Harold Bawlzangya Racing

Harold Bawlzangya Racing

"That's Good!" - Jimmy Shorts

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Holy Crap – that is some serious run-out

A couple of weeks ago I noticed the disk brakes making some noise right at the start of a drive. It would only do it when the brakes were cold and go away after a minute.  Yesterday I figured I would finally look into why they have suddenly started making noise.  I started with the drivers side wheel in the air and when I spun the tire, I was amazed at how much the caliper was rocking back and forth.  I couldn’t believe how warped the rotor was.

I pulled the tire off and then got the rotor off.  When I checked the rotor, it wasn’t warped.  I then broke out the dial indicator.  There was no good place to mount the indicator on the front suspension, luckily the big anvil provided a solid base.

So after getting it set-up, this is what I find:

 

 

At this point I thought the hub must be warped.  I popped out the spacer that was short and traded places with the one on the other side.  When I spun the hub around again, the same spacer in a different location was still coming up low.  So now it looks like the spacer is the problem.  I pulled all 4 spacers and checked the hub. It looked good.

Taking the spacers to the table saw top, I found that the shoulders weren’t the same.

I don’t have a lathe or a mill, so I improvised with what I do have – a file and a drill press.

After several hours of taking metal off, checking, taking metal off, checking, this was what I ended up with.  I am feeling pretty good about this.  When I rebuilt two-stroke cranks, the run-out spec was .001″ for most of them.  I am really close to that here:

I am kicking myself for not catching this when I installed the brakes.  I just didn’t hear anything and definitely didn’t have any vibration or pulsating from the pedal.  But now that I look at how the caliper is mounted, I see why.

The passenger side wasn’t nearly as bad, but I spent some time and got the run-out near .001″ as well.

 

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Well that was short lived – shroud testing and fail.

This shroud took longer to make than it stayed on the cart.  Sunday I went to the local elementary school with a laser temp gun and a 10mm socket & ratchet to test the effectiveness of the shroud I made.

The engine was somewhat warm from an earlier ride. I took the shroud off since it was cool and then drove about a mile to the school.  Driving around the parking lot was 1.03 miles.  For all testing, I tried to maintain 20 mph and 3k RPM.

I did 4 laps and pulled over and took a temp reading.  I then did another 4 laps and did another reading. The results were pretty close to each other so I felt good about that.  I simply laid the shroud on top of the engine and didn’t bolt it down.  I didn’t want to impact the temp readings while I took the minute or two to remove the 3 bolts that held the shroud on.   With the shroud on, I drove 4 more laps, removed the shroud and took a temp reading in the same spot as before.  I put the shroud back on and did another 4 laps.  I pulled the shroud and took the final reading.

The results were not what I expected and had hoped for.  With the shroud on, the engine ran about 10 degrees hotter.

The laser temp guns read a little strange when you try to use them on shiny or semi-shiny surfaces.  So this morning I thought I would try something different.  I put one of the prob from my digital thermometers that I use for smoking in between 2 of the cylinder fins and then packed it in place with aluminum foil.

This time I drove around the neighborhood.  It is a mile circle that is relatively flat, so I can maintain a constant speed fairly well.  I thought I would go 15mph instead of the 20mph from yesterday.  I thought this might even the odds between the shroud and no shroud.  I had already been out for a 9 mile drive, so the engine was already warmed up.

 

With the temp probe in place and the shroud off, I drove around the neighborhood and took a picture of the temperature monitor as I pulled in front of the house.  After a mile at 15 mph, this was the temperature:

Since I could see the temperature without lifting the seat, I bolted the shroud on this time and went around the neighborhood again.  Another mile at 15 mph and this was the reading with the shroud on:

I don’t think my laser temp gun was very accurate and there are certainly some flaws with this digital thermometer test.  But since both methods showed that the engine was hotter with the shroud than without, that is good enough for me.  Clearly there is plenty of cooler air flowing up and around the engine compared to the confined warmer air that the fan is blowing around and down the cylinder head.  I would guess that if you drove 5 mph the results might be different.  But who only drives 5 mph?

 

 

Hopefully the last of the stainless steel work

I finally got two projects that have been on the back burner for a while done.  With those completed, all I have are stainless steel scraps and am just about out of gas.

The first project was making a shroud to better direct the airflow from the fan around and down the cooling fins.  I spent way more time than I thought it would take on this.  It isn’t pretty, but it works really well.  I tired to make the cover fit tight in areas I didn’t want air to escape from.  With the engine running, the air from the fan will blow off leaves off the ground directly under the engine.  Forcing that hot air down, instead of just the area under the seat should help cool things off.

This project went way faster than I expected. I’ve been meaning to cover up with mangled hole where I had to make the electric body fit the gas frame.

Luckily I had one piece of stainless that was just big enough to cover it.  I tapped the 4 holes so I could just thread in 4 SS bolts.

