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1974 Kawasaki F7

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Somewhere, I have a pic of a skinny Me, in My custom bell-bottoms, doing a high speed stand-up wheelie on My Kaw 175. I was Senior in High School.:sun:
 
If you are sucking air you should look at the seal under the flywheel. The rotory valve side will suck oil.
 
sporthog93 said:
If you are sucking air you should look at the seal under the flywheel. The rotory valve side will suck oil.
Click to expand...

Hmm, interesting. I am sucking air - so I'll go 'round to the left and look in there. BUT, I also found one problem on the valve side:

Getting into the valve cover, all the screws came out fairly easy and nice and clean. Except the top one:

P2089382.jpg


Rusted pretty badly! And the 120mm o-ring behind the cover was in good shape - everywhere except at the top:

P2089383.jpg


The screw boss is outside the o-ring, but I've got to think that a rusty screw at the position of that o-ring failure have to be related. And - a leak up that high would almost certainly suck air - especially that close to the intake.

The valve seal itself looks brand new. I've got an NOS seal on order. If I can't tell the new from the old, should I bother replacing the old one?

There was visible wear behind the rotary valve:

P2089385.jpg


It's not deep, but it's more than I expected. That's on the engine case itself, which again is a bummer. I'm nervous about leaving this as it is, but I'm also nervous about trying to smooth that out without really screwing up the case. I'd really rather not have to fully rebuild this engine.

I'm going to test the oil pump. The injector sprays the oil into the intake before the valve. Unless either of those two holes at the bottom of the case behind the valve provide oil from the crankcase, then the engine-side of the valve would be totally dry. So, maybe the engine was run with too little oil in the case?


In other news, I had a hard time getting the clutch hub off. Bought be a clutch removal tool, but the teeth on it were way to big to get a good grip on the teeth on the hub. So, I build my own tool:

P2089373.jpg


Didn't take too much pressure to get it all apart then. Clutch plates, springs, and everything else in there look brand-new. I'll measure all to make sure we're in spec, but only 750 miles on this thing, so all should just re-assemble as-is.
 
Your hands don't get very dirty working on this scoot! How are the forks? The oil is most likely the fish oil shipped from the factory. Those were the days, they put drain screws in the forks. Or did they on this one?
 
thencamedonson said:
Glad I could be of assistance.
Click to expand...

Yes - THANKS! Every bit of advice I can get is VERY helpful. I'm not coating my tank, as you suggested, but rather just de-rusting and leaving it like that. I'm going to see if the o-ring I found fixes my leak before opening up the crank case to check those seals. That's at least my current plan - I'm waiting on the friendly delivery guy for a buncha parts and a compression / vacuum tester before any more progress is made...

DaveC said:
How are the forks?
Click to expand...
Like jello :) No drain plug on mine. But, this'll wait until I get the air / fuel stuff sorted out.
 
Jeff S said:
Hmm, interesting. I am sucking air - so I'll go 'round to the left and look in there. BUT, I also found one problem on the valve side:

Getting into the valve cover, all the screws came out fairly easy and nice and clean. Except the top one:



Rusted pretty badly! And the 120mm o-ring behind the cover was in good shape - everywhere except at the top:



The screw boss is outside the o-ring, but I've got to think that a rusty screw at the position of that o-ring failure have to be related. And - a leak up that high would almost certainly suck air - especially that close to the intake.

The valve seal itself looks brand new. I've got an NOS seal on order. If I can't tell the new from the old, should I bother replacing the old one?

There was visible wear behind the rotary valve:



It's not deep, but it's more than I expected. That's on the engine case itself, which again is a bummer. I'm nervous about leaving this as it is, but I'm also nervous about trying to smooth that out without really screwing up the case. I'd really rather not have to fully rebuild this engine.

I'm going to test the oil pump. The injector sprays the oil into the intake before the valve. Unless either of those two holes at the bottom of the case behind the valve provide oil from the crankcase, then the engine-side of the valve would be totally dry. So, maybe the engine was run with too little oil in the case?


In other news, I had a hard time getting the clutch hub off. Bought be a clutch removal tool, but the teeth on it were way to big to get a good grip on the teeth on the hub. So, I build my own tool:


Didn't take too much pressure to get it all apart then. Clutch plates, springs, and everything else in there look brand-new. I'll measure all to make sure we're in spec, but only 750 miles on this thing, so all should just re-assemble as-is.
Click to expand...

Those clutch spring bosses that you screwed your tool into will break really easily. It is cool that you found a solution but be very careful using the bosses to hold the hub. They are not made to take ANY side load at all. Maybe find some one that will let you borrow their electric or battery-powered impact. No holder necessary then if you can get the torque close to what the spec is.
 
Johnf3 said:
Those clutch spring bosses that you screwed your tool into will break really easily. It is cool that you found a solution but be very careful using the bosses to hold the hub. They are not made to take ANY side load at all. Maybe find some one that will let you borrow their electric or battery-powered impact. No holder necessary then if you can get the torque close to what the spec is.
Click to expand...

