This Forum is now CLOSED use the link to get more details viewtopic.php?f=3&t=13924#p102587
User avatar
By windmill john
#94232
Up until now, I’ve been in the ‘if you want more power, buy a different bike’ camp. But after a year of ownership and a ride yesterday which involved a bypass and an annoying car three up ahead, I’d like a tad more speed.

Now I know this has been covered in different ways and I don’t want to start a twenty page thread..... but without resorting to too many part changes and this is something for next year. Just watching a few of BW’s videos, what would be accomplished by, at this stage, just knocking a mill of the barrel bottom? Having the head off I can see I can play with a mill or two.

Do I need to change valves too? I’m sure each change adds a bit more, but just wondered, without going too mad in parts changing, a couple of pointers would help.

Or stick my barrel and head in an envelope to BW :mrgreen:

Thanks.

John
#94234
Hi John,
The best things to do / fit are Meteor Minor Sports piston [available from our hosts in standard size only], retard the standard inlet cam by 1 tooth [but only with the afore mentioned piston, or it will become revvy and gutless], or fit a set of Redditch 'S' cams if you can find any. Any improvements you can make to the breathing [carb and exhaust] and porting would be good. A barrel on a 350 can be shortened by up to 2 mm, even in conjunction with the MMS piston. The standard valve gear is 'up to the job', but slim stemmed ones are not expensive and will contribute to better gas flow.
I wouldn't be too tempted to raise the gearing - I went up 1 tooth on mine and think I should have let it be.
It is possible to get performance like this [and for my trolling friend, I know it rattles, due to my having fitted a shortened skirt, well used MMS piston which saw much use in our 350 racer beforehand, so it has lots of piston slap].
My 350, running 17t / 38t gearing ...
https://youtu.be/qbhm19lDboM
User avatar
By stinkwheel
#94237
When I went drag racing on my 350, I got an extra 5mph on my 1/4 mile terminal speed by removing the rear subframe and mirrors and emptying the toolboxes during the lunch break. That put me both over 60mph and under 20s for the standing 1/4 mile which was my aim for the day.

Just saying all tuning does not necessarily start with the engine.

Image
User avatar
By windmill john
#94238
Many thanks Paul, I appreciate your reply. Hopefully me being on the south coast and just working on my bike won’t affect your business :mrgreen:

Working initially:

Can I fit the piston alone without retarding by one tooth, nothing else?
Can I fit the piston with one tooth retarded and nothing else?
In other words can I leave the barrel for the mo?

I will polish the inlet port and I do have a MK1 930 Amal to play with too.

stinkwheel, I only weigh 11 stone, so not putting too much on the bike; not saying you’re bigger of course!


John
#94239
Hi John, yes, you can fit the piston alone, it will give the engine a lot more 'punch' but you might get pinking - if so, retarding the inlet cam should help with that at the cost of some of that punch at lower revs, but a larger gain of power from the mid range and upwards. I wouldn't retard the inlet cam alone, though, it will just make the engine gutless. It will, of course, need adequate fuel and air to go with this.
By vince
#94242
Hi, stinkwheel the road test for a 1958 redditch bullet shows terminal speed 1/4 mile 68mph 19secs so yours sounds to be in the right zone. Vince.
User avatar
By stinkwheel
#94246
Another "not tuning" mod that would probably benefit the bike is a close ratio gearbox conversion. Won't change the top speed but will probably make the bike faster overall.
User avatar
By Nitrowing
#94252
As much as 'weight hinders acceleration' can lead down a dark path, it won't give you that 4mph.
The one very simple way to improve top speed (and fuel economy) is aerodynamics.
It's cheaper than mechanical tuning, it puts less strain on the engine and it's much easier to adjust.

Now, I know a lot of people might baulk at the idea of popping a fairing on but it really can be that simple.
  • 1
  • 2
  • 3
  • 4
  • 5
  • 7

Shop for accessories at Hitchcocks Motorcycles