Bonneville America Forums Forums Technical Forums Performance Mods Who's done the Big Bore? Thoughts, etc.

I was ready to ask the above question, then read the Big Bore w/Mikuni thread. So now I really want to know all about the Bore.
Who has it? What do you think?
Wants it?
Has it and wished they didn't?
Cost and time involved?
Etc.

Thanks,
mert(shari)

Big Bore Thread and links
Says it all. In my case at least.

thanks pat.
too bad i won't be able to see you and benny eat each other's dust.

mert

I'll be doing the majority of the eating. Have to wait for spring to force feed anyone

Right now it's on the list but not a priority for me. Way too many other things I want to do with the bike before I get to that. I'm still not convinced I really need it either, but then again I haven't needed any of the other things I've done on the bike.

mert,
I basically asked the same questions several weeks ago. Seems only a few have actually done this mod and have any advice to offer. I thought I would have got more response. The reason for my inquiry was because I have seen some negative reveiws about the Big Bore Kit on other web sites. Once again, I'm a little frustrated that only a few want to talk about their experience.
Regards,
Stan

Can you provide links to the negative information?

Since I put the BB in I just haven't had as much time for the forum. The bike with BB is hard to get off. Sorry Indianstan but when the weather turns to crap I'll give a little more. My opinion, I'd do it again. It really is like day and night and wakes up the bike. I am a bit of a speed / performance freak. If you aren't don't do it. Cost can be up there when you have it done. I did mine with a few other mods but you can expect to spend min about $600. when on sale up to(I'm guessing)$1,500. or so if you had a dealer do it. As far as time, if you are prepared and doing it yourself figure a couple weeks. Dealer? depends on your dealer, but I would guess 2 to 4 weeks.

Phil,
I wish I had earmarked the sites I visited, but didn't. How I found them was through a web search where I typed in the words "Triumph Big Bore Kit" and hit search. You may have to sift through a lot of different sites as I did to find the forums. Seems I may have added the word "reviews" to the search. The usual surfing stuff you do when looking for some specific info. What I found was sort of a mixed bag of opinions. One I remember said not to waste your time or your money. Others say it was only a slight improvement, better than stock, but not what they expected for the money. Some say it was the greatest thing they could have done to their new Triumph. These discrepencies is what motivated me to asked our members opinions.
Regards,
Stan

Stan,
I guess since the mod and the bikes themselves are still retively new there aren't a lot of them out there yet. As far as a review, I love mine and would do it again in a heartbeat. I think it made a big difference. I haven't dyno'd it since, maybe I should get one done soon before the white rain falls.
I have spoken with about 5 people that have done them and they all had positive remarks. And, if you do it yourself, it's not a bad investment or big cash outlay. A little more than my pipes cost actually.

Hi Stan,

Well, I for one can attest to it being a big improvement.

I've done everything short of the BB and Pat (Dinqua) and I ran hard down some of the GA roads. He flat pulled away from me every time. Not like I was standing still but definitely disappearing quickly. No way I could keep up...

thanks for the feedback, guys. Trying to decide if I want to line up winter projects.

Do I want more power?
Other ways to get it? Etc. Por ejemplo: My air box and snorks are still in, I run a stock front sprocket(not certain I want to make that change)
Any other thoughts appreciated.

Happy Be-lated, Dinqua.
mert(shari)

honestly it is surprising how much of a difference good pipes, no snorkles and some jetting do. try that stuff out first then if you need more maybe freak and/or big bore. it was like night and day going form stock pipes to tbike pipes. like a whole new bike

Frank

If you're thinking about it I would look on Bellacorse. They've got it as an end of summer special for $400 right now. I picked one up to save for a rainy day.

Shari, with your pipes, doing the snorkles and re-jetting will make a noticable difference!! Also, unless you do a lot of highway, from my experience riding with you I doubt you would get much out of a sprocket change, BUT! Ya never know Changing to an 18 made me ride differently and is more fun to me. Plus you don't ride 2-up... So you won't miss the 1st gear grunt at all. But it sounds to me like the BB is a grin-maker!! It's on my wish list for sure.

