By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

4 stroking a Merco...

All Topics | Latest Posts

Search for:  in Thread Title in  
Foxfan13/08/2019 19:59:56
avatar
686 forum posts
6 photos

Hi all, I have a couple of Merco 61s which are basically fine and I was wondering about making one of them into a 4 stroke. I can't justify the expense of a new or even s/h 4 stroker, but can make stuff on my wee lathe.

Does anyone know of a thread covering that, what shape would the cams have to be, etc., etc.?

Cheers,

Martin

jeff2wings13/08/2019 20:25:28
avatar
779 forum posts
1830 photos

You mean like this ?

imga0747.jpg

imga0748.jpg

Foxfan13/08/2019 22:14:43
avatar
686 forum posts
6 photos

That's what I kind of had in mind, Jeff, yes, but what goes on inside? I assume a new liner with no holes in it, same with the piston, which I assume is flat topped instead of squish, but what shape and how big the cams?

I have considered belt driven overhead cam or even twin cam, too.

Rebuilt the other one today. All was well, but the carb (the only one I have for the pair of them) looks fine, but has way too small an inlet spigot. I'm wondering if an adaptor sleeve would be OK. The carb. itself is quite a big one. I don't know if it's a Merco or not, though.

Martin

Tom Sharp 213/08/2019 22:27:19
avatar
3430 forum posts
17 photos

How to reinvent the wheel in style. laugh

Foxfan13/08/2019 22:33:32
avatar
686 forum posts
6 photos

I've always liked to use what I have.

Sure I would love a Laser 45 as I really don't want anything much bigger than a 61 and I only have these two Mercos because they were a tenner the pair on a charity stall at a village dog show. I'd love to know where in the village they came from! BUT, there ain't no Lasers at a reasonable (affordable for me) price, but I can make stuff. Not big enough stuff to include crankcases unfortunately, hence the conversion.

Oh the carb. does appear to be a Merco shaped one, but why the narrow inlet spigot?

Martin

David Davis14/08/2019 07:06:17
avatar
3349 forum posts
580 photos
Posted by Foxfan on 13/08/2019 22:33:32:

... Oh the carb. does appear to be a Merco shaped one, but why the narrow inlet spigot?

Martin

It looks like an early Irvine carb to me.

J D 814/08/2019 08:36:51
avatar
1198 forum posts
74 photos

Yes an early nylon body Irvine carb. They can go tight on the barrel over time but a light sanding in the body will sort it.

Jon - Laser Engines14/08/2019 08:40:40
4730 forum posts
174 photos

The example above seems to have a number of magnum parts on it. The carb, intake, head and cam follower bush all look like magnum parts to me.

Engine Doctor14/08/2019 10:01:38
avatar
2254 forum posts
24 photos
Posted by Foxfan on 13/08/2019 22:33:32:

I've always liked to use what I have.

Sure I would love a Laser 45 as I really don't want anything much bigger than a 61 a

Martin

Keep looking on the BMFA cassifieds and at swap-meets . The smaller Lasers are out there and don't fetch high prices as power / weight ratio is a bit low compared to the modern lasers . You should be able to get a reasonable example for £70 £80. OK it will probably need bearings but they a cheap .

Last Laser I bought at an auction was a Laser 80 unused in a Focker D7 aiframe for £70 ! The airframe needed some TLC but it flies well.

Converting a Merco is a relatively big job and will probably cost more than buying a used Laser .

Good luck whatever path you choose .

Jon - Laser Engines14/08/2019 10:10:58
4730 forum posts
174 photos

If you buy a laser 45, 50, 61, 62, 75, 90, 120v, 150v or 180v thats fine but dont pay much for it and dont expect any support if you have to fix it. They were all discontinued the best part of 30 years ago and we no longer support them in any way for spares or service. I cant even supply a new exhaust or carb so be warned, you are on your own if it needs repairs.

Foxfan14/08/2019 10:41:45
avatar
686 forum posts
6 photos

Yes, that's a shame, Jon. Especially where the smaller engines are concerned. We don't all want vast airframes in the shed, requiring huge, expensive engines.

I was thinking I could probably make all I need for the 4 stroke conversion as I have a lathe, but no mill. But thinking about it, a set of decent gears won't be cheap. If I could get a smaller Laser for around £70 I would. I can't believe anything that desperate can go wrong with them and many will have had very little use. I have a friend with a ceiling full of them, barely ever used, but he has gone down with a massive dementure and his family have asked his friends not to call, but what will they do with all his Lasers I wonder? And his filing cabinets of Futaba 35 meg, other engines (Saito, OS), covering materials, timber, accessories, etc. Such a shame.

Doc, where are these swap meets I keep hearing about? And what I've seen of BMFA classifieds wasn't very encouraging.

