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lingeringstin...
Trackday Trickster



Joined: 01 May 2014
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PostPosted: 00:03 - 25 Apr 2024    Post subject: Reply with quote

If you've been inside your carb then you've probably already seen everything but one time I had a bike that would start and idle fine but the moment you opened the throttle it would die. Turns out the fecking needle had actually come loose from the slide (little clip thingy failed) and it was just sitting loose down in the main jet regardless of what I did with the throttle.

I don't know which carb you've got but on a lot of them the idle jet and the main jet are at two different levels in the fuel bowl, so the idle may be getting fuel but if the floats are out of order there may not be enough fuel in the bowl to come up to the main jet.

Also some carbs (old Honda designs as I recall) incorporate a little pump mechanism that was supposed to give a wee squirt as you opened the throttle but they were shit and if the pump wasn't working right all you'd get at initial throttle blip was a suction of mostly air and the bike would die.
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vorlon
Derestricted Danger



Joined: 14 Apr 2024
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PostPosted: 22:39 - 28 Apr 2024    Post subject: Reply with quote

so update.
took the carbs off and cleaned them, put back and found the choke cable was no good. ordered a new one. carbs off again and another clean. put back on. took all the fuel out of the tank and replaced with new E5.
engine started but seemd to be on choke all the time. so off again and given a good look. it seems that i bent a tab which is part of the return spring. bent it back and back on again. success and its seems to be running ok.
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vorlon
Derestricted Danger



Joined: 14 Apr 2024
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PostPosted: 18:44 - 08 May 2024    Post subject: Reply with quote

so bike runs now but a new issue. the trip meter is not working, this appears to be digital. any clues please?
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lingeringstin...
Trackday Trickster



Joined: 01 May 2014
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PostPosted: 01:21 - 12 May 2024    Post subject: Reply with quote

I'm running near as dammit that same engine and they're basically quite reliable with not much complication. However, I have found mine to be the pickiest engine I've ever had regarding carb issues. It throws a wobbly at the slightest malfunction when most of the bikes I've ever had would tolerate with all sorts of carb shananigans.

I don't know why those particular Honda engines are like that but bear in mind that it's basically a 125 twin (exact same valves and cam) that was poked out to a 250 before they stopped making them altogether.

I don't remember if your model had one or two cv carbs setup but mine is really happy now with a single 27mm slide carb and a Quadzilla quadbike single carb intake. Never had any issue with the ignition system. It's the easiest bike to bump start I've ever had, so I wouldn't think spark was the issue.
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stinkwheel
Bovine Proctologist



Joined: 12 Jul 2004
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PostPosted: 08:48 - 12 May 2024    Post subject: Reply with quote

vorlon wrote:
so bike runs now but a new issue. the trip meter is not working, this appears to be digital. any clues please?


I don't know about yours in particular but Honda went through a phase of using a flexible PCB in the back of their instrument panels. They turned out to be very prone to corrosion or delamination of the tracks. If your bike has one of these, the damaged tracks are visually obvious as a darker colour than the others or even green and corroded or broken. The tricky bit is getting to the back of it, usually requires a lot of dismantling.

If you're very good with a soldering station, you can re-flow the tracks or solder a wire to bypass the bad sections. Or you can rip the whole thing out and relace it with conventional wired connections. Both options take a degree of familiarity with building/repairing electronics and a methodical approach.

Could also be as simple as a bad or corroded connector either in the back of the clocks or at the sender. If the speedo is working, it's probably the clock end.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.
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