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Transmission Problem? 1993 XR100

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I am having a shifting problem with my stepdaughter’s 1993 XR100. It is becoming difficult to shift into second, usually I get another neutral.

Going into first from neutral is not a problem, from first to second works about half the time, usually requires a few stabs to find second. Since first gear is so low, I usually start in second. This is a hit or miss operation. Usually a miss. Up through third, fourth, and fifth and back down seem fine.

I suspect that I’ll be opening the cases this winter to find out what’s going on, but I was hoping there might be some suggestions as to what to look out for. The clutch is adjusted properly and all plates looked OK and were well within spec when I checked earlier this year. The bike only has about ten hours on it since I checked the clutch, but I know it had a hard life before I bought it.

Any help would be appreciated, as I’m the one who is riding this until my stepdaughter graduates from her XR80.

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Most likely a bent shift fork. A left side crash can jam the shifter and bend a fork.

Fix it soon before it starts popping out of gear and causing more damage.

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Most likely a bent shift fork. A left side crash can jam the shifter and bend a fork.

Fix it soon before it starts popping out of gear and causing more damage.

 

:thinking: Are you by chance referring to the "shift spindle", that the shift lever bolts to........and not the actual internal "shift forks" ?

 

 Impacts to the shift lever damage the lever and shift spindle when it hits the end of it's travel .............just knocks trans into neutral or a different gear with no damage to shift forks usually.  Bent forks don't cause hard shifting, bent forks  symptom is no engagement at all, or popping out of gear under load (on the under engaged side).  A damaged spindle can cause hard shifting if it's binding or no longer engaging properly with the shift drum.  A bent shift lever hitting the case is something to watch for also.  

 

First thing to check with a hard shift problem like this is clutch free play.  Too much clutch free play will cause clutch drag, which puts a slight load on trans gears during shift...........and hard shifting.  Always check the basics first.......and go deeper from there! 👍 Also........once in a great, great while a change of oil can improve shifting, depending on what happens to be in it for oil and condition. :excuseme:

 

Old School Al

Edited by Old School Al

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Agree it will most likely be the shifter that engages the star wheel thingo. They bend from being stamped on to get first gear. Easy fix. Just bend it straight again.

A badly adjusted clutch will cause an issue getting all gears. Especially first.

This is a problem on XR 200 gearboxes as well.

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Could be a bent countershaft or loose rear sprocket bolts or a bent wheel or a tight chain link etc etc causing the vibration on back off.

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Bent Shift shaft, worn star, worn shift forks, worn left case where the shift fork shaft goes into.  See pic.   If you need any tranny's or cases or bottomends, let me know. motor1a.jpg

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Bent Shift shaft, worn star, worn shift forks, worn left case where the shift fork shaft goes into.  See pic.   If you need any tranny's or cases or bottomends, let me know.

 

 

Is the pin in the center of the shift plate slot actually supposed to limit shift plate throw on these, or does contact with the the case?   What type of wear exactly would you be looking for on the star that would cause problems shifting from first to second?  And exactly what type of wear on the shift forks would cause problems shifting from first to second?  I'm not really disagreeing.......just curious.  :thinking:

 

Old School Al

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The part in case wears out and cause the shaft to move.  I tried a new case and it helped.  You've never seen an oblong looking shift fork??? As far as the start goes, I've replaced the a couple times and helped the shifting.

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Also check to make sure the Shift Lever is not hitting the case as you shift up.

They get bent sometimes.

I've bought several bikes that had "shifting problems", I buy every one, bring it home, un-bend the shift lever... Problem solved.

Sometimes the shifter just needs to be moved on the shaft splines.

Good luck

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The part in case wears out and cause the shaft to move.  I tried a new case and it helped.  You've never seen an oblong looking shift fork??? As far as the start goes, I've replaced the a couple times and helped the shifting.

 

:thinking: Where none of the shift forks are detented to the fork shaft, end play wouldn't caused a problem till fork shaft came clear out of the left case.......or hit the back of the clutch basket.

 

Can you post up a pic of of a "oblong looking" shift fork.........?

 

I assume you referring to star (start)............?  What was wrong with the old star?  XR100 stars are for the detent roller to stop the drum in correct position "only".  Not used for shift plate engagement also like a XR200.  On a XR100 the shift plate engages with the pins under the star in the end of the shift drum.

 

Old School Al

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You never seen a worn star?? The points get pointier.  I'm sure I threw all my bad tranny stuff away ages ago.  Everything I have now is with in the last ten years.  But back to the original post.  My bet would be a bent shift shaft.

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You never seen a worn star?? The points get pointier.  I'm sure I threw all my bad tranny stuff away ages ago.  Everything I have now is with in the last ten years.  But back to the original post.  My bet would be a bent shift shaft.

 

You wouldn't by chance happen have a close up pic of a star worn pointier would you........?

 

:thinking: Wouldn't a bent shift shaft tend to cause binding of shaft rotation during shifting..............and affect more than one gear, and both up and down shifts?

 

Old School Al

Edited by Old School Al

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You wouldn't by chance happen have a close up pic of a star worn pointier would you........?

 

:thinking: Wouldn't a bent shift shaft tend to cause binding of shaft rotation during shifting..............and affect more than one gear, and both up and down shifts?

 

Old School Al

No on the star and maybe, but that's why instead of speculating, you just tear it down.  It's only like an hour from bike to the bench and split cases.  Not that big of a deal.  As long as you have a center and clutch gasket to go back together.  

