1st gear problem

madsen5

XS650 Enthusiast
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Finally i got a chain and brakes sorted out and took the bike for a test ride, only to discover that I have a problem with my 1st gear. The bike sort of jumps out of first gear, revs up a couple of thousand and then snaps back into gear with a load clonk. This goes on as long as I keep it in 1st. All the other gears work fine.

Please tell me that there is a chance that this can be fixed without splitting the cases.

What do I do?

/Mads
 
If all the springs are on the shift shaft arm under the right side case then I would think that the bottom case would have to be taken off.......won't have to interupt the top end at all....watch hidden nut under the right side clutch cover....and be sure to check that the shift fork for first gear isn't bent or scored..if so replace...replacing at least the large first gear wheel ..........

xsjohn
 
Thanks John

Can anybody point me to a picture that shows how everything his suposed to look like in there. Also, will i need a gasket for the side cover or do I use gasket cement for that. (Asuming that the problem can be fixed without splitting it)
 
- selector return spring...in case you need to split the cases the bolt hidden behind the clutch is shown here between the shafts

xs650rightur2.jpg


- shift shaft spring

file-3.jpg


- selector

gearslector.jpg


- lower case bolts

005_063.jpg


- gears

BottomShafts.jpg


GearPairs.jpg



- selectors

attachment.jpg


shiftforkk.jpg
 
Wow... thanks a lot. I don't think I even need the Haynes book now. :thumbsup:

You guys are great.

I hope I have the time to take the cover of tomorrow. Crossing fingers that I find a broken spring and won't have to tear into the gearbox.

I'll let you know.

/Mads
 
So tonight I had the side cover and clutch of the engine. Unfortunatly I didn't find much wrong in there.

The only thing I could find was the smal bolt that holds the star-shaped plate on was i bit loose. I really hoped that was enough to cause the problem so I assembled everything and poured some fresh oil in there. Fired it up, but the first gear still jumps out.... :banghead:

Guess I will have to split the cases then.:eek:
 
I spend the last week trying to figure out if I should wait untill winter to get this thing running. I also have a running honda CB650.

Well... I just can't leave it there, so tonight I pulled the engine and split the cases. The 1st and 4th gear look a bit worn and maybe also the shift fork, but nothing look really damaged. Could you tell me what to look for?
 
Look at the mating surfaces where the dogs meet the mating gear.......2-5 the gear dogs are slightly beveled so the gears actually pull themselves together when torque is applied.....now first the bevel is not there so if worn any the gears will pull apart..........I always build the bevel back into first gear........ dremmel and all.....yea but that's me......I also try to tell people other things about these but usually all that goes unheeded also...........for instance my 8-1 80 at 92 degrees now runs wonderful........not that way 12 years ago...........Tee Hee for the summer on these .............LOL

xsjohn
 
Well... I wasn't quite sure what was wrong, so I took the day of and brought the open engine to a shop nearby that actually specializes in XS650's. (www.xs650danmark.dk) They have a huge stock of parts and say that they know what they are talking about. They also sell parts from Mikes.

The mecanic spend about an hour taking the transmission apart checking gear dogs and shift forks. He concluded that the gears was fine, but the shift fork for 1st and 4th gear was worn and a little bent. He found a used one that was ok and mounted everything back up. I also got an oil filter (the one at the bottom of the engine) a complete set of oil seals and some gasket cement for the cases. Total cost for parts and labor was 250 dollars. I think that's very reasonable.:thumbsup:

I have attached a few pictures of the worn shift fork and the open engine in my garage. Its been a while since I did something like this, but it was fun.:)

Now I'm just waiting for my MikesXS 2-1 exhaust to arive. I sold my original headers so i can't test it right now. Crossing fingers though.:bike:

/Mads
 

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So last night I finally got the bike all back together. The exhaust from Mikes sound great and the engine is running fine with freshly set valves an all.:thumbsup:

The first couple of minutes of the testride went fine, but the third time I used 1st gear the problem returned.:yikes: :wtf: :banghead:

Ah well... I tell myself that I bought this thing because i like to wrench. But I didn't think I would have to take the engine apart several times before I got it on the road.

