Dyno testing 'performance mods'

[cloakedvillain]

When an engine cant overcome the road you get engine braking, it will definitely drag.

 

[ImpulseRocket]

After a short break thanks to finally catching Covid i'm back! I've got my 66cc mounted to a new frame, my new crank seals arrived and once the rains stop we'll get to testing some ignition timing - from rotating the stock magnet as far advanced or retarded it'll go on the shaft, then grinding the key a little to get more movement, then I'll fit that fully programmable CDI that I got from aliexpress ($80 isn't too bad for what it can do!) and see if it's worth it.

Now i've got two bike frames, I also want to dyno both bikes at the same time to see what the numbers show. I'm guessing the torque numbers will add, my brother thinks they'll add until the weaker engine drags the stronger one down. FB experts say it'll only show the curve of the strongest engine. What do you think?

Covid caught you.

A tandem dyno won't quite work how you believe it will. The engines will compensate one another in their weak areas and somewhat muddle the results together. Hard to compare and contrast that way.

Unless you just want to see what their combined power would be?

 

[WillitBoost]

It got me good haha. Wasn't the worst flu i've had but the longest lasting for sure.

Yeah, more as a curiosity than anything. Also interested to see how two different power bands merge, for if/when I build a twin cylinder china doll with two different very peaky power bands

 

[Chainlube]

I think it will add. The short comings of one will make up for the other. Sounds interesting for sure.

 

[Jayraye39]

I didn’t think he was being negative at all. He was telling you the truth. You call yourself an innovator, but the truth is that innovators don’t guess at what they can measure, calculate, or predict. I went on Amazon and found compression testers.

my negativity comment wasnt derived from merely from my ebay cnc head post their has been multiple post through out the years in which his comments were belittling and down right rude. And yes Innovation is 100% guess work you take as much information as you can and you fill in the rest with your mind. sooner or later you will find somthing that has never been done. Albert Einstein once said "I never failed I just found a thousand ways it didn't work" why because guessing is a massive part of innovation

I am also poor and dont have the money for tools and testers. this is why im so good at using things that surround me. What i do is test real world theories. something like bore out the top of a carb. I test it then post my findings. I dont have anything that tells me how much more power it gave me. but it did and I culd feel it. so thats what I post. It wasn't until the member that wrote This Thread tested my guess work on boring out the top of a carb that it was proven and indeed increase performance. by a decent amount also. so this in turns created a new innovation or free mod on carburetor performance that was neither posted or had been talked about previously so again yes guessing does create innovation.

 

[GW's Motorized]

Please don't hijack this thread arguing. If you wish to continue this conversation please do so privately. I also suggest you read this

Turning an ebay CNC 12cc head into a 7cc powerhouse.

It’s not even your technique that is the issue. It’s the fact that you’re shotgunning it. The only benchmark you have for performance is a speed clock that you have no idea when is the last time it was calibrated. I’m a creative person as well, but if I’m going to deck a head, I’m going to...

motoredbikes.com

 

[WillitBoost]

small update on the bt100, I raised exhaust timing to 180deg and widened the port another 1mm. It now makes power out to 10,500rpm before it drops off sharply. The pipe is no longer 'peaky', instead i've lost 1hp at the peak but its a much shallower slope. I tried halving the stinger length and lost more power so that was definitely the wrong direction to go. I suspect a smaller stinger might pick it up a little but at this point I think I'll design a new pipe for the current engine specs and target 10,000rpm.

Raising the exhaust timing this much kind of ruined what the BT was good at, low down torque. After testing the new pipe I'll put the new cylinder and piston in and maybe build a pipe for a more reasonable RPM.

I should probably try the adjustable CDI with the current setup. I expected a slightly higher RPM with the stinger cut shorter but I didn't really see it. It might be ignition timing related...

 

[robe]

I'm glad I didn't go to town porting on mine. From what you have shown a little cutting makes a huge difference. A couple you tub vids does not make a motor specialist, I'm speaking for myself of course.

My last motor just got port matched and the intake ground out a bit and that's all. Runs great, lots of power for 66 cc.
This next one I'm slowly putting together is getting the same treatment plus decking the cylinder and head as the squish is excessive at over 2 mm. I'm trying for just under 1 mm. Also upgraded to a better fitting wrist pin and have yet to make some shims for it.

You must be getting on to farming season where your at. Spring must have sprung and all that.

 

[BruceBanner1983]

I'm glad I didn't go to town porting on mine. From what you have shown a little cutting makes a huge difference. A couple you tub vids does not make a motor specialist, I'm speaking for myself of course.

My last motor just got port matched and the intake ground out a bit and that's all. Runs great, lots of power for 66 cc.
This next one I'm slowly putting together is getting the same treatment plus decking the cylinder and head as the squish is excessive at over 2 mm. I'm trying for just under 1 mm. Also upgraded to a better fitting wrist pin and have yet to make some shims for it.

You must be getting on to farming season where your at. Spring must have sprung and all that.

Knowing how much material you want to take off is the way to go. Commendable.

 

[molash]

was wondering if you could test different oil ratios, there seems to be lots of opinions on the subject and it would be nice to have some confirmation.

thanks