I echo mert's thanks to all who share their experience and opinions on the BB mod. Personally, I'm looking to gain torque, and not at the expense of reliability. Going faster would be nice, but it is that good old fashion low end power that I would like to get more of out of this thing. In my opinion, Triumph failed us all in that regard, because these bikes were initially aimed at the American market, and most of us American riders are use to more usable low end power. I would just about go as far to say that had Triumph not short changed us in usable torque, this would be about as close to the perfect motorcycle as you could get, at least to me. Can any of you guys with the BB experience describe the difference in your low end pulling power over the stock powerplant? In other words, can you go up a hill now without lugging engine clatter and without having to call on on a lower gear to get you over the top? Thanks guys for any new imput on this.
Later,
Stan

I don't think Triumph has shortchanged us at all. For the retro design of the engine, the size of the motor, and the weight of the bike, I think it's performance is as good as could be expected. The torque curve is relatively flat from 2,000 rpm to redline. Yes, I have to downshift at times when going uphill, but just how hard is it to downshift? If you're waiting until it's lugging to downshift, you're waiting too long. If you want gobs of torque, buy a Rocket III.

I know you probably meant no offense by your post, but it's borderline bashing on our bikes, and I won't let that slide.

You probably bought a Triumph to be different. Then be different and do not try to drive it like V-twin. No offence intended, it was a v-twin guy many years ago that set me straight.

I meant no offense at all SalMaglie, but obviously you do. First off, I have not been without a motorcycle since 1973, so I don't appreciate your insinuation I don't know how to properly ride a motorcycle. If you can't relate to what I'm talking about, then those of us who do would appreciate you keeping your snippy remarks to yourself.
Regards,
Stan

stan,
yes, the biggest most saught after improvement is the torque. I live in very hilly/twisty country and the difference is what makes it all worth it. I can climb hills without downshifting and when I open the throttle the power just rolls on, no delays.

Benny,
I might start with the snorks and another re-jet. It's running fine. Yet sometimes it feels like something is missing. The almighty 6th gear or some more low end power like Stan was referring to.

Certainly not looking for another BA.com he said/she said argument to get boiling. Relax all. Go grab some Jaffa cakes, a beer, a cup of coffee, what ever makes you happy. Leave the mud slinging to the politicians.

mert(shari)

Indianstan,
I got lucky with performance prior to BB install. Yup I put all the gadjets like everyone else does. On best of 3 pulls on a dyno had me at 66 HP. I beleive that is about as good as it gets. Torque was there about 50ft lbs. I did my share of shifting with that configuration when playing with some of the V twins(no hills in Florida). Not so much anymore. I gained a fair amount of torque but I have to also admit I put cams in it. Once Dinqua and I get on a dyno we'll let everyone know what BB accomplished. I am still futzin with jets for that perfect set up. For me there was a noticible difference even with the 18 tooth sprocket. I find I shift far less than I used to. On rides with many if I'm in 5th at 40 I need not shift when speeds increase. My buddy trys with his 1638cc Indian and stands little chance to get ahead of this 904. Eventually he might, if he catches me, but by then we are then talking jail time speeds.

Dinqua,
Thanks for you responsible reply. This is what I'm wanting to hear from you guys that have done the mod, and I'm sure mert is also intested in hearing this. I too live in a hilly area, so you know where I'm coming from. Any of you other guys with the BB mod see this kind of difference. Thanks again Dinqua, and ride safe.
Regards,
Stan

Mert - I put TBS needles with 2 shims in my carbs based upon some drunken advice at the GA Rally, and that has been a big improvement to the flat mid-range. I also have my snorks out, which was the first big improvement across the board (that and pipes). I have since gone to the 18t, which hasn't done much to the low end but has done a whole lot to highway cruising. The bike is totally different at 80mph with the 18t. I am very happy with the 18t regardless of any negatives on the low end.

I am waiting to see what Triumph does in the 2007 line (1500cc?) before I invest in the Big Bore. We'll see if I can wait that long!

p.s. I also modified my SS pipes to Triumphant's specifications and am very happy with the enhanced sound, especially when "on" the gas.

Ride Safe

Ryan

No, I didn't really take THAT much offense to it since I put that smiley face on the end. I didn't mean to be snippy, and I also don't think my comments are out of line. Lugging the bike uphill means you're not in the right gear.

I for one knew exactly what I was getting when I bought my bike. I knew what the torque numbers were, and from that had a good idea of how the bike would perform. I knew I'd have to be downshifting going up a steep hill. This isn't a big CC V-twin cruiser with gobs of torque. Triumph didn't do a disservice to us, the bike behaves almost exactly what it is spec'ed out to be.

Go ahead and do the big bore kit, I hope you'll be happy then. I'm quite satisfied with the bike as is. When it gets tired and worn out, I'll probably put in the big bore kit myself if the rest of the bike is still in good shape. Hopefully that won't be until I hit 100,000 or more on the odometer.

Try the snorks, re-jet and needles. All cheap upgrades, and upgrades you would have to do anyway with the BB, so you might as well get some practice!!