Martin

Cuban814/08/2019 11:17:28
2581 forum posts
12 photos

Don't be put off by the few problems some have encountered on BMFA Classifieds. Buying second hand is always a risk, but providing you take reasonable precautions, (biggest is always use full PayPal and NEVER PayPal Gift) trust your instinct and preferably have a talk with any prospective seller - you can then filter out the idiots selling junk.

Took me six months, but I bagged a NIB OS120FS (unpumped version) for £220 delivered.

I'm afraid swap meets can also be very risky, some good honest bargains are about, but equally, a hell of a lot of what's offered would be better off in a skip. Caveat emptor and all that.

 

Edited By Cuban8 on 14/08/2019 11:21:26

Jon - Laser Engines14/08/2019 11:33:05
4730 forum posts
174 photos
Posted by Foxfan on 14/08/2019 10:41:45:

Yes, that's a shame, Jon. Especially where the smaller engines are concerned. We don't all want vast airframes in the shed, requiring huge, expensive engines.

 

The problem for us was cost. A 45 or 50 costs the same to make as our 70. as the 70 is the same physical size as the 45, 50 and 62 used to be it just didnt work. When we brought out the 50 it killed the 45 dead. The 62 did the same to the 50 a few years later, and finally 70 killed the 62. Moving forward to 2012 the 155 killed the 150 stone dead even though it was a little more expensive. As for support of discontinued engines we had to call time on it in 2016. nearly 25 years of support after discontinuation was deemed to be more than satisfactory and the vast majority of the engines were worn out by this point anyway and beyond economical repair.

while i understand that not everyone wants a massive model the only way we could offer a 50 size engine would be to charge the price of the 70 for it and shift the whole range up in price to make the stack work. I suspect this would not be a popular move!

For your merco efforts if you like i can supply some cams and a pinion drive to save you the gear cutting problem. I can either supply new ones at their normal prices or i could rescue some from a deceased engine and let you have them for a considerable discount. if you let me know the width of the crankcase i will try and work out if our cams stand a chance of fitting.

Edited By Jon - Laser Engines on 14/08/2019 11:33:50

Foxfan14/08/2019 11:38:30
avatar
686 forum posts
6 photos

Wow, Jon, that's a wonderful offer! I will PM you with the details.

I quite understand the problems with your production. It's just a pity we can't get a smallish British 4 stroke.

But with your very kind offer, I can probably do it just for me, of course. I can't imagine the problems involved in putting any engine into production!

Many thanks,

Martin

Jon - Laser Engines14/08/2019 11:58:59
4730 forum posts
174 photos

the problems are significant, thats why half my range and our petrol are still nowhere to be seen

Foxfan14/08/2019 12:01:51
avatar
686 forum posts
6 photos

People will wait for quality. I know I would if I were in the position of ordering a new Laser.

Aren't people going off petrols already? Barking exhaust, lack of power, heat, etc.?

Anyway, I have PM'd you and don't want to take up any more of your time. I'm a keen amateur. You have a job to do!

Martin

jeff2wings15/08/2019 21:06:53
avatar
779 forum posts
1830 photos

Just popped the back off my stebo/merco 61FS

img_20190815_203221.jpg

img_20190815_203515.jpg

this is a cambox of a Enya 46 for comparison,not unlike a Laser

Foxfan15/08/2019 22:18:35
avatar
686 forum posts
6 photos

Those are very interesting, Jeff. Thanks for those.

Martin

Engine Doctor15/08/2019 22:33:02
avatar
2254 forum posts
24 photos
Posted by Foxfan on 14/08/2019 10:41:45:

Yes, that's a shame, Jon. Especially where the smaller engines are concerned. We don't all want vast airframes in the shed, requiring huge, expensive engines.

I was thinking I could probably make all I need for the 4 stroke conversion as I have a lathe, but no mill. But thinking about it, a set of decent gears won't be cheap. If I could get a smaller Laser for around £70 I would. I can't believe anything that desperate can go wrong with them and many will have had very little use. I have a friend with a ceiling full of them, barely ever used, but he has gone down with a massive dementure and his family have asked his friends not to call, but what will they do with all his Lasers I wonder? And his filing cabinets of Futaba 35 meg, other engines (Saito, OS), covering materials, timber, accessories, etc. Such a shame.

Doc, where are these swap meets I keep hearing about? And what I've seen of BMFA classifieds wasn't very encouraging.

Martin

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E! 

Support Our Partners
Addlestone Models
CML
Pepe Aircraft
Wings & Wheels 2019
Gliders Distribution
Cambridge Gliding Club
electricwingman 2017
Slec
Advertise With Us
Sarik
Latest "For Sale" Ads
Does your club have a safety officer?
Q: Does your club have a safety officer, or is the emphasis on individual members to each be their own safety officer?

 Yes we have a SO
 No, it's down to everyone

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us