348 to 405 Big Bore Kit

 

Over the last few months we have been developing a big bore kit aimed at increasing the power of the 348 engine fitted to most of the Harley Davidson MT350’s.

Heres some pictures of the work in progress

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A 348 base engine was used with the electric start components removed.

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The engine ran perfectly and sounded great on the test bed.

Next job was to fit it in a chassis, run it in and see what figures the engine produces on the dyno.

 

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Great facility as used by a number of race teams judging by all the bikes and memorabilia.

The guys at Dynotech Performance really know their stuff
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Results as follows:

With the 667 cam as in the 348 the 405 made a healthy 33.64 bhp at 8300rpm

With the 670 cam fitted the 405 made a very healthy 36 bhp @ 9000rpm a proper little screamer which sounded great on full song!

405 Piston kits will be available very soon as will cams exhausts and carburettors as used in the above tests.

Heres pics of the graphs form the dyno runs..Image

This graph shows the difference between standard 350 and the 405 with the 670 cam. The test was carried out in 4th gear and was over 70 mph with a 14T final drive sprocket.

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This graph shows the difference between the 667 cam and 670 cam.

The 667 produces good power lower down but runs out of steam where the 670 keeps going. The fuelling with the 670 cam is much better too.

 

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