Special Tuning Tips for ’77 GL1000s + Carb Top Service

You might consider this item: Randakk’s GL1000 Carb Rebuild Video

Honda made a number of jetting tweaks in ’76 (K1 and LTD) and again in ’77 (K2) for US-bound GL1000s to cope with tightening emissions regulations. Other markets were affected as well. Honda necessarily made the bikes progressively leaner through these model years. Social responsibility is a good thing for large corporations, but these were not great moves from the rider’s point of view. Riding a bike with overly lean carburetion may be “green,” but it certainly can be frustrating.

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December 5, 2012 5

Air Cutoff Valve Overhaul

You might consider this item: Randakk’s GL1000 Carb Rebuild Video

The air cutoff valve is a simple but vital component of the carburetor system on GL1000s. Its function is to eliminate backfiring on hard deceleration (throttle fully closed). Hard deceleration creates a high vacuum signal in the intake tract which activates the valve. When activated, it restricts the flow of air to the external idle circuit air jets thereby richening the mixture. This slightly richer mixture is calibrated to eliminate backfiring in this operational mode.

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December 4, 2012 9

Problem with Aftermarket Jet Needles

You might consider this item: Randakk’s GL1000 Carb Rebuild Video

Recently, I’ve discovered some improperly sized jet needles that were provided with aftermarket carb rebuild kits. The needles looked identical to the original but did in fact have a significantly narrower cross section at the mid-point of the tapered section.

Effectively, this made the needles much richer. The brand in question is NAPCO and the kits were for a ’76 which happens to be one of my bikes. The result of these improper needles was the bike in question ran fine near sea level (although a plug check showed it was running slightly rich in the mid-range and the fuel mileage was terrible).

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November 30, 2012 0

Throttle Return Spring Details

You might consider this item: Randakk’s GL1000 Carb Rebuild Video

Recently, a GL1000 owner was in my shop with an odd complaint. He reported that very heavy pressure was required at the throttle twistgrip to increase or maintain engine speed. Suspecting that the throttle cables were worn or damaged, the owner had just replaced both throttle cables, but this offered no improvement.

My test ride verified that indeed there was something amiss. This bike ran great, but after just a few miles the effort required at the throttle made my right forearm ache!

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November 29, 2012 2

Old School Carb Cleaning Methods

If you’ve watched my GL1000 Carb Rebuild Video, you know that I’m strongly opposed to total immersion chemical carb cleaning methods. The very harsh ingredients in these “buckets of doom” are bad for your carbs, your health and the environment. The lubricating/sealing felts used on the throttle and choke butterfly shafts on GL1000 carbs are particularly vulnerable to such abuse.

Heaven forbid you were to carelessly dunk your GL1100 carbs in one of these buckets. Your air-cutoff valves as well as the accelerator pump would quickly be history if they were left in place. Sadly, GL1100 air cut-off valves and accelerator pumps are frequently ruined by indiscriminate use of carb cleaners (even with no dunking) due to their vulnerable locations.

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November 15, 2012 15

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