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Discussion Starter · #1 ·
Hi Everyone

I’m looking for some guidance on getting my H1 back to smooth running.

Backstory - the bike was stood for a few years & wouldn’t run so I had a major service including a carb deep clean & reset from a local mechanic here in Northants, UK. The assessment on the carb post clean was that it was on the limit.

The Problem - when I picked the bike up it was not running well, backfiring & bogging down betwen 2500-4000 RPM. So I took it back & it was sorted with adjustments to idle & carb settings - so I’m told !

Fast forward six months & half dozen Sunday trips of 40-75 miles at pace later & the problems back.

Scenario is:

Cold starting with half choke & no problem. Pulling away from a 5 minute idle - smooth & no problems.

15-20 minutes into steady 10-12,000 riding & all is good until dropping down to low revs / speeds.

Slowing & coming to a stop needs a lot of throttle management to keep from stalling.

Pulling away takes revs & clutch to get through the 2,500-4,000 flat spot.

Once back above 4,000-10,000 there’s some noticeable flat spots on the way at about 6-8,000 and it takes effort to keep the right gear / rev / speed combination.

Next Steps: with the cold weather coming I’m not likely to ride again so am thinking to diagnose the fault & get back to smooth running again next spring.

Any advice & experience shared appreciated & any referrals to top notch ZXR mechanics welcomed.

All the best, Will

4,860 Posts
On older bikes, the cleanest carb in the world can get plugged up in a matter of minutes or days or weeks depending on the condition of the fuel, the condition of the fuel tank, the tank's sock filter and the condition of the fuel lines IF it does not have an inline, aftermarket fuel filter between the petcock and carbs.

Since the rubber fuel lines can degrade and send tiny bits of rubber to the carbs, I would replace all fuel lines just on spec and add a filter and then clean the carbs.

Now of course it could be something else causing the problem, but if you don't have an inline filter, I would be considering dirty jets as a likely suspect.
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