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PostPosted: Thu Jul 29, 2004 2:37 pm
by rayjb60
Now I have new condensers, but when I turn the engine over by hand as quickly as possible on the kitchen table, but I dont see a spark.

Does it take a really good pull on the starter cord to get a spark, or should hand flipping produce a visible spark as well?

I did have a voltmeter hooked up as well and saw a good voltage fluctuation,
when I turned the flywheel over, so Im hoping I just need a vigorous pull to see an actual spark.

Anyone know what I should see here?

PostPosted: Thu Jul 29, 2004 3:23 pm
by Guest
Did you clean the points like we suggested?

Did you put in aftermarket parts like we suggested NOT to do?

Did you retime like we suggested?

Have you checked all the wiring after installing the condensors? Wire routing
should be checked carefully before tightening down the bolts. Check, check and recheck.

Don't scrimp on parts. Do it right and it will work the first time.

PostPosted: Thu Jul 29, 2004 9:16 pm
by JPXman
i know that on the JPX, if you don't give it a good pull on the starter, you won't see a spark. if you slowly pull it over, there won't be a spark. I can't speak for the 185's tho, maybe their ignition is stronger...

"2 weeks to go?"

PostPosted: Mon Aug 02, 2004 3:06 pm
by rayjb60

Ive got two Rotax 185's running great...Yaaaaaaaaa!

Turns out that setting the points and spark gap perfectly and making shure the flywheel is 2 paper thicknesses away from the coil ends results in a very smooth and easy starting engine.

Yes I sanded the points clean as well.

Points are .14" and plugs are .18" gap.......Purrs like a tiger.

I destroyed one of the new condensers by applying to much heat with the soldering iron, but apparently the old 22 year old ones work just fine still.

You have to give the engine a good hardy pull to get some nice sparks going, which is not that easy when the engine is on the kitchen table.

The engines start and restart so easily I was surprised, with such a long fuel line, even with bubbles, which eventually cleared.

I dont like the pull starters much....they dont recoil the line very well.

I think I read that the Tecumse starters are a good replacement?
Any comments, good or bad on the alternate starters?

PostPosted: Mon Aug 02, 2004 3:11 pm
by rayjb60
Does anyone know how to set the timing on Rotax 185's.

If you briefly describe the setup and process and the pertinent numbers I would
appreciate it.

I saw a photo of a meter hooked up, but did not understand what was going on with the meter, and what the person was adjusting to.



PostPosted: Mon Aug 02, 2004 4:32 pm
by ozzie
while you have your engine off could you please put it on the scales and see what it weighs. i would like to compare it to some small engines i am looking at thanks in advance ozzie

PostPosted: Mon Aug 02, 2004 8:35 pm
by Chappy

It's not advisable to use sand paper on points, or any switch type contact. Although the contacts will look clean and work better afterwards, grit pieces from the sand paper can become embedded into the metal. It can cause them to become unreliable in short order! Always use a file to clean contacts. Electrical supply houses usually sell special files and diamond files that will do a much better job of cleaning contacts. Auto supply shops also sell small files just for this purpose, but the ones they sell now a days seem pretty poor quality.

I built my own points test light for setting the timing 25 years ago. Someone came out with a very inexpensive one after I built mine. I liked it better because it had a little speaker in it, and it made it easier to use than mine that you had to watch for the light while also trying to look at the engine. You might check out the small engine repair shops online. Actually, you probably can do it with a modern digital ohmmeter, as they can see the small change in resistance when the points open, even though the low resistance mag coil shunts the points. Even a very cheap digital meter should work, I would think. Can someone else confirm this?

California Power Systems sells a timing kit, and the 18mm spark plug hole adapter for their kit that should work. Being really cheap, I made my own by taking an old 18mm spark plug and gutting it, drilled and tapped it for a long setscrew, and used it as the mount for a dial indicator I all ready had. CPS has a write up on setting the points in a big Rotax in all of their catalogs (probably online too), but it should help you understand how to set the points in the little Rotax a little better.



PostPosted: Tue Aug 10, 2004 1:22 am
by rayjb60
OK, I have the timing figured out......the meter was just to indicate when the points make contact, and the .17" is the distance of the piston from the top of its stroke, in the compression easy.

I have a Vernier with a long shaft out the end when you open it perfect for this purpose.

As a side note....almost had a setback.

The left engine starter cord was not retracting the line very well, and on one run the cord was dangling about a foot and slowly retracting through engine vibration.

But when I reved the engine the handle blew back in the blast and then swung all the way forward into the prop....whack.....and then wraped itself firmly around the prop shaft.

Its a good thing I saw what was happening and hit the kill switch early in this cycle of damage to the prop....but I did replace the got frayed....and tightened up the recoil spring.

Moral of that story is never let go of the start cord until its fully retracted.

Almost had to buy some Prince P-tip props ;)

The engines are almost broken in now.....about another hour to go, and they will be all set.....the engines feel powerfull and reliable with a nice solid idle, and restart very easy.

I pulled a spark plug and see that its black and sooty......that seems to be to rich in mixture, or is that normal.

I use 91 octane unlead car pump fuel and some lead substitute product along with the 30:1 oil mix.

What sort of fuel is everyone else using?

PostPosted: Tue Aug 10, 2004 7:49 pm
by Chappy
HA, I can relate! When I had just started flying my modified Pioneers with redrives I had about six feet of the right engine's starter spring slowly work out of the plastic housing! When I finally got on the ground I had the greasy spring tied in knots around the lift strut to keep it out of my new homemade prop that I had just spent a day making. That's the day I found I could hand prop my redrives to get the engines running if I had to.

Don't worry too much about running your engines somewhat rich to begin with. About the worst thing you can do to a 2-stroke engine is to run it too lean, especially when it's getting broken in! Do not fall into the trap of trying to transfer a good working knowledge of 4 stroke engine tuning to 2 strokes - THEY ARE DIFFERENT and must run richer than 4-strokes can if you want them to survive. Warm them up real well, tune for best RPM, then enrichen some. Shut down, let cool off. Start cold, warm up just a little (10-20 seconds) after getting off the choke, then try quickly advancing the throttle. If the engine falters, enrichen some more. A partially warmed up engine should be able to run up quickly when the throttle is quickly opened, otherwise it is too lean. You will need to play with the high and low speed needles as they interact.

And don't be surprised if, after getting them set up just perfect, a week later they will need readjusting - especially if the weather has changed!

Also, don't fall into the trap of trying to get more power by running with very low oil mixes (beyond 50:1, especially). Run the amount of oil the engine manufacturer specifies. The real hot rod types get the best power by running the most oil they can without fouling plugs and gunking everything up. The idea is to reduce the engine's internal friction as much as possible.

Penzoil sells a 2 stroke oil "for air cooled engines" that is just terrific, and keeps the innards amazingly clean too. Don't use their 2-stroke outboard motor oil though; they are not the same!


PostPosted: Wed Aug 11, 2004 11:50 am
by Lazair_guest_please_registerdetr
Ray - I went to mfgsupply and found this condensor. It doesn't look like the one in the 185. Did you have to modify it? Picture on their site shows 2 prongs on top and in the 185 is just 1 nutted tip. Thx