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Allan G, Semper Gumby
Total Likes: 4
Original Post (Thread Starter)
#857037 08/26/2021 3:11 AM
by Snakepitt
Wondering if I might get some feedback from those that have done it. A lot smoother running? Or better to just get the stock 360 degree crank dynamically balanced. I know what is required cam and ignition wise and it's expensive but might be worth it for me anyway.
Liked Replies
by NickL
Fair bit more stress on the old lumps when you stroke them more than about 85mm.
Stroking always makes balance harder too.
For 95% of the use of these, 750 is adequate.
Just my 2c.
1 member likes this
by NickL
When he had his firm going, my older brother carried out many
conversions to road going bikes, fitting norton offset cranks into
750 triiumph engines and several a65's. None of those bikes
needed or had electric starters.
Starting various engine types is largely a matter of sorting out a
technique rather than brute fore and ignorance. My sidecar outfit
for example as a 880-920 offset twin with high comp and hairy cam,
could be started by myself in five or six paces, when racing the pair of
us used 3 paces to push start.
1 member likes this
by Mark Parker
Mark Parker
My 360 Firebird is 650 and easy, 1 kick usually hot or cold unless you leave it sit for a month or more. My 883 is a pig, bounce off that kick starter. I park it on a hill, with that backup when warm one kick, without it no way. At home I made a roller started, it's instant but my right boot lets water in on a wet day because the kickstart cracks the sole. Otherwise boots last years.

Ben's 750 can be good or not. It has two 12v CDIs and a trigger for each I made. It can stand you up. The 360 with Pazon never does. I've read that SRM recommend removing the carb balancer on a 90degree. I do mean to try that. The head I made to try on Ben's has no balance fittings. The Firebird doesn't have them, or need them, but the carbs were set up that way. The tube will effect it when removed why we haven't done it yet.

This is with the old mufflers, the new ones go through at 51mm not 38mm. A 750 big bore can give very good power and even 11 or 12-1 is better to kick than two 441 singles with no valve lifter. On the 883 you do not open the throttle with your foot on the lever. Put chokes on 3 or 4 kicks no ignition, turn chokes off, don't touch the throttle and kick and see if the lever moves fast enough. PWKs on the 650 have chokes that work perfectly, so we will see how using a pair of them effect the 750. carbs and fuel and ignition all play a part, what the balancer may do I don't know but with a single cable and a splitter near the carbs it's not necessary.

I'm hoping we can get the 750 to match the grunt of the 883, it isn't bad really, it's just that it may be possible to get most of the grunt, and it's a better configuration for rpm, easier to do.

Head ready to go. The ports flow about the same as what's on it, but are high speed.

[Linked Image from]
1 member likes this
by Mark Parker
Mark Parker
Smooth running is dependent on a few things. Std stroke and big bore is best. Aim around 50-52% don't make the crank too light. Don't gear too low, it pulls better, fix the head. The big bore isn't necessary but pistons are lighter by a little usually and good forged ones from Ed V have a modern ring pack and run tighter. Use good rods.

1 member likes this
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