Honda 4004

[John rainford]

Hi everyone
Got a Honda 4004 had the engine professionally rebuilt had the carbs cleaned but not stripped or any parts replaced. When I ride it, it develops a knocking noise it doesn’t rev right and stalls at low speed also it runs very hot I’ve checked cam chain,valves  did put a electronic ignition in it. I’m leaning to rebuilding the carbs if anyone has had the same problems I would be interested to hear from you
Thanks John

[Bryanj]

Knocking is bad, along with overheat could be a siezed piston

[Sesman]

Just to clarify, Was it ‘knocking’ before you fitted the electronic ignition?

[Matt_Harrington]

What sort of knocking noise. If timing is out, then it could run hot and 'pink'. Just a thought...

[John rainford]

Not right sure, cold not be sure on that one, the bike was a mess when I got it 4yeas ago and completely rebuild it ,looks the part I’m leaning towards the carbs might just completely rebuild them and see how I go.
Thanks again for looking

[Matt_Harrington]

Getting the carbs clean and operating well will help you pin point the issue.  Photos of bike? We all like a photo.....

[K2-K6]

Quick and dirty check to confirm if it's actually running on all four cylinder to give you a base line, start from cold, run 20 seconds and switch off.
Then check each header pipe for temperature, spit and wet thumb method  just to give you a reality check. Often they're not and it will still pull itself around but with similar to symptoms you described.

[McCabe-Thiele (Ted)]

They certainly can run very poorly when the carbs are not spot on plus the dynamic timing needs to be correct for cylinders 2 & 3 not just 1 & 4. Depends what system of electronic ignition you have if that is fixed or adjustable.

Cylinder in-balance during running can make some horrible noises - as regards running hot most probably as it's running too lean.

If the carb emulsion tubes have never been out they could well be full of dirt - easy enough to remove and clean out if you are careful. New O rings a must - did you replace the fuel strainer in the tank - worth doing imho.

Lastly have you tried removing the plugs and turning the engine with the kick start by hand to get the feel of the engine as the pistons move through the cycles - does it feel reasonably even. Try to avoid thinking the worst until the carbs are done it will feel like a different bike. I assume you did the camshaft chain tensioning adjustment - another source for noises.

[K2-K6]

Don't forget the Ted special Ted  coils fire the outer two from one coil and inner two cylinder from the other coil.

So, 1&4 fired from single coil, then 2&3 from the other single coil, not (as may seem logical to the uninitiated) one coil firing the two plugs nearest to it on one side of bike and visa versa.

Often done over the years if not familiar in fitting a new ignition setup.

[McCabe-Thiele (Ted)]

Will no one ever forget my beginners blunder.

I still marvel at the fact it got me to Ashbourne & back a couple of times as a two cylinder bike
.