Bonneville America Forums Forums Technical Forums Performance Mods Big Bore- Is it really worth it??

Well I talked to several shops in the area and the consenses is it is not worth it just to go to 904cc. I am starting to agree with this. If they would come out with at least a 1000cc kit it would probalby do better. I am still contemplating this purchase myself. I do agree the freak is a good mod. It just seems that the big bore kit is so much for such a little gain.

What do you think? espically if you have this.

Joker-

Power - Some aspire for all they can get. Some are happy with what they have. I've never been embarrassed for lack of speed. I've never been left in the dust for lack of power. J-Lo the Speedmaster has never been called a dog. The cost of the Big-Bore feels a whole lot better in my back pocket.

From all I see around the gain is minimal for the price. But I bought one anyway and will install it myself and let you know. They were on sale for $400. and I like to tinker. The Speedmaster or Ba with minor mods is far from a dog and really doesn't need it. But for the moment this is my passion, my hobby, my therapy. One thing I will say I would have never done it without cams and I am working on that as well.

i'ma lso interested what the power gain really is. was thinkin about it in a year or 2. if it was like 20 hp and around the same in tourque it would be worth it.

Frank

I got the big bore kit from BelaCorse when he had them on the cheap ($350 I believe, now they're over $500 again). I figured I would do it someday anyway so I bought it on sale. I will be tossing it in next month sometime, stop in and give a hand if you want to.
I'll post dyno results later in the spring and compare them to my current setup. I got about 65 last time, hoping for close to 80 with the BB.

The only time I saw dyno results with BB was on a Bonnie. Now this was the Bonnieville Performance bike that had all kinds of goodies on it that included (I believe CR carbs). Just after I ran my near 69HP he ran a low 75. I may stand correct but the limiter maxes at 7K which could have influence the results. I also think his pipes may have restricted him too. My thoughts have changed about trying it since I am going to do a little cam work as well. Within 2 months I should have some results and would hope to see 80+HP.

Jango

One of the Bonneville guys (the guy who's bike Wiseco developed on)...posted his numbers...61 to 66bhp and
52 to 62ft.lb same setup only diff was the Wiseco kit.

http://speedthrills.us/Dyno/Bubstockdata.jpg
http://speedthrills.us/Dyno/BigBoredata.jpg

If you really think about it...if you spent $399 for the kit and $160 for sleeving (which is I think what Wiseco charges)...you aren't talking much more if anything over a set of pipes (assuming you do the work yourself)

P.S. After adding the Mikuni Flat Slides he went to 71 bhp...

http://speedthrills.us/Dyno/BBoreBCarbsdata.jpg

Hey Jango I feel the same and am about to go the whole route with south bay;s parts. Cams, pistons, head work, new manifolds etc. It's an addiction I guess. I have the Rocket III and am working on some exhaust and the Power Commander and remapping that to get up to 160+ HP. I'm really thinking hard on the turbo kit for that but thats just getting insane!! I just the other day sent my 95 FLH out for some experimental modifcations to the fuel injection module and installed a set of 2 into 1 Thunderheaders. I've already got that puppy up to 90 HP and you haven't lived until you have ridden a full dressed harley that will yank the front end up a foot in the air in 1st, 2nd and 3rd gear!! It's sick!!! It's an addiction and it just started in the last year or so. A mid life crisis I guess... I'm gonna have the R3 and the BA dynoed before all the engine work and will post the results so others will know if it's worth the money. It's all in what you like. If you want 10 HP and money is no object then it's worth it. I'm not wealthy by any means but I no longer have a house payment so I now have some money to play with. The hell with saving it!! I'm gonna do all the BA cams installs and the jugs etc but the Rocket I'm having done because I know zilch about fuel injection.
Rebos

Hey Rebos! Just curious. What about thar green "avatar" (I had never heard that word before). You no longer have the red BA?

