'80 GS1100 Jumps Out of 2nd Gear

[Guest]

Now that the engine seems to be well sorted and I am slowly getting used to the amount of power this thing has I have found a problem with the trans. In second gear, full throttle, the gear will jump out just as I hit 6000rpm. If I don't exceed 6000rpm or if I use less throttle, the problem doesn't happen. I have done a search on this problem which has been addressed here before. I have made sure that my foot is nowhere near the gear lever when this happens, the clutch is properly adjusted and the chain and sprockets are in good order and adjusted.

From what I have read, it looks like this can happen to a trans that has been abused by clutchless changes. It has been suggested that what needs to happen is the engine needs to be split and the gear dogs have to be under cut. If this is the case, I won't be doing that for a long time but is there anything else I should be checking or adjusting to see if I can fix or improve this situation?

[rapidray]

Time to undercut the trans as the 2nd gear dogs & engagement slots are beat up. No other fix when it gets to that point.
Ray.

[blowerbike]

dogs get rounded..it just happens.
you need a back cut(may need welded or replaced) and maybe a drum and fork or two.
there is no band aids besides a quick shift to 3rd gear.

[chef1366]

That is a bummer

[blowerbike]

That is a bummer

what is up peter?

[Maddevill]

Usually the first time it does this it slams the shift fork out violently bending the shift fork. After that the gear dogs start getting rounded off due to the now bent fork not engaging the gear completely. You'll need to split the cases and replace any bent forks and worn gears. Like the others have said, that would be a great time to have all the gears undercut as well.

[almarconi]

I would just replace the parts with new OEM parts or a carefully inspected used transmission. If you shift your bike like its supposed to be shifted you shouldn't need to undercut the trans. I don't think there is anything wrong with the design of the transmission in that bike, just sounds like your bike was abused.

[stetracer]

I would just replace the parts with new OEM parts or a carefully inspected used transmission. If you shift your bike like its supposed to be shifted you shouldn't need to undercut the trans. I don't think there is anything wrong with the design of the transmission in that bike, just sounds like your bike was abused.

Actually there was a design flaw in bikes of the past in not being under cut maybe that's why they under cut the tranny dogs from the factory now . It would be cheaper to fix and under cut his tranny than to buy new gears.
Under cutting the tranny only helps a tranny and does not hurt it in any way

[Carter Turk]

I just had this done in May, but 3rd gear was popping, second was fine. Pearson in Ohio did the work. I had a spare transmission I sent before I split my cases. Works great now. I did renew all the shift forks, shift rods as well as the shift drum. I've seen used trannies on the bay for $80. There's gotta be a shop down under, who could do the job.

[almarconi]

Actually there was a design flaw in bikes of the past in not being under cut maybe that's why they under cut the tranny dogs from the factory now . It would be cheaper to fix and under cut his tranny than to buy new gears.
Under cutting the tranny only helps a tranny and does not hurt it in any way

I went back and forth on this issue with the RF900 I have. The gears are going to have to be replaced anyway if they are worn. Makes no sense having worn gears undercut. I could see possibly undercutting 2nd gear on a sport bike but I really could not justify the added cost. Not saying that there is anything wrong with having it done especially if the transmission is known for having problems. I am also not an aggressive rider, don't run the bike up to 100 mph in first gear and then shift without using the clutch. In your situation since you race your bike I could understand having this done.

[koolaid_kid]

My own recommendation:
Purchase a used complete transmission, including the shifter drum and shift forks. Have the gears undercut.
Then pull the engine, turn it upside down on your work bench, split the cases, swap everything out, and reassemble.
One weekend's work if you do it in this order. Did it just 2 years ago on my bike.

[almarconi]

The problem with used transmissions is that you can't tell the condition of the parts until you remove the gears from the shafts and inspect them. This happened to me when I bought a low mileage transmission off of Ebay. It looked great on the outside until I took everything apart. I soon realized that 3 of the gears were trashed. Used shift forks and drums are also a crap shoot.

[Eli69]

i thought it might be useful to post a picture of a transmission with rounded dogs.



this one would jump out of gear if ya looked at it funny... worst thing was it would jump out of 4th and into 2nd. caused some wild, sudden rpm changes.

it was my fault though. too many drunken power shifts and holeshots. just glad i'm still alive.

[almarconi]

Those look like some worn out dogs I'll bet the slots they ride in on the opposite gear are worn as well. Both gears will need to be replaced.

[MiketheBike]

Guys. Thanks so much for all the info. I'll look around for a guy that can undercut the gears in Sydney. Since this only happens under extreme acceleration (which I rarely use), and since this is now my daily rider until I finish some long overdue restoration and upgrades on my old Harley, it will be a while till I get back to this. Thanks again for all the advise.