I agree with everyone else Shari. There's no sense in skipping the step of taking out the snorkels and changing the exhaust and heading right to the BB kit. Do the easy things first and see what you think. I was surprised when I opened up the engine so that it could breathe easier, the power gain is noticable. If you're not happy after that then think about the BB. As for the 18T sprocket, if your not doing alot of highway cruising, don't bother, it's not worth it for you.

thanks guys,
this is the kind of input that really helps.
I run BuB slash cut pipes with a 130/42 main/jet set up.
AI is out as well.
So snorks(and airbox?)are the next step(s).

Again,thanks a lot.

mert

Hey Jango,
It would be interesting to see the difference in yours and Dinqua's dyno tests in regard to what the cams do. I say this because I think Dinqua still runs the stock cams. (correct me if I'm wrong here Dinqua). I have no plans to change cams if I decide to go with the BB, I really just want to keep it as simple as possible since I'm not looking for increasing all out speed. I beleive PapaDean made mention in a previous thread that the Weisco BB kit worked extremely well with the stock cams if low end power was the main objective, which in my case is. From what I gather from you guys who have done the mod (regardless of cam change or not) the BB kit does increase pulling power, so this has me interested. Although I never force my America to lug in higher gears now, I would look forward to eliminating some gear changing. That's not just from experience with American V-twins. I also own and ride vintage Triumphs, which incidentally, pull better in high gear than my America. Have a good day and thanks for all of your input.
Later,
Stan

Mert, with your pipes, you will gain some 3 to 5 *free* HP by popping the rubber bits out of your airbox. Also, because the engine is not working so hard to pull the air in, you will probably see a small increase in you highway fuel milage.

For those already bored out to 904CC, how does your bike do on middle grade fuel? A WAG is that your compression ratio is around 10.5:1 now unless the new piston crowns are lower than stock.

Shari, I would try the snorkles for sure. The airbox is a lot of work, but also noticable increase. Try the snorks, needles, jets. All easy, all stuff you'll do with the freak. The freak or something similar is pretty much necesary once you go big bore I would think...

I've done the Big Bore Kit (and Bub slash cut exhaust, and Mikuni carbs). The difference in power is EXTREMELY noticeable. More so than the difference from going from stock to new exhaust and removing airbox. I did my work in stages, so I could feel the difference of each modification. As for reliability, in some senses only time will tell. But I will share this with you: I had the BB kit dropped in, took it out each night for a week to get through the break-in period, and then headed out for an 1,100 mile weekend far from home with the bike (not without a little concern over this reliability factor). But the bike did fine. Hauling me and all of my gear for 4 days. Highway blasting from DC to NY, and then back roads and hills through NY state. The bike was great. No oil useage, no hiccups in running, and definitely more power. I would do it again - the only caveat being the cost - it costs a good dollar. But if you have the money and are willing to spend it on this, then I would have no reservation recommending it. There's my 2 cents....

By the way Jango....those JCW 32" turnouts you are running. How do they sound and what do they look like? I'm trying to locate my JCW catalog, but can't seem to find it. Gotta be around here somewhere though. If I go with the BB this winter I would like to find some mufflers that would sound similar to that deep mellow thump of the '60's Triumphs. Yours anything like that?
Later,
Stan

Indianstan, I have a mpeg that is visually awful but the sound is there. Here is the link to the pipes at JCW. http://www.jcwhitney.com/autoparts/Searc...p;searchbtn.y=6 As far as sound, I can't recall what the old 60s sounded like. They do have a thump. One older fellow I ran up to knew I was riding a Triumph before he even saw the bike coming and said the sound gave me away. Also, if you look at my pics you will see them mounted. I will still try to get better pics loaded soon. Oh one other thing, I do get a lot of compliments on the sound when riding with others. Performance wise I would put them up against Thunder Pipes anytime.

Thanks Jango. I'll certainly keep these in mind. I'm kinda surprised that the aftermarket pipes I've heard thus far for these models don't really have that classic Triumph sound. Several are simply too loud to me. Of course, I haven't heard them all, only a few. To me, the vintage Triumphs sound every bit as good as a Harley, if not better. Back to the Big Bore thing. Do you have any idea what the compression ratio is after adding the BB? Mainly wondering if it would make running premium gas mandatory, and/or if mid-grade would still be sufficient. I ran premium the first couple of years, but discovered recently when I couldn't get premium that my bikes performance, etc. has not been effected at all by switching to mid-grade.
Ride safe,
Stan

Dividing the stock CR by the displacement and multiplying by the big bore displacement cones out to about 10.5:1. The current price of premium gas would easily justify hotter cams just so you could burn middle grade again.