RPS Hawk 250: 2 issues
 

Hello I'm new here. I hope I'm using this site correctly. I've been riding china bikes for a few years now and love these cheep bikes.

I have assembled a few questions I hope you may have a possible answer.

Question #1
I purchased a Hawk 250 and have been riding for a a little while now. It's hard to convince my friends to get one when it idles like a junker. I have switched the carburetor to a mukini 30mm (suggested on this site). I rejected it to a 115 main and a 30 slow (suggested on this site). It idles wonderfully for a few seconds then randomly cuts off sometimes. After I drive for a little while or so it will idle incredibly high and spudders up and down like a mad man. I don't even have to apply gas to engage the clutch at red lights. turning the idle screw does nothing I can even take it out with no change. I've removed the carb a few times to inspect and reinstall to no results. My bike has become a joke at the work place as a result. :cry:

Question #2
My little scooter is a better off roader compared to my Hawk. This is because the hawk's rear shock is so squishy. The rear wheel gets flung in the air throwing rocks at my friends when riding trails. and the ride is extremely uncomfortable. I have tools to adjust rear shocks but, the Hawk seems to have no adjustments what so ever. odd?

This is such a cool bike and I really enjoy it when it behaves. I bet it's an easy fix that I'm simply not getting. I know this can be a great bike with your help. Thanks! :)

I was chasing idle issues like a mad man, same thing. My mixture screw didnt seem to do anything as well. I realized the idle was way too rich, and I ended up going all the way down to a 20 pilot. Idle issues almost completely resolved now, and it idles happy at around 1900 rpm.

I still have to tune it more to get it 100% perfect, but its more than rideable especially after it warms up.
It will die when you come to a stop when its cold, but after a minute or two its good.

I believe you can take the measurement of the shock and go online to find one with adjustments, or the CSC tt250 rear shock may work.

https://youtu.be/34yYWSolKc0Take a look at this video. Pay attention starting at the 1:30 about removing the black plug and adjusting the idle mixture screw. Made a HUGE difference on my two hawks (I can start and idle without the use of the choke now) and yes I'm still using the stock carbs, just rejetted them. Also go to his Youtube channel and check out all his videos on the Hawk. He does a really good job on different mods on the Hawk.
https://youtu.be/34yYWSolKc0

I'm with mq1991. If you're still on the stock exhaust and are close to sea level, the 30 pilot is probably too fat.

I thought the slow was a bit large. But, I have noticed the stock carb says it has a #40. I wounder why that is. I so happen to have a #20 I'll give it a shot if I can find it lol. :thanks: There is no black plug, I'm no longer using the stock carb. The carb I installed can be tampered/adjusted easily. How do you even adjust fuel/air without burning the crap out of yourself anyway?

As for the shock I literally see absolutely no adjustments. Maybe it's different design? It's a 2016 but, the only difference I found from 2015 is mine has black rims and 2015 are chrome. :shrug:

Is the stock HAWK carb a "Keihin" clone or a "Mikuni" clone? That can explain the huge jump in jet sizes

Keihin jets are numbered higher, example, a 110 Keihin main jet is ABOUT the size of a 100 Mikuni main jet (and about a 106 DynoJet)

http://jetsrus.com/FAQs/FAQ_mikuni_v...ihin_sizes.htm

My hawk idles great. 20 pilot and a 110 main in a mikuni vm26. As far as it it kicking up junk at your friends off-road.... Added benefit 😄. Knobbies bite in to dirt therefore slinging dirt and mud is evidence it is working. Me and my buds constantly do that to each other on purpose.

Just curious, have you ridden dirt bikes off road before? You should be on the pegs a lot. There will be a bunch of suspension travel. The only time is will look to get different shocks is if I bottom it out. Honestly then I just migh need a different bike. The hawk will handle most casual to intermediate off-road use. If you are nailing 30 footers or skipping across the tops of a series of whoops then get a ktm or Honda. Otherwise it should be good.

Oh before you even tinker with the carb make sure your valves are properly set. I also tossed in an iridium plug for good measure.

I actually adjusted mine about where MotoCheez did his. I did have to tweek them a little using a jewelers screw driver. Just have to be careful.;)

All good suggestions thank you! :)

I'm not much of a carb nut that's interesting about the Keihin's jets vs. Mikuni. The mains both fit each other but, not the pilot jets it seems.

I do some hard off roading with the hawk. It seems to handle just fine wheelies and jumps and all that. I'm actually quite impressed with the welds compared to my Japanese bikes. I might of got a good one out