It is kind of hard to tell, but the cut end of each bolt is sitting below the surface of the plate.  That way I can weld them together but grind off the excess.

All done:

 

 

Mother nature is making it tough to get around

Strong winds 2 nights ago did this:

And then some storms last night did this one:

Oil recycling run

I went on a drive that started as just a trip to walmart to recycle some motor oil.

It was still cool so I went to Napa to get some fuel line and then back to Home Depot to get a propane cylinder.  14 miles later I was back at home.

 

Oil Filter

I have been collecting parts to add an oil filter to the engine for quite some time.  Winter and then building the stainless steel swingarm/cradle this spring put this project on the back burner.  Then came the PZ30 carb.  I finally decided to commit to adding an oil filter to the GX390 engine.  It also helped that I found the pump I had been wanting on sale.

I decided that I was going to pull the oil from both the front and rear oil drains.  That way oil would feed the pump no matter if I was going up or down hill.  I also figured I would pump the oil out for oil changes, so no need for a drain.

I considered returning the oil back to the engine through the valve cover.  But the more I read about the design of these engines, I opted not to go that route.  I never found anything that identified lack of lubrication to the valve train as being a weak point for these engines.  And from what I have read, the passage(s) that drain the oil back to the lower end are the same passage(s) that feed oil to the top end.  So my biggest concern was that dumping more oil than the engineers planned for down those passage(s) would interfere with the proper lubrication of the valve train.  Finally, I already had a hole tapped in the top of the block where the governor used to be, so that sealed the deal.

I had removed and installed the engine more times than I wanted to keep track of when I was building the swingarm/cradle.  I got curious how long it actually takes me to remove the engine.  Turns out it is just about 23 minutes.  That included removing the seat back because the basket was in the way of the rear panel access opening.

With the engine on the workbench I could get started.

I also decided to remove the oil sensor while I had the side cover off.  I don’t know why I didn’t do that when I removed the governor when I first got this engine.

Plugged that opening and added the rear drain fitting:

Front oil drain fitting:

And finally the fitting for the oil return:

I wanted to use 3/8″ aluminum fuel line to plumb most of this system.  I thought the aluminum lines would help dissipate the heat as the oil moved through the system.  I was really impressed with myself that I nailed the bends on my first try.

But as I sat back and looked at it, I talked myself out of using the compression fittings and aluminum line.  I figured that even if I tried my best to support the lines, the continuous vibrations would eventually cause a leak in one of the fittings.

So I switched out the compression fittings to barbed fittings for rubber lines.  At this point I was still planning on having lines run from both the front and back drain plugs.  I used some clear tubing and connected the front and back to a T fitting.  I experimented a little with tilting the engine up and and down to see how far I could tilt the engine before I got air in the line.  It turns out that I could tilt the engine up to a 24 degree angle and still pull oil through the fitting.

24 degrees is right at the point that oil is still in the tube:

I didn’t think I would be able to tilt it that far and still pull oil, so I made the final revision to the system to just use the front drain fitting and plug the rear drain.  Pulling the oil from just the front will simplify things and will be one less place for a leak to occur.

This is the pump I will be using.  It uses about 3 amps, is rated for continuous duty and is self priming up to about 3 feet.  I got lucky and caught this on sale. It wasn’t that much more than the cheap, noisy pumps on eBay and Amazon.

I wanted to mount it below the oil level so it would never have to dry start it.  There was really only one place for me to put the pump and pull that off.  Luckily I still had a few pieces of scrap stainless that I was able to weld up a simple mount on the front corner of the engine cradle/swingarm.

Side view:

Top view.  The engine is about as far forward as it will ever need to be, but just to be on the safe side, I positioned the pump so I could still slide the engine forward 1.5 – 2 inches.

It was a lot easier to decide where to mount the oil filter.  I welded on a bracket to the frame here:

And that puts the filter next to the engine with enough clearance to remove and install it with no problems:

Turns out I think my concern about dumping too much oil through the valve cover was valid. This pump moves quite a bit of oil:

 

The last piece I needed was a way to control when the pump runs.  I currently have this timer set to run the pump for 15 seconds every 10 minutes. It is easy enough to change if that combination doesn’t work out.

With the motor off and the seat down, I can’t hear the pump running.  I think I may hook up an indicator light somewhere so I can keep an eye on when it is running.

PZ30 carb dialed in

I thought I had the original PZ30 carb working pretty well.  I wanted to experiment with a few things so I spent $23 and got another one from Amazon.  There were a few areas where this new carb looked to be better made.  At least this manufacturer (right) is making an attempt to look like an original:

I put in the new carb and it was in fact better.  I was able to use a smaller pilot jet and my idle is now a steady 950 RPM.  Plug looks good as well.

I quickly bought another one before Amazon ran out of the ones made by that particular manufacturer.