Removing the choke valve nuts

[icenian]

I'm tempted to try and then to take it round to a local engineering shop and see how much they'd charge me to turn a bunch of them up. Would anybody be interested in buying one if I do?

Yes, for an RD07...

I wonder what the differences are between RD03, RD04 and RD07? I think the thread is the same (everyone seems to agree that the wee "cap", that fits over the end of the brake pad pin, can be used to blank off the choke). The other critical thing would be the length of the nut, i.e. how much free play is there in the cable when assembled?

[fergus1964]

Yes, for an RD07...

I wonder what the differences are between RD03, RD04 and RD07? I think the thread is the same (everyone seems to agree that the wee "cap", that fits over the end of the brake pad pin, can be used to blank off the choke). The other critical thing would be the length of the nut, i.e. how much free play is there in the cable when assembled?

on the rd03 the wee cap thing from the brake pad pin doesn't fit. it's too big. I think the choke plunger on the rd03 might be smaller. i might be wrong, but i definitely tried this out when playing with the carbs from a bros 650, trying to fit them to the rd03. The bros carbs have a bigger bore diameter, giving the engine more low speed punch, but don't quite fit within the rd03 frame rails, so i had to put the old ones back. the rest of the bros engine is identical so far a mounting points are concerned, but has a close ratio set of gears. a project for another day...

[AIRWOLF]

on the rd03 the wee cap thing from the brake pad pin doesn't fit. it's too big. I think the choke plunger on the rd03 might be smaller. i might be wrong, but i definitely tried this out when playing with the carbs from a bros 650, trying to fit them to the rd03. The bros carbs have a bigger bore diameter, giving the engine more low speed punch, but don't quite fit within the rd03 frame rails, so i had to put the old ones back. the rest of the bros engine is identical so far a mounting points are concerned, but has a close ratio set of gears. a project for another day...

Are you sure you got this bore size the right way round.

With trials bikes we used to go for smaller bore for clean pick up at low rev's, at the expense of top end power.

where mates that raced went for bigger bore for flat out high speed, at the expense of bottom end power.

[fergus1964]

Are you sure you got this bore size the right way round.

With trials bikes we used to go for smaller bore for clean pick up at low rev's, at the expense of top end power.

where mates that raced went for bigger bore for flat out high speed, at the expense of bottom end power.

what you say is right. if you have twin weber 45's on your escort, it won't pull the skin off custard at low revs. i also had an off-road machine with a ford pinto 2 litre engine, with a poxy ford variable venturi carb from a transit van. it had huge torque at low revs. i think it's something to do with the mass of air and inertia.

however, having driven a bros 650 for a while, it really did take off from the lights, and had great torque out of low speed curves, much more so than the africa twin. might have been a combination of the close ratio gears, and bigger carbs which allow more fuel into the engine across all the rev range. the inlet rubbers are also different on the bros than the standard rd03, similar to those on the 750 version.

we all know that the rd03 carbs, airbox and exhaust are sensitive to any defects, and have to be balanced for the bike to give good economy and reliability. perhaps the overall set up on the bros is tuned more to road use, with not only larger carb intake diameter but different profile needles . both bikes give 57hp as standard max power.