downpipe colour

[tobyd]

what for it mean if the downpipes are burnt a different colour?

the left-hand side is a sort of dull browny colour, whereas the left is more shiny bronze colour.

I'm tentatively thinking one cylinder is running hotter than the other but with the carbs sync'd they should be receiving the same mixture and I can't really change it anyway?

Can only really think one slide isn't as good as the other since it doesn't spend a lot of time idling?



like so. they are about the same from halfway down the vertical section.

[J_Walker]

when you choke the engine, one side becomes leaner than the other. its how the choke works on these bikes.

[Kito]

Notice that the carb sync only matters on 1/4 of the throttle or less... actually is important to have a smooth idle, it would never result in such a difference.



I would check for:

1)needle jet and main jets.. check if they are clean.. (if second hand bike) ideal would be to measure them at both sides.
1.1) needle shimming
2)the spark plugs... and also the spark strength(length).
3) valve clearances.. this also could lead to different performance.

As my bike has OEM rusty pipes.. I cannot even say if I have the same problem or not ( wuld need a IR thermometer)


Well.. those are my thoughts. The work is yours... lol.



Good luck.

[sledge]

Could just be the way the pipes were plated?

You need to get a digital thermometer on each one and determine if their actually is a difference in temperature.

[Kookas]

Can't believe I didn't notice those weren't stock at first - I was wondering what went wrong for mine to be such piles of rust in comparison! I agree with the others, take out the guess-work and get yourself an IR thermometer; I got one off Amazon for just over a tenner. No idea if the actual number on it is accurate or not, but it's at least consistent and the readings are what I'd expect.

[Kito]

The pipes itself already are pointing to the temperature of each cylinder, you can also notice that is not a tiny difference, is about 10% in temperature. It would be nice to measure with a thermocouple or a Ir thermometer. However this difference in temperature can be specific of an engine power regime. ( different jets)

Is likely to be where the pipes becames hotter (because the steel annealing records the highest temperature.... AFAIK)

So probably this is happening on the main jets operation... then will be kind of hard to get precise measurements,, since you would have to be  opening the throttle wide.. (thus... going kind of fast) and reading the thermometer at same time.

Some multimeters (cheap ones) comes with thermocouples ( you could tape it on the tank.. and have a little fun) while measuring.

One more and final hint.. if you could....check the compression on each cylinder.
A compression gauge is a more specific tool... but consider to buy one!
I bought one a year ago. and I am really glad that I did ..  I always using it to monitor the cylinder an valves health).

I use an OTC-BOSCH gauge

https://www.amazon.com/OTC-5606-Compression-Tester-Kit/dp/B000R5CPAQ/ref=sr_1_fkmr2_1?ie=UTF8&qid=1532982916&sr=8-1-fkmr2&keywords=otc+bosch+compression

But.. for me bet #1 would be.. carbs!

Keep us informed!

[tobyd]

IR thermometer on order, been meaning to get one for ages as it is. Will report back with findings.

Might just be sloppy metal, the whole BW exhaust was sub £250 so maybe they used ex Renault fuego's for the steel...

the valves are all in spec, checked within the last few weeks. The plugs are new but got a bit gunked up when I was playing with the mixtures so might be due replacing. I think they got mixed up the other day too. the jets are quite recent, 125 and 40.

I had wondered about compression testing, the pistons have new rings but maybe I bollarded that up and one isn't running as nicely as the other? I'm not unhappy with the idle, im not hugely happy with the last 1/8th of the choke but the rest of it is ok. A compression tester would be useful to have but i'll check the actual temperatures first then move on. I'm not hugely concerned just doesn't look quite right...

cheers for pointers though, appreciated!

[tobyd]

looks like its 15 to 20 degrees celcius cooler on the RHS (when sat on the bike, facing forward).

I'll check the carb sync again at the weekend in case its that, seems odd though.

[tobyd]

might have just all been a big lump of skank in the air-jets (tiny little things on the intake side at the bottom). Whole load of carb cleaner and cleaning and its running happier if now a little rich.

developed a bit of a clickety noise spinning the back wheel even though the chain is in spec.

anyway, running nicer now. its spending some time at motorway speeds of late and once you get over being a sail its not too sad at 70 (or so). if you hunch down over the bars and look like a total hack its borderline pleasant!