Swifty's build of Nemett Lynx

[Swifty]

Thanks Pete, although it runs, idles well and revs, I'm thinking that the carby may have to have some mods done on it. Others try over the counter carbs, and probably get better results, but I like the fact that I make nearly everything.

Paul.

 

[Brian Rupnow]

Swifty---A true masterpiece. Very, very nice.---Brian---What do you think needs to be done to the carby. I found that on my Jaguar carb, (which I believe is identical) that it works great except for the throttle idle stop screw.

 

[johnny1320]

Very nice Paul, I was wondering how the the valve clearance is adjusted on this engine?

 

[Cogsy]

Runs beautifully, sounds great. Very impressive.

 

[Swifty]

Johnny1320, the valve clearance is set when I built the motor, there is about 0.1mm clearance. If the valves bed in a bit, I will have to tweak the length of the valve stem to reset the clearance.

Brian, I will still have to play with the carb a bit yet, if I have it wide open and adjust the needle so it gets maximum revs, it doesn't run so well on idle, I haven't touched the idle jet screw yet, maybe that will fix it. The idle screw jet only appears to let in a bit more air in through the small hole, surely I only have to adjust the idle stop to get the same result, maybe I'm not looking at it correctly, still it's early days yet.

Paul.

 

[Brian Rupnow]

Paul--The more it runs, the better the idle will get because your compression will increase. Malcolm stride says to let the engine warm up, then with the throttle wide open, close the needle jet to get max revs. Then open the needle valve just a little bit. Then close the throttle until the engine will still idle, but starts to stumble. Then open the air bleed screw until the revs pick up again. Then close the throttle a bit more until it starts to stumble, then open the idle screw a bit more. I have tried this and it "kind of" works. For something to think about---On the engine I built, with cast iron rings in it, I could get the engine to run "at speed" but couldn't get it to idle. I ran the engine on and off for four to six hours, and seen no improvement. Finally I gave up and put the piston with the Viton o-ring on it back in. By "feel" the compression doubled, and the engine would then idle right down to a "tick over' with no other alterations.---Brian

 

[Jasonb]

Looking good Paul, as you say still needs a bit of a tweak as it seems a little slow to throttle respone and is dieing as teh revs increase.

The air bleed is designed to give a leaner mixture at lower revs, the idle stop really just sets the lowest speed and stopps you completely shutting off the engine.

J

 

[johnny1320]

Is it possible to put a shim under the cam box to adjust the valve clearance?

 

[Swifty]

Johnny1320, you could use a shim, but it's far easier to adjust the valve stem.

Brian and Jason, thanks for that, I suppose that I should have read the end of Malcolm's article again to see the tuning advice. I will be doing that today.

I was worried a bit about all the smoke out of the exhaust, every one that I have watched on YouTube has the same problem.

Paul.

 

[johnny1320]

Thanks Paul, I am finishing drawings for a parallel twin that I hope to start soon, your engine sounds great and the finished product looks great!

 

[gus]

Hi Paul.
Congrats.That was a MasterPiece built by a MasterCraftsMan. The roar is sweet,steady and cyclically firm because of intake and exhaust valves cam driven.
I am stuck with the Foot Pedal Speed Controller and trying to balance the gap between dead stop and full speed.Won't be till midweek to cam cutting. Fishing yesterday was good. Landed a 3 pounder Red Snapper.

 

[Swifty]

Hi Gus, I have a friend coming over today to see the engine, I will try to tune the carby better then. I don't know how your neighbours are going to react when you get yours running, apartment living has it's downside sometimes.

I know how you feel about having to get other jobs out of the way before you continue, can be a real distraction sometimes, but the fishing should always be relaxing.

Paul.

 

[SixSixSevenSeven]

Paul

As you say the tacho's are cheap and they help you understand what the engine is doing. There is a patch available to make it display the units but its not official and there's no way back.

many PIC ICSP programmers can actually take a firmware dump from an already programmed chip. This would serve as a way back to the original firmware. Dump existing firmware, reflash new firmware, don't like it, reflash to dumped firmware

 

[bmac2]

Wow Paul that is a beautiful engine. It runs great and (to me) has excellent throttle response. Once again I see a new level to aspire to. Thank you for posting this build, I’ve learned a lot from it.

 

[gus]

Fortunately its a small engine. No complains so far when I revved Webster and Rupnow engines.But the spinning sessions were very short. Will put a very good exhaust silencer if required.
Now that the mental block ----------Foot Pedal Speed Controller is done,calibrated and dry tested with 110v supply,I can return to the Nemett-Lynx Engine.The M.I.C. carbon rheostat speed controllers don't last too long compared with original US made which lasted 10 years.

The RT Calibrated,table lapped with worm and wheel spun by Cordless Drill,I should have no chattering when I take heavier cuts. Put in USA worm and worm wheel and they mesh very well with no back lash. I had very bad back lash with the very first RT.

 

[gus]

Wow Paul that is a beautiful engine. It runs great and (to me) has excellent throttle response. Once again I see a new level to aspire to. Thank you for posting this build, I’ve learned a lot from it.

Hi Bob,
Paul's Nemett-Lynx Engine ran and roar like a real engine. Very solid and smooth and good Vroom Vroom response. I am 2----4 weeks behind.

 

[Swifty]

I've been having a couple of days break after getting the engine to run, however I did check out a couple of hobby shops in the local area and managed to get a nice 15" wooden propeller to use for display on the engine. The propeller is very light, I suppose that I will have to do at least one run with it mounted to see if the engine runs as well as it does with a flywheel.

A friend who came over the other day bought his latest acquisition, a 1/4 scale remote controlled dirt bike. It's the first time that I've seen one of these, it has a gyroscope in the rear wheel which stops it falling over, we had a ball trying it in the local park, it runs great.

Paul.

 

[gus]

Hi Paul,

SOS SOS

Please advise cam blank diameter??? Will be finishing the preps and go into cam cutting. Having difficulty locating cam blank OD.

 

[Swifty]

Hi Gus, I have a sketch of my blank and I used a 12mm dia for the cam outside dia. Where I got that size from, I can't recall, I had a quick look at the magazine article and can't see a size. I can only assume that I used the stated 2mm lift added to the base radius of 4mm. The 2mm lift is stated in the specs on the cam calc sheet.

Paul.

 

[gus]

Hi Paul,

Thanks. Ypu are right Malcom's drawing has no cam blank O.D.
Over the next two weeks, a lot efforts will be put in and more work results to post. The Foot Pedal Speed Controller did perform
to expectations.This two year mental block done and gone.