904 v. 944 v 988 kits

[neuroboy]

I know the Bonneville pretty well, but I'm a totally amateur when it comes to these performance kits. Can someone give me a primer as to what's involved with upgrading to the 904cc vs. the 944cc vs. the 988cc kits? Keep in mind that I have no garage so this is all going to be handed to a shop to do.

 

[mondrian5]

Hi Neuroboy,
Sorry to hear about your St3. I hope it's recovered. Glad to find you back here though.
Have you checked out http://www.bonnevilleperformance.com/engine_kits.htm
I was once thinking about trying to make my Thruxton a higher performing bike and was looking at these. I met these guys in NYC at a Moto show. They definitely know their stuff.

 

[sweatmachine]

I know the Bonneville pretty well, but I'm a totally amateur when it comes to these performance kits. Can someone give me a primer as to what's involved with upgrading to the 904cc vs. the 944cc vs. the 988cc kits? Keep in mind that I have no garage so this is all going to be handed to a shop to do.

You mean 994cc, not 944cc.

Both the 904cc and the 994cc kits are just big bore kits. The 904cc kit is just a bored out stock cylinder and the 994cc kit is a completely new billet cylinder. The stock cylinder can't be bored out to 994cc because it isn't thick enough. The 994cc also requires splitting the cases and boring them out.

The 989cc stroker motors are bored out to 904cc then stroked (I believe 4 or 6mm) to attain the 989cc displacement. The 1087cc motors are bored out to 994cc then stroked to achieve the 1087cc. These are the biggest, baddest, and most expensive mofos.

The easiest and cheapest to do is the 904cc, obviously.

If you really feel like making a strong Bonnie, I think the way to do it is to build it to 994cc and do the cams/carbs/headwork/etc. I would like to do that one day, when funds allow. A healthy 994cc engine with cams/carbs/headwork engine will set you back about the price of a nice used Bonnie, so for the price of 2 used Bonnies you can have a faster used Bonnie. Not practical, but fun.

 

[mikenva]

A 994 with all the right cams ,head work machine work done right will cost pretty close to a brand new bonnie.With the 994/1087 bores you need a pro stock head and shim under bucket cams.You should allso have the crank strighten balanced and harden.You will need good after market rods.You will need fcr carbs some high flowing pipes.I built my 1087 and i think parts ,head work and machine work was real close to $10,000.
TPUSA is who you want to talk to with any motor you want to build .They have way better stuff then the other guys.
It all depends on how much power you want done right a 904 will make around 85 hp and 65 torque a 988 will make around 90hp and 70 ft/lbs a 994 will make 95 to 100 hp.A 1087 makes 100 to 115 hp and 75 to 80 ft/lbs.
I have had a 904 a 988 and now have the 1087.the 904 and the 1087 where tpusa kits and had 0 troubles with them .The 988 was the other guys in the post above and was a pos oil leaking oil blowing pos.

 

[BlueJ]

...The 988 was the other guys in the post above and was a pos oil leaking oil blowing pos.

But Mike, tell us how you *really* feel about it????

 

[strokerlmt]

A 994 with all the right cams ,head work machine work done right will cost pretty close to a brand new bonnie.With the 994/1087 bores you need a pro stock head and shim under bucket cams.You should allso have the crank strighten balanced and harden.You will need good after market rods.You will need fcr carbs some high flowing pipes.I built my 1087 and i think parts ,head work and machine work was real close to $10,000.
TPUSA is who you want to talk to with any motor you want to build .They have way better stuff then the other guys.
It all depends on how much power you want done right a 904 will make around 85 hp and 65 torque a 988 will make around 90hp and 70 ft/lbs a 994 will make 95 to 100 hp.A 1087 makes 100 to 115 hp and 75 to 80 ft/lbs.
I have had a 904 a 988 and now have the 1087.the 904 and the 1087 where tpusa kits and had 0 troubles with them .The 988 was the other guys in the post above and was a pos oil leaking oil blowing pos.

My 988 813 stroker engine is one of Matt Capri's early works. I would have to look up the receipt but I believe Matt did the engine in 05. Other than having to weld the primary gear to the crank I have had zero problems and the engine is a wild cat waiting to be released every time I turn the key.
LMT

PS I believe they weld the P gear as norm now. Stock is a press fitting and the beast in the engine eventually spins that gear free of the crank grrrrrrrr

 

[henrys]

Damn thats a lot of $ for 115hp. She's gotta fly though.

 

[mikenva]

Damn thats a lot of $ for 115hp. She's gotta fly though.

Its more fun to ride then anything I have been on.think of this it makes as much toruge at 3000 rpms as stock bike does at max torgue.
and hits you in the ass from there to 9000 rpms.In that way its more dangerous then most sport bikes that make the same or more hp because they dont have the low end torque.staying on the seat is a job sometimes it feels like it will tear your arms off.
On damp roads better be easy leaveing a stop twist the gas alittle at 25mph and it lights the rear tire up.I have seen the front wheel off the ground at 80 mph on a 2to3 shift and thats with a 19tooth sprocket up front.
Is it worth the money Is to me .that hp is rear wheel hp that more then a 675 on the rear wheel allthough its heavy but the torque takes care of that alot.

 

[sweatmachine]

For some cost perspective, I bought a cherry used FZ1 that makes 140hp for about $4k. It also has better suspension and insanely good brakes.

I'd love a 1087cc Bonnie but I just can't justify the cost.

 

[B06Tang]

What are the indirect costs when doing any of these kits? With that I mean what other things would have to be changed:

1. Carbs
2. Camshafts
3. Clutch
4. Headwork
5. Pistons
6. Rings

Anything else? Are these items included in the kit or are they additional items that have to be worked on top of what you have to do with the kit?

 

[Mark]

For some cost perspective, I bought a cherry used FZ1 that makes 140hp for about $4k. It also has better suspension and insanely good brakes.

I'd love a 1087cc Bonnie but I just can't justify the cost.

my thoughts exactly but if you want to build a hot rod go for it that's cool I'm not that guy. Wonder if heat becomes an issue with big motor?

 

[strokerlmt]

My thoughts......I have had 4 bikes in the garage at one time. I never rode each bike enough to justify having them. Plus the insurance for each bike and depreciation did not make sense.

Not recommending......just for me......I would rather put 5 k into the bonne I have than purchase another bike. I like having a unique ride.

just my thoughts.......

LMT

 

[Mark]

as they say..different strokes..no pun intended

 

[mikenva]

nope the 994 and 1087 have more metal around the bores then stock they dont run hot.As far as that goes even the bored out stock 904 and 988 dont run hot ether.

 

[strokerlmt]

My 988 has never run hot. Usually normal or slightly lower probably coast climate.
LMT

 

[rodhotter]

those kits look great but get $$$$$ quickly especially when the machine work comes in, if you got $$$$ and want the HP i say ENJOY! its nice to have a bike much faster than people expect a SLEEPER!!