Big Bore Kits-Recommendations
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3rd Gear
Joined: Sep 2007
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Big Bore Kits-Recommendations
Newbie here looking to upgrade my bike which belonged to my dad, who passed away a few years ago. He rode his 89 FLHTC for about 55K miles before he passed away. Since inheriting the bike, I have done some cosmetic upgrades, added chrome and other stuff, but am now looking at pulling the jugs to fix some oil leaks and figured while they were off, I might consider going to a big bore kit. What will work on this bike without machining the cases and who sells the best kit for the money? Also, is it any benefit at upgrading to a 6 speed tranny to cut the revs down while on the highway. This think turns around 3 grand on the interstate. Thanks.
HDF Community Team
Joined: Dec 2005
Posts: 5,428
Likes: 2,629
From: NC USA
To answer your intial question - There is no "big bore" kit that does not require case boring for the EVO. There is an aftermarket kit that will give you 3 more cubic inches with 10.5:1 pistons, but the increase in performance will never equal the cost. There's an endless number of mods you can do and untold thousands of parts people who will more than willing to take your money so you can have "more power"
Otherwise...
They say advice is only worth what you pay but I'll offer this free of charge. The bike is 20 years old and I'm assuming near stock. (?) Maintain it and keep it that way because every penny you spend to "modify" it for performance, will devalue it -period. A bone stock bike has much better re-sale or trade-in value. And you don't need to take my word for that, ask ANY motorcycle dealer salesman, they'll tell you the same.
That's a nice bike and 88 - 91 had the best cam ever produced for factory Evo engines. 3600 RPM in high gear will never hurt the engine provided it's maintained. So do yourself a favor and first decide whether you want to talk about what it will do after all the endless time and dollars in performance mods, or would you be happier putting those thousands of dollars into the gas tank and enjoy what mortorcycles are really about....
Otherwise...
They say advice is only worth what you pay but I'll offer this free of charge. The bike is 20 years old and I'm assuming near stock. (?) Maintain it and keep it that way because every penny you spend to "modify" it for performance, will devalue it -period. A bone stock bike has much better re-sale or trade-in value. And you don't need to take my word for that, ask ANY motorcycle dealer salesman, they'll tell you the same.
That's a nice bike and 88 - 91 had the best cam ever produced for factory Evo engines. 3600 RPM in high gear will never hurt the engine provided it's maintained. So do yourself a favor and first decide whether you want to talk about what it will do after all the endless time and dollars in performance mods, or would you be happier putting those thousands of dollars into the gas tank and enjoy what mortorcycles are really about....
Stellar HDF Member
Joined: May 2005
Posts: 2,137
Likes: 17
From:
Can't argue with what T150 says, but it was your dad's bike, so you're probably going to keep it, right? And just keep fixing whatever goes wrong. For more power, I'd go with an EV13 cam from Andrews, which is a great bagger cam for low end. Even the 88-91 cam had some pretty oddball EPA timing numbers, plus the EV13 is great at keeping oil temps down. If you don't get too throttle-happy, it won't decrease your gas mileage either.
An 81.6ci engine (which is the actual displacement of a stock Evo) is plenty big enough to haul an Electra Glide around as long as you ease the strain of breathing by a better cam, exhaust and air cleaner.
Your dad might have upgraded this, but check and see if you have the bad transmission pulley. '91 was the last year for it; you want to upgrade to the '92 and later. Make sure you upgrade to the torrington B-138 inner cam bearing instead of the OEM INA. Change your cylinder base gaskets to the silicon-coated metal type. I think Cometic makes the best gaskets.
An 81.6ci engine (which is the actual displacement of a stock Evo) is plenty big enough to haul an Electra Glide around as long as you ease the strain of breathing by a better cam, exhaust and air cleaner.
Your dad might have upgraded this, but check and see if you have the bad transmission pulley. '91 was the last year for it; you want to upgrade to the '92 and later. Make sure you upgrade to the torrington B-138 inner cam bearing instead of the OEM INA. Change your cylinder base gaskets to the silicon-coated metal type. I think Cometic makes the best gaskets.
HDF Community Team
Joined: Dec 2005
Posts: 5,428
Likes: 2,629
From: NC USA
Can't argue with what T150 says, but it was your dad's bike, so you're probably going to keep it, right? And just keep fixing whatever goes wrong. For more power, I'd go with an EV13 cam from Andrews, which is a great bagger cam for low end. Even the 88-91 cam had some pretty oddball EPA timing numbers, plus the EV13 is great at keeping oil temps down. If you don't get too throttle-happy, it won't decrease your gas mileage either.
An 81.6ci engine (which is the actual displacement of a stock Evo) is plenty big enough to haul an Electra Glide around as long as you ease the strain of breathing by a better cam, exhaust and air cleaner.
Your dad might have upgraded this, but check and see if you have the bad transmission pulley. '91 was the last year for it; you want to upgrade to the '92 and later. Make sure you upgrade to the torrington B-138 inner cam bearing instead of the OEM INA. Change your cylinder base gaskets to the silicon-coated metal type. I think Cometic makes the best gaskets.
An 81.6ci engine (which is the actual displacement of a stock Evo) is plenty big enough to haul an Electra Glide around as long as you ease the strain of breathing by a better cam, exhaust and air cleaner.
Your dad might have upgraded this, but check and see if you have the bad transmission pulley. '91 was the last year for it; you want to upgrade to the '92 and later. Make sure you upgrade to the torrington B-138 inner cam bearing instead of the OEM INA. Change your cylinder base gaskets to the silicon-coated metal type. I think Cometic makes the best gaskets.
