Classic Triumph Bonneville

[Mr. Dazzle]

I went out in the garage today to do something else and I have to move the Bonnie out of the way, whereupon I spotted that she's lost one of the rocker inspection ports and two bolts from the fairing I can only assume that now loads of the bolts have been undone/redone they're not seized up and more and are free to escape!

As my wife's uncle says; "She's a collector's bike. You have to keep stopping to collect the bits which fell off".

[Taipan]

Can you not fit an OEM airbox to this? I can't see it ever running well in the lower/mid range with bell mouths on it. As I've said before, open bellmouths are normally only good for full throttle and with the meshes fitted you won't even be getting that benefit?

[Mr. Dazzle]

No such thing as an OEM airbox as far as i know, just pancake filters on the carbs where the bellmouths are.

My wife's uncle used to dispatch on this bike, set up as it currently is (high comp pistons, no filters etc.) so it can't have been that bad. Or maybe it was and he just didn't know any better

[Le_Fromage_Grande]

He probably just rode flat out everywhere, a lot of people did on 50 bhp bikes.

[JackyJoll]

I went out in the garage today to do something else and I have to move the Bonnie out of the way, whereupon I spotted that she's lost one of the rocker inspection ports and two bolts from the fairing I can only assume that now loads of the bolts have been undone/redone they're not seized up and more and are free to escape!

As my wife's uncle says; "She's a collector's bike. You have to keep stopping to collect the bits which fell off".

If you fit an O-ring in place of the fibre washer, the rocker caps stay in place.

[JackyJoll]

Can you not fit an OEM airbox to this? I can't see it ever running well in the lower/mid range with bell mouths on it. As I've said before, open bellmouths are normally only good for full throttle and with the meshes fitted you won't even be getting that benefit?

I wouldn’t be surprised if the mesh covers do choke it at high rpm/open throttle.

I’ve messed about with Amals a lot and I find it’s easiest to tune them for low speed running with no air filter, just the bare carb.

[Mr. Dazzle]

I spotted that she's lost one of the rocker inspection ports and two bolts from the fairing

For the sort with slots you used to be able to get spring clips to hold the rocker caps in place. If all else fails lockwire them.

Yeah the escapee had the spring tab!

[Mr. Dazzle]

I took a look at the float height as a first port of call. If that ain't right any subsequent fucking around with needles and jets is pointless AIUI.

I think they were both miles off. I didn't ask the mechanic to do anything with the fueling so I'm not too surprised. I don't have the clear bits of pipe necessary to check the fuel level directly, so I used the older Triumph handbook method of measuring how far below the top of the bowl the float sits. They were both set so that the fuel level would be way too high AFAICT.

Took her out for a spin tonight....can't get past 4000rpm under load now! It'll rev past that with no load easily enough (gotta be super careful cause there's no rev limiter).

I had a look at the plugs...they both look brand new still. Not enough miles I guess That said, the left one got coked up in about 5 miles last time, so this is an improvement.

In other news, the gearbox is definitely loosening up with use. I can use all four gears now!

Edit: One other thought also just occurred. This is the first time I've ridden it with the lights on. Should check the voltages.

[Mr. Dazzle]

I've got the day off today so decided to have another look.

I moved needle clips down a notch to richen the mix, seems to work better now. Still really struggled to get above 4000rpm under load though. Comes off idle really snappily now whereas before you had to be careful when first opening the throttle

When I got back I had a look at the plugs. Left is a bit sooty, right is absolutely pristine. Like brand new pristine.

Half of all carb problems are electrical right? On a hunch I started her up again then pulled the right plug cap off...it stuttered a bit but kept going. Putting it back on made some difference but its not night and day.

Pulled the left one off....engine died instantly!

Reckon my HT lead and coil need looking at. I think the coil end of the lead is not in properly, but its hard to tell without taking the tank off.

Gonna put the needles back where they were for now too.

[Le_Fromage_Grande]

Take the HT cap off, wet your finger and put it on the bare wires of the HT lead, if you get a fairly hefty shock the lead and coil are okay.

[Mr. Dazzle]

When I first started it after the rebuild j checked i had sparks on both sides (take the plugs out and kick it over while they're sill plugged in).

I reckon the coil end terminal of the lead is just falling out with the vibes. They're a bit shit.

[Le_Fromage_Grande]

Don't do the finger thing, it was a fairly unfunny joke we used to play on kids with mopeds, but most motorcycle coils are the same, so you could try a more modern coil, you could get it working with modern plug caps that have the coils built in, it's pretty easy wiring to do.

[Mr. Dazzle]

If I was gonna fo it, I'd use my tongue

[weeksy]

If I was gonna fo it, I'd use my tongue

Ja Ja Binks special

[JackyJoll]

When I first started it after the rebuild j checked i had sparks on both sides (take the plugs out and kick it over while they're sill plugged in).

I reckon the coil end terminal of the lead is just falling out with the vibes. They're a bit shit.

If it’s like the original coils, with the HT lead pushed into a hole with no screw-on spike, you can stick it in with silicone.

[Rockburner]

What plug caps are on it?

If they're the standard black 'push fit' then throw them out, they're shit. NGK all the way.

[Rockburner]

oh - also - if the plugs still have their little screw on caps - make sure they're done up TIGHT. If they're at all loose then you'll get weaker sparks.

[Mr. Dazzle]

It's got the ones like this...



I did buy some of the kind which actually screw into the end of the cable, but they're too big to fit in the female side on the coil. The caps are new red NGK ones, they fit on the plugs without the little screw caps. Everything about the leads is brand new.



Having looked closer I can see the right HT lead is wobbly in teh coil. They just rely on being sorta wedged in there, they're not very secure. I like the idea of the silicone although I guess I could also try packing/wedging it with something. You can feel the left one 'connects' more solidly than the right when you push it in.

[JackyJoll]

Don’t know how relevant to what you’ve got, but analogue Boyer ignition works better with two 6 volt ignition coils in series, or a single dual output 12 volt coil.

Two 12 volt coils in series give a weak spark.

Also, it’s possible (though not that common) to have too much suppression resistance in the spark plug HT circuit, by having 10 kOhm caps on 5 kOhm plugs, for instance.

[Mr. Dazzle]

Pretty sure I've got two 6V on series, but I'll have a poke. Deffo in series but I'm not sure what 'size' they are. I also added a dedicated earth line straight back to the battery just for the Boyer, I've heard they prefer that too.

99% sure there 5kOhm caps on non resistor plugs, but I'll double check that too.