Experience sought..

[thetrickcyclist]

....about the DCOE/bike carb conundrum.

CVH running Twin 40's. Now just been professionally rebuilt/serviced.

Which is fine.

However just have this bloody itch.

They are great when running well but they start to drift off peak performance with use.

Now this wouldn't be an issue however when it comes to these I personally don't have the depth of experience to diagnose or fettle these correctly.

Now, ok, TB's and injection are obviously the gold standard, however not having much in the way of gold, I'm looking in other directions to gain longevity of tune

I have read some interesting things about bike carbs BUT what has generated my interest is their ability to stay on tune/sync once set up.

Engine is my ubiquitous tuned cvh, output is 130 ish when everything is singing to the same hymn sheet, I'd like it to stay that way as a minimum.

So what are peoples experiences going over to bike carbs?




PS and yes, I am not considering the ZVH route for the foreseeable future, far too complicated with the de-dion rear setup.

[PeterBurgess]

To be honest I don't know why your carbs would change settings unless something on the linkage is wearing rapidly or a screw has vibrated to a different setting? I suppose, if the throttle stop hasn't been set well and the pedal still has a bit to go at full throttle the linkage could get bent and not work evenly. Usual culprit is spark plugs need a clean or replacing. Always make sure air filters are clean and not over oiled. Don't overtighten the carb to manifold gaskets.
I have never been a fan of bike carbs on car engines. Most of the manifolds made or for sale are absolutely cr*p and have very poor flow and fuelling characteristics. Most of the available carbs are donkeys years old and worn out, especially when you find out the slides/pistons are made from plastic! Most folk who have fitted bike carbs, in our experience, thought about Dellortos or Webers but didn't want to shell out in the first place but wish they had with hindsight.

[anonymous-user]

The first question is "what is your ignition system"?

Sure, fuelling is important, but an AFR or two actually doesn't make that much difference (ie the engine will still run) but if your ignition is all over the place, then you really notice that!




(note: i'm not talking about emissions, or ultimate performance here, i'm talking about say being 11 to 1 rather than 12 to 1, on a low tune engine, that really isn't going to make a lot of difference)

[stevieturbo]

Cars used carbs for decades, people did, and still do tens of thousands of miles a year in carb cars without major issue.

So if yours are built/setup correctly, as others say there is little reason you shouldnt get many thousands of happy miles without needing to look at them.

[thetrickcyclist]

Fair enough.

Two reasons that I can see from my...position..

..all controlled from same shaft with no dodgy widget in the middle ..

and some have TPS rigged already, a big plus..

Sorry should have been FOUR, CV operation as opposed to pulsing.and most importantly someplace to set them and map ignition-probably the most important.

cheers..

Edited by thetrickcyclist on Sunday 30th December 22:02