Author Topic: downshifting problem - pics added (Read 3199 times)

uwjberg · « **on:** March 14, 2009, 04:24:03 PM »

i'm having a bit of trouble with down shifting - let me try to explain. upshifting is fine and no problems whatsoever. when i downshift, it's sometimes not clicking into gear, and it takes me several tries to get it in gear. it's odd to me, because it seems to not be related to what gear i'm in - if i get into 3rd gear, i can downshift into 2nd fine, but not first. if i get into 5th gear, i can downshift into 4th fine, but not 3rd. in other words, the first downshift goes fine, but not the subsequent downshifts.

through riding it, i've discovered that after my first downshift, if i put a little upward pressure on the gear shifter, and then downshift, it goes in about 80% of the time. i can get into all of the gears, but it's a bit cumbersome to have to put a slight amount of upward pressure on the pedal every time i need to downshift.

what could be causing this? is there an adjustment i can make? i had the engine out for my cafe build, but other than that, i haven't done anything to the trans (just replaced the leaking pucks - no other engine/trans work). i only drove it around the block a few times after i bought it, and before i blew it apart, but it didn't do this before. i'm hoping there is some kind of adjustment to make, rather than the problem being the syncros, sift forks, etc.

any help or advice is appreciated....

mystic_1 · « **Reply #1 on:** March 14, 2009, 04:55:24 PM »

What bike?

Sounds like a problem with the rotary gear selection mechanism to me. On a 750 it's behind the rear left engine side cover aka mission cover. Scrutinize the shift pawl arm and the pins on the end of the shift drum.

mystic_1

uwjberg · « **Reply #2 on:** March 14, 2009, 05:05:30 PM »

whoops - sorry. '75 750F.

so that's the cover that is over the gear shift pedal, right? what exactly should i look for (aside from obviously broken parts)?

uwjberg · « **Reply #3 on:** March 14, 2009, 05:43:41 PM »

ok - i pulled the cover and took some pics. does anything look out of place? is the spring on the gear shift shaft mounted correctly? i took a look in my clymer, but of course the diagram is unclear.

mystic_1 · « **Reply #4 on:** March 14, 2009, 05:52:40 PM »

OK, the return spring is mounted wrong. You can see it in your last pic. Give me a minute and I'll find a pic of how it should be.

mystic_1

Hush · « **Reply #5 on:** March 14, 2009, 05:55:11 PM »

Have you owned one of these 30 year old plus classics before?

The gearbox's are industrial/agicultural compared with modern day bikes, I have to stomp mine through some gears and find a few false neutrals on the way, I'm hoping the more I use my bike (it was boxed for a few years) the more user friendly it will become.

mystic_1 · « **Reply #6 on:** March 14, 2009, 06:01:12 PM »

OK, so basically, the ends of the spring in that last pic shouldn't be crossed. Pull the spring back a bit and flip each end of the spring to the opposite side of the metal tab on the lever, such as the blue lines in the attached pic.

mystic_1

mystic_1 · « **Reply #7 on:** March 14, 2009, 06:08:54 PM »

These pics more or less show how it should be. Sorry for the crappy pics, I swiped them off of eBay.

mystic_1

mystic_1 · « **Reply #8 on:** March 14, 2009, 06:11:34 PM »

Oh, and the reason this is causing a problem is, when you're downshifting, after you release the lever the mechanism isn't retracting all the way, so it never resets properly for the next downshift. Once you've reassembled everything, before replacing the cover, pop the lever on and work the mechanism by hand several times, and you'll see what I mean. It's a ratchet-like action.

mystic_1

Hush · « **Reply #9 on:** March 14, 2009, 06:13:41 PM »

Ah yeah I see now, that would put a different bias on the lever altogether... well spotted Mystic.

mystic_1 · « **Reply #10 on:** March 14, 2009, 06:21:24 PM »

Yup, you can see in this pic how the shift lever is not centered in it's travel as it should be:

Should look more like this:

mystic_1

uwjberg · « **Reply #11 on:** March 14, 2009, 06:36:33 PM »

...and in 30 minutes, problem solved by mystic. good eye, and thanks a million! i'll make my way into the garage in a minute to rectify.

fdbrat · « **Reply #12 on:** March 14, 2009, 06:40:07 PM »

Wow this was a quick solve. Bravo bravo...Makes me want to take mine apart and fix it. Even though its not broken.HAHAHAHAHAHaaaaaaa Yeah sory.............

GammaFlat · « **Reply #13 on:** March 14, 2009, 09:11:55 PM »

Oh Mystic One..... You are the man.

Spanner 1 · « **Reply #14 on:** March 14, 2009, 10:33:03 PM »

+1, Mystic, very well 'copped' !

Steve_K · « **Reply #15 on:** March 15, 2009, 01:12:31 PM »

I have found that rotating the shift lever a notch one way or another makes it easier to shift with out missing a shift.
I do have big feet. It may help
Steve

luder · « **Reply #16 on:** March 15, 2009, 01:26:18 PM »

Very nice post and fix.....Mystic nice eye...

uwjberg · « **Reply #17 on:** March 15, 2009, 01:43:36 PM »

one last question - i thought i had an extra gasket for the cover, but i don't. can i use some silicone to put this cover back on? doesn't seem to be much oil under the cover (i've read much about permatex and the associated problems). i hate to lose riding time for ordering a new gasket, but if it needs to be done, it needs to be done.

mystic_1 · « **Reply #18 on:** March 15, 2009, 01:46:22 PM »

You could dab a tiny amount of permatex at the bad spots, where the gasket it torn, and get a good enough seal to ride it around a bit and see if the fix worked. It'll likely leak a little but that way you don't have to wait on the new gasket to verify the fix.

mystic_1

uwjberg · « **Reply #19 on:** March 15, 2009, 01:53:02 PM »

well, that might work, except being the idiot that i am, i scraped the old gasket off to make a good seal, then realized that i didn't have the replacement. would it work without the gasket? i'm nervous with all of the bad things i've heard about the permatex.

and i fixed the spring, and ran it through the gears on the centerstand - snicks up and down beautifully now. looks like the fix is a good one...

mystic_1 · « **Reply #20 on:** March 15, 2009, 02:03:00 PM »

I wouldn't try just permatex. You'd be pretty guaranteed to get some inside the motor. Got any gasket paper? Cut a new one.

mystic_1

Spanner 1 · « **Reply #21 on:** March 15, 2009, 02:03:09 PM »

For years and years when we were kids working on our 2 strokes..we never bought a gasket..just made 'em out of a Cornflakes box ( it HAD to be C'flakes, for some reason )...!!!

Hush · « **Reply #22 on:** March 16, 2009, 03:51:46 AM »

Yeah us too, Corn Flakes made the best 2 stroke gaskets ha ha.........I have made gaskets using only gasket maker, comes in a tube and lasts just as long as an original Honda gasket, doesn't leak either.

bryanj · « **Reply #23 on:** March 16, 2009, 07:44:51 AM »

You need a gasket to get the correct end clearance on everything, Honda factored in the gasket when doing all this

Bob Wessner · « **Reply #24 on:** March 16, 2009, 08:07:39 AM »

If you have access to a scanner, you can make a gasket pretty easily.

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Author Topic: downshifting problem - pics added (Read 3199 times)