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74 to 80 inch increase. Impressive

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Sidecar
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74 to 80 inch increase. Impressive

#1

Post by Sidecar » Sat Feb 04, 2006 1:12 am

I figured that this would be the proper forum to post this.

After talking about 84 inch stroker kits and $$$, I decided to change the cylinders considering I have less than 6000 miles on my bike. As most of you know, I run an S&S pan/shovel generator style motor. It seems that there are quite a few 74 inch motors around here with 80 inch cylinders on them. I figured what the hell, I'll give it a try. I let a bike mechanic do this by the way. I decided to jump from 24 to 25 teeth on the tranny also so I wasn't expecting much difference.
After they took the tanks off my bike, they found that the motor mount was broken, so I asked them to re-shim the motor and fix the mount. I stopped back in and they suggested that I go to 9.5 to 1 compression since I have this "new" S&S motor. Okay, what the hell, I said.
After a while I get a call. My bike is almost impossible to kick start. I had an Andrews J cam previously and replaced it with an A. Neither seemed to do anything for the performance. Maybe becase of the low compression ratio ? Andrews says that this bike needs a BH cam. Now it starts much better.
Bike is done and I pick it up with my closed trailer because it was snowing. I put it in the garage and started it every once in a while and let it run for 5 minutes or so. It's harder to kick and I had to change my cold start procedure a little.
New years day I put 50 slow miles on it. January 28th I twisted the throttle half way open, after I had 150 or so miles on the bike, and it REALLY surprised me. I ran it up to around 70 and shut it down. I almost got arrested by a cop that was coming towards me. I thought for sure he was gonna turn around and nail me.
I could actually hear the air cleaner sucking fuel and air. I never heard that before. I already had a big main jet in the bike and before I tried this I jumped up on the intermittent jet. I need to keep pulling the plugs to see how the fuel is burning. I won't know for sure until summer what the HP jump was but it seems to be BIG. I was shocked that the bike ran that good with the taller gearing and it put a serious smile on my face.
I started with 74 inch and 7.5 to 1 compression with an A cam which developed around 44 HP on the Dyno. I'm now at 80 inch, 9.5 to 1 and a BH cam. After I get 600 miles or so I'm going to put it on the Dyno and I'll post the results.

Damn, I'm one happy camper !!!!!!!!!
Sorry for taking up so much space with this post.



Cotten
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Re: 74 to 80 inch increase. Impressive

#2

Post by Cotten » Sat Feb 04, 2006 2:38 am

Congratulations!

Your formula is contrary to "conventional" sidecar dogma, but who cares!

...Cotten

Sidecar
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Re: 74 to 80 inch increase. Impressive

#3

Post by Sidecar » Tue Feb 07, 2006 12:33 pm

I have to admit, I think I'm going to quite happy with this setup. I did not set out to make it fly, just pull my fat ass up these Pa. mountains.
I sure hope I never get in a situation where I have to kick this thing too many times. It makes you realize that you ain't 20 anymore. ;D

kell
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Re: 74 to 80 inch increase. Impressive

#4

Post by kell » Tue Feb 07, 2006 4:20 pm

Did you bore the cylinders out to 80 or did you put new cylinders on?

Sidecar
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Re: 74 to 80 inch increase. Impressive

#5

Post by Sidecar » Tue Feb 07, 2006 9:02 pm

Kell.

Put new cylinders on the bike.

Cotten
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Re: 74 to 80 inch increase. Impressive

#6

Post by Cotten » Wed Feb 08, 2006 3:26 am

Why did you choose so high of a compression?

