Having recently purchased a 1973 Commando 850 Interstate, I have been working through some issues and have finally got her running okay but she struggles above 5000RPM becoming very sluggish and jerky to accelerate. Starts second kick and isles nicely when the choke is off, albeit a little high at circa 2000RPM. Bike is fitted with a single Mikuni carb. Any suggestions or help appreciated.
Acceleration
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I fitted a mikuni to my…
I fitted a mikuni to my 850mk3 many years ago. It takes a fair bit of jet changing to get it right. When you do it's worth it . Victory tuning for vm carbs was invaluable. Still available ? Also , after a three year lay up I had to strip it and totaly clean it out due to modern petrol crap! Obviously check timing etc first! Roy Jack.
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Thanks Katherine. Plugs are…
Thanks Katherine. Plugs are fine and the bike has had an electronic ignition fitted at some point so I suspect your suspicion may be right. looking at the paperwork, the bike has only done around 200 miles in 5 years so hasn’t moved a great deal. I’ll get the carb stripped and start from there. Regards. Craig
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Hi Craig
As you have not shared to much detail on plug colour, Ignition system etc bike history. This can only be a guess if the bike has been subject to a long layup and old fuel turned nasty in the float bowl ? coul be the main jet has a restriction of lacquer float level and fuel flow are always worth a check.
Best regards
Katherine Scott