Now the problem is I really don't know what to do about this. Maybe I should follow xsjohn's sugestion and undercut or build some bevel into the gear...

Back in the garage..:(
 
Go back to the place that worked on it and let them test ride it. See if they will fix it, they said it was fixed, it wasn't. Maybe they will make it right. If not they might put in different gears at cost. Worth a shot.
 
Hi Madsen5,
I have had the same problem with my '82 XS650SJ for several years thinking it was a clutch problem. After replacing everything in the clutch from the lever on down close to eight times, I ran across this forum.
Like you, I took my engine apart and found a well worn shift fork.
100023

I thought that the worn fork was a symptom of the problem and not the problem itself. Even with the worn shift fork there was not enough free play to allow the dogs on the gear to back out of the holes. Some things I did notice was that on mine is that the dogs did not fully engage in the holes when in first gear (they only engage about half way) and that the 1st gear was more wobbly on the shaft than the other two freewheeling gears on that shaft. The wobble was also not enough to make the dogs disengage. My stopper wheel on the shift drum was also well worn. I have been reluctant to reassemble the engine because I'm not sure I have found the problem. The latest theory is that over time the dogs and holes have become worn in the opposite direction of an undercut and that coupled with a worn shift stopper allows the spinning gear (4th) to slide out of 1st gear and rub against the shift fork either wearing it down or bending it.
After talking with XSJohn I tried to undercut the dogs and holes with a dremmel tool but I haven't gotten very far. The metal seems to be harder than any of the bits I have.
 
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Hi XLalan

It would seem that we have the same problem. Like you I have concluded that the gears must be undercut to solve the problem. Actualy I'm going to start diassembly tonight. What kind of bits did you use for the dremel?

Anyone else have any thougts on what tools to use for cutting the gears?

/Mads
 
Well I didn't have the right one. The small tipped metal bits didn't seem to be hard enough and I tried a grinding stone that had a cupped end. It seemed to remove some material but it was too big to get in the holes. I talked to a machinist and he suggested a narrow hone and lots of time. I tried a small hone that I removed from a mangled brake cylinder honing kit but had no luck. I also emailed a race shop and they said they could do it for $100. but they were backed up for four weeks. At the time I thought that was $50 too much and three-and-a-half weeks to long but now I'm beginning to wonder... I heard about someone using their chainsaw chain grinder to cut the dawgs but it would not work for the holes. XSJohn says he has done several with his dremel but I failed to ask him what bit he used. Maybe if he is reading this he can help.
Alan
 
You have to use a small stone tip to back cut the gears so they lock together.....you can look at the other gears to see how much..........

xsjohn
 
The good thing about all of this is that I get some wrenching done. 1 hour 50 minutes from complete bike to gears in hand. :rock:

The bad thing is that the new shift fork i but in is exactly as worn as the old one now and i only ran the bike a couple of times in 1st gear. So I need to undercut the gears AND buy a new shift fork. :banghead:

Another option is to spend 400 dollar on a big box of engine spares I found. The box includes engine cases with gearbox and crank, barrels and pistons, complete cylinder head and a lot of other bits.

I want to do a rephase later so this way I will have a new crank and cam that I can work on while still riding the bike.

Only thing is the parts is from a '76. Will I have any complications mixing those parts with my '79 engine?

One thing is for sure - this thing is turning in to a moneypit. :yikes:

Mads
 
At last.... SUCCES!!!! :D

I got half an engine from a local guy and swapped first and fourth gear, all the shift forks and drum for less worn parts. I just got back from a short test run. :bike:

Hope to have the thing inspected and plated on friday :wink2:

/Mads
 
Well it's only 810 km to Gernsheim, but my German is very bad, to say the least :cussing:

I just spent the evening making sure the bike is ready for inspection. I had to fit a chainguard from an old Honda because that was all I had. A few weeks ago I sprayed the tank and side covers real fast.

Here's a few pics...
 

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