Hitchcocks Forum

I have a 2004 classic Bullet 500cc - right hand, 4 speed gearbox.
It is stuttering at speed - ie with throttle open and pushing around 70mph, it starts to stutter. It does not cut out as such, but speed falls away, and it struggles to respond to blips of the throttle. If I drop down to third it helps 'clear' it, but not necessarily. It is best to pull in and let the revs drop right down to tickover before pulling away. It does not 'stutter' at normal cruising speed (60mph) or across the gearbox. Just at full on throttle and at the higher end of the speed range.

The bike has about 1500 miles on it. Changes include Hitchcocks 30mm Amal Mark 1 carb; high level Woodsman style exhaust pipe and high level open Triumph style silencer with minimal baffling. No changes to carb from Hitchcocks. No other fuelling or ignition changes. It has the standard NGK 8ES plug, points and magdyno.

We drained the carb float bowl three times and some grey 'swarf' dropped out on the first occasion. It looked like shavings from within the carb. But on second and third drains, it has been more or less clear.

This stuttering is unpleasant and dangerous on the motorway - happened twice! Any thoughts or comments welcome. I have exactly the same carb on my 1961 Velo Clubman - no problems whatsoever and that bike keeps pulling all the way...

Thanks

Fuel starvation? Is there a filter in the fuel tap (usually is) - that could be blocking up.
Could be the main jet needs to be a bit bigger.
New Amal carbs are often full of swarf - perhaps there's a bit in the main jet partly blocking it?

After Checking The Fuel route etc (& Air route) I Would think Carb & Needle, Different Notch or Needle......
.."My 350 With MonoBlock use To pull Nice to 60 then Slow down if I went above it, Till I Adjusted the Needle & added a Bit of Baffle"...Just Noted That you said No Changes to carb From H's??..They all need Tweaking abit..."But that is a dark art" Good Luck.
Chhers Craig....

70 mph, I wouldn't worry about the stuttering, you are going to pull the top off the piston

Hi Mate,
Get it up to the conditions where it stutters, then push choke/enricher on, if it clears then you need a bigger main jet.

"Well said that Man"! (Triton)... Agree

Hello SOFIASPIN, ---------- a 2004 with magdyno ???--Interesting--are you sure about that ??...I'm concerned that you are taking a standard geared Classic 500 onto a Motorway--- then pushing it up to 70mph (even allowing for the optimistic speedo)it's not a good place for it to be !!--However,this seems to have all the hallmarks of weak setting on main jet..and that "stuttering" might well be the start of a partial seizure..Agree with both TRITON re}--- try the choke & NORM re}----- The piston crown parting company !!.....but rest easy as our hosts now do a forged piston at standard comp. ratio...PLUS}--- You really must do a plug chop test to be certain of what's going on in there----With those carb and exhaust changes you should find that a 19t output sprocket will help drop the revs a tad and you can make better use of the increased TORQUE that's now available....

Many thanks for the excellent replies and advice. Will try Triton suggestion. I don't hold it at 70 for long but these bikes should cope with a turn of speed - no? It is getting new 5 plate clutch too so once fuelling is sorted it will be quicker as well as sorted to realease the torque. Thanks again for the wise comments. The bike is getting well used the Velo is for sale!.

My 535cc lightning custom did the same when opening up to 70mph,i shut off and pulled the clutch but it came back to life at 30mph.The next time it does it i`m going to shut off the fuel tap which would be easier than putting choke on (same hand as throttle).Also it`s happy at 60mph with a freeflow silencer and filter.When turning fuel back on and looking at the flow will tell me what your talking about.Thanks as well.

First thing I have never ridden an Indian Bullet.

I have a Super Meteor and a few other British bikes both single and twin cylinder, I really have to ask, Are the people who indicate that 70mph is too fast and risky for the health of a 500 Bullet right?.

I have a 1964 350 twin Triumph Tiger 90 which I rebuilt 25 years ago which will cruise happily for hours on end a 70mph and still gets the odd run up to it's max of 90mph, I also have a 1945 BSA B31 350 single rebuilt 3 years ago with oversize high compression piston (415cc) and Gold Star clubmans cams, this bike will cruise all day if asked at over 70mph and will top 95mph.

Is the Indian engine really so weak?, the original Redditch ones weren't. Ducks and runs for cover.