Hobbit CDI

does a hobbit cdi have a rev limiter?

Re: Hobbit CDI

not that i am aware of.

Re: Hobbit CDI

i always ditch hobbit CDI when i could have points instead, the honda electronics are seriously bulletproof.

Re: Hobbit CDI

Before you decide to switch out your points, check your timing. Who knows, it could just be off a smidge.

Re: Hobbit CDI

King Drunky JCams /

Can you advance timing on a Hobbit?

Seems like I've looked and you can't... at least on the ones with points....

If you can, please enlighten me.

Justin

Re: Hobbit CDI

>i always ditch hobbit CDI when i could have points instead, the honda electronics are seriously bulletproof.

why would you have points rather than CDI? CDI seems more bulletproof -- nothing to wear out

Re: Hobbit CDI

Raymond Rexroad /

Timing for the PA50 CDI is not adjustable. Neither the stator baseplate nor the CDI pickup mounts are slotted.

Timing for the PA50 points is adjustable - somewhat. Similar to the stator for the CDI system, there are no slots for adjustability. The point gap can be changed, and changing the point gap will change the timing. However, this method of changing timing is limited in its usefulness - since in order to "advance" the timing, the gap would have to opened slightly wider than the stock setting - and when you do this the dwell time (the amount of time that the coil "sees" current) is reduced. Without enough dwell, the spark "strength" or intensity will be reduced.

When your dwell is too short, you'll "see" it at higher RPMs - the point contact is closed shorter than normal, and the as engine speed increases, from a time perspective, measured in milli- or micro- seconds, the amount of time gets shorter and shorter - until it is too short - the coil does not saturate (the amount of current does not build up to its normal value), and the available spark energy (when the points open again) drops.

So - yes, you can "play" with your points to advance timing, but you may create high RPM problems. The only way to know if it will work for a PA50 is to try it. OR - maybe someone else already has . . . ?

Re: Hobbit CDI

Raymond Rexroad /

does a hobbit cdi have a rev limiter?

This question has been asked before, and the answer has always been NO, but I'm not so sure.

Usually, the question revolves around whether or not the stock CDI design contributes to, or is a part of the overall "speed limiting" designed into our Hobbits.

However, it is NOT clear whether or not the stock CDI becomes a limiting faster at higher than stock speeds.

I mean, at the stock 5500 RPM (or so) top engine speed - I'm confident with everyones answer that the CDI does not retard the timing. There would be no need to, since the points bike was already limited to the same speed before CDI came along.

However, at 10000 RPM, I would venture to say that either no one knows, or that I haven't read that anybody knows.

The point is - that the CDI used in our Hobbits was also used in a number of other bikes (see the wiki in the Parts section). Honda may have designed in a limit for another bike, but that limit is above what a stock Hobbit would ever see.

But - let's get this question answered!

Anybody out there with a fast CDI Hobbit? Put a timing light on your Hobbit, and run it on the center stand wide open. Let us know the results. Most CDIs with a "designed-in" restriction will start to retard the timing at a RPM point - and the amount of retard grows after that point is reached.

If you send me the results, I'll update the wiki.

Re: Hobbit CDI

To put it simply no the hobbit cdi dose not have the capability to change timing or limit your revs, how ever on my currant set up I can exceed 10k and I know for a fact that the CDI dose not preform as well on the top as the points. Im not an engineer, I cant tell you why it dose this, only that it dose.

Re: Hobbit CDI

hence the reason i swap for points.

CDI isnt always the best.

Re: Hobbit CDI

Raymond Rexroad /

Nate,

Have you used a timing light, or some other means, so that you KNOW that the timing is not shifted at the higher RPMs? Or was it a case where the spark became intermittent (i.e., a high speed miss, or similar)?

For other CDIs that do have a limit, a capacitor is used in a specific part of the circuit to cause this shift. Without dissecting a CDI unit, how do we know that this is designed to limit or not?

I'm only hoping that someone will use a timing light and do a simple test. Then we'd know for certain.

Re: Hobbit CDI

nate, I can't wait to see you hit ten thousand revolutions per minute. You'll have to give me a head start though.

Re: Hobbit CDI

To make it be restricted, the CDI unit would have to be "smart". AFAIK, the Honda CDI unit is relatively inexpensive and is small -- there's no way it can have logic inside that would restrict the timing like that. The problems are high RPMs are merely a function of coil and capacitor size. The cap just cannot charge fast enough at high speeds.

A generic CDI unit is pretty simple to build. It's trivial to find bigger caps, and to save space you can also find one of those nifty coil-on-plug devices, although that may be overkill. Let me know and I can find some schematics.

Re: Hobbit CDI

Raymond Rexroad /

No - it does not have to have logic in order to be restricted. An analog design can be simply designed to cause a shift - using simple and cheap analog components.

I agree with you that there are limits to how fast a capacitor can charge, and it is also dependent on coil inductance. However, there are other small, cheap, analog CDIs that are designed to change timing.

First, I'm just trying to get to the facts, and get away from opinion.

Second, since the Hobbit CDI was used on various other Hondas, it is possible that a "limiter" of some type/design does exist - and again - that the limit is not used as part of the 30 MPH design limit of the system on a Hobbit.

Re: Hobbit CDI

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

i bet the cdi timing is just set to perform for a stock bike is all. turn your backing plate holes into slotted holes so that you can adjust the timing, then you can time for top speed if you like.

i haven't seen this cdi setup, so i can't say for sure, but from the descriptions in this thread, it sounds pretty easy to fix.

Re: Hobbit CDI

I would also throw out the opinion that someone should just put a timing light on it and see what happens. Generally at the extreme high rpms a CDI should be more consistent then points. It's simply why that is true so I'm not going bother going into details. Also if the CDI does seems to be somewhat flaky at high rpm it would point to the box and those can often are interchangeable for another box. Coils and Pickups are usually very reliable devices. I also wouldn't bother swapping out the ignition for something else, I would either figure out why my CDI is being lame or I would just stick with whats on the bike since the honda points ignition is very reliable.

-naz

Re: Hobbit CDI

Raymond Rexroad /

urn your backing plate holes into slotted holes

Unfortunately, you can't do that on a Hobbit stator :(

Re: Hobbit CDI

You can't turn the stator but you can turn the pick up on the stator to adjust the CDI. There are some screws on it, by where the blue/white wire is.

This is from a Camino though so I don't know if it's different than the US version. Once I have it hooked up I'll get Naz to shine his timing light upon it. And it will be glorious.

Re: Hobbit CDI

looks the same as the US units.

Re: Hobbit CDI

I'm going to guess about any Yamaha jog or similar 2-stroke cdi box should work with that assembly.

-naz

Re: Hobbit CDI

Raymond Rexroad /

My spare CDI stator does look different that your pic.

The pick-up for the CDI is not adjustable on my spare part.

Not only that, buy my spare has two coil assemblies, plus the one CDI pick-up.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account