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First gear skipping out at high revs

Started by 86njfj, November 01, 2014, 07:52:37 AM

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86njfj

Hello fellow FJERS, I recently did the clutch in my 86 1200. OEM frictions, Barnett spring conversion. Bike performed excellent for several hundred miles of beating it like it owed me money. Now at high rpms in first gear it will skip out of gear. She will skip right back in and does not do this in any other gear. 19k on the bike. I would appreciate any advice on which direction I should take in examining the problem. Has anyone ever had this or heard of this symptom before? Thanks in advance

Arnie

Others will chime in, I'm sure but you have the start of the dreaded "worn engagement dogs" and "bent selection fork" illness.  This is usually caused by lazy shifting, but can sometimes occur even if you don't miss shifts but hit them hard.
The later selection forks are thicker/stronger, but still sometimes bend.
To properly repair this requires the engine cases to be split.
It is a fairly common problem on FJs and other hi hp bikes.

Your temporary work-around is to short shift and make certain to fully engage the next gear before dropping the clutch.

FJmonkey

Welcome 86njfj (till we know what you want to be called by). What you describe is not common to first gear, it is very common in second gear like my 86'. The shifter fork is bent and it will not unbend itself. To fix it you need to drop the engine and split the case to replace the shift forks with newer (stronger) forks. When you chose to go this far down the rabbit hole, have the dogs undercut for gears 1 to 3 (or all of them) to ensure positive engagement.

I just spent a few days at RPM Motorsports with Randy to find and fix an oil leak. I will post my tip report later today on this. In less than two days we dropped and installed my engine twice. The second go around we timed the process. Randy and I started with my bike off the lift table and started the tear down at 5:00 PM, we had my engine on the welding bench at 5:21 PM. So dropping the engine is really not that big of a deal. No special tools just a floor jack and the drive to get it done.

The short answer is to live with first gear jumping out, however, if you don't short shift and prevent it from jumping out then the jump will start to happen at lower revs and and eventually the fork will be so bent you will not have a first gear.

Sorry to be the bearer of bad news but the truth is always the best path. Koookaloo brother (except in first gear)....
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

86njfj

Ouch! Oh well, riding season is really winding down and I guess it's teardown season. I would hate to go in completely blind does anyone have a line on a workshop manual? I have been lucky in finding them for other bikes I've owned over the years, but have yet to find a factory FJ manual

FJmonkey

Quote from: 86njfj on November 01, 2014, 09:37:10 AM
Ouch! Oh well, riding season is really winding down and I guess it's teardown season. I would hate to go in completely blind does anyone have a line on a workshop manual? I have been lucky in finding them for other bikes I've owned over the years, but have yet to find a factory FJ manual

Check the files section, some links have been posted for manuals.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

86njfj


aviationfred

Quote from: 86njfj on November 01, 2014, 09:37:10 AM
Ouch! Oh well, riding season is really winding down and I guess it's teardown season. I would hate to go in completely blind does anyone have a line on a workshop manual? I have been lucky in finding them for other bikes I've owned over the years, but have yet to find a factory FJ manual


Welcome to the group,  :hi: Not much more to add, FJmonkey gave you the skinny. There are members all over the world and most of the 50 states. What part of the world are you from? There may be other FJ owners nearby that could offer hands on assistance.


Fred
I'm not the fastest FJ rider, I am 'half-fast', the fastest slow guy....

Current
2008 VFR800 RC46 Vtec
1996 VFR750 RC36/2
1990 FJ1300 (1297cc) Casper
1990 VFR750 RC36/1 Minnie
1989 FJ1200 Lazarus, the Streetfighter Project
1985 VF500F RC31 Interceptor

Bill_Rockoff

I will go against the grain here, because 2nd gear is usually the problem, or usually the biggest problem, with shifting.  Also, I have not had one jump out of gear and then back in.  (I have had one jump out of gear and then rev in neutral, and I have had it TRY to jump back in.)
Quote from: 86njfj on November 01, 2014, 07:52:37 AMShe will skip right back in and does not do this in any other gear. 19k on the bike.
How are the chain and sprockets?  This sounds more like "a chain slipping over worn sprockets" than "a bike jumping out of gear."  The only time I have ever felt/heard a slip and then resumed hard acceleration, it has been a chain slipping over worn sprocket teeth.

And 19,000 miles is getting to be the end of service life for a typical set of sprockets and chain if it hasn't been regularly adjusted.

I hope it's chain / sprockets, and not anything internal.  Chain / sprockets are fairly easy and they are normal maintenance items.

Good luck,

- Bill
Reg Pridmore yelled at me once


FJmonkey

My second gear pops in and out like a rev limiter.  :ireful: :ireful: :ireful: :ireful:
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

simi_ed

Quote from: Bill_Rockoff on November 01, 2014, 04:26:10 PM
I will go against the grain here, because 2nd gear is usually the problem, or usually the biggest problem, with shifting.  Also, I have not had one jump out of gear and then back in.  (I have had one jump out of gear and then rev in neutral, and I have had it TRY to jump back in.)

Good luck,

- Bill
I had this exact problem with 1st gear, after an excess(?) application of throttle with a fresh 1314 motor.

1st time!  Bent the F'in shift fork!  Tried 1-2 more times to be sure, and it behaved just like 2nd gear had done previously!  Replaced 1st gear fork, and installed an undercut trans from Randy.  So far so good, but it's a PITA, an expensive, time consuming PITA!
-- RKBA Regards,

Ed
===
Ed Thiele 
Simi Valley, CA -- I no longer have SoCal manners.
'89 FJ12C (Theft deterrent Silver/White)


- All that is necessary for the forces of evil to win in the world is for
enough good men to do nothing.

- Edmund Burke

Firehawk068

Quote from: Bill_Rockoff on November 01, 2014, 04:26:10 PM
I will go against the grain here, because 2nd gear is usually the problem, or usually the biggest problem, with shifting.  Also, I have not had one jump out of gear and then back in.  (I have had one jump out of gear and then rev in neutral, and I have had it TRY to jump back in.)
Quote from: 86njfj on November 01, 2014, 07:52:37 AMShe will skip right back in and does not do this in any other gear. 19k on the bike.
How are the chain and sprockets?  This sounds more like "a chain slipping over worn sprockets" than "a bike jumping out of gear."  The only time I have ever felt/heard a slip and then resumed hard acceleration, it has been a chain slipping over worn sprocket teeth.

And 19,000 miles is getting to be the end of service life for a typical set of sprockets and chain if it hasn't been regularly adjusted.

I hope it's chain / sprockets, and not anything internal.  Chain / sprockets are fairly easy and they are normal maintenance items.

Good luck,

- Bill

I also had this happen about a year after I first got my FJ.
It would only do it in first gear, and it would only do it under really hard throttle use...................................It turned out to be the chain/sprockets.....

After doing a bunch of mods to the bike all at once, just before the 2010 WCR, one of them being New Chain and Sprockets....................and with proper slack adjustment, I never had the issue again......



Alan H.
Denver, CO
'90 FJ1200