58 IRS Carb re-build
04-28-2022, 03:43 PM
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Join Date: May 2005
Location: Alexandra, Victoria, AUSTRALIA
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58 IRS Carb re-build
Guys, after a weekend of frustrating non-starts, part starts and running for a few seconds, I’ve dumped my fuel and decided to rebuild the HDA 189 on my 58 IRS using the Walbro K21-HDA kit.
The Regulator side is OK. Went together with no problems.
The Pump-side is another matter. The different diaphragms shown in various YouTube videos and the Walbro HDA manual are very confusing. The kit I have will cover a number of HDA variants. The question is, which of the 3 diaphragms supplied apply to the 189? The issue is the intermediate diaphragm – the one between the primary on the carburettor body and the cover gasket.
As supplied with the engine, the intermediate diaphragm has no valve leaves, yet the Walbro manual shows both this and the primary with leaves.
Here’s a link to the Walbro HDA manual. HDAseries.pdf
Part # 26 on the exploded diagram is the one.
Your guidance please. Peter
The Regulator side is OK. Went together with no problems.
The Pump-side is another matter. The different diaphragms shown in various YouTube videos and the Walbro HDA manual are very confusing. The kit I have will cover a number of HDA variants. The question is, which of the 3 diaphragms supplied apply to the 189? The issue is the intermediate diaphragm – the one between the primary on the carburettor body and the cover gasket.
As supplied with the engine, the intermediate diaphragm has no valve leaves, yet the Walbro manual shows both this and the primary with leaves.
Here’s a link to the Walbro HDA manual. HDAseries.pdf
Part # 26 on the exploded diagram is the one.
Your guidance please. Peter