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No on the star and maybe, but that's why instead of speculating, you just tear it down.  It's only like an hour from bike to the bench and split cases.  Not that big of a deal.  As long as you have a center and clutch gasket to go back together.  

 

 

:thinking: What are you calling a "shift shaft", one the shift forks are on inside the center cases, or the one the shift lever bolts to that rotates the star.....shift spindle?

 

The shift spindle is the one that gets bent............not the shaft the forks are on.  And, the one the forks are on doesn't rotate.  The only time I ever recall the shaft the forks are on being bent was in a tranny that had a gear split in half and jam up, seems like it ruined a case to.

 

Myself, probably the last thing I would even remotely consider splitting the cases for with the symptoms described would be looking for a bent shift fork shaft............!  If "everything" external was eliminated, I would  split the cases looking for a shift fork pin hanging up on one of the ramps on the shift drum.  This I have run into this a couple times with similar symptoms, but 99% of the time the problem is external.  Myself I would "always strongly" suggest educated speculation and inspection before tearing a engine completely apart with problems like this.

 

And.........."as long as you have a center and clutch case gasket"......what about base and head gasket?  :confused:   Not to mention the cost for "quality" gaskets......and time involved!

 

Old School Al

Edited by Old School Al

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You can get Honda gaskets for pretty cheap online.  I don't know what gaskets you use, but I use only OEM.  Time??? People on here will speculate for weeks instead of simply work on the bike.  It's a simple 30-45min job to tear it down. Too many people want to go back and forth and not go forward.  As you tear it down, you check all the externals, it's as simple as that.  If they get stuck or have a question, then post pictures or youtube it.  One could give much better advice.  And with me, I've blown up a bunch of trannys, so they are not 99% external.  In fact around 2001, Honda increased the strength of the main shaft.  I used to break countershafts, and 3rd/4th gear, and idle gears a bunch of times.  But my motors have more HP than stock.   XR100's are so simple to work on, they're not rocket science.   But yea, as everyone including me has mentioned check shift shaft, clutch, (I never have clutch issues), and clutch cable adjustment issues, even a bent shifter.  But with all these variables, you have to work on it and check it out.  It's not going to fix itself. 

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You can get Honda gaskets for pretty cheap online.  I don't know what gaskets you use, but I use only OEM.  Time??? People on here will speculate for weeks instead of simply work on the bike.  It's a simple 30-45min job to tear it down. Too many people want to go back and forth and not go forward.  As you tear it down, you check all the externals, it's as simple as that.  If they get stuck or have a question, then post pictures or youtube it.  One could give much better advice.  And with me, I've blown up a bunch of trannys, so they are not 99% external.  In fact around 2001, Honda increased the strength of the main shaft.  I used to break countershafts, and 3rd/4th gear, and idle gears a bunch of times.  But my motors have more HP than stock.   XR100's are so simple to work on, they're not rocket science.   But yea, as everyone including me has mentioned check shift shaft, clutch, (I never have clutch issues), and clutch cable adjustment issues, even a bent shifter.  But with all these variables, you have to work on it and check it out.  It's not going to fix itself. 

 

:thinking: Sorcal................we're darn lucky you didn't try to be a docter!  If someone came in to see you after all you can eat Taco Tuesday at Rosarita's Taco Bus with heart burn......................you would figure open heart surgery was needed! :excuseme: 

 

I'm sure you have blown up lots of "everything"..............and yes, at that point it's not external any longer! 😉

 

Old School Al

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You only split the cases if the gearbox is damaged. If you had let the oil out and metal came out.

To check the shifter you only need to pull the clutch cover off. Maybe a 15 minute job if you have some basic tools and knowledge.it will be slightly bent and not engaging the star wheel correctly.

Or it could be a bent gear lever.

Just have a crack at fixing it.

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You only split the cases if the gearbox is damaged. If you had let the oil out and metal came out.

To check the shifter you only need to pull the clutch cover off. Maybe a 15 minute job if you have some basic tools and knowledge.it will be slightly bent and not engaging the star wheel correctly.

Or it could be a bent gear lever.

Just have a crack at fixing it.

 

Amen............to The Land Down Under! 👍

 

There are actually a couple things that may cause these symptoms that require case splitting to repair, but they are very rare.  

 

Also, on this trans family the actual shift star does not engage with the shift spindle.......shift star is for drum detent only.  Not like the SL/CL/CB 100 - XR200R which do.

 

Old School Al

Edited by Old School Al

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There are a bit more than a few issues that a bottom end spit.  Bent shift forks, broke, gears, broken dogs, broken main shaft or counter shaft, Idler gear (very very common).  But also, we built out motor close to three times for power than stock.  I'm currently running a 148cc , web cam, Kitaco head, Powroll  9mm stroke, mikuni vm26 carb with the carb going in at a straight angle, with a reverse meg pipe, 5 disc clutch.  So I'm getting somewhere about 16-17.5HP, instead of a 6ish hp for a stack one.  Jimmy Lewis from Dirt Rider dynoed them at about 5.8ish for stock.  Anyway when you build race motors you learn very quick what the weak links are.  That's why we could break so many bottom ends,  Even when we were doing 120cc motors we broke are share of trannys.  They are a kids bike and not meant to be put in a serious roller like CR85 and pinned for hours at a time.  They're made for little kids as a trail bike.

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