mitovarna

Here is a video of the bike running, with my audio commentary concerning what is apparently a lean condition evidenced by the backfire you hear.  Like many things, the advice/suggestions to deal with the condition are often contradictory...

According to online forums, the backfire could be caused by a lean condition, or an exhaust leak.  Of course, timing could be the culprit, which is evidenced by the very hot headers even at idle.  However, many mx450 engines do this, so glowing headers do not necessarily mean a lean condition.  There is no exhaust leak in the pipe, but the slip fit by the muffler is somewhat suspect, but that shouldn't cause the backfire alone.  Finally, nonstandard pipe and carb is no help, so the baseline to start is nonexistent.  Since the advent of fuel injection, no one stocks carb parts, so pilot jets will need to be ordered (already on the way...)  The joys of building and fabricating!!!  I'll get it figured.  Over the winter I will likely drop the engine and do a full inspection -- valves, timing, filters, etc.  Will have lots of time to do it!

RIP Marco

mito details

Some pics for your enjoyment.  Waiting on a $9 part to check to see if I've got the cooling system fixed.  Rad came from Germany quicker than a rad cap came from the US.  Typical teutonic efficiency.

new clothes

Had some time with an extended fall to get the new fairings mounted and painted.  Clear coat applied over the top.  Plain numbers for now... or in compliance with AMA rules...?

Also still working on the mitovarna.  Since getting the completed exhaust back from cycleboyz, have gotten it running.  Still facing a typical bugbear -- cooling.  Seems to be a regular problem with most of my projects, save the klx400.  The KTM rad sits too low, and my theory is that despite purging the system of air, I still had a vapour lock/cavitation issue.  I have seen pictures of this exact frame and this exact engine, but the radiator used was a mito rad.  A bit small, but it would be better than what appeared to be no water flow that I was experiencing to date.  So, I will simply copy what apparently works, so a mito rad is on the way.  Cycleworld did an article on a crf450 engined mito, with again some fancy plumbing but the mito rad as a base.  I found a complete cooling system off of ebay Germany, so I will see if this works better.  Hopefully it gets here soon, as I would like to put the mito to bed for the winter knowing that it runs (which it doesn) but that it is adequately cooled (not yet).  I also tore the entire machine apart this past weekend, and rebuilt it wet -- using grease, etc on the bearing surfaces.  Went together nicely, and I think the suspension as is is not a million miles off.  Still need some minor parts -- a shipment of husky-specific stuff is on the way, a jet kit from thumpertalk, and some spacers to fit the r6 front caliper.  Some brake hoses, and I welded up a tubing mount for the rear muffler.  Not seen below due to it being painted.  IF I get the mito rad to work, I will be a bit pissed, as the radiator flares on the sides of the fairing will be made redundant.  Oh well... the bike still looks pretty cool.





Round 5 Report

Weather was forecast to be beautiful all weekend, and the predictions turned out to be true.  As an extra bonus, my folks were coming out to join me as well.  Dad would be able to lend a hand in the pits, and while mom is definately not a race fan, they offered to let me sleep on the spare bed in the hotel in Gimli.  So only 1 night of camping in the back of the car -- feeling like a factory racer!
As I had wrapped up the ULGP category already (I ended up winning by 15 points) I didn't bother bringing the tigcraft -- actually, most of it had been sold off by now (more $$$ to finish the husky).  So only 3 races this weekend.
Practices
Practices went well -- the continued modifications/tweaking of the bike are making it more and more comfortable, which will always allow me to go faster with less drama.  The rearsets were huge, as I was no longer griding my boots away; however the chin fairing was developing a sizeable hole on the right hand side due to turn 4.  I guess I was getting the bike heeled 'reet over since the repaving smoothed out the entrance to that turn.  Took a bit longer, but the low 1:06s did come, sadly no 1:05s.
Race 1:  Cdn Thunder GP
Check out the video:

My apologies, I think I now can post 15min+ videos, but there was no need, I wasn't able to pass Jason at the end, so another fighting 5th.

  Race 2:  Cdn Thunder #2:  10 laps

I was most happy with this race, perhaps my favorite from all season.  A bit of argy-bargy going into turn 1 on the first lap, but I was able to get into 4th and stay there, keep Wilson on his TZ in sight the whole race, and turn a series of 1:06 laps times -- finished 6 seconds out of 3rd, and 7 seconds ahead of the 5th place rider.  A boring race, actually, but technically solid.  Unfortunately, no video... some goofiness with the camera -- also affected race 3.

