Cylinder wall scoring

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Postby artman12us » Sat Oct 22, 2005 12:18 am

With eight day's of rain in the northeast I decided it was a good time to do the cdi conversion. No problem. But with time on my hands I read up on decarbonising and couldn't resist doing it for the first time. I took the head and cylinder off and wrestled with the wrist pin clip. I did this with the second engine and suprise there was scoring on the cylinder wall. I supply safety glass for a local BIG engine rebuilder and remembered he told me he did work for motorcycle guy's and ATV ers. So I took the heads, cylinders and pistons down to him. He told me , " Just use the glass bead blaster to decarbonise the heads, piston crowns and cylinder ports. He honed the scored cylinder but scores remained. So I said maybe I should just buy a oversized piston and rings. He responded, " Why not just do both of them". Sure ,"I said. I went home called Wilfire and found out why not, 175.00 US for oversized pison and rings, no wrist pin (gudgeon), no clips.
He had told me I could just use the old pistons, new rings and the scored cylinder, but would lose some power. The thing is these engines were running fine (5700-5800 on both). Do I go oversized on the one only? And now at one o'clock in the morning I'm wonderering who's going to tell me I screw'd up using the glass bead blaster even tho every thing I read told me to soak and use a stiff brush. any advise would be appreciated. (Chappy, Shannon) thanks Art
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Postby artman12us » Sat Oct 22, 2005 12:20 am

Piston
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Postby artman12us » Sat Oct 22, 2005 12:20 am

Head
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Postby xgary » Sat Oct 22, 2005 5:54 am

Art --drop this guy a email or call him aerocontrols@clearwave.ca

One solution is to call BOB, He is a rotax instructor and runs his own shop
110% honest and excellent.
Call him and he will tell you what he thinks.


Bob Robertson
Aero Control Enterprises, Inc.
Light Engine Services Ltd.
Rotax Service Center
St. Albert, Ab. T8N 1M8
Ph: (Tech Support) 1-780-418-4164
Ph: (Order Line) 1-866-418-4164 (TOLL FREE)
www.rtx-av-engines.ca


Also do you know history of this engine? I would suggest replacing crank bearings now. Rotax pistons are ususly 150 to 200 $ each I think there is a snowmobile piston that fits the 185 ( maybe a 277 or 377 piston ?)

check or get checked cylinder specs --taper -out of round etc. then piston availability for over sizing. BOb will guide you through this. Bob Is a great guy and if you attend rotax seminar --he might just be the teacher :)
Shorty .............
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Postby Shannon » Thu Oct 27, 2005 11:19 pm

Decarboning.
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Postby artman12us » Thu Oct 27, 2005 11:37 pm

Thanks Shannon. I received oversized pistons today and am having cylinders rebored tomorrow. Richard didn't seem to know how many hours or when it was last decarbonised. I will surely be recording this info. Now it's on to making a test stand putting on new carbs and breaking in newly bored cylinders. the new cdi's are on, so there is going to be alot of adjusting etc. I hope I'm up to the task. Thanks again Art
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Postby uscgairdale » Fri Oct 28, 2005 6:26 pm

I actually know a bit about your series III. I have flown with Richard (previous owner) in the past and he is a good friend of my uncle's. You may have seen a picture on-line of your lazair with Richard flying lead with a Pterodactyl and a Quicksilver MX. I have posted it below. That's me in the Dac and my uncle in the MX. Richard didn't own that particlular lazair for very long, although he has had significant experience with them over the years, I know that he and my uncle flew the heck out of a couple series II machines.
The owner before Richard also built the plane. His name is Ted Strater (spelling?) and he by all acounts has an amazing attention to detail and did a great job building the airframe, but maybe not the best engine guy. I have heard that he didn't fly it all that much though either, but when he did it was at max smoke and his total flight time would be only about 15 min or so and then he would put the machine away for two weeks or so. Perhaps your engine problems are a result of his ignorance, I can't say for sure.
I found out that Richard was selling his machine a day to late to get it myself or I would have snatched it right up and flew it off of his grass strip the next weekend. I was bumming big time for a month or so until I was flying my brother's series III and found my two-place in a pole barn at an old ultralight airstrip in Glens Falls, NY. Funny how things work out.


Dave
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Postby uscgairdale » Fri Oct 28, 2005 6:27 pm

Another Picture from that same day.....
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Postby uscgairdale » Fri Oct 28, 2005 6:29 pm

It's from a distance, but here's a pic of your Lazair.....
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Postby artman12us » Sat Oct 29, 2005 10:52 pm

I'm pretty sure these engine are not high time. Do you think I can get away with the old wrist pins and bearings. I picked up the bored cylinders but forgot the Mark-3 manual. Do you know the ring gap for the oversize pistons. How much are the p-tips. You seem to be very enthusiastic about them. Thanks again Art
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