Topic: pops out of gear when riding...

[asom]

several times in the last week when riding the bike pops out of gear when I hit bumps, go over railroad tracks, etc.  Is this a clutch problem, is my cable adjusted whacky, bad gears.  what should I do first?  Also grinds a little when I first go into first.  thanks

Scott

[scrapvalue]

Start with clutch adjustment. The fact that it grinds when you put it in 1st sounds clutch oriented.
Is always the same gear it is popping out of? If it is just one gear, then it could be a worn gear issue.
How many miles on your bike?
Have you been drag racing it?

[asom]

23k on the odometer.

no drag racing (known by me)

different gear just depends what gear I'm in when I hit the bump.  could be my foot and I just don't realize I'm hitting the gearshift.

I bought the bike with drag bars on it and didn't like the feel so I went back to vintage.  Ever since I haven't liked the way the clutch feels.  And that's when I noticed this happening.  This is all within a month or two of purchase...

[scrapvalue]

I would start with the clutch adjustment.
The PO may have installed a shorter cable for the cafe bars.
Or you may have routed the cable wrong when you installed the stock bars.
Maybe not either, but it does sound clutch oriented.
If it is a gear issue, it is usually just one gear,(2nd mostly), and it is caused by hard shifts under heavy acceleration.
Is there any excessive movement in your shifter? Does it feel sloppy?

[MCRider]

several times in the last week when riding the bike pops out of gear when I hit bumps, go over railroad tracks, etc.  Is this a clutch problem, is my cable adjusted whacky, bad gears.  what should I do first?  Also grinds a little when I first go into first.  thanks

Scott

Always helps to let us know what bike?

99 times out of 100, its a bent shift fork/worn dogs on gear issue. If a CB750, requires removing engine, flip it over, take the bottom case off, replace offending parts, reassemble.

Of course try all the other stuff first, clutch adjust etc.  The drag bars are suspicious. Previous owner probably did some bang shifting.

Problem now is finding good used parts as new ones are unavailable from Honda. But good trannies are on eBay often. Yamiya sells repro gears for this problem, but they're like $750 for the set. This is a not so uncommon problem following abuse, there are many threads here of people who had to fix it.

[Nikkisixx]

WTF Asom!! You want it to start, idle, charge the battery, and stay in gear?  

Seriously though, scrapv may be onto something.  Make sure the cable isn't in a bind and moves freely, then adjust the clutch.  Also, make sure you confidently shift gears - half hearted shifts can cause this problem too.  

[asom]

adjusted the tension at the caliper and down by the gears.  much better feel and couldn't make it pop out.  went on the bumpiest roads and the roughest tracks I could find.  but...

while out there it started reving up.  throttle closed.  I backed off the idle screw at the stop sign.  It was idling at 1100.  Few blocks down the road reving up to 4k, adjusted the idle again.  haven't had a chance to check but is there something simple like a loose bolt that cause this or is it more likely ANOTHER carb issue?

ideas...

oh yeah 78 CB750

[scrapvalue]

Cable tension issue i'll bet.
Make sure the cable housing has play in it when you turn the bars all the way to the right and the left.

[asom]

I'll check.  I don't understand how that would cause this.  It's not sticking it's rev'ing up from lower rpm's and it doesn't matter if it's a straight away or curve.  could you splain it to me?

[scrapvalue]

The fact that you were not having any problems with gears popping out or high reving before you changed the bars,
leads me to believe you did something when you changed them. Or the PO installed shorter cables when he installed the shorter bars.
Does the bike just rev up by itself, or do the revs not come down after you let off the throttle?

[asom]

all by itself.  I installed the cables and got them from motion pro.  they fit perfectly and were the same length as the PO's.

It just manifested today.  I've put 500+ miles on it since the change.

[scrapvalue]

Sounds like a vacuum leak. For some reason it is running lean at idle.
My bikes all have the older style carbs that are just straight pulls.
I think your bike has the newer style that has the vacuum operated carbs.
If that is the case, I don't know a lot about them, but someone here may be able to offer more info.