Rebos, 90HP awesome, that thing must fly. Sounds like you caught the same bug I did lol. Keep us all posted on your projects. Are you going for the 900 or 1000cc kit and are you to do anything to the carbs on the BA. I am in research mode for carburation and for now staying with the stock setup. I will play with jets and maybe look into the TBS needles.
I was half tempted to go for a R3 this year but the more I ride the more I like my SM. Many in here feel the same way I'm sure. Another bike would be fun but I am not parting with my baby and can't afford both. So I pampering her instead. Looking into doing some custom paint as well.

A lot depends on your situation. If you have done everything else you can to get more power, and the fool down the way with the turbocharged bummer can still keep up, then it's worth it.

If simply gaining more horsepower were the goal, we all made a poor investment buying our 790cc parallel twin. Good gravy, all one would've had to do is, for about the same price, buy a Speed Triple. That would've accomplish 128bhp being stock as a rock.

Nevertheless, I may at some point install a big bore kit. Especially when I start adding up the miles and I'd want to replace my piston rings anyway. I would, however, opt for that kit that comes with a "Nickelsil" coating (which is offered as a complete bolt-on kit at http://www.danddcycles.com/ ).

-BT

So why "Nickelsil"...what is the benefit if any over cast liners?

Many are comparing 2 different dyno machines on this thread. The Eddy and the DynoJet, they both interpret HP differently with the Eddy claiming to be a more "true" HP rating, Eddy computed HP much less than DynoJet. The BB Kit with carbs is easily over 80hp on the DynoJet machine. Personally, I'm close to 70hp with limiter raised to 8100k and the CR carbs. The carbs yielded 8% more HP (from 64.7)

I too looked at both kits, the Nicasil liners are what is presently in our motors, that is one reason you can probably get 100k miles on the motor itself. However, cast liners have been used for the decades, nothing wrong with them. Bigger point is heat displacement between the Nicasil liners and the cast liners. The motor is setup to operate at a certain temp. optimally, therefore Nicasil would be my choice since cast will displace heat quicker than retaining the heat like the Nicasil liners do. Is it worth it, sure if you want over 80hp and better low-end torque.

I am sorta color blind.... yes it;s still red.. I thought it was red. oh well as far as the big bore kit,South Bay moto claims 95 HP with their pistons, cams. carbs etc. I will soon find out. I need a good winter project and am in the process of tearing my engine apart to give it a try. I'll post the results in a month or so.
Ron

rebos -

i've neen spending time at triumphrat.net lately - hadn't been there for ages.

nice info on R3's !

where are you with pipes on that? i liked the look & dyno results with the Maddog pipes.

i recall you posting you'd done some mods with your airbox. what have you done with pipes/catylitic converter?

I have Mukunis and Big bore kit. Don't know what the dyno says but I do know that my trump will run away from my stage 1 Dyna with a TC88 and 69 RWHP. The Harley will still out do her on the top end due to the gearing but from about 3500 RPM to redline hold on. This is enough in a 1/4 mile. Ride safe.
Signed: Just another oldtimer

"Nicasil coating on cylinders" I am a bit lost after the conversation I just had with the people doing my cylinder work. "why bother with the liner if you can recoat with nicasil after rebore to correct piston size?" If this can be done what do we need a liner for in the kit? Or am I missing something? I guess a call to Wiseco is in order.
Jango

I got the 904 big bore, while we had it down, ported, polished, & shaved a bit off the head. Worth it ??, heck yea, it's like a different bike. I run the 18 tooth front sprocket, & now on the low end it pulls hard. It's still not a sport bike, or R-3, but it's alot faster than it was.

Hey Randy, who did your machining? Was it hard to find someone? So far I can not find anyone with a machine that will work on these jugs? I guess my only option now is to contact wiseco. Even my Triumph dealer counld not turn me on to someone who could do it.

