Ngk B6hs

[Cisco]

the engine HAS to spin over 15k just to hit 65mph never mind 70

Maybe he meant 65kph. Still, I'm glad that you calculated the necessary RPMs. I think a lot of claims are exaggerated. 10T X 44T with 26" wheels on my bike, I doubt I can go over 28mph.

 

[Cisco]

I doubt I can go over 28mph.

Unless I'm going down hill, with a tail wind, and I fart real loud ;-)

 

[darwin]

30mph on a bicycle is fast enuff, nuff said!

 

[Street Ryderz]

Maybe he meant 65kph. Still, I'm glad that you calculated the necessary RPMs. I think a lot of claims are exaggerated. 10T X 44T with 26" wheels on my bike, I doubt I can go over 28mph.

I've gone just over 50mph with a stock engine and a 40 t on a 27" wheel and that's around 11k pushing the crap out of it!
I've gone well over 65 on this one but it's geared with 11t on the engine and a 30t on a 27" wheel which keeps the rpm in check and requires 10,600 rpm for 73mph which is hard as heck to get to ! And that's fully modified with balanced crank, altered port volumes and timing, reworked cdi for proper ignition timing at those rpm plus a whole bunch of other mods that are all listed in my previous posts over the years.

 

[Cisco]

plus a whole bunch of other mods that are all listed in my previous posts over the years.

I just watched your Balance Factor video. I hadn't considered rotational mass vs. reciprocating mass. The Zeda 80 advertisements claim a balanced crank, but that's just accounting for the rod weight, right? Still an improvement (as you say) over the old style cranks.

 

[DAMIEN1307]

The Zeda 80 advertisements claim a balanced crank, but that's just accounting for the rod weight, right? Still an improvement (as you say) over the old style cranks.

I can't tell ya exactly what Zeda did on the "80", but i can tell ya its a hell of a lot more stable with next to zero vibration than any of the other CGs ive built over the years...Its my favourite thusfar for a stock setup...im totally sold on them...DAMIEN

Here is their technical comparison PDF of others like the PK80s and GT5s verses their Zeda 80s and what they do different.

https://www.bicycle-engines.com/product_images/uploaded_images/Zeda-Technology-Co-Zeda80-Brief.pdf

 

[Cypher_Xero]

I run an NGK BR6HS in winter and an NGK BR7HS in the summer, also upgraded the plug boot to an NGK boot because the stock one didnt connect to the plug tight enough for my liking.

 

[Cisco]

@Street Ryderz In the Balance Factor video, you drilled to remove material to under balance the crank, compensating for ~35% of the reciprocating mass/weight (piston, rings, bearing, pin and clips). Is there a way to add material on the opposite side to over balance the crank by the same percentage? Would the increased inertia of the rotational mass yield greater output torque at low RPM? I was thinking of lead strip weights, like glue on wheel weights, adhered with epoxy. Has anyone tried it?

 

[Cisco]

Drill and fill?

 

[Street Ryderz]

@Street Ryderz In the Balance Factor video, you drilled to remove material to under balance the crank, compensating for ~35% of the reciprocating mass/weight (piston, rings, bearing, pin and clips). Is there a way to add material on the opposite side to over balance the crank by the same percentage? Would the increased inertia of the rotational mass yield greater output torque at low RPM? I was thinking of lead strip weights, like glue on wheel weights, adhered with epoxy. Has anyone tried it?

So you still want to offset the reciprocating mass at the desired percentage but adding that weight to the rotating mass does have some advantages, as you said it will improve torque some and carry more inertia into the higher rpms at the cost getting there quickly, again with the happy medium's. lighter mass cranks spin up faster and carry less inertia meaning they don't like being over geared. More mass on the crank spins up slower but aids in carrying through a loaded gearing better. Many builders will drill and fill to get the desired offset and keep the cranks mass the same or similar, they use tungsten pressed into the flywheels or some have tried lead but stuck on I can't recommend as I could see them flying off doing all kinds of nasty damage.