...Cotten

1950bobber

Re: 74 to 80 inch increase. Impressive

#7

Post by 1950bobber » Wed Feb 08, 2006 4:29 am

Your compression (9.5-1) is about as high as you should go with domed pistons and still get a decent "burn" in the cylinder (unless you get up to the 12 0r 13-1 and DEFINATELY dual plugs...although these ratios on our old pans doesn't make sense to me!)....I think I agree with that compression ratio if you're climbing alot of hills such as here in Washington State or the areas in Penn......you should climb well and might I suggest some mild head work to increase flow, A or B grind Andrews, and CV or Super E carb (Stay WAY clear of Mikuni or Webers...OVERKILL or just not good combo's). I think there are many different theories on how to achieve power...but I've found the 9.5-1 great for my Shovel with the climbing we do here on the west side of Washington....hope your new build gives you what you need...I know your enthusiasm when you twist the "wick" after driving with a 7.5-1 or 8-1....just be sure to keep the grinning to a minimum and you'll find you'll pick less bugs from your teeth!!!!
Jim in Seattle "1950 Bobber"

Sidecar
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Re: 74 to 80 inch increase. Impressive

#8

Post by Sidecar » Wed Feb 08, 2006 1:16 pm

Cotten,

I went with the advice of the mechanic that I deal with.

Jim,

Thanx for your input.
Got the Super E figured out pretty well now. My older brother is taking the Mikuni off of his shovel and replacing it with an E. Most of the bikes around here are running E carbs.

waiteitei
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Re: 74 to 80 inch increase. Impressive

#9

Post by waiteitei » Wed Feb 08, 2006 9:37 pm

got a few questions 80" hd barrels are just 74" barrels bored 60 thou oversize, this alone will not give you an 80" motor withour stroking it
have you used a bore bigger than 3 1/2" to get to the 80"
have taken my pan out to 80", used 80" shovel flywheels and bored the barrels to 60 thou oversize to suit standard 80" shovel pistons

Rammy
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Re: 74 to 80 inch increase. Impressive

#10

Post by Rammy » Thu Feb 09, 2006 12:22 pm

That is what I am doing with my 51 this winter, .060 over pan cyl. with the 4.25 stroke wheels to make for the 80. I went with the 8.0 comp pistons. I thought 9.5 would get hard to kick when someone was watching. I think you can use 3 5/8 shovel cyl. with outside oil lines and STD`s w/ pan shov bolt pattern and open the case`s. I wonder if you could bore the one head bolt hole that is differant and put thread insert in on standard pan heads . then use any shovel cyl.....

Cotten
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Re: 74 to 80 inch increase. Impressive

#11

Post by Cotten » Thu Feb 09, 2006 12:42 pm

Sidecar!

I take it that you're not really running a sidecar?
And that Pennsylvania gas stations always have high-octane gas?

...Cotten

Jack_Hester
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Re: 74 to 80 inch increase. Impressive

#12

Post by Jack_Hester » Thu Feb 09, 2006 1:48 pm

Rammy -

Have you bored your cylinders, yet? If not, don't. You only gain approximately 2 cubic inches, from the stock bore 74" cylinders. Give your engine the extra wear life, and leave the cylinder metal on, for as long as you can. You won't feel the difference that the 2 cubes will give you. I doubt that a dyno will show a difference, either. And, I don't think that anyone will mind if you have a 78", rather than an 80" Just my thoughts on preserving your engine, and your cash.

Jack

Sidecar
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Re: 74 to 80 inch increase. Impressive

#13

Post by Sidecar » Thu Feb 09, 2006 2:58 pm

Cotten:
No sidecar. Haven't had one for 5 or 6 years now.
Always run highest octane.
I can't remember what they told me the bore size was. They are shovel cylinders. I can tell you it's a lot harder to kick.
I would assume that it's probably a big bore kit ?

Cotten
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Re: 74 to 80 inch increase. Impressive

#14

Post by Cotten » Fri Feb 10, 2006 1:24 am

Sidecar!

I would only assume that you are at the mercy of your mechanic.

...Cotten

Rammy
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Re: 74 to 80 inch increase. Impressive

#15

Post by Rammy » Sun Feb 12, 2006 12:29 pm

Jack,
My pan cyl. are at + .060 now that is one reason for the 80 std. piston . I desided to do the T&O torque monster wheel with 4.25 stroke . T&O told me that the heaver wheels are more like the stk. wheels so I went with that.... I am useing the 8.0 compression pistons so I can Kick it over and use the questionable gas that is out there now days. I also use the J cam. What do you think of this combo?

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