Dreaming of thr Big Bore

[miller7346]

For a couple of years now, I have been wanting to install the 904 big bore in my 2004 black bonnie. I'm sure some of you dream of that new hp and torgue also, esp. if you have the 790 engine. I'm wondering, if those who have had it done think its worth the $2,000 - $3,000-depending on how many exrtas you put had put on. Since I'm 66 yrs. old, I don't care about racing with a harley or whatever, but I would like to have a little more punch when I pass slow moving traffic and when I'm on the interstate going in to a 30 mph wind. I also debate if I should just sell my 2004- even though I have all the mods I just about can add- and only have 8600 miles on the bike- take the money and by a used thurderbird. I would like to know your opinion.
Ronnie

 

[CarlS]

I know of a few folks who have added the big bore kit. Two of them are racers and adept mechanics. From what I have read, the big bore kit definitely improves performance. Whether the improvement is worth the cost is a whole different story. I suggest that you consider getting a 900 cc engine from a salvage yard and installing that. I did this with Mae Lyne's bike. That would be considerably less expensive.

To sum up what I have read , the big bore kit will give you an increase in horsepower and torque. The Bonnie engines are strong and can handle the the kit. The downside is that you essentially have a race engine and it is more finicky than the stock engine. Of course the cost is a downside. At the end of the day, you still have a Bonneville which was not designed to be crotch rocket.

For me, I have adapted to my 790 and I do a lot of riding. I know its limitations and I choose to live with them because I enjoy the bike. In most situations, it will do anything I need it to do. If you like the cruiser style, IMHO you would be better off and money better spent with the T-Bird. If, like me, you are not a cruiser guy, you might look at the Tiger 1050 or an older Tiger 955. These are good bikes on the road with ample punch.

Just my $0.02.

 

[dazco]

If the bike is stock you may want to consider an alternative....air mods, pipes etc. I know you said you have mods but i'm not sure if you mean accessories or actual performance mods. If the former you might consider modding the airbox, free flow filter, less restrictive pipes, etc. Even irridium plugs made a sizable difference in response when i had my speedmaster. the Bonnie's airbox is different, but the same mods apply. I cut the bottom out which doubles the intake area. Put a uni filter in it, thunderbike pipes, irridiums, nology coils, and jetted it accordingly. I got a pretty healthy power gain from that. I'd bet about as much as the BB will net you. The coils i'm not sure about, but they may have helped the freeway speed roll-ons.

Of course you could always get a thunderbird 1700 with short tors. One thing about power most people don't realize, or at least it doesn't seem like they do from the things they say, is that having a ton of power is a lot more enjoyable even when you don't ride fast. It's just a whole different feel when the huge power is there even when you aren't using it. Riding is so much more fun for me when i have the kind of power that doesn't leave me wanting more even tho i'm riding sedately. Many people question my desire for big power saying things like "yuou can't possibly use it all" or "you can kill yourself with a lot less power". They just don't get it.

anyways, good luck. And tho it may be the last thing you'd want to do, consider the Tbird. It's literally the most incredible handling bike you'll ever ride short of a sport bike. Several bonnie owners and even a thruxton owner have said they bougth a Tbird and think it handles better. Whether or not thats true, it gives insight into just how easy this thing handles. And with the 1700 you will be way past the point of wanting more power ! Amazing bike. Oops...sorry, i can't stop raving about it even after 2 years ! But thats one possible solution for ya.

 

[miller7346]

Thanks Carl and Dazco. Both of you made great points. I have done several perf. mods (as Carl has suggested in the past): no snorkle or AI; Uni filter with bell mouth polaris; recently decided to keep the air box even though I bought the do-it-yourself kit from bellacorse; have epco commando pipes; and had her dynoed and tuned 2 wks ago in Pensacola. I'll be in a "mull" state for a while, and will probably make a knee jerk decision in the near future about the Bird or big bore. Am leaning toward keeping the bonnie- just can't beat that classic look.
Ronnie

 

[CarlS]

I agree; you cannot beat that classic look. Let me know what you decide.

 

[DaveM]

I was also thinking of the big bore for my Speedmaster at one time but the cost could not justify it for me. So I went for the mods that Dazco suggested and now I am very happy with what I have

 

[dazco]

I feel the Tbird is a very classic looking bike. Not in a standard way, but it looks like a huge twin that could have been made in the 70's and was customized. I saw bikes back then that were customized in a way that reminds me of what i own now. But i know what you mean. The bonnie is a totally classic and un-customized look. If thats your cup of tea then thats what you must stick with. I gotta tell you tho....i have never ridden anything like the 1700 Bird. It's truly an incredible machine, but you may (may, tho probably not) have to ride one for a bit till you're used to it enough to fully "get it". Once you do i believe almost anyone would feel the same as me. I even think Carl would get over his distaste for the cruiser ergos. There have been a lot of converts from bonnies and it's variants and rockets. One guy bought a bird, thought maybe he should have got a R3 for the extra power, so he sold it and got a R3. A few months later he sold the R3 and bought another Tbird ! Give the 1700 a demo at least just so you can be sure you aren't missing something amazing. If i knew youd feel like me i'd demand you demo one !

 

[miller7346]

Dale,
I do plan to do a demo ride in the future before I make a final decision. And I do like the way the bird looks, although I woul want to make several accessory mods. Thanks agiain for your advice.
Ronnie

 

[CarlS]

Ronnie, keep us posted on what you decide. I suggest that you talk with the Triumph shop in P-cola about the big bore kit. Those guys are pretty knowledgeable.