Thought all day about what I wrote earlier and wouldn't change it all except - nothing wrong with doing some tuning to make it "all it should be." Cam change, carb and exhaust mods and what-have-you are certainly good even for economy and add a level of personalization.
My earlier point was, I've seen so many people try to make a bar-hopper, drag bike out of a really nice Tour bike and end up with a mess, many dollars later....
Seeing you're new here, hope you didn't feel I was jumping on you about your ride. Not unlike a lot of others who been doing it a long while, we tend to become legends in our own minds
... well, my hand is raised in guilt. And no one here is a literary genuis and often our thoughts don't come out in text precisely as intended So, hang around BM1961
Road Captain
Joined: Aug 2008
Posts: 550
Likes: 8
From: Twin Cities,Mn.
Can't argue with what T150 says, but it was your dad's bike, so you're probably going to keep it, right? And just keep fixing whatever goes wrong. For more power, I'd go with an EV13 cam from Andrews, which is a great bagger cam for low end. Even the 88-91 cam had some pretty oddball EPA timing numbers, plus the EV13 is great at keeping oil temps down. If you don't get too throttle-happy, it won't decrease your gas mileage either.
An 81.6ci engine (which is the actual displacement of a stock Evo) is plenty big enough to haul an Electra Glide around as long as you ease the strain of breathing by a better cam, exhaust and air cleaner.
Your dad might have upgraded this, but check and see if you have the bad transmission pulley. '91 was the last year for it; you want to upgrade to the '92 and later. Make sure you upgrade to the torrington B-138 inner cam bearing instead of the OEM INA. Change your cylinder base gaskets to the silicon-coated metal type. I think Cometic makes the best gaskets.
An 81.6ci engine (which is the actual displacement of a stock Evo) is plenty big enough to haul an Electra Glide around as long as you ease the strain of breathing by a better cam, exhaust and air cleaner.
Your dad might have upgraded this, but check and see if you have the bad transmission pulley. '91 was the last year for it; you want to upgrade to the '92 and later. Make sure you upgrade to the torrington B-138 inner cam bearing instead of the OEM INA. Change your cylinder base gaskets to the silicon-coated metal type. I think Cometic makes the best gaskets.
Last edited by Brettfullthrottle; Mar 1, 2009 at 01:16 AM. Reason: missed a word
Cruiser
Joined: Nov 2007
Posts: 216
Likes: 2
The bad cam bearings started in late 92, early 93 time frame. I agree, 89 is a classic bike, minor changes like cams and exhaust are ok. I own 90 ultra, I think bikes from that era are the best.
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Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
The earlier Evo cases cannot be safely converted to give a larger bore, like 93 onwards can, or the twincams. I had my 1990 motor stroked with a JIMS crank, higher comp pistons, gas-flowed heads, cam, giving 89 inches. You'll need a larger carb, but with the same air filter cover, the bike will look stock, go much better.
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Road Warrior
Joined: Apr 2007
Posts: 1,354
Likes: 1
From: S.W. Florida
BM1961,
All the above replies make alot of sense from that standpoint. To answer your original question, Revolution Performance offers an 85" big bore kit that is totally bolt on and is compatible with stock HD components. I work part time for a Revolution dealer and run one myself at 10.5 to 1 compression with ported SE heads and some other goodies. We have also done several Twin Cam kits up to 98". The cylinders/pistons carry a lifetime warrany through Revolution and in our experience customer service has been top notch.
Considering the downtime, cost of re-powdercoating if needed, boring cylinders, purchasing a quality set of pistons, rings and so forth I considered this kit to be quite cost effective for my needs. You still would have your original cylinders, pistons and so forth to keep or sell to help offset the costs if you chose to do so.
Bigger is sometimes better and I'm looking at doing the 3.875 kit at 100" that would require case boring for next year. The extra cubic inches would maximize the cylinder head porting and the peformance of the cam I have installed.
Check out the website at www.revperf.com and call Andrew at 866-892-2109 with any questions. Then with the facts you can make an informed decision and go the way you wish.
All the above replies make alot of sense from that standpoint. To answer your original question, Revolution Performance offers an 85" big bore kit that is totally bolt on and is compatible with stock HD components. I work part time for a Revolution dealer and run one myself at 10.5 to 1 compression with ported SE heads and some other goodies. We have also done several Twin Cam kits up to 98". The cylinders/pistons carry a lifetime warrany through Revolution and in our experience customer service has been top notch.
Considering the downtime, cost of re-powdercoating if needed, boring cylinders, purchasing a quality set of pistons, rings and so forth I considered this kit to be quite cost effective for my needs. You still would have your original cylinders, pistons and so forth to keep or sell to help offset the costs if you chose to do so.
Bigger is sometimes better and I'm looking at doing the 3.875 kit at 100" that would require case boring for next year. The extra cubic inches would maximize the cylinder head porting and the peformance of the cam I have installed.
Check out the website at www.revperf.com and call Andrew at 866-892-2109 with any questions. Then with the facts you can make an informed decision and go the way you wish.
Thread Starter
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3rd Gear
Joined: Sep 2007
Posts: 7
Likes: 0
I appreciate all the answers and advice. Sounds like the best advice is to keep it stock and perform some minor tuning, possibly cam. Everything is original on the bike. I would like to clean up the engine when I have it downthough , like it used to be. All the black coating is completely gone from the block. I have thought about powdercoating the jugs if I pull them to replace the base gaskets, but is there another alternative. Thanks
