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Thread: Freakishly hard to start......!!

  1. #1
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    Freakishly hard to start......!!

    First off, AAAARRRRGGGGHHHHHH!

    Okay, now that I've got that out of the way-

    1977 R100S, only 40K, has always run like a champ for the couple of years I've owned it... including starting- I have to use the choke/enricher maybe only 5% of the time I'm starting it.... Until about 3 weeks ago, it started stumbling at speed, so..... checked the gas, completely disassembled and cleaned the carbs, reset valves, swapped spark plug wires, checked the points, etc etc, and nothing worked- after doing all the checks I couldn't even get it restarted....

    So, checked the timing and it was off, readjusted the timing and tried to restart.. very, very, very difficult to start.... but after about 20 min of turning it over, she finally started and was actually running very nice. I took it for around a 25 mile jaunt to charge the battery and see how she was doing- it was glorious! She's never run that good! A buddy and I raced all over the county at high speeds, and through town in stop and go traffic, and she didn't miss a beat! Not a single stumble, just flat-out joy, and she idled perfectly in between hauling ass!

    I came home and had some dinner and let the bike rest for an hour or so, then took her on another jaunt up the canyon, once again- joyous! Just the touch of my finger to the starter and she would leap to life, and idle perfectly- then accelerate without any hangups. Went to bed very happy that night.

    Next morning- tried to start her up and it took a little prodding, I actually had to use the choke... But before I could even go a block , she sputtered, bucked and stalled out and would not start back up... Pushed it back to the garage, and while fiddling with her/turning it over I got her to start up again, and once again, she idled very nicely (with choke off), but just the touch of the throttle she died again.........

    So to sum up- she runs perfectly when she's warm... but when cold, she's impossible to start.... what am I missing??????

  2. #2
    Registered User festes's Avatar
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    Are the enricheners installed the right way after you disassembled the carbs? Although this doesn't address why it started acting up in the first place. I got nothing.

  3. #3
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    Quote Originally Posted by festes View Post
    Are the enricheners installed the right way after you disassembled the carbs? Although this doesn't address why it started acting up in the first place. I got nothing.
    I was mindful of their installation when I was reassembling the carbs- and once again, I prob drove 30-40 miles on sunday with the bike- if the enrichers where in backwards I don't think I'd get down the block.....

  4. #4
    Smoooooth at 430 gch71's Avatar
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    I think you might have some contamination in your gas tank, if it these symptoms just started then I would suspect contaminated fuel. Flush/ drain your gas tank (take it off and rinse it out etc.) and take a good look at the pet cocks and filters. Its easy and quick, and you'll have the confidance of knowing you got a clean supply going to your carbs. See what happens.
    Glenn
    ...driving to work on my airhead
    '74 R60/6, '75 R60/6(boxes)

  5. #5
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    Quote Originally Posted by bobinthemtns View Post
    I was mindful of their installation when I was reassembling the carbs- and once again, I prob drove 30-40 miles on sunday with the bike- if the enrichers where in backwards I don't think I'd get down the block.....
    I'm not saying it's the chokes (ok, enrichers), but I remember seeing a story (in the Airmail?) about a guy getting a carb rebuild at a tech day and realizing his chokes (ok, enrichers) were on backwards for years.

    But, my R90 recently displayed symptoms similar to yours and it was the condenser. My first round of troubleshooting ruled out the points and the centrifugal advance mechanism, but.. the condenser got me.

  6. #6
    Old Salt MEAirhd's Avatar
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    Quote Originally Posted by crazydrummerdude View Post
    I'm not saying it's the chokes (ok, enrichers), but I remember seeing a story (in the Airmail?) about a guy getting a carb rebuild at a tech day and realizing his chokes (ok, enrichers) were on backwards for years.

    But, my R90 recently displayed symptoms similar to yours and it was the condenser. My first round of troubleshooting ruled out the points and the centrifugal advance mechanism,[ but.. the condenser got me.
    79 R100T "same train"

    I've got one word to say, "Plastics"...........................wait.. *condenser*. All the earmarks..........

