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 Post subject: Big bore kit and mods.
PostPosted: Mon Feb 14, 2011 11:32 pm 
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Joined: Feb 10, 2011
Motorcycle: Honda 250 Rebel
Rebel: 250
Country: Canada
State/Province: BC
City: Vernon
Lilgrebel
I learned to ride on my 2005 Honda 250 Rebel and although fellow riders stated over and over “you will want a bigger bike after you ride for a year” it was not the case. I love this bike! It fits me perfectly. All I wanted was a little more power and a bit more “cool” factor. After searching the internet we came to a few conclusions in the aftermarket. You could go the bobber route or the full dress touring style however nothing in between. Also after looking virtually everywhere in the world we could not find a big bore kit to fit the bike. We decided to do some customization on our own and to build a big bore kit from scratch. Here is the list of what modifications have been made:
- We had pistons custom made to 250mm overbore and with compression of 10:1 vs stock of 9.2:1. (Note we had to have multiple sets made up for this and will probably sell our extras on ebay as Lilgrebel big bore kits.)
- Main jet to 112 from 108
- Drilled holes in air box.
- Installed shorty mufflers from Blue Collar Bobber. Nice units, good value and good service from Blue Collar Bobber.
- Powder coated the Blue Collar Bobber mufflers black.
- Chopped and customized the rear fender, tail light and turn signals.
- CRG bar end mirrors.
- Painted rims black
- Removed all decals and repainted bike black.
- Black bars, lower with less pull back. Almost a drag style bar.
- Seat upholstered with side to side stitching to give it a bit of an old school look.
- Smaller front sprocket. (Bike was now strong enough to pull it)
What I ended up with was a pretty cool Rebel that is as close to a “one of a kind” as can be imagined. Displacement was increased approximately 10% and compression about 9%. Our rear wheel dyno tested performance gains showed horsepower went from 15.9 to 16.67 and torque from 11.7 to 13.79. 5% gain in hp and 17.9% gain in torque. The big story however was in what happened to the power in the lower rpm range. At 5500 rpm where most people would be riding the hp went from 12 to 14.5 and torque from 11.25 to 13.5. That is a 20.8% increase in hp and 20% in torque at 5500 rpm. It made the bike much more fun to ride and allowed us to gear the bike up by downsizing the front sprocket. My little Rebel will cruise all day at 60 mph and although I have not run a top speed test expect that it should be able to top out at close to 80 mph.


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 Post subject: Re: Big bore kit and mods.
PostPosted: Tue Feb 15, 2011 7:23 am 
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Joined: May 6, 2004
Motorcycle: 2005 Yamaha Vstar 650
Rebel: None
Country: USA
State/Province: TX
City: Fort Worth
So how much for the over bore and custom pistons?

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 Post subject: Re: Big bore kit and mods.
PostPosted: Tue Feb 15, 2011 9:30 am 
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Joined: Feb 10, 2011
Motorcycle: Honda 250 Rebel
Rebel: 250
Country: Canada
State/Province: BC
City: Vernon
First off sorry but there is a couple mistakes in my posting. The over bore is 2.50 mm not 250 and we went one tooth bigger on the front sprocket not smaller. You bore out your cylinder liners for the mod so the kit includes pistons, rings, gaskets etc and will run about $600.00 Canadian.


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 Post subject: Re: Big bore kit and mods.
PostPosted: Tue Feb 15, 2011 5:09 pm 
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Joined: Sep 17, 2003
Motorcycle: 5 Shadows, 3 Rebels
Rebel: 250
Country: U.S.A.
State/Province: NV
City: Las VLX-as
Out of curiousity, did you dyno the bike with the stock sprockets? Taller ratios can sap any motor. Just sayin'...since intake and exhaust mods can add 5-15% to any motor sans internal work.

I'm not sandbagging this in any way, mind you...but I can see where this would pop up when others might read the 5% gain in HP. Dyno figures on stock gears would be a more accurate "advertisement" of what this kit can do.

_________________
"Ride Safe, Chop Safer"
Dismantling, sawzalling, and rattle canning does not make a bobber. That's called an "ANCHOR".
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 Post subject: Re: Big bore kit and mods.
PostPosted: Tue Feb 15, 2011 9:49 pm 
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Joined: Feb 10, 2011
Motorcycle: Honda 250 Rebel
Rebel: 250
Country: Canada
State/Province: BC
City: Vernon
The original dyno numbers are taken off the internet for a stock Rebel 250. We actually punched out the original exhaust and had the intake modified before the engine work was done and this did not give it any extra power. It just made it sound louder. So, the dyno test that we had done was with the larger sprocket, the overbore and the new pistons. I couldn't believe the extra power it gave me in the lower gears. It was quite noticeable, with or without the dyno test and now I can actually get in the passing lane!!


