Clutch engaged clutch. then loose 1/2 my rpm at full speed?throttle.

[WINDY CITY BOB]

When clutch is disengaged my motor screams! Once I let IT out I start off slow (because I have a 30 tooth sprocket.
Still,,,,, when I reach top speed I'm only. At around 1/2 of full RPM??? Too small a sprocket?

 

[FurryOnTheInside]

What is full rpm? Which engine is it? 66/49? Grubee or generic one? Some say (and I believe it, and am designing around it, but haven't run yet) that the engine will last longer, have less chance of catastrophic bearing failure miles away from help, if the RPMs are kept low, like maybe 4100 cruising speed. Obviously that has to limit power but I don't mind that personally, only wanting a bit of help to get somewhere and not being bothered about the power that I "could" be missing.

 

[crassius]

yes, sprocket too small - on most motors one would need to weigh less than 90lb for a sprocket that small

 

[WINDY CITY BOB]

Its a 49 CC generic I don't have a tax so I don't know RPM However it does very high and expecting that it runs at full capacity whatever that may be 6000? I really don't know what the highest RPM is but it runs at full capacity with the clutch disengaged.
I knew I would lose power off the start and I have to pedal a little bit off the get-go to get moving sometimes. Currently the plug I am using is an iridium BPRH7HIX Just like the LG K7 it works well at around 70 degrees at night I live in Chicago and it gets to about a hundred degrees with the heat index in the humidity , Regular air temperature is that around 90 degree High eighties and nineties, . I get much much greater speed but at night time when it drops down into the seventies it could be in the mid-70s That's when I get balls to the wall speed.
I have a stock CD and whatever I put on a standard Automotive spark plug wire. Tired of having you take the nipples off of all these nice spark plugs that I have bought. I have also tried to NGK BPH5,6,7 In the southern works the best I even tried the lower ones during the day and no good no bueno. Single or I want the worst performance I got I also have been using an E3.22 plug it works just as well as. The iridium, & NGK 7 .
I would like to be able to eat it one more tooth to my drive sprocket on the engines because for every Tuesday at 2 that is like Removing 5 teeth in the back. I don't know if that's possible on this engine But I was talking to a friend who used to be a pro racer and he told me that about the gear ratios front to back. If I could do that and then go up to a 36 tooth rear sprocket I'd be where I'm at but get more torque So that's what I'm working with right now if you have any other questions feel free to ask me and share what else on the other knowledge you have with me please thank you

 

[FurryOnTheInside]

I think Crassius got it. Idk how I skipped past that bit but a 30t rear does seem way off the scale for a 26" wheel. There's definitely a 34t available from a few places.

 

[WINDY CITY BOB]

I can get any size sprocket I want from 30 all the way up to32, 36, 38, 60 48 50 and 52.
any even numbers I have mags

 

[FurryOnTheInside]

Can you find an online gear calculator? If you have a speedo you should be able to figure out your engine speed from your road speed and try a few hypothetical gear ratios. You will need your (loaded) rollout to be truly accurate but it would still be interesting to see, even if not entirely accurate the differences between the gear ratios will be the same IMO.

It is a pity no one is making a top hat adapter for the ISO disc mount that is drilled to take ordinary bicycle chainrings. We could have UNeven numbers then and people outside the USA wouldn't have to pay the huge amount for shipping.

 

[WINDY CITY BOB]

IMO? (Loaded)rollout? I'm still pretty much a newbie here sir LOL SORRY

 

[FurryOnTheInside]

In my opinion IMO
In my experience IME
I can't remember ICR
If I remember correctly IIRC
As far as I know AFAIK
I can't be arsed I CBA

Loaded rollout - sitting on the bike and rolling forward one revolution of the wheel for accurate real world tyre circumference, rather than relying on the nominal 26" measurement.

 

[WINDY CITY BOB]

How does a tach connect to a engine anyways I have no idea how they work how they connect to the motor and calculate the RPMs to that dial Where do the wires go?
I mean I understand the gear ratio chart a little bit and stuff like that but, There are just some terminology I just don't understand and some techniques I have no idea what they are? I'm one of those jack of all trades master of none Guy's.