Race 3:  Cdn Thunder #3:  10 laps

A weird race for me -- felt like I was going faster, but I couldn't get out of the 1:07s -- neither could Jason just ahead in 4th, but I couldn't get by him.  A race pace similar to my pace in Race 2 would've secured another 4th, but I couldn't do it.  5th by 2 seconds, half a minute ahead of 6th.  Not the greatest way to end the season, but I drove home with the realization that I have a lot of rooom to go faster, especially going into turn 1, where the most time is made up.

Overall, I finished the season in 5th place in Cdn Thunder.  Not bad for my first season "back"... to start the "whine" flowing, the other bikes and riders ahead of me have either been at it for longer, or have obviously faster machines.  Racing an essentially stock ex650 against a Buell 1200 or a GP 250 bike won't be easy by any stretch.  Somehow, however, Doug's 650 is incredibly fast and he is a talented rider.  To make things worse, Pete turned a 1:02 on the weekend on his Buell, which puts him in another postal code compared to my laptimes.  I think my season-long dices with Jason, who you see a lot in my videos and his "pipe and dyno tune" SV show the parity between our bikes.  Whine session over -- I'll get 'em next year!

Now what?  The off season is upon us.  Dad was kind enough to make another bike part delivery for me --- the 650 full fairing is now being test-fitted to the ex -- even coming from an identical bike, some modifications and tweaks need to be made.  A slipper clutch is inbound, and perhaps some new rubber.  One of my competitors tuned his sv up, and while it was a rocket, it also had a catastrophic failure in race 2 on Sunday -- as in, thanks for the oil pan, piece of case sitting in a bath of oil, style failure.  Not interested in risking that -- so the exhaust experiement and perhaps a lightened flywheel will be the extent of the souping up this winter.  That, and finishing off the Husky.  Of course, I will keep you posted with updates and pictures...                                                                                                                     

Round 4 Pics

Thanks, AJ!

Exhaust Questions

Since I started to build supermonos I have been curious as to the science of 4-stroke exhaust tuning, especially now since compromises can be covered up with idealized jetting.  However, in taking a look at the EX650 exhaust, it is so unlike anything I have seen before that Kawasaki either finally figured out how to properly create an exhaust, a "lightbulb moment" after 40 years of racing, or, more likely, it is a packaging or aesthetic compromise.  Basically, the whole system appears far too short in length.  The primary headers snake around a bit in order to find some length, and the old Leo Vince slip on system does a full 360 with the tailpipe in order to get some length...

Take a close look at this pic and you can see the tailpipe turning full circle!

In doing the reasearch, I stumbled across this website that is based on the famous tuner A. Graham Bell.  http://www.mez.co.uk/mezporting/exhaust_length.html  If you go there, you can plug in information about the characteristics of your engine (single to multi) which will then spit out the ideal header length and diameter; proper collector length; and the length of the tailpipe PRIOR to fitting a muffler or slip on.  I punched in some scnearios and proofed it against Bell's book, and it did check out.

So, how did the EX650 do?  After getting the BBDC and ATDC figures, and putting the idealized hp peak at the 9000 rpm mark here is what is suggested ( based on 1 of the 2 cylinders):

Header length:  27"
Header ID:  1.5"
Collector Length: 6"
Tailpipe Length: 18"
Tailpipe ID: 2"

Sounds pretty typical.  I went out the to the EX and this is what I measured (based on the Muzzy exhaust system I currently have mounted:

Header length:  26.75"  CLOSE!
Header ID:  1.5" (note this is the OD, but CLOSE again!)
Collector Lenght:  4" (a bit short)
Tailpipe ID:  2" (again, this is OD, but a negligable difference)
Tailpipe Length:  2" (YIKES that is short) -- that is the length of the tailpipe before it begins to expand into the megaphone exhaust.

As you can see, the exhaust is quite stubby; according to the tuning guru, I need an additional 16" of tailpipe, over 1', before the muffler should even be added.  Makes for some interesting concepts for experimenting.  Would it make a difference?  Again, with proper tuning, it should.  A smaller tri-oval muffler could be tucked away, mounted close behind the RHS peg for ground clearance.  Perhaps a project for the winter?  We'll see.