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hjr 421 cub


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Get to tuning...

I got 84.8 from a cleaned up 421 with stock carbs and T5 pipes....no lockup.

 

:)

 

Kevin,

Since it's your porting, what do you think about having someone else cut domes, etc.

 

Once you run alky, you'll never go back.

However, for a duner, IMO it's a waste.

 

Hill shooter or drag bike, fine...but for duning, it's a waste.

 

A dyno is good for comparing mods...that is it.

That number doesn't equate to crap in the dunes or on the track.

 

I've seen bikes come hot off the dyno fall on their face at the track...like I've said before, the lights and timers dont' lie!

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The numbers are low cause he didn't have alky domes in it. He was at 16:1 UCCR. He would do much better at 18:1 UCCR. Looks like he has these guys taking care of it. He is in Vegas so he's not close by. Its a hassle for him to drive it back and forth. Not sure why it let go with no timing and only 16:1 UCCR.

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don't take this the wrong way but sounds like the guys at the dynoed might of had it tuned good for a 90sec dyno pull but not for a wide open run out in the dunes.with alky that couple hp gain from running it on the edge isn't worth blowing the motor up.run it fat it will just blow the extra out the pipes!

i was only able to ride it 6 seconds wide open maybe. never even got to launch it. according to them they actually still had it fat. i have numerous dyno sheets from them. they said when i brought it to them the jetting was way off. they drilled out like 8 mains to get it close. then they were still off. they actually had to start running gas jets they said. to get the air fuel mixture close.

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Get to tuning...

I got 84.8 from a cleaned up 421 with stock carbs and T5 pipes....no lockup.

 

:)

 

Kevin,

Since it's your porting, what do you think about having someone else cut domes, etc.

 

Once you run alky, you'll never go back.

However, for a duner, IMO it's a waste.

 

Hill shooter or drag bike, fine...but for duning, it's a waste.

 

A dyno is good for comparing mods...that is it.

That number doesn't equate to crap in the dunes or on the track.

 

I've seen bikes come hot off the dyno fall on their face at the track...like I've said before, the lights and timers dont' lie!

]thats what it is for hill shooting and dragging

 

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i was only able to ride it 6 seconds wide open maybe. never even got to launch it. according to them they actually still had it fat. i have numerous dyno sheets from them. they said when i brought it to them the jetting was way off. they drilled out like 8 mains to get it close. then they were still off. they actually had to start running gas jets they said. to get the air fuel mixture close.

 

I haven't tuned on alky much but I would be concerned that they went small enough to get to jets that would work with gas. You should ask them straight up what they had the dumps and mains drilled out to, then report back. I know someone from here could get you close, and if these guys went way too low, then somethin's up.

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seems to me that maybe something is up with there a/f gauge and it was way lean.i know my stock cylinder 4mil kevin drag ported i had the dumps at .125 and the mains the same and tuned it with the power jet.the power jet was i believe one turn out,it ripped.hope you get it figured out blanco

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We have the same cub, and my alky tubes mains to start aredrilled out to .125. Im in St George, lemme know what Tommy and TJ drilled you out to. Should even be runnin gas jets

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Just curious but when you talk of alky, is it methanol or ethanol?

 

 

 

That is a smart and GOOD question. I have had many instances where a customer brings us a new bike that will not run right where the previous owner ran Meth and the new owner thought E85 was alky! Um, even 100% Ethanol will be WAY off. Good thing to check.

 

 

 

 

B

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