Yes - getting it off actually didn't take a lot of torque. Getting it torqued back on will likely strain those bosses more than intended.

But - even with an impact driver, that's still going to try to twist that whole housing around. Right? Or, are the impacts quick enough to be able to lock the hub down a little easier?
 
Jeff S said:
Yes - getting it off actually didn't take a lot of torque. Getting it torqued back on will likely strain those bosses more than intended.

But - even with an impact driver, that's still going to try to twist that whole housing around. Right? Or, are the impacts quick enough to be able to lock the hub down a little easier?
Click to expand...

It will spin some but tighten right up. The torque wrench police will probably call me out, but as long as you use some sense with an impact (don't hammer it on with a 200 ft lb air wrench) it works well. Most modern bikes have a lock washer that bends up over the clutch hub nut, so it is not going anywhere.

That all being said, you do not want to over tighten either. Most dirt bikes these days call for around 50-60 ft pounds on that nut. Yours is probably less. I'd hit it with my 3/8 inch butterfly impact and call it good.
 
Johnf3 said:
Most dirt bikes these days call for around 50-60 ft pounds on that nut. Yours is probably less.
Click to expand...

Service manual says 36 ft-lbs for the primary gear nut. I can't find any spec for the clutch hub nut. Guess I'll do about 36 there, too. I'm still waiting on parts to arrive - but with any luck I'll be starting the re-install this weekend! If I can't find any better thing to do, I might just make a new clutch hub holder that attaches to at least four of those hub bosses, but I'll see if I can devise a way to hold the hub by the teeth - like the 'special tool' shown in the shop manual.
 
Congrats on the new bike, Jeff. That looks like a fun little scooter.
 
Well, it's been too dern cold and I've been busy with "real" work, so little has been done.

I did replace that 120mm o-ring and button 'er all back up, but even very slight compression testing showed I was still leaking - BUT that pointed to the rotary valve seal (which I should have just replaced while the valve cover was off). So, pulled the cover back off, replaced that seal (removal and replacement was much easier said than done) and now I'm holding compression!! At least a bit - my compression test setup is a bit, uh, imprecise, as I can't find a 30mm expanding plug to properly fill the carb intake port. So, a 28mm plug a duck tape was my stand-in. And that alone leaks slowly.

So, 30mm plug is en-route from China via my best friends at ebay. That'll take a week - so in the meantime, I might look at cleaning up some of the rusty bits, cleaning the engine case covers, etc. Or, maybe not.
 
As long as you've got it that far apart, probably should tighten the power band. ;-)
 
Jeff S said:
Ahh, of course! Especially on this Kawasaki! You guys are full of great advise!
Click to expand...

:clap:

Anxious for you to get it going, Jeff. Those little rotary valve bikes were lots of bullet proof fun.
 
Long time, no update...

I've been distracted with other stuff, so the bike has been sitting in pieces since early March. Last weekend, I put 'er all back together and tried to fire it up.

No spark!

That's a new problem, and is frustrating as the electrics in this thing were working perfectly. Tried a new plug, then ANOTHER new plug, and that didn't help. So, I need to pull the flywheel and examine the coils.

So: that's where I am now. I bought a gear puller to try to extract the flywheel, but no luck so far. Who knows the magic process to remove a flywheel that's been stationary for about 40 years? I've tightened the gear puller more than I'm comfortable doing. How much torque should I be applying here? Would an impact wrench on the gear puller be a bad idea?
 
Keep a load on the flywheel puller and gently rap with a mallet...lightly as too hard can wreck the manetism.
Then see if allows you to get a little more on the bolt.
Walk away and leave a load on it and sometimes you can come back after a day and it will be off.
Finally, if need be apply heat to the rivets and that will transfer heat where needed.
 
Some models required a two piece device that outer screwed into the center of the flywheel and the inner bolt when tightened would force the fly wheel off. That is after you removed the nut or bolt holding it from the factory.

IMG_0682_zpstbyjyr75.jpg


IMG_0681_zps32si7zhz.jpg
 
Jeff S said:
Long time, no update...

I've been distracted with other stuff, so the bike has been sitting in pieces since early March. Last weekend, I put 'er all back together and tried to fire it up.

No spark!

That's a new problem, and is frustrating as the electrics in this thing were working perfectly. Tried a new plug, then ANOTHER new plug, and that didn't help. So, I need to pull the flywheel and examine the coils.

So: that's where I am now. I bought a gear puller to try to extract the flywheel, but no luck so far. Who knows the magic process to remove a flywheel that's been stationary for about 40 years? I've tightened the gear puller more than I'm comfortable doing. How much torque should I be applying here? Would an impact wrench on the gear puller be a bad idea?
Click to expand...

The correct tool is cheap and effective in this case. I think this is it:

http://www.rmstator.com/en_ca/produ...i-1970-2007-suzuki-1987-2008-yamaha-1968-2007
 
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