2nd Gear Issue

[MotoRoboto]

So of course the donor motor for my 7/11 has a wonky 2nd gear. I know I will have to fix it. That being said...

Basically runs great but when in 2nd it will do a neutral like lull and then surge and rest of 2nd is normal. The lull/surge happens within less than a second. Maybe half a second. Doesn't fully pop out of gear. Tach is also acting up but I would have to guess it happens around 5k rpm with casual acceleration. Does anyone have any experience with these symptoms and what it ended up being more precisely? Just curious about others experiences with it and what it was. Have done a lot of searching but the actual damage is rarely covered.

[TonyGee]

have you got a gear linkage on your bike ?  if so make sure thats free and smooth before you delve into the engine. 

[Duckndive]

Second gear tends to get the most abuse... 1-2 shift power wheelies etc 

The dogs on the gear's wear and then wont hold under power .. 

Later box's had a better undercut and are less prone to the damage ..

But as Tony said check the linkage is smooth 1st and fully moving the shift shaft 

[MotoRoboto]

Will do. It is more difficult to shift into 2nd gear than the rest. It's also just generally more difficult to upshift period. Downshift seems normal.

[MotoRoboto]

1 hour ago, TonyGee said:

have you got a gear linkage on your bike ?  if so make sure thats free and smooth before you delve into the engine. 

It's a '90 1127R motor in an '86 750 frame with the stock linkage from the '86 750 but the clutch push rod from the '90 1127R.

Edited April 29 by MotoRoboto

[MotoRoboto]

49 minutes ago, Duckndive said:

Second gear tends to get the most abuse... 1-2 shift power wheelies etc 

The dogs on the gear's wear and then wont hold under power .. 

Later box's had a better undercut and are less prone to the damage ..

But as Tony said check the linkage is smooth 1st and fully moving the shift shaft 

I've thought about getting the Factory Pro detent arm and stiffer spring. If it's not the actual trans this is said to help make shifts cleaner. It's a '90 1127R motor with the stock '86 750 shift linkage but the clutch push rod from the '90 1127R.

[clivegto]

I bought a B12 brand new when I was younger. Hooned it about on the back wheel every where I could changing from 1st to 2nd gear a lot this resulted is what you described. Rounded the dogs of 2nd and 5th gear. Got new one's of Robinsons Foundry whipped the bottom crank case of and replaced them. 

[MotoRoboto]

50 minutes ago, clivegto said:

I bought a B12 brand new when I was younger. Hooned it about on the back wheel every where I could changing from 1st to 2nd gear a lot this resulted is what you described. Rounded the dogs of 2nd and 5th gear. Got new one's of Robinsons Foundry whipped the bottom crank case of and replaced them. 

Yeah that was the original prognosis and plan. Was curious if forks or cogs or maybe something else. Also wanted to check the linkage suggestion above.

[clivegto]

6 minutes ago, MotoRoboto said:

Yeah that was the original prognosis and plan. Was curious if forks or cogs or maybe something else. Also wanted to check the linkage suggestion above.

I was lucky with the forks as they were still alright on that one.

Edited April 29 by clivegto

[MotoRoboto]

The shifter linkage was a bit balled up. I reset it so it was as it should be. It shifts much easier and cleaner now. The lull/surge still occurred but it was way less frequent and severe. Also noticed as I adjusted the clutch lever further out the frequency and severity lessened even more. Wondering if the '90 1127R push rod isn't long enough. The stock '86 750 pushrod was way too short. I"m using the '86 750 sprocket cover with the '90 1127R pushrod. I've heard mention of needing to find the right length pushrod when doing a 7/11.

Anyway, not gone but much less severe. It's almost livable for the time being. I just got done doing the swap and don't feel like doing that shit all over again just yet. 

[MotoRoboto]

8 minutes ago, clivegto said:

I was lucky with the forks as they were still alright on that one.

Yeah I'm amazed there's anything left new. 2nd driven gear is obsolete now.

[clivegto]

3 minutes ago, MotoRoboto said:

Yeah I'm amazed there's anything left new. 2nd driven gear is obsolete now.

2nd engages 5th dogs as well look close for any rounded ends. 

[MotoRoboto]

1 minute ago, clivegto said:

2nd engages 5th dogs as well look close for any rounded ends. 

Will be sure to check. Thanks 

[Buzuki]

After you remove clutch assembly check for condition of two gear shift pawl , upper and lower one , sometime they go broken making gear shifting difficult .

[MotoRoboto]

3 hours ago, Buzuki said:

After you remove clutch assembly check for condition of two gear shift pawl , upper and lower one , sometime they go broken making gear shifting difficult .

Ok. Will check those. Thanks for the info!

[MotoRoboto]

Just going through the trans. Was expecting more damage. Shift arms look decent but will double check. Got some new old stock 2nd and 5th gears.

Putting the Factory Pro dentent arm and stiffer spring in while I'm in here.

 

[Gixer1460]

Those dogs are Donald Ducked for sure. Sharp square edges are req'd for positive engagement & retention. Even better is an undercut as later gears got.

[MotoRoboto]

18 minutes ago, Gixer1460 said:

Those dogs are Donald Ducked for sure. Sharp square edges are req'd for positive engagement & retention. Even better is an undercut as later gears got.

Yep. The ones I got got are the latest versions so should be much better. Those early ones are so blunt and basically as cast it's not surprising they fail so easy.

[MotoRoboto]

Bike is back together and shifting great. Thanks!