sgilkey

My Feedback: (180)

I've been very pleased with the performance of my 40 LAs when 1) removing the muffler baffle, 2) reaming the tailpipe with a .250 reamer (mostly to remove any burrs/flash in the opening, if any) and gently radiusing the inlet to the tailpipe from the inside of the muffler, 3) filing off any casting flash at the inside of the junction of the "header" portion of the muffler and the "can" portion- there is almost always some step or flash there, 4) remove the head gasket, 5) enlarge the airbleed hole to about .072" (to enable the idle/midrange to be leaned out a bit more). While the LA40 is a comparatively weak engine, these changes will provide a substantial and noticeable power increase over stock. Next step would be a larger carb- enlarging the stock barrel is difficult because it is hardened- a carbide drill or burr is required. the Tower 40 carb has a slightly larger barrel which might give you another couple hundred rpm.

NM2K

My Feedback: (14)

Another "trick" that some have discovered with the plain bearing .40 type engines is to drop down in pitch from a 10x6 to a 10x5. I have seen this make quite an improvement while flying some types of models. Especially on hot summer days. Yeah, it is counterintuitive, but it works.

loughbd

They missed the point. The LA series are a beginner/sport type engine designed to be simple to operate and dependable as well as economical to buy and run. Perfect for thje first time user. Messing around with one will take most of those features away from it.

If you need a more powerful engine, buy one in the first place.

loughbd

They missed the point. The LA series are a beginner/sport type engine designed to be simple to operate and dependable as well as economical to buy and run. Perfect for thje first time user. Messing around with one will take most of those features away from it.

If you need a more powerful engine, buy one in the first place.

asmund

put a tuned pipe on it and call it a day. If it`s not enough power, get a bigger engine with more oommph!

proptop

My Feedback: (8)

Someone is missing the point alright... The O.P.'s question is mods to an LA .40, not which other engine should I buy...
It's his engine...if he wants to try his hand at modifying it so what...so be it...have fun and go for it...don't mind what some sticks in the mud have to say...maybe they're stuck in the mind set that the manuf. is perfect and the easiest thing to do is just buy another engine?
It's fun to tinker with engines, and a cheap LA is a good candidate...

There are plenty of good ideas here to get it running faster...if that's what he wants.

asmund

You are absolutely right about that, I love to fiddle with my engines tooHere`s what I do to my twostrokes: bigger carb(not always), tuned exhaust (most important) then I fiddle with headshims to increase compression and I also port the sleeves(always) to squeese the last rpms out of the engine. Fold up yor sleeves and get to it. Tach the engine on a given prop for each mod you make to monitor your pursuit for more power

asmund

About the porting, many aero folks have never heard of it or done it, but it is quite common in car and boat racing. I have no pictures of my own sleeves but I found a great link that explaines how to do it. This guy has ported the transfers a more to the side than below the ports. I myself port only downwards and leave the with of the port as is because it has to fit the channel in the case. Trial and error (and some research) will give success. here`s the link: http://www.rcuniverse.com/forum/Port...2507656/tm.htm

DarZeelon

Asmund,


This is an ABN sleeve you are talking about.

It may not last long if any porting is done.

asmund

Hi Dar, I am aware of the quality of OS nicle sleeves, however I never ever touch the inside of the sleeves, all work is done on the outside of the sleeve and do not come in contact with the nicle or crome (in other engines) this is mentioned also in the text in that link

asmund

This is the only mod I have done to my MVVS 49 to make it swing the APC 12.25-3.75 at 13600 rpm, it works I have also done it to a friends 61 fx (nicle) and it holds up so far

asmund

When I think of it, I have given this threatment to: 91 fx, ASP 52 xls, MVVS 49, 61 fx, thunder tiger 50 heli engine, and several of my buggy engines. All of which have given more power. It`s a little hard to tell on a buggy engine but my aero engines have been tached before and after, always with considerable gain

proptop

My Feedback: (8)

asmund...that link you put in post #55 is what I was talking about in post #26...thanks. You and I know how much the mods to the outside of the sleeve can do

The sleeve in the LA .40 is very thin though, so I don't know how much benefit one might see? I did my LA .40 but haven't run it yet...it needs a needle valve assy.

Motorboy

I saw at the link of porting the sleeve, this is not pure porting as we are talking about remove the material in the ports to increase timing. At these pictures show are to improve cas velocity with less resistant from crankcase to cylinder. To increase timing: we can raise the sleeve and add shim between crankcase and sleeve, but a problem are lack of pinch between piston and sleeve who make more leakage between piston and sleeve, maybe more difficult to start the engine with less compression cause leakage while the engine are warm.

You can do it with ABC sleeve to increase gas velocity. ABN sleeve are useless ,and nickel will flake of sleeve later, not possible to last long time. Steel sleeve no problem, important all edges in ports must be smoothed after work to prevent damaging the pistonring/cast iron piston.

Jens Eirik

proptop

My Feedback: (8)

Jens, you are right, of course...it's not actually "porting" the sleeve...

I like to call it "flowing" the ports or "massaging" them along with de-burring the inside of the case. Actually, it's more than de-burring, but you know what I mean...it's putting a radius on the sharp edges that might impinge on the air/fuel mixture flow, without removing a lot of material.