I'm putting so many klms on my bike, it can't be long before the motor's going to need a rebuild. & being a Mad Modder, I usually take these times as a chance to beef up the original. So I'm thinking of cubing up the Scrambler. But I don't want to turn it into a tyre shredder. Can any of you guys who've already gone the big-bore route tell me what kind of milage you're getting out of your rear tyres, & any increase in fuel consumption, since you did it?
I haven't noticed much of an increase in rear tyre wear from my Thunderbike performance kit, but the fuel range suffers a bit if I'm on the throttle a lot.
Also, what would be the best kit for a 270 motor? Has anybody else done it to a Scram? Or planning to? I'd love to hear your thoughts.

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"They told me I was goin to have to work for my living, & all I wanna do is ride." Jackson Browne (the Road & The Sky)

mileage = same
tire/tyre wear = probably about the same

It all depends on your right hand. Also, the 904 kit alone won't turn it into a fire breathing monster, we're talking 10-15hp more at the most. It makes for a lot more fun ride though, that's for sure. The questioned items are basically a non-issue.

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Ride, Wrench, Post, repeat.

Bonnie cafefighter!

Your mileage will be directly related to how hard u use the bike, just like now. The difference will be the additional 10 rwhp and torque you have, and the added temptation to use it. I wouldnt expect a dramatic decrease in mileage unless you went to a aftermarket carb...( like the 42mm mik's )...I have the mik's on my bike and my mileage dropped significantly.

I also however cant resist the temptaion to use the power thats there...( see above )

Tire wear wouldnt be any different...

Bill Gately race's 270* motors in his flat track bikes...a wiseco kit would be fine.

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Hated By All....cause thats just how it is.

How many miles are you putting on your bike?

Originally Posted by Old Scratcher

I'm putting so many klms on my bike, it can't be long before the motor's going to need a rebuild. & being a Mad Modder, I usually take these times as a chance to beef up the original. So I'm thinking of cubing up the Scrambler. But I don't want to turn it into a tyre shredder. Can any of you guys who've already gone the big-bore route tell me what kind of milage you're getting out of your rear tyres, & any increase in fuel consumption, since you did it? I haven't noticed much of an increase in rear tyre wear from my Thunderbike performance kit, but the fuel range suffers a bit if I'm on the throttle a lot. Also, what would be the best kit for a 270 motor? Has anybody else done it to a Scram? Or planning to? I'd love to hear your thoughts.

How many miles do you have on your Scrambler? I had 52k miles on my Bonnie when I wrecked it. There are plenty of others that are at or above 70 & 80k miles... So don't be so sure that a rebuild is right around the corner...

Also, you have an 865 cc motor... the 904 kit isn't going to add a whole lot... Especially if the rest of the intake/exhaust side of things are pretty much stock...

airbox elimination kit, port/polish the heads, open exhaust, cams... that will make the most performance difference...

If you want to do the big bore thing then fine, but don't go thinking you will NEED to do it anytime soon. People with these bikes are heading up towards 100,000 miles with not much more than routine maintenance.

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Paul.

Herts. UK
Opal & Tangerine 05 T100 (865cc)
(Previously Ducati Monster S4 and numerous UJMs)

Originally Posted by SCbonneville

How many miles do you have on your Scrambler? I had 52k miles on my Bonnie when I wrecked it. There are plenty of others that are at or above 70 & 80k miles... So don't be so sure that a rebuild is right around the corner... Also, you have an 865 cc motor... the 904 kit isn't going to add a whole lot... Especially if the rest of the intake/exhaust side of things are pretty much stock... airbox elimination kit, port/polish the heads, open exhaust, cams... that will make the most performance difference...

10 rwhp is a bunch on our bikes over a stock 865 besides I think the 790 dont give up anything to the 865 it has much better cams and high rpm hp dont go by what triumph says as far as hp most stock bikes are just 49 to 51 rwhp.you make more hp by going up on compression with the big bore kit then you do from its size.size gives you more foot lbs at low end.

Put it this way with a bit more power/rolling grunt you wont need to crack the throttle as heavily as something with a bit less get up and go, especially if a larger sprocket is used.

Id say get the 1100 kit, turbo it, and then see what yer mpg is

My 904 big bore with gas flowed head, 39mm FCR flatslide Keihins velocity stacks (no filtration) and Predator exhausts is more econimical than the bike was in stock trim. 19/41 sprockets may help, but I doubt it as the bike is thrashed everywhere. 50 miles per UK gallon is easy, and I have had 54mpg as a best figure. I was lucky to get 45mpg in stock trim.

Tyre wear is not an issue as far as I can see.

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Rob
http://www.triumphrat.net/memberalbu...ry.php?cat=524
http://www.triumphrat.net/memberalbu...ry.php?cat=529

My bonnie had the same treatment as yours, minus the carbs and big bore kit, I think it was the bob farnham package (gasflow/skimmed headwork) which pushed it up to 70 rwhp.

What do you have at the rear wheel now? Also, how long is your average journey? I have found that makes a big difference, shorter journeys reduce my overall range by about 20 miles. I have the 19t and usually get to between 100 - 110 miles before reserve.

One more thing how much were those carbs? Are they any more/less user friendly than the stock ones?