about 5 MPG. Us cheap old reprobates would cut a slot and advance timing to the old spec to get the little 3 banger back up to 40MPG.
    lakeview, timbeck, Jan_P and 2 others like this.
  16. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Ignition timing actually has very little to nothing to do with burnt and/or overheated valves... which I'm gathering is your main concern?
    A large part of exhaust valve (intake too actually) cooling comes from the 450-500° (of crank rotation) they're closed. The heat in the valve is transferred (through the seat) into the head where it's dissipated through the cooling fins. Overheated and burnt valves are caused by them not seating completely... either by warping or from carbon buildup on the seat or valve face. If they don't seat, there's no heat transfer. Eventually this will cause the valve to burn from over heating. To repeat this is not a function of ignition timing.
    The only other danger of engine damage would be from detonation... but that's caused by either too much advance or too lean a mixture... usually both. Since we a reducing advance, that's not a consideration either. So nothing we are doing here is getting us into the danger zone. Will we be down on power? possibly. Will we be down on fuel efficiency? Possibly. Will we damage the engine? Highly unlikely.
    Note; although I was addressing Jan-P's questions, this is a general answer addressing the question of are we risking damage to our engines... It's a tough one to answer when we don't have direct control over what else you are doing. All I can say is that reducing advance to 35° is highly unlikely to cause engine damage to an otherwise stock engine.
    Last edited: Nov 12, 2020
    timbeck, Jan_P, gggGary and 1 other person like this.
  17. 5twins

    5twins XS650 Guru Top Contributor

    Keep in mind that the timing on these actually was a little less advanced when they came out. Full advance was only 38° on the first few models. Yamaha changed it they claim to help improve and smooth out the idle and low speed running. While it may have done that, I think it stole a little top end power too. I've "reverted" both of mine to that early 37° or 38° full advance timing and I think they run better, a little stronger at high RPMs. But I do think 35° or lower might be pushing it a bit. That much retard might start hurting the power output and mileage.
    timbeck likes this.
  18. stinky78

    stinky78 XS650 Addict

    one other factor would also be what the stock set up is actually delivering, combine a bit of cam chain stretch with the fickle stock advance mech and throw in a slightly out of spec points gap with timing set using a light bulb, the average XS’ timing/advance is probably not spot on even just after a tune up, let alone after a couple of hundred miles, (not every one does their timing every week) I’m thinking this set up is probably delivering more consistent results than stock, and a few degrees less advance isn’t gonna kill anything.
    Team Junk likes this.
  19. Jan_P

    Jan_P XS650 Addict

    Having thought some more about it.
    My view is following
    We are talking about a major Motorcycle Manufacturer on of the big ones
    At that point in time in a nation with " Ridiculous " Quality standards
    With a Motorcycle in production at later years well over 10 years
    At least a number 6 digits produced at post 78 seen numbers in total of 250 000 ---500 000

    Since I have been working on a Automobile manufacturer I know that there are huge not to say massive efforts to get feedback from the market
    Which at times can come with input as soon as Possible. It happens that something is not perfect.
    Or customers is complaining about
    And selling a dangerous product in the USA can lead to costly lawsuits and need too take Products back. Something that must be avoided..
    Safety features are today something that can send a Company out of business.

    So where I Worked it was the Best Designers in the Nation .. Experts With good feedback ..Often with a Doctors degree. in Technics.
    There were automobile models that was so good at the later production years that Customers would not quit buying them--- being fully thoroughly sorted out.
    Especially ladies who was not interested in the latest model but instead wanted a reliable uncomplicated thing that ran every day the kids should go somewhere.

    So The rule of thumb is If the experts above says 40 degrees advance that is usually the right value.

    Having said that there are changes ..40 years on Today Fuel can have other properties not foreseen .Many are no longer running on stock exhausts or intake
    ( filters )
    Stock exhausts might not even be possible to find ..So the first factory setup .Can nowadays have room for changes ..Might even be forced to do these .Changes that makes things better
    I am not saying that the Gonzo solution is not a good one .I am just saying that some caution is not wrong.
    Given the background I describe above. ..

    I notice Stinky78 . s comment And that is right the Stock advance unit was a solution from Steam engines without even a proper bearing for the advance rod.
    So the Experts did cut corners in that design.
    The alternator is not thought to last for ever either but perhaps OK given the years.

    I have had crap bikes ..that dealers recommended me not to put any money at .So I have had electrical problems.
    Large ones In the first years No internet and nothing but factory parts. I did use automobile parts for charging much cheaper.
    From that viewpoint a Gonzo solution is attractive if it is cheaper. .My goal was and to some extent still is to get i running one more year.
    If the bike costed 800 dollars it don't make sense putting a ignition system a 2 -3 -400 dollar .And the first week the bike breaks down
    That is the money pit --Black hole were all your money goes down Not riding any bikes

    Again i am not saying that this is not a working solution .But I would feel more at ease if the Possibility to adjust to specs were there.
    And compromises has to be made in life . I like the effort and the job done. That is how progress is achieved.
    But one needs to be careful at times. As I mentioned I have seen people getting it wrong with large shop costs.
    Again a dark hole were all the Money goes. Not riding any bikes
  20. RichRide

    RichRide 570Ride

    Seems to be a good deal of negative attention on this thread lately. I recently had my tci fail, after hours of troubleshooting and reading, this option saved me hundreds of dollars... and to anyone else running the gn I’m sure they feel the same. This is a huge development, to be able to take a product from 2020 and replace 40+ year old electronics for less than a Jackson! Here is a snapshot of a timing video of my first start after installing the new box. NO TIMING adjustments made yet. I am unable to upload the video file, not sure why. ABB792BA-AA40-45BD-952D-4356370DBBB3.png

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