Triumphrat

triumphgeezer

Bonnevilles come from the factory with engines that range from 790 ccs to 865 ccs. The Wiseco big bore kit offers 904 ccs. Bonneville Performance is fielding a flat tracker with 989 ccs.

Back in the day of Edward Turner's design the result of increase in displacement from 500 to 650 to 750 and beyond, increased vibration. I had a smooth little Daytona 500 that always seemed just as fast and certainly smoother than the 750 OIF Bonnevile that I bought later.

Having said all that, can anyone comment on the counter-balancers in the various iterations of the new engine. Are there different versions for a 790 versus an 865?

Is there an owner of a Wiseco equipped Bonnie that can compare (subjectively, I know) the before and after levels of vibration?

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Alcohol, Tobacco and Firearms -
should be a convenience store, not a government agency.

Dinqua

I have not noticed any increase in the vibrations.
After I did the big bore, I installed the belt drive and noticed a big drop in vibration.

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Pat Whitbeck
Canandaigua, New York 14424

keef

As far as I can tell, there has been no change in engine vibration on my Bonnie whatsoever following the 904 conversion, even to the point where I hit the rev limiter.
The only increase of this sort has been in the good vibes I get from the extra power.

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sweatmachine

Keef, what kind of power increase did you experience? I have a 865cc T100 and I'm thinking of doing the 904cc kit.

Thanks.

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Macgruber!


Click for a picture of my slightly modified Bonnie

Dinqua

??? Why? To gain 39CCs? Makes no sence at all.
The 904 cc big bore is best used with the 790 motors.

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Pat Whitbeck
Canandaigua, New York 14424

keef

I'd have to say I'm with Pat on this one as far as the 904 conversion is concerned. However, that's not to say that your 865cc T100 wouldn't benefit from one of the other big bore kits out there. I'm afraid I'm a little scetchy on their details but, offhand, I gather they range from about 980cc to as much as 1100cc (possibly more even with a kit to alter the stroke in addition to the bore).
I'll have a little look and see what I can find on the subject and get back to you.
Meanwhile, I must confess I did rather plump for the Wiseco 904 kit before having really spent enough time researching the other options available. Though having said that, I'm very happy with the improvement in performance that it has given over the 790cc I had before. Any additional performance gains due to my tinkering have been more down to good luck than good judgement really, but there we are - sort of like a confused octopuss fiddling with a marine anti-ship mine and somehow coming away alive.
In a couple of days I'm off down to Yorkshire to get it dyno-tuned, rejettted and all that so I expect to get a bit more yet. As with the above, I'll let you know how it goes.

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ocman

According to the guy(cant remember his name)at Bonneville Performance, you can expect roughly 10 more hp and 8 more lb/ft of torque from the wiseco 904 over an 865, plus additional gains later if you choose carbs, cams, etc. The 904 is the largest displacement for the 865 SM w/o splitting the cases and all the extra labor($$$). Not a bad bang for the buck. Not as good as pipes and airbox, but not bad.