What did you do to your Yamaha today?

Yeah I gave up on seeing the road at 1/4 mile intervals after I totalled my CBX, the outer cylinder saved my leg.

 

What did I do today? I tore my exhaust system apart. First I dropped the system as a unit. Fortunately it was quite easy, as all of the nuts on the head pipes and mufflers came off easily. After hearing horror stories of broken studs and the like, I was very happy about this. The pinch bolts on the two outer headpipe/collector clamps came right out. Cylinder 2's pinch bolt was a little harder, but with a bit of work it too came out. Cylinder 3's pinch bolt snapped off, of course. That gave one of my friends, who accumulates gadgets like this, an opportunity to play with his new induction heater. This is a little loop of wire attached to a power supply, and it uses magnetic fields to heat up conductive materials. It got the nut (welded to the clamp, which is spot-welded to the collector) to glow a bright orange, without getting the broken bolt very hot. A couple cycles of this and the bolt came out. Wish I'd taken a picture!

With the system off, the first order of business was to get out the Sawzall and hack away the rotten mufflers. I cut right on the weld between the collector pipe and the front of the muffler, just behind the (welded on) heat shield:



The two inner pipes are 1.25 and 1.4 inches in diameter respectively. Too small to fit the Sportster mufflers' 1.75 inch inlet. I found some iron pipe that is a snug fit on the 1.4 inch pipe, and cut a pair of reducers:



The plan is to weld these in place to prevent exhaust leaks and provide structural rigidity (the Maxim's mufflers are welded to the headers, and as a result there is not central hanger).

The Sportster mufflers slip right on:



The O.D. of the iron pipe "reducer" I made is almost exactly 1.65 inches, a tiny bit bigger than 1-5/8 inch. Amazon carries an inexpensive EMGO reducer set that includes a 1-5/8 to 1-3/4 reducer. It will arrive tomorrow. With the TORCA style clamps, the muffler-to-pipe attachment should be as rigid and structural as a weld. Interestingly, the Sportster mufflers' internal pipe narrows slightly as you go back, and the slightly skinnier pipe from the inside of the Yamaha's muffler becomes a reasonably snug fit inside it when the front end of the muffler is clamped into place. Maybe a bit more structural rigidity. Nice.

The next step is to re-attach the system to the bike (with some newer and shinier head pipes from the hoard) and start working on the specifics of hanging the mufflers. Whether the tabs on the Harley mufflers will line up with the hangers on the Yamaha frame remains to be seen. I expect I will have to do some welding, cutting and drilling. I am hoping to re-use the existing Yamaha rubber mounts, both to minimize vibration and to allow for vibration and thermal expansion/contraction. Once I have everything lined up, welded and drilled, I will tear it all back down and re-install and tighten with new gaskets.

While waiting for the reducers to come, I intend to replace the nested bits of brass tubing I used to shim the Progressive Sportster shocks with steel bushings that I drilled out from 1/2" to 9/16" (14mm) last month. And I intend to install the set of cheap case guards that were in the box o' stuff I received with the bike. They are just little things, but I am probably riding the Maxim on the "Hügellandschaft Adventure Ride" gravel/dirt rally next month and figure I could use all the protection I can get.

Yesterday I put 60 miles on the Maxim with the wife. My first two-up ride on this bike, on a warm but windy Sunday afternoon. We went for ice cream. The bike ran flawlessly except for the tach needle jumping all over the place and eventually dropping to zero. I thought it was a broken cable until I started taking off the exhaust system, at which point I found the gland nut had loosened up and the cable had backed out of the engine. Well, that's easy enough to fix...

 

Continuing the exhaust saga… yesterday, while waiting for Amazon to deliver the pipe reducers (they are now scheduled for today), I re-installed the head pipes and collector to see how much of a PITA making a proper bracket for the Sportster mufflers will be. There was a bit of cussing until I discovered that the four head pipes are each unique and do not interchange. Luckily they are also stamped H1, H2, H3 and H4. Once I noticed this, things got easier. At this point I have not replaced any gaskets, because I expect to take the system apart at least one more time. With head pipe nuts and clamps snug but not tight, I slipped my iron pipe reducer into place and slid the muffler over it:



Not too shabby. The Sportster muffs go more straight back (vs sweeping up like stock pipes) because the stub pipes that come out of the collector don’t go down the middle of the stock mufflers; they actually follow the lower part of the cone. I think that when I’ve got things tighter the mufflers will sit a little higher, but it appears that fabricating the hanger won’t be too hard. One small problem is that while the mufflers and pipes splay out a few degrees, the mountings on the bike are straight forward-back, so the hanger will need a few degrees of twist. Ah, well, that’s what CAD (Cardboard Aided Design) is for…

One other potential annoyance is that the Harley mufflers are a bit longer than the stock ones, and it looks like they are going to be perfectly aligned with the rear axle. So the right muffler will have to come off to do tire changes. Oh well. Could be worse.

I am hoping (based on the availability of my friend who welds) to get this job done sometime next week.

Oh, and the observant might also notice I have installed a set of small “case guard” crashbars. They were in the box o’ stuff that came with the bike, so the fact that they have some scrapes does not mean this bike was crashed!

 

Nice. Those Sportster mufflers are a good look, and being lower slung looks better to me. Unfortunate about the axle bolt, but not the worst thing ever.

