TartanMac

I don't think I can get the rod pic any better but I think you can see the pin

The focus is bad it is hard to get a good shot of it I will try again with better light. The dark line actually does not feel like a scratch and that line sits right in the centre of the left cylinders rod if you were looking from the rear of the engine. Everything left of that line is scuffed up and just a small amount right of it is scuffed the very end of it is still polished. The inside of the rod bushing if I take a small Allen key and run it across it I can feel the ridges.

For some reason these photos did not turn out well but you can see the very end of the crank pin is polished shiny and the rest is scuffed up the rod is the same. I put a pic of 2 cranks together to show how compact the V Twin crank is. The black and polished crank next to it is a Moki 61LS 2 stroke crank amazing really that it is that small you would not think it is a 25cc crank. I suppose this is another reason there is so little vibration for its capacity such a small throw and small counter weight. I realised there is not many pics of the Laser engines in pieces especially the V twins. So I thought I would put it up as it is pretty interesting.

I don't think there could have been any media in there as I washed it in old glow fuel then put it in the ultra sonic cleaner and refreshed the water till nothing was coming off it. I can remember that the pin had some scores on it when I stripped it but not that bad really. There is some grey gunge in one of the followers where the push rod fits in so maybe there was some residue but the little ends are fine. I will strip it right down again clean it and just do the wet /dry on the pin and bushes like you say then replace the bearing and seal the front housing and cylinder bases. I suppose when the pin and rods wear out I will hear it knocking like my irvine. I ran it on 10% for 1/2 a tank and found I could hand start it from cold very easy and got 200 rpm more 8,700 on a mejzlik 16x8 but the low end needles were a little tricky to setup and it did not want to quit straight away kept idling at 1,100-1,200. Also at a prolonged idle (1,800 rpm) the left cylinder dropped off. I think maybe the Irvine fuel runs the cylinder cooler with 10%. With 5% Laser it was difficult to hand start from dead cold but tuned better and was more reliable at low revs started easy by hand with just slight temp in it. I think with fresh 5% fuel I will be able to hand start it to an idle of 2,000 rpm easy I fixed the exhaust also there was a metal piece in the muffler rafting around with the threads on it the screw caught the threads and it torque up nicely. After running this engine through a few tanks now I got used to it and it is a super engine I am very happy and hopefully the crank pin and rod issue get sorted easy. This is my favourite engine now and I prefer 2 strokes mainly but this is pretty special.

Well I took the front housing back off the engine to take the size of the front bearing to order a rubber sealed one and get some new silicone high temp sealer and found that my sealant was no longer there and had come off. No big deal I thought at least I know where some of the oil came from. But then I took the crank out and noticed the crank pin has been very badly scratched by the rods big ends and found that the bushings are not smooth either. I was wondering if there is a fix for this. I remember polishing up the crank pin with 2000 grit but did not touch the rod bushing. Will I need to replace the bronze bushings ? I have a Q40 Irvine that needs the rod bushing replaced and a few other things on a list for when I can get to a family members work shop. But he can only get time off once a fortnight and not every fortnight is he gonna want to be there. But I can put it on the list as I have not got the aeroplane started for this engine yet. I will put photos up soon. I took the heads and cylinder off and they look fine the pistons move nicely in the cylinder now and the heads look great with a light yellow golden colour but no carbon. Can I just run some 1200 grit round the inside of the rods bushing and clean up the pin ? I have only run 4 tanks I think and it has scratched up already.

I figured it out easier than I thought. Edited By TartanMac on 01/02/2018 20:49:42

Well I ran my 1.50V again to try out the muffler. The end cap flew off the last time and I found the threads are shot and there is a crack in the piece it screws into so I tried epoxy it lasted 5 seconds. I will try and solder it I got some 450F stuff and used it on a Weston UK headed that had a crack right at the start of the pipe. But I ran the engine anyway to practice tuning it, and have it down I think the main needles are a little vague and don't change top end much but I found that once I get them set the low end is fairly easy to set up both cylinders seem to like 3 clicks rich from when it just starts to surge and quit on quick throttle response. When I click them in leaner the engine will run at 1,900 rpm with the throttle pulled right back. And slowly wants to die. And also will not give good response time this engine sound way bigger than 25cc with the exhaust plate removed only one of them came off and I could not hear the other cylinder by listening to it I should have stood 4-5ft away so you could hear it a bit better it sounds very grizzly.   Edited By TartanMac on 01/02/2018 20:50:08

For anyone wondering about the carb

Posted by John Emms 1 on 13/01/2018 22:50:17: I was going to say that there was a slight mod to the MVVS glow carbs, maybe a little short of 20 years ago to improve throttling. But then I saw the carb - that is of a type that I don't recognise. The answer, as always, is a short e-mail to MVVS. Regards, John Yes I can remember reading about that on the forums when searching around. They had an 8mm carb on there at one time but I think it was for making all there engines with the same carbs 61-77-90 but then I think they went to 8.5mm and settled on that. They had this carb early on but I think it was costly to make it is very nice just like an O.S type 86 carb without the pump and fuel shutoff return line. The needle on the carbs changed also much like the difference between the webra ultra mix and the pro mix the low speed had been rounded instead of straight cut at the tip. I think they changed the shape of the mains aswell. Yes I think I will send an email.

Thanks Denis yep the piston is starting wear. It still has the horizontal scuff marks but way cleaner than it used to be.