Hitchcocks Forum

Hi, I have been faffing about and trying to fix the reason why my 2004 65 keeps on nipping up at around 55/60 indicated. I have had it all apart and used new piston and matched barrel, new oil pump and changed the fuel to be richer. But still keeps nipping up. So I want to go back to the original carb. I have the Amal and it's too confusing for me to set up. So what I need to know is what do I need to get to revert back to original ? Anyone got the kit I need who has converted to Amal? It's the last chance for this bike !!!! I have no confidence in it, short ride today, 10 miles into Cambridge - all ok, then on the way back, hour later, it nipped up twice , both at similar speeds. 50/55. Any help on returning back to how it was would be great. The conversion was done when new. Thanks Andrew

I suggest your first Port of Call is the parts catalogue on this Site. Then you can play a game of 'Spot the Difference'.

FWIW I do not think its the Amal that's causing your engine to "nip up". Whats your spark plug like? The Amal is very easy to set up, as our hosts sell the kits to convert to Amal I think they would be very helpful in sorting you out with some advice. I've never known a carb cause a partial seizure (that is what you mean by "nipping up"?) on the other hand incorrect piston to bore clearance, dodgy piston, "lugging" the engine when running in, badly timed ignition can lead to problems. Its probably nipping up at 55-60 because the engine has reached operating temperature & something isn't right, you need to find out what, I don't think a different carburetter is the solution to your problem

Perhaps the ring gaps are not quite large enough.

I was referring to the carb because I feel that the mixture may be too lean, I thought I had made it richer, but still the same nipping up problem, the are so many variables that I thought putting it back to standard would be a good staring point. I bought a used barel and piston set from Hitchcocks on the thought process that all was well with the enjoin that the barel and piston came from, so end gap was not measured. This is the third time I have had to strip and replace barel and piston, and always with the same result. Nipping up at around 50/60. This time I replaced the oil pump just to eliminate the lubrication side. I really would like to replace the engine with another brand. Any thought as to what fits or has been done in the past? My patients are being stretched with this bike, I have had it for 14 years, 6000 miles 3 barel and Pistons , teather is nearly reached.

Is the piston/bore clearance to the minimum required by Royal Enfield?
Because on the majority of other motorcycles that level of slackness would require a rebore.

Hi 555

I think Papasmurf has hit it on the head. I had similar problems with my 1996 CI 500 a while back – kept having light seizes at around 90kph (~55mph) even though I wasn’t thrashing it to get there. Eventually I learned that it was the piston-bore clearance - the engineer who bored/honed the barrel was used to aluminiium barrels and had not allowed for a cast iron one (or maybe the piston was an odd alloy) but anyway the piston-to-barrel clearance was about 1thou too tight. As soon as that was sorted, then that problem went away.

Doesn't the 65 have a CI barrel as well?

Anyway, I would have thought that if the carb were that far out lean to make the piston run so hot at such a modest speed, then it would be tough to start and the engine would be farting and spluttering all the time.

Cheers, ChrisD

555: One of the Royal Enfield Group ( REG )in Australia is also fed up with breakdowns and is fitting a Suzuki DRZ 400 engine, he calls it a Zenfield. Unfortunately, no pictures available at present.

Chris D and Pappa S. thanks for the replies. I have previously used new components , barrel and piston, matched and sized correctly as the supplier was well recommended. But using new components meant another 500miles bedding it alll in again. Only for the same thing to happen. So my logic was to buy a used barrel and piston , on the assumption that all was well with this set up , on inspection of barrel all looked well. So all the measurements and gaps should be ok . So why is my so****g bike still nipping up? I'm not trashing it, careful to keep below 60, good oil flow. I am loathed to have to spend another £££ on barrel and piston, then the time spent putting it back together , for it to do the same again. There must be something I am missing. Nearly had it all ripped out and converted to diesel, but can't use my 5 speed left foot gear box. Anyone' know of a good motorcycle man near Cambridge who I could give it to broken and come back fixed.

Leon, that sounds just the thing I am looking for, just need to find a capable person here in the UK who could do it. Confidence in the RE engine 0%