I discovered the same thing about the headpipes on my 650 this past week..."Maybe they are all 4 the same part, nope. Surely there are only 2 unique parts? Nope...all 4 unique."

 

Yep, I like the way those mufflers hang on the Maxim too. Those are some well traveled mufflers. From their original Sportster home they spent time on my Moto Guzzi California 2 and now on your Maxim. Of all the things you can say about Harley they really know how to do chrome on their mufflers.

 

Justifies the big ticket price tags.

 

Yep, I paid 99p for mine.
I almost felt guilty getting them for that.
But hey, nobody else wanted them.

 

So with the harley muffs does it have that putt-putt-potato-putt-putt-potato-potato sound?

 

Tax, Title, and Tags.
woohoo

 

Okay so today I dropped my original emulsion tubes back into the carbs and took it for a ride... definitely leaner all around and I can say the MPG's are back in the high 40's but is also has a far more peaky powerband when it hits the magic 7000 point. I'm running #122 mains & #42 pilots on the stock float levels and that 6000 flat spot really stands out. Going off the beaten path tomorrow with the aftermarket emulsion tubes I was using and opening up the top pinhole with a 0.059mm wire drill leaving the other 0.032's below and back to my #126 mains to see how this compromises. I really like the power the richer mix gives as the motor pulls hard from about 6500 up but as a daily machine it's hard to justify the 34 MPGs when my 3800 Impala gets near the same. One thing the bike did before was go from about 20 MPH on up in 5th without jerking and right now it will start cold without the enrich on only 2.5 turns of the pilot screw (fine thread) with a smooth idle. Carbs all got balanced to one inch Hg and it really has a nice hum.
Will let ya know how the tube mod works out.

 

I ran the wheels off a LeSabre. 30+ mpg. Power, luxury. I think I changed spark plugs at 275,000 miles and they probably didn't need it. 3800 was a great motor.

 

Unfortunately the supercharged 3800 in my Park Avenue Ultra was hooked to a plastic transmission. Engine was running great when I blew up the trans around 150K. The car delivered a pretty solid 22mpg in suburban driving, would touch 30 on the highway. The car would run on regular without damaging itself, but then performed worse (both power and mpg) than the normally aspirated Park Avenue—mpg in particular was so much worse that it was actually cheaper (in terms of miles per dollar) to run the expensive fuel.

 

Meanwhile, the exhaust project… the reducer set I found on Amazon didn’t work. The smallest one was loose on the header outlet, and I managed to get the bigger one stutso badly in the muffler that I almost wrecked the muffler inlet.

OK, back to the drawing board… I took one of the mufflers to the auto parts store and matched up a short piece of 1-3/4 pipe that fit properly into it. Sorta reassuring, as Harley exhaust pipes are supposed to be that size. Then I took the short piece of iron pipe that was loose both over the ~1.4” collector outlet and inside the 1.75” muffler inlet. Put it in the vise, hit it with a carbide cutter wheel, and cut a ~1/8” slit in it. Squeeze this in the vise and it fit nicely into the 1-3/4” exhaust pipe I bought at the parts store.



Happily, the inside of this assembly was a tight—as in, it took a piece of pipe and a few whacks of the hammer to get it into place—fit over the collector outlet.



I will probably weld this adapter into place, but I doubt it’s necessary. I’ll probably cut off the extra pipe, too. The mufflers slip on, though one’s a bit tighter than I’d like. Of course it’s the one I have to take off when changing the back tire.

So the remaining challenge is the hanger. I think I’ll have that done in the next week.

 

After engine pulldown #2, she did |NOT want to fire on all 4 yesterday, so today I looked at the pickup coils, and to my shame and horror the baseplate was missing all 3 screws. Replaced them, and she runs on all 4, but not well. Could I have trashed my pickups, rattling around (not for that long a time, but feeling sick right now)

 

He was back there in the hedge/field and you went right past- (my version)

 

Like that version better myself

 

So back to the bike. Swapped in the aftermarket emulsion tubes and #122 mains in place but did enlarge the one set of holes at the top of the tubes to 0.059MM leaving the others. Floats set to the book and I ran four loops that equaled 100 miles, math says 36 MPG with a mix of nice and not so nice riding taking the bike to the century mark. Motor feels strong again but still has that flatness from 5500 to 6500 or so then waking up to the redline and beyond.
The "street feel" is better with a more linear off-idle feel working into the clutch without the chunking and the idle is very smooth without the hunting. Once our rain passes I'm going to do a longer and more realistic road trip of mixed riding thru the cities, real traffic and stoplights with real fools playing on their phones behind the wheel. This is what I consider the "acid test" be it on a bike or in a cage.
Basically it comes down to keeping the bike running right and if that means compromising on the MPG's some I'm good with that. Right now it's fast and rides well.

 

I actually did look for a parting of the bushes or tell tale skid mark, but pretty sure it was a case of faster bike and better rider.

 

I won't tell

 

I recall being tail-gated in my ShitOldJapCar on a set of twisties.
I gradually increased the speed as I went and when I got to the end of the section the tail-gater had vanished. I kept an eye on the mirror for a long time on the straight road and he didn't appear.
Silly boy.
Might have looked like a ShitOldCar, but had really good suspension.