Hawk REV LIMITER??

[davisbm2]

I have had this issue where the bike cuts out suddenly at high RPMs. Like it is starved of fuel or has some electrical issue.

It only cuts out for a second and then is right back to it. It does this in every gear, cuts out at high RPM. When I reach the bikes top speed it cuts out or "stumbles" (the bike is not turning off just missing).

Then it occurred to me, does the Hawk/ Magician have a REV LIMITER? Maybe in the CDI? In that case I have been hunting a made up problem.

[JerryHawk250]

The RPM limiter is set at about 8500 rpms. Are you still running the stock carb with stock jets? If so, then it is running lean.

[davisbm2]

Just took it out to 8000rpm. If I do it slow it will go to 8,000 no problem, if I punch it it does the jerking thing at 6000rpm.

It does feel like a fuel issue but it has done this since the first day I had it, and I upjetted first to 115 then to 120. Im not the first to have this issue with the Hawk/Magician but I have never read a thread where anyone solves it.

[Ariel Red Hunter]

Originally Posted by davisbm2

I have had this issue where the bike cuts out suddenly at high RPMs. Like it is starved of fuel or has some electrical issue.

It only cuts out for a second and then is right back to it. It does this in every gear, cuts out at high RPM. When I reach the bikes top speed it cuts out or "stumbles" (the bike is not turning off just missing).

Then it occurred to me, does the Hawk/ Magician have a REV LIMITER? Maybe in the CDI? In that case I have been hunting a made up problem.

Wow, you're banging on it pretty hard, hitting the rev limiter in every gear. That's 8500 rpm. Power peak is 7300/7500 rpm, and peak torque is about 4500 rpm. Power is falling rapidly after 7500 rpm. If you want better perfomance, you will have to explore C.P.E. Carburetor, port job, exhaust system. I write a column called "Hawk Talk" on here that goes into this in excruciating detail. If you want to learn more on this subject start from the first post and skim until you get to "Joe Craig". Read it carefully, put it aside, then read it again, at least three times in order to let what he says take root in your brain. He was called "The Wizard of Bracebridge Street" for a reason...ARH

[davisbm2]

Ha nah I shift like I should, the bike only has 500 miles on it and I still consider that a break in period. I just wanted to engage the rev limiter to see if that's what I was feeling.. It's not. Problem remains.

[JerryHawk250]

Are you running stock exhaust? May be running rich and loading up on fuel when you punch it. 120 main is on the rich side even for a free flowing exhaust. 110 is about right for stock exhaust.

[Megadan]

I agree, too Rich on the main. My last Hawk had similar behavior when I tried a 120 main with full exhaust, pod filter, and upgraded NGK Iridium plug gapped to .034 and upgraded coil. I found a 115 to work the best on hotter summer weather, and a 117.5 for cooler months. This effect can be even more prevelant if you are running a tad on the lean side with the needle jet. If it goes from a bit lean to a bit rich fast enough, this will cause a stumble as well. If you can raise the needle another notch, see how it acts. Otherwise, swap out the main a half or full size lower.

[davisbm2]

Thanks guys... however... this EXACT problem happened when I first got the bike (super lean), when I put in a 115, and now it still exists at 120. My needle is shimmed already.

I did a plug chop, looks really good. Maybe a tad on the rich side, but acceptable. It feels like it is losing fuel when it stutters, but I doubt it. Lines are all good, it has good gas.

So.. electrical? Plugs look good... Bad CDI? Bad plug wire? What known problems exist with these bikes that can cause this problem???? This seems like a more rare issue, but like I said before THIS IS A KNOWN ISSUE, I have seen it posted on here before but no answer was ever established..


http://www.chinariders.net/showthread.php?t=14417

[JerryHawk250]

A few things to check are grounds and connectors to CDI, coil are good. A bad ground or loose connection can cause a weak spark which would explain the sputtering if you punch it. Too much fuel at one time and the spark is too weak to burn it. I had a loose pin on one of the connector to the CDI that caused the same issue. I also upgraded to a coil on plug and now have a much stronger spark.

[JerryHawk250]

Did you upgrade to a NGK plug? The stock Torch plug are junk. That was one of the first things I changed. It didn't take long before it was acting up but I knew that was an issue before I bought the hawk.

[bogieboy]

Check the wiring to the coil.... mine had loose wiring and did just that.... also check the CDI connectios are tight as well...

[davisbm2]

Gracias Amigos, looks like I'll check all my connections again. I did put in the recommended NGK.

Two questions, one off topic and one on:

What is a coil on plug?

And what oil are you guys using? I use rotella 15W-40 and I haven't been happy with how my gears feel (a bit "clunky"). I see motocheez uses Valvoline 10W-40 synthetic for motorcycles. I'd rather use the Valvoline to be honest, the bike has 500 miles, is it ready for synthetic?

[JerryHawk250]

Originally Posted by davisbm2

Gracias Amigos, looks like I'll check all my connections again. I did put in the recommended NGK.

Two questions, one off topic and one on:

What is a coil on plug?

And what oil are you guys using? I use rotella 15W-40 and I haven't been happy with how my gears feel (a bit "clunky"). I see motocheez uses Valvoline 10W-40 synthetic for motorcycles. I'd rather use the Valvoline to be honest, the bike has 500 miles, is it ready for synthetic?

Click on the link (Direct Ignition Coil) in my sig.

[bogieboy]

Coil on plug is exactly what it sounds like.... modern automotive ignitions have moves away from a single coil and distributor set up, as well as multi coil packs, and have moved towards "coil on plug" i.e. theres a coil built in to the spark plug "boot" and does away with the need of high voltage spark plug wires that wear out.

As for oil.... thats a whole nother can of worms....LOL i would say go ahead and run the syn... but i am also a fan of a hard break in technique, vs the long and slow 500-1000mi techniques that some use... 99% of the stuff thats gonna "break in" has done so in the first 30 miles (all my opinion, i dont have scientific backing on hand, but i am a mechanic, and have over 10,000miles of trouble free running on my Roketa db07a that had hard break in...)

[Megadan]

Originally Posted by davisbm2

And what oil are you guys using? I use rotella 15W-40 and I haven't been happy with how my gears feel (a bit "clunky"). I see motocheez uses Valvoline 10W-40 synthetic for motorcycles. I'd rather use the Valvoline to be honest, the bike has 500 miles, is it ready for synthetic?

Run whatever oil floats your boat. The Rotella is good for the break in period, and you have basically passed that at 500 miles. No matter what oil you run the gears will still feel a little clunky. My Hawk was pretty notchy shifting until I had over 1000 miles on it. Just also remember that these engines have a small capacity and rely heavily on the oil for cooling, so the oil takes a lot of abuse and doesn't tend to last as long. Depending on where you live and how hard you ride, a 500-1000 mile oil change interval isn't unusual. This is true even of many big brand dirt bikes. I like Rotella T4 because it has a higher ZDDP content which is good for the tappets and camshaft wear resistance and the fact that a gallon is 15 bucks, making an oil change 5 bucks. My favorite motorcycle oil is Motul 300V, but that comes out to $20 an oil change.