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How do bikes know when to break?

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Greebo:

--- Quote from: MarkCR750 on May 20, 2016, 08:35:54 PM ---I've done about 350 miles without issue , tomorrow I'm booked in for a dyno fuelling run, I start the bike tonight and it's running really rough, a quick feel of the pipes says No1 cylinder isn't firing, or hardly firing, all I've done in the last few days is take the carbs off and put them back on, and adjust the mixture screws, when I put the carbs back on No2 carb overflowed, I gave it a few taps with a screwdriver handle and it stopped overflowing, so I guess it was a sticking float/float valve, I had turned the mixture screws in a bit yesterday so just now I turned the No1 screw out half a turn, then tapped the No1 carb in case the float/valve was stuck and not letting fuel into the bowl, it ran rough for about 30 seconds then after giving it a few revs it's running fine and the No1 pipe has come up to the same temperature as the others , how does an inanimate object know to start playing up just when it shouldn't ??🙄, any thoughts on what the issue could have been, I'm thinking stuck float?.

--- End quote ---

Hi Mark
this is exactly the same as what I had trouble with after the winter lay-up, when I put her to bed last November it was running great, when I put her into winter storage I emptied the fuel tank & drained the float bowls...
This April filled the fuel tank opened the fuel tap & within 2 minutes petrol was p*ssing out of carb 1, like you i tapped the carb, & then sprayed carb cleaner into the air intake,& that did the trick, when I got the engine started cylinder 4 was not firing, looked at the plug which looked OK, just a tad brown[ which is a new iridium] so then tested it for sparking out of the cylinder & it seemed Ok, so then checked that the accelerator pump was pumping fuel into that cylinder that's was Fine...scratching head violently ,.... so I phoned a friend , he said put another new plug in, so I did, & bingo it fired up & all was well again...for a while >:(
.....what very strange & temprimental animals these bikes are... ::) :o

Re: Dyno I reckon you get around 57bhp ish...which at the rear wheel is quite good.
We await the verdict ...
just hoping you are not also a fisherman Mark...
I caught one this ********************************* Big ... ;)

MarkCR750:
I got 53bhp, he said the exhaust is too restrictive, I'm not changing it though cos it's quite loud enough!, I was thinking it would be closer to the original claimed 67bhp but did Honda give the power at the crank?, if that's the case take off their exageration and dial in the transmission loss and wear (plus tappets etc need setting) and it's not such a bad result, fuelling is bang on which is what I was most concerned about , here's a YouTube link, no that's not Guy Martin, it's world champ Sam Ermelenko , google him .

https://youtu.be/dzyp3A1TQBY

PS that result was with 3 plug caps pulled off, God knows what it would have made on all 4 cylinders! 😀

royhall:
If its an F2 engine and carbs it should be 72hp.

MarkCR750:
It's a K6 Roy, PD carbs though , do you know if Honda quote crank or rear wheel bhp in their specs ?, I've been googling but can't find anything, my guess is crank because they'd want the highest figure for marketing reasons, so they'd get the best engine possible, then run it in perfect conditions , then lie a bit as well 😀 , my T250 was marketed by Suzuki as a 100 mph 250, then years later they brought out the X7 and called it the worlds first 100mph 250, maybe they forgot they'd made the T250 ? 😏

Trigger:
Had a look at the vid Mark and it doesn't look like he took it to full power, did he take it to 8500 RPM ? The figures look all blurry to me.

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