Rev Limiter on CDI??

[lynngarner]

2001 Gasgas xc250. Runs great with one exception. When maxing revs in lower gears it feels like a rev limiter is kicking in. It has the stock CDI on it which I assume is Kokusan with an angled side and black wire covering.

Does this CDI have a rev limiter on it?? All this time I have been thinking I had a jetting problem, but I had not considered the possibility of a rev limiter with shorter gear ranges than I had anticipated.

Any input or thoughts are appreciated. The bike has a new nickasil cylinder sleeve and Wiseco Pistons and Rings with the stock Mikuni PWK. New Power valve as well. The bike idles and wide open its a monster till it hits that limit that I had considered jetting. Thanks for your help. lg

 

[SS109]

Two strokes don't have rev limiters.

 

[lynngarner]

1. Thanks for answering that part of my question. Is there anything else at play in a 2 stroke that could cause symptoms similar to how a rev limiter feels on a 4 stroke...moving up in power and speed beautifully, then suddenly pretty much falling flat on its face, very much like what it feels like when a rev limiter kicks in? Am I just hitting the top limit of the particular gear I'm in?? Is it a jetting issue?? Is it something else?

2. By the way, I see you are in the Southern AZ trail riders. I wrote to the AZ Trail Riders asking if I could post a couple of classifieds and I haven't gotten a response. Do you know who I should write to in order to find out?
Thanks..lg

 

[Zman]

I would:

1. Make sure the carb is level (it is on a complex angle on two axis.
2. Set the float level (see the sticky in carb section).
3. Make sure the plug gap is not too big.

It is odd that it will rev out in upper gears.
What needle and jets are in the carb?

 

[SS109]

1. Honestly, it can be a few things. CDI could be bad, could have a bad ground connection, bad plug wire (it happened to me!), bad coil, poor jetting, partially clogged main jet, silencer needs repacking or is internally broken (again, happened to me!), or something I can't think of right now.

What have you done to it so far? Clean air filter? Repacked silencer? Fresh and correct plug? If you're in Tucson I'll gladly help you figure it out.

2. Yes, I belong to TRS (Trail Riders of Southern AZ). We are a completely separate club from ATR (Arizona Trail Riders). They are Phoenix based and we are Tucson based. I don't know who would be the person to contact up there but fellow GG forum member AZRickD (http://www.gasgasrider.org/forum/member.php?u=459) is an ATR member so I suggest contacting him and maybe he can get you hooked up.

Do you do Facebook? If so, you can post on the AMRA Racing group (https://www.facebook.com/groups/106228189435274/ to sell or place wanted adds. In covers the whole state.

 

[(F5)]

It is entirely possible to engineer rev limiters in modern 2 stroke ignitions. Ignitech and several other are programmable which is amusing as I've had mates chase their tails before reaslising what was happening.

However the std ign, if it does have a limiter, I've never hit it that I've noticed.

Follow above advice but also check the jetting thread. Depending upon what gas is available and altitude you may find stock jetting may be too rich. My old 07 300 when fitted with later carb and RM needle is great, but it wouldn't rev out. On 300 and with our tight trails it took me a while to get bothered but done a main size and it was better, then another and better still. Probably worth trying another. One day.

Results may vary.

 

[gasgasman]

Also, check your power valve. It may not be opening all the way.

 

[lynngarner]

I'm working on answering your questions today to help eliminate some of the issues and clarify what has been done so far. I did most of this work in 2018, so I'll need to refer back and take a hard look at the bike and my documentation.

Thanks again for your help and interest. lg