BritBike Forum logo
BritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorThe Bonneville ShopBritBike Sponsor
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
ShoutChat Box
Comment Guidelines: Do post respectful and insightful comments.
Buy BritBike staff a coffee
Buy BritBike's staff a coffeeStill here since 1996 serving BritBike enthusiasts..
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Member Spotlight
breeze1954
breeze1954
S.W. Pa.
Posts: 660
Joined: August 2006
Show All Member Profiles 
Newest Members
Stormbringer, Noah from PA, DGW Auctioneers, GoTriples, Jan Hellinge
10830 Registered Users
Top Posters(30 Days)
franko 139
NickL 73
reverb 60
DavidP 58
Popular Topics(Views)
975,112 mail-order LSR
a word from..
Forum Statistics
Forums34
Topics67,414
Posts677,585
Members10,830
Most Online14,755
May 5th, 2019
Who's Online Now
59 registered members (Al Eckstadt), 280 guests, and 770 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Venom tuning - from a distance! #772920 05/07/19 4:26 pm
Joined: Aug 2011
Posts: 100
B
Brid Caveney Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
B
Joined: Aug 2011
Posts: 100
The 61 Venom we just did a top end job on ran great on the lift, and tootling around outside the shop (through 1st/2nd gears) and when back with the customer, did 2 road runs - both over 100 miles. On those runs, he was under strict orders to not do much over 50mph, not to let the motor lug on hills - more keep running it up and down through the rev range.
He was having trouble starting it at home, though it was starting first kick on the lift, and on bringing it back for a post run check, we couldn't find anything amiss. More - it now takes a slightly different technique to fire it up than he's been used to. On picking the bike up this last Sunday, he fired it up outside our shop -- first kick, using the 'new' method, and was very happy. We told him the rings seemed to be seated correctly, and he could now start 'goosing' her a bit on rides.
Later that day, he called to say he'd taken the bike for a run at home (2+ hours from our shop) and it was doing some something odd.
Though it fired up quite readily - he said once warmed up and out on the road and at a normal cruising speed (50mph or so) when he opened the throttle, it didn't want to accelerate -- more just sort of baulked, then slowly started to pick up revs. Once he got back home (he wasn't far away) he said he pulled into the garage, and as he let go of the throttle, it returned to idle - but then started to 'hunt' -- revs rising and dropping without him touching the throttle. A couple of hours later, he again fired it up - and it reacted normally (though he didn't ride it again) just sitting and idling.
I have asked him to mark the throttle, to try and ascertain what rev range it is in when it is acting 'odd' --- which may tell us something. However - the hunting thing has me a tad miffed?
It has an AMAL Premier 930 on it - and though not sure of jetting, they came stock for that model, with a 200 main, 106 needle jet and #3 slide (not sure on the pilot jet)
Magneto was rebuilt (professionally), with new points/Brightspark Easy Cap etc.
Any thoughts?

Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK
British motorcycles on e-Bay North America
Re: Venom tuning - from a distance! [Re: Brid Caveney] #772977 05/08/19 12:20 am
Joined: Apr 2005
Posts: 1,784
A
Adam M. Offline
BritBike Forum member
Offline
BritBike Forum member
A
Joined: Apr 2005
Posts: 1,784
Air leak between a carb and head when hot ?
Air leak in the carb when hot ( air screw o' ring broken ) ?
Carb getting loose ?

Re: Venom tuning - from a distance! [Re: Brid Caveney] #772979 05/08/19 12:29 am
Joined: Jul 2016
Posts: 234
Joolstacho Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: Jul 2016
Posts: 234
Yes, that occurred to me too, but usually you'd get some popping-back symptoms with a carb air-leak.

Re: Venom tuning - from a distance! [Re: Adam M.] #772982 05/08/19 1:03 am
Joined: Aug 2011
Posts: 100
B
Brid Caveney Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
B
Joined: Aug 2011
Posts: 100
Originally Posted by Adam M.
Air leak between a carb and head when hot ?
Air leak in the carb when hot ( air screw o' ring broken ) ?
Carb getting loose ?


Adam -- we just rebuilt the complete top end of the engine -- and it was put together very carefully. It's only done a couple of hundred miles 'break in'. It's a new 930 Premier, so I'm not suspecting any of those faults. In fact, with it running on a 'hang tank' when it came back in (after the 200 miles) we blew brake cleaner around the manifold, and it showed nothing.

Re: Venom tuning - from a distance! [Re: Brid Caveney] #773019 05/08/19 1:46 pm
Joined: Feb 2007
Posts: 803
E
edunham Offline
BritBike Forum member
Offline
BritBike Forum member
E
Joined: Feb 2007
Posts: 803
Is the ignition advance automatic or manual? If automatic, could the springs be acting up or the unit not retarding smoothly? If manual, is it a tight or loose cable advance? Could the lever have slipped from retard to advance or otherwise without the owner noticing? Timing have slipped a bit?

Ed from NJ

Re: Venom tuning - from a distance! [Re: Brid Caveney] #773480 05/12/19 5:03 pm
Joined: Feb 2006
Posts: 629
R
RGSROB Offline
BritBike Forum member
Offline
BritBike Forum member
R
Joined: Feb 2006
Posts: 629
I ran a 930 AMAL Concentric with a 270 main jet, needle on the middle groove, No air cleaner.
Bike ran fine at these settings


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | DVD- Manuals & Parts books
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
BritBike Sponsor
Powered by UBB.threads™ PHP Forum Software 7.7.3