Engine questions

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Postby nightwave51 » Fri Apr 08, 2005 6:39 pm

Hi Everyone:
Well, I'm at the stage of my rebuild where I'm about to try and fire up the Rotaxs. I have new points and condensers that I will install and I have the heavy duty spinner backing plates too. Although I have followed recent posts, I still have a couple of questions:
1. What is the recommended fuel? I almost hate to ask this one, as I have seen a firestorm of controversy over this issue. My thinking is regular unleaded should do just fine. Wajax pumps still uses this engine. I can't imagine fire crews using anything other than the most available fuel. I used to work for the MNR in my summers during university (long time ago). Pumps sat in a dusty warehouse, got dumped in a fire zone and ran under smokey, dirty conditions. I don't think they would be worth much if they were super critical about what fuel you used. Maybe the new ones differ somehow from the early 80s era Rotax's we use though.
2. What is the recommended oil and in what mixture ratio?? I really don't know what ppl are using here, but I am open to suggestions. I live in a small town (North Bay, ON) so "exotic" brands may be dificult to come by here.
3. What are ppl using for spark plugs these days?? The assembly manual says Bosch M240T1 or Champion K-7. Canadian Tire has neither and the kid there was as helpful as a anchour to a drowning man. In the spares were Bosch Super RO 168 and NGK A-7 plugs. The kid couldn't tell me much about those either. I have two SeaDoos and have found that on two strokes, platinum plugs are a big advantage (no fouling problems). I don't know if this is relavent to the Rotax's but something tells me this is NOT an area to pinch pennies.
Any advice on what members are using would be greatly appreciated.
Thanks, Mark
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Postby Guest » Fri Apr 08, 2005 6:48 pm

Unleaded at 32:1 using a good petrolium based oil (not synthetic)

NGK A-7's are great.

Postby Guest » Sat Apr 09, 2005 2:12 pm

1. Unleaded 89-92.
2. Pennzoil "air cooled oil" 32:1 or other quality 2-stroke oil. Stay away from outboard oil.
3. NGK A-7 preferred, Champion Cross reference from K-7 is D-14. Original type sparkplug caps should be changed for a more secure type (See Wildfire Mark 3 tech notes).

Postby nightwave51 » Sun Apr 10, 2005 8:31 am

Many thanks for the fast response guys!
I kind of suspected that regular fuel was OK and going slightly higher octane can't hurt (should avoid any tendancy to knock). Thankfully Canadian Tire carries NGK A7s - they were jus out of them when I was there last. I guess the local motorcycle shop should have the Pennziol - dirt bikes are often air-cooled 2 strokes.
Thanks, Mark
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Postby Guest » Sun Apr 10, 2005 8:53 am


Postby bdiedenhofen » Mon Apr 11, 2005 10:01 am

I've been using Yamalube. It's easily available from any Yamaha dealer and burns very clean. No carbon build up on the plugs in the past 25 hours. While you're at the motorcyle dealer, get new NGK plug caps. The origonals tend to fall off easily. I prefer the type that clamps on to the threaded end of the plug, rather than just clipping on to the screwed on plug tip as the stock cap does. You have to unscrew the little tip off of the plug, so be careful not to buy plugs with welded tips. These caps are very secure and are standard on most motorcycles because of it. I got resistor caps and with shielded ignition wires, my hand held radio works just fine with very little electrical interference.

Brian D.
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Postby Guest » Mon Apr 11, 2005 10:33 am

Plug caps are cheap. Get rid of those original ones. Manufacturers Supply has NGK caps for cheap.

http://www.mfgsupply.com/SnowPlugCaps.h ... d=NHKb3ird

Postby flyalaz » Mon Apr 11, 2005 11:14 am

Canadian Tire in Canada also sells the NGK resistor caps

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Postby nightwave51 » Mon Apr 11, 2005 9:26 pm

Thanks for the advice guys. I never thought about the plug leads, but I will definately check them and if they're not the screw on (secure) type, I will replace them.
Any last bits of advice before I start these suckers?? They are very clean and had been oiled prior to storage, so I'm keeping my fingers crossed that all will go according to plan when I pull the starter cord. A welded test stand came along with the engines. I'm just making modifications so I can attach it to a post (very solid) in my yard.
Thanks again,
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Postby Guest » Mon Apr 11, 2005 10:29 pm

When were the engines last run ? Were the carburetors gone through ?


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