Jeff, I haven't been to RAT.Net in a while myself. Still haven't. I kind of gave up on the R3 pipe mods after taking out the 1 set of baffles. I had visions and bad memories of doing all that work with the BA only to have it sound like a giant "fart machine" as some one put it. They came off that night when that comment was made. I hated the sound and those went to the landfill and I put on the Sceptres which I wouldn't give up for a $1000!!! With the R3 I have a great plan going. I'm buying the 3 into 2 exhaust from Thunderbike Powersports in N.Z. and was informed by email yestrday they have been shipped and on their way. The guy who does the dyno work and any kind of work on any bike is going to dyno it before installing the pipes then after. THEN. Him being an authorized Dyno Jet dealer is going to install the new Power Commander module and oxygen sensor bypass and download and try out some of the Power Commander maps until he gets the best peroformance out of the bike. He's cutting me a break on the cost because this is going to make him money in the long run. His dyno machine is in a trailer that he takes to Daytona, Sturgis, Laconia etc. and now he'll be able to do some Rocket work. His business is American Cycle performance and if you ever see his trailer set up and you want you bike dyno tuned, he's good!! We'll see how it goes. I'm excited about the whole thing!! Like this bike really needs to go any faster and If I ever come up against another R3 it'll be nice knowing I can whup him.. unless he;s got that turbo kit for it that boosts the HP and torque to around 200.

how did you manage to up your RPM limit

I feel the same about my Bonneville America. I still consider that my baby, I did enough work and chroming to it to have bought a harley, but then, it would be just another harley. Nothing special about them anymore. Not to me anyway. I saw the BA at a bike show and fell in love with it instantly. I have a Rocket and it's got power you just can't imagine in a bike. I don't know how I got bit by this power thing. I started buying harleys years ago because they aren't fast and figured I was getting a little older and needed to slow down. I have 4 Triumphs and 2 Harleys and if I had to get rid of all but one, I'd keep the America. My 72' Tiger would be a tough one to part with. The Harleys I inherited and have been trying to sell and can't get the money out of them that my father put into them so I guess I'm keeping them. There's a lot of nice bikes out there but I like the Americas and Speedmasters the best out of anything being built these days. As far as the carbs. I think I'm going to go with the bigger kehins. Everything I've read about the Mikuni's isn't good. Sounds like they are too hard to set up or are just too much carb for an 800cc bike. I just dumped the Mikunis I had on my 73' bonny chopper and went back to Amals.
I'm not a Mikuni fan but a lot of people swear by them. I think I'm just going to go with the 900 or 920 or 904.. upgrade. I have a 2300cc bike if I really want to go fast. I just want to be able to smoke some of the built up TC88 harleys.... with the America.
Ron

Here's a literbike big bore kit for ya, and don't they look snazzy :-)

http://www.southbaytriumph.com/america-performance2.html

go down to the british custom set. 998 cc and up

rebos -

you're a man after my own heart !!! i love your attitude !

"smoke a few built up TC88's with my America... " great stuff.

i'd done it in the past so decided to double check. when i figure all i'd want to do (certainly not necessary - but tools that lead to ego stability are always worth consideration) with a speedmaster regards performance upgrades i'd easily have dropped 6k. when i added MY customization ideas i had spent another 5k on paper.

it was about at that point that the R3 started looking even better to me . truth is that i'd really like to own the R3 and both a Speedmaster & America !!

not being rich & remaining HAVING to own other toys besides bikes i find myself forced to do what a 54 year old man shouldn't have to do ..... think PRACTICALLY !!

i refuse to give up my 71 which is now destined to become an expensive Rat so it's likely i'll end up going with the R3 (rumours state 06 will have blacked out engine option) which i can get what i want done for about 4k total.

for your sake i hope southbay is accurate regards claims of 95HP. that would be unreal for an America & more fun then imaginable blowin off the RUBS ridin Milwaukee Iron.

lookin forward to your coming reports.

If you run into ping with your new higher compression ratio, Dinqua, might you install a water injection unit? (Of course, you'd need to mix the water 50/50 with alcohol, so it doesn't freeze up there in the far north!)