Carburetor KEIHIN Carburetor troubles

[Noddy]

Try a repair on the outside of the the carb with some thing like Aradite (or similar). It will prove that the 'crack' was the problem. It will be OK to ride with but it may not be a permanant repair.

[The Yukon Sizzler]

Originally Posted by Charlie Brown

Carried out a thorough crack search on the inlet manifold with a magnifying glass, none found but looking over the carb in the same way I found what looked like a crack and yes, petrol brushed on the outside appears on the inside! The crack is on top of the carb just inboard of the choke valve.

PMSL. There ya goo Char....told you it was carb icing or the coil.....

[Charlie Brown]

I was thinking along the araldite lines and also have been told about 'liquid metal'.I know nothing about it,how about you guys.I think it is an apoxy resin with aluminium powder in it.Sounds good to me.
I will keep you posted.
Cheers.

[Phil]

If you are searching for an intake leak warm the bike up & let it idle.

Spray around the intake manifold esp where it joins the head with carb or brake clean. Listen for the engine note to change where there is a leak, including the carb.

Inspection visually will not show up a loose manifold connection, or worn out gasket.

[English Steve]

Originally Posted by Phil

If you are searching for an intake leak warm the bike up & let it idle.

Spray around the intake manifold esp where it joins the head with carb or brake clean. Listen for the engine note to change where there is a leak, including the carb.

Inspection visually will not show up a loose manifold connection, or worn out gasket.

Yes, or use WD40 - if there is a leak the revs will increase slightly.

[Charlie Brown]

Repaired the crack with steel putty, good product, after carefully grinding small groove over the crack. Reassembled cleanly and carefully and hey, the bugger got worse! Pretty confident that the carb is airtight and good and that the problem lies elsewhere. Got a new coil ordered, should have it mid week.
I would try testing with a spray but it barely runs before it coughs out now.

IRONHEADS FOREVER (broken)

[rich16]

Bit fiddley but try taping the manifold joints and also over your repair with electrical self adhesive tape and burnish down. Clean surfaces of oil and grease before. This is no way permanent but may help confirm you have an airleak.

Also check your bypass or idle ports and bleed tube are clean, it's not always the jets. From memory, you have an accelerator pump on your carb, check the accelerator pump diaphragmn is not damaged, this can be a symptom of poor acceleration, if it is renew.

Cheers Rich

[kiwidave]

just as a thought, you can pick up those carbs for very little money now, especially off swap meet forums online such as

THE HORSE BC Swap Meet

or even go to a CV. They work good on Ironheads. See other threads here.

Just in case you get tired of messing with that one.

I actually have a spare Keihin butterfly but it's in a garage in Newcastle and I am in Melbourne....but someone else here might have one....

They are good carbs, despite what many folks seem to think of them. My 1985 FXEF still has that carb on it as per OEM, and it always performed great. Good luck.

[Scotty]

My money's on electrics, if i were you i would put new HT leads on with a set new plugs when you get that coil.
Any one or mixture of the three can cause your problem.
Or even the ignition.

[Charlie Brown]

Finally got the new coil today. Whilst waiting for this to arrive I checked inside behind the points cover and found that one of the advance retard springs had broken, replaced the pair, made no difference. Fitted the coil this evening, again made no difference. Time to step back and think again. Checked the valve clearances, all good, checked the timing, good then remembered to check the points gap, virtually closed! Set the points and re-timed. Result, Job done. Can only think that bits of spring flying around in there must have had some bearing on the gap closing.

You have to bear in mind this all started hot on the heals of me cleaning muck out of the accelerator pump and fitting an inline fuel filter. My mind was understandably thinking carburetor.

Here endeth the lesson! We live and learn.