Big Bore with stock Intake and exhaust?

Does your Spree/Elite already run great, and you're trying to make it quicker/faster? Need a monster motor swap? Discuss your ideas here.

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NBraun
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Big Bore with stock Intake and exhaust?

Post by NBraun » Mon Mar 09, 2020 10:40 am

Not really looking for performance. Trying to get a spree back on the road. Already put a new piston/rings in and that only bumped my compression up to 90. It could have been something I did, though i don't believe so. Thinking the cylinder may be too far, so i'm looking into putting a new top end on it, and the oversize bore is the only thing i can find.

If I put a big bore on, can I still run the stock intake/exhaust for the time being?

Brivander
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Re: Big Bore with stock Intake and exhaust?

Post by Brivander » Mon Mar 09, 2020 10:48 am

You can run the stock exhaust, but it's pretty well known they are hard to get running right. Seems adding an SB50 intake or porting the stock intake alleviates a lot of those (not all) issues.
1985 Black/Purple Spree-39 GPS
1985 Red/White Spree-40 GPS
1987 Black/Purple Elite-44 GPS
1985 Red/Black Aero-42 GPS
1992 Red/Gray Jog- 56 GPS

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eclark5483
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Re: Big Bore with stock Intake and exhaust?

Post by eclark5483 » Tue Mar 10, 2020 5:06 am

Stock exhaust will be fine, stock intake you'll run lean, and probably blow the piston. Check out the link in my signature for a complete rundown.
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1 Indian AMI-50
The World's Greatest Spree: https://www.youtube.com/watch?v=lU49lL_Xx4s
Want to make a Spree engine go fast? CLICK HERE: LINK

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harleyracer59
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Re: Big Bore with stock Intake and exhaust?

Post by harleyracer59 » Tue Mar 10, 2020 4:58 pm

funny how I have had the opposite reactions. ive ran many of stock or ported intakes and carbs with bigger jets. but have had terrible luck with stock exhausts. they overheat or strain the engines. after I build a big bore motor. first upgrade is to up jet. next is a new exhaust.

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Re: Big Bore with stock Intake and exhaust?

Post by Brivander » Tue Mar 10, 2020 9:51 pm

Hey we all have our own experiences, that’s totally ok. The kits for these are absolutely not consistent. Two of my friends were not able to get there kits to run decent at all until they swapped to a good intake. They changed everything else, and I mean everything before that. The last was never able to get it right, that kit was a time bomb.

I like to refer to it as BBK roulette....they kits just aren’t the same....at all, even if you buy 2 together, who knows what you will get. That’s why I kept the stock bores and optimized them. Stock cylinders, 86/87 piston, 84/85 heads milled .020 and 86/87 gear ratios. Combining the best of the OEM parts.

I’m still planning on getting a cylinder bored +2mm and using a service part from Europe. That will net ~55cc. We will see how that goes when I have some time to do it.
1985 Black/Purple Spree-39 GPS
1985 Red/White Spree-40 GPS
1987 Black/Purple Elite-44 GPS
1985 Red/Black Aero-42 GPS
1992 Red/Gray Jog- 56 GPS

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harleyracer59
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Re: Big Bore with stock Intake and exhaust?

Post by harleyracer59 » Wed Mar 11, 2020 3:17 pm

I agree with this guy^^^^.
the key is to ask questions. study old posts and use the knowledge to your advantage. if you have trouble, make a thread and give all the info you can for your situation. that will net you faster more complete answers and hopefully solutions to your problems.
if you big bore get a temperature gauge. that will save your kit before you f it up if any issues arise. good luck. have fun

NBraun
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Re: Big Bore with stock Intake and exhaust?

Post by NBraun » Thu Mar 12, 2020 7:07 pm

Went ahead and put another set of rings in, and we seem to be on the right track. Went ahead and cleaned the exhaust port and ported the intake while i was in there. Doing some heat cycles but seems to have some power now.

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