  7. #7
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    Since one of your early symptoms was timing, ignition is definitely worth a look. The only starting problem I ever had with my 78 R100S was out of whack points. BTW a Boyer electronic ignition solves a lot of these issues, i have been running one since 2003.

  8. #8
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    I keep going back to the fact that when the bike's warm, it runs GREAT.
    When it's cold.... ugh.

    Thanks for the input so far guys, a couple of questions/comments--

    I replaced the condenser about 2 yrs ago- and when that one failed, there was never a time when it ran good, it was just a horror-show.
    I went for a 30 mile ride on sunday and the bike was great- would a bad condenser allow that?

    But along those lines of 'it runs when warm':

    - Could a bad condenser operate normally if it was warm?
    - Are there other components that might be defective, but are getting by once the engines warm? I'm thinking perhaps the coils, while they are throwing a spark, perhaps it's a weak spark, but one that's just enough once the jugs are hot....
    - Are there any other components that might be affected the same way??

    Regarding the fuel/fuel tank-- at this point I've cleaned/checked/re-checked all the needles so many times, I"m confident it's not the carbs.....
    And ditto for the enrichers- I spent quite a bit of time figuring out how they work/fit when I was reassembling the carbs.....

    Uggghhhhhh......

  9. #9
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    Have you run any checks on whether it is getting spark when cold?

    I guess I am at a loss, but I would think maybe (if you are sure carbs are ok) that there could be wire loose/poor connection anywhere in ignition system, coils, etc. Could spark advance mechanism be sticking when cold? But rotates when warmed up?

    Has the ignition timing been changed or checked lately? New plugs. I have seen plugs do that.

    Have you run a compression check lately?

    Could moisture be collecting somewhere (inside a cove) that is causing a problem while still wet, but later burns off when engine gets hotter?

    I know these are crazy, but I guess, this whole situation is crazy!

  10. #10
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    Hey Jimmylee--

    It is getting spark when cold.. but once again, I'm beginning to think perhaps its not sufficient...
    Regarding moisture- I live in Colorado, we don't really have moisture here.....

    Checked and adjusted the timing sunday. I haven't checked the compression, but last time I did it was something like 147 outta 150 in both cylinders...

  11. #11
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    Valve clearance

    My 85 R80RT had become hard to start. Checking the clearance on the valves showed that they had closed up. One of them didn't have any clearance, but when it finally got started it ran well. I set the clearance and starting was much improved. I had found the tip on this forum. Good luck Frank Coleman

  12. #12
    Nickname: Droid
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    Years ago I installed a Dyna Ignition system on my 76 R100RS. Now even if it sits for quite some time, as long as the carbs are clean and the gas good, fires right up. Sounds like ignition to me.

  13. #13
    Registered User lmo1131's Avatar
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    Kill switch? The Starter Relay is connected directly to the Battery. The Ignition Switch draws it's power from the Starter Relay and feeds it to terminal 15 (fused) in the headlight nacelle, where ... the Kill Switch picks it up and feeds the Coils.

    Not sure how to test all of those things (starter relay, ignition switch, fuse, kill switch), but if you "hot wire" the coils directly to the battery and it still doesn't start you'll know it's one of them. Granted, not too skyentific, but a quick way to narrow it down; especially if it lights right off when cold.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  14. #14
    Registered User cpitale's Avatar
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    Hard when cold great when hot I would check out your coils and ign wires for any hairline cracks

  15. #15
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    Quote Originally Posted by franko View Post
    My 85 R80RT had become hard to start. Checking the clearance on the valves showed that they had closed up. One of them didn't have any clearance, but when it finally got started it ran well. I set the clearance and starting was much improved. I had found the tip on this forum. Good luck Frank Coleman
    Valve clearance (too tight) usually affects bike when hot as everything expands and won't let valves close. Not usually a "cold" issue.

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