Honda XL500 carb spacer

[tevie54]

Hi, Does anyone know what the phenolic spacer that goes between the carburettor inlet rubber and the cylinder head does, do I need it? I'm fitting an XL500 engine to my XL250 so obviously there will be a certain amount of modification needed but I'm just wondering what this spacer does.
Any info would be greatly appreciated
Steve

[Propellor]

A heat break I'd guess

[tevie54]

It could be although the 250 doesn't have one

[johnr]

500s ran hot. they had a problem when they were really hot of fueel evaporating in the carb causing uneven running.

[tevie54]

Of course, when I googled phenolic spacer it immediately came up with heat insulator. They're no longer available from Honda and they're quite expensive second hand so I wonder if I could make one out of nylon or tufnell

[themoudie]

Aye tevie,

Nylon 6.6 sheet [-40˚F to +390˚F (-40˚C to +199˚C)] has better heat resistance than either Tufnol [Continuous = 90°C, intermittent = 125°C] or Nylon 6 sheet [Continuous = 115°C, Intermittent = 170°C].

Amal supply Tufnol spacers for Monobloc and MKI and MKI½ that are 5mm thick, but I suspect are too small a diameter bore (26mm) for the inlet you have and cost £11-99 inc VAT + P&P. Amal_Tufnol_spacer_26mm

Alternative would be to use nylon 6.6 sheet. Direct Plastics supply (many other suppliers, I have not bought from this or other suppliers) Direct_Plastics_nylon6.6_sheet_6mm_thick

Another possibility is to buy a spacer from NRP-Carbs, they also supply diaphragm kits for carbs and their products are good. NRP-Carbs_XL500_carb_spacer

Hope this helps.

My regards, Bill

[Moto63]

Morning Bill, as usual your knowledge of part suppliers astounds me. I certainly know who to ask shud I ever require that elusive part..... you da maaan 👍👍👍😁🤘
Cheers, Michael

[johnr]

i suppose you could buy a chunk of bakelite and get busy with the files and emery paper.

[tevie54]

Thank you all for the information, I think I shall be making one out of 1/4 nylon. I have something in the shed that looks awfully like one so I'm wondering if I've previously experimented with carb spacing on the 500RS