250 Rebel


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 Post subject: Re: Big bore kit and mods.
PostPosted: Mon Mar 12, 2018 4:30 pm 
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Joined: Mar 8, 2018
Motorcycle: Honda
Rebel: 250
Country: United States
State/Province: NC
City: Kernersville
Hi there Rebel fans. I am new here. I recently joined this site. I bought a Rebel 250 for my girlfriend and i also want to give it a little more power. Does anyone know what happened to Lilgrebel or possibly know how to contact them? I am interested in the extra pistons that they had made.


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 Post subject: Re: Big bore kit and mods.
PostPosted: Mon Mar 12, 2018 6:17 pm 
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Joined: Feb 23, 2009
Motorcycle: Rebel 250 plus a few others
Rebel: 250
Country: Canada
State/Province: NB
City: Fredericton
The OP did not hang around long, This thread was pretty much all we ever heard from him.
This subject comes up often however, and the consensus is that there is no practical way to get significantly more power out of a Rebel in any kind of an economic way.
Moreover, IMO Honda designed the Rebel to have a low horsepower, mild mannered engine, and everything else about the bike is designed that way. The frame, suspension and tires are well up to the stresses they were designed for, but the bike would become much less safe if it had , say 30 HP instead of less than half that. That much power would push the Rebel to a top speed in the high 90's where it would be way over its head in the handling department. The frame and forks are just too flexy to take the potential stresses at those speeds
If it was me, I'd take the $600 you were going to spend on the big bore kit and trade the Rebel for something that will give you the performance you want in a factory engineered package that will have the engine as well as the rest of the package.

_________________
2004 Honda Rebel 250
2003 BMW K1200GT
2004 BMW R1200GS
1996 Ducati 900SS
1973 Norton 850 Interstate
1968 Triumph Bonneville


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 Post subject: Re: Big bore kit and mods.
PostPosted: Tue Mar 13, 2018 8:23 pm 
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Joined: Mar 8, 2018
Motorcycle: Honda
Rebel: 250
Country: United States
State/Province: NC
City: Kernersville
Thanks for the info Duckster. I wasn't really looking for top end speed. Just a little more power in order to up a tooth on the front sprocket so the bike isn't screaming at 65mph even though I know the engine is tough enough to take it. I am a gearhead by nature and enjoy the challenge of getting a little more power out of things. I'm not sure how long my girlfriend will be content with this bike. I'm guessing atleast a year or so. Even if she gets another bike I would love to keep the Rebel. I ride a Roadglide ultra and the little rebel is so much fun to ride for me. Thanks again for your valued opinion. And thanks for sharing the cornering video you posted. Very cool and informational.


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 Post subject: Re: Big bore kit and mods.
PostPosted: Tue Mar 13, 2018 8:56 pm 
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Joined: Feb 23, 2009
Motorcycle: Rebel 250 plus a few others
Rebel: 250
Country: Canada
State/Province: NB
City: Fredericton
Your welcome.. Happy to help.
Some people do fit a 15 tooth countershaft sprocket on the Rebel just to drop cruising RPM a little, but you do lose some rear wheel torque that makes hills and headwinds more of a bother than they already are. If you don't mind that, it might be worth the tradeoff, though most that have tried it go back to stock and learn to love the howl of the Rebel at full song when it can reach maximum speed.

_________________
2004 Honda Rebel 250
2003 BMW K1200GT
2004 BMW R1200GS
1996 Ducati 900SS
1973 Norton 850 Interstate
1968 Triumph Bonneville


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 Post subject: Re: Big bore kit and mods.
PostPosted: Wed Mar 14, 2018 10:05 am 
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Joined: Sep 17, 2003
Motorcycle: 5 Shadows, 3 Rebels
Rebel: 250
Country: U.S.A.
State/Province: NV
City: Las VLX-as
KennyD wrote:
I ride a Roadglide ultra and the little rebel is so much fun to ride for me.


A lot of people come to that realization. My progression has been starting with a 600 Shadow (still have it), a 1500 Vulcan, and a 250 Rebel. I've come to the realization that people who don't like 250cc street bikes have never ridden 250cc street bikes.

_________________
"Ride Safe, Chop Safer"
Dismantling, sawzalling, and rattle canning does not make a bobber. That's called an "ANCHOR".
Image
http://shadow-shack.20m.com


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 Post subject: Re: Big bore kit and mods.
PostPosted: Wed Mar 14, 2018 11:47 am 
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Forum Moderator

Joined: Feb 23, 2009
Motorcycle: Rebel 250 plus a few others
Rebel: 250
Country: Canada
State/Province: NB
City: Fredericton
I'm looking forward on getting out on my new to me '68 Bonneville.. a 650 that weighs 360 odd pounds dry. So different from the bloated behemoths that carry that name today.

_________________
2004 Honda Rebel 250
2003 BMW K1200GT
2004 BMW R1200GS
1996 Ducati 900SS
1973 Norton 850 Interstate
1968 Triumph Bonneville


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