Winter project '72 Kawasaki F7

[Dan-o]

I'm amazed at how many F7 parts are available on Ebay.

[Stein]

I found the cause (or a cause probably) for the smoking.  I removed the exhaust to see if I could fix the leak at the head and the muffler had about a 1/2 cup of black tar oil in it.  I'm pondering how to clean that out that doesn't involve making a bomb, if anyone has ideas I'm all ears.  I was thinking of just using good dish soap to get a good amount out and then burning the rest.

The bigger question is how it got in there.  I'm hoping it's just an accumulation of years and years including a couple times trying to start it when it wouldn't run.  I do remember my dad idling it for a long time before riding which probably didn't help either.

The oiler was set a bit rich which was easy to fix.

What's not so handy is you need to pull the head to get the exhaust gasket off and replace with a new one.  I haven't decided if I want to mess with it or not.

Can you post a pic of it?

Here you go, there was oil in the curve right where it attaches to the head as well as plenty more in the main part where the baffle is.

[Stein]

Here's the head, you can't get the flange or gasket off unless you either pull the head or somehow coax the bolts out.  Interestingly, the bolts are only used to position the flange, gasket and pipe, the entire thing is held together by the two springs.  I was tempted to just put two nuts on and snug it up but I'm sure there is a reason it isn't bolted on.

It was leaking around the gasket.

[Stein]

Correction, looks like there should be nuts and lock washers which makes obvious sense.  I saw at least 2 other YouTube videos and they didn't have nuts either.  The nuts hold the flange on and the spring holds the pipe.  They also some asbestos rope that is made into an o-ring, probably not going to use that so I'll have to figure something else out.

[Sandberm]

My motocross bikes always had a rubber o-ring that was in the pipe that sealed, for the most part, where it connected to the cylinder with a couple of springs to hold it on. My bikes would spooge a bit too and from time to time i would have to put a new o-ring in.

So, could you find a rubber o-ring at somewhere like Tacoma Screw that would work instead of the asbestos ring? I assume there is a groove either on the pipe or the flange for the asbestos ring to settle in. Maybe a ring of high temp silicone?

I'd put some gasoline in the exhaust pipe and swish it around a few times and let it sit to break up the oil and carbon in the pipe. Dump out the gas and let it dry, perhaps heat it up with a small propane torch and then whack on the outside with a rubber mallet to break stuff loose and dump it out.

If you think that flange gasket is leaking, take the motor out of the frame to replace it. I bet the leak is just from the pipe not the flange. https://www.chapmoto.com/oem/kawasaki/f7/?timestamp=2022.8.38&year=1972&assembly=839230

[Stein]

Thanks, shouldn't be tough to find an o-ring as long as it can tolerate pretty high heat.  I also found a NOS asbestos rope or I could probably find some type of fireplace gasket material to use as well.  I'll try just bolting it back together and see if that fixes it.  I don't care if it leaks a bit, but dripping oil onto the pipe means it's smoking from both ends.

The heat gun method seems to be working on the pipe, I didn't want to smoke out the neighborhood so this seems like a slow and steady way.  I'll run it until it's all burned and then knock out the solids.

[Stein]

I'm amazed at how many F7 parts are available on Ebay.

No joke, there are also a ton of NOS parts.  I even found a place to buy new tank and fender if I want to go all out.  Most of the stuff is reasonable, but there are also guys trying to sell a gasket for $149 on ebay.

[Sandberm]

Your heat gun method is impressive. Well done 

[CP]

Early model oil injected 2 strokes were problematic even when they were new.  They were known for blowing great clouds of smoke and running very dirty (like you are finding).  Many owners chose to just premix their fuel.  Easier in the long run. 

Kerosene works well for cleaning out the carbon ooze, but it looks like you have already found a solution. 

[Stein]

I'm split on bypassing the oil injector, I did my homework and it is only oiling the carb on this model.  Some models oil the main bearing too which would be no bueno.

I'll probably run it with a new plug and correct adjustment on the pump and carb and see what happens although I'm super tempted to bypass it and run premix.

It had the oil pump adjusted rich, wrong plug and wrong jet for the altitude it was in, so I can't draw too many conclusions yet.

Some smoke is expected, but it was smoking from the front and back and I could only do two loops in the cul de sac because I couldn't see where I was going.   Neighbors are more impressed with me every day.

The heat gun just scratched the surface, so I upgraded in the back yard.  I got a good hour of massive burnoff, should be at least enough to make a big difference.  It needed repainting anyway.

[CP]

Now that’s impressive.  Looks like it could double as a potato gun.

[Stein]

Any good reason to spend more on a tube than this?

https://www.cyclegear.com/gear/bike-master-performance-motorcycle-tube?sku_id=1087221

It's obviously not going to be seeing extreme use and I figured that tube is as good as the one from 1972 that's still holding air.

[CP]

Any good reason to spend more on a tube than this?

https://www.cyclegear.com/gear/bike-master-performance-motorcycle-tube?sku_id=1087221

It's obviously not going to be seeing extreme use and I figured that tube is as good as the one from 1972 that's still holding air.

That tube should be fine.  I'd replace the rim strips as well, I expect that they would be pretty brittle after all these years.

[Stein]

 

I'm actually going to pay a shop in Lynwood to do the tire change for $20 a tire and having new tires, tubes and strips put in.  It is less money than me buying the tools to do it myself and I don't plan on changing bike tires very often.  I must be getting old...

I still have to burn off the muffler baffle but figured I would wait until the neighbors are at work and school tomorrow as it looks like it was used to stir peanut butter and molasses and I might have to talk with the fire department should they arrive.

Pipe looks good, one more battery charge on my drill for the wire brush and I should be ready to go for final rust off and primer followed by paint.

If the weather holds I should be able to degrease the rest of the bike and at least have an idea of where the oil is coming from.

[Stein]

I just ordered the tires and a few odds and ends.

The muffler has been painted with header paint and heated to 200 then 400.  I replaced the two bolts that hold the exhaust flange on and some stove door gasket material to replace the missing asbestos string.  There was nothing holding the flange on and no gasket between the flange and the muffler so the fix should help a bunch.

I went back and forth on bypassing the injection pump but decided to keep it as there are several pretty good arguments on why it is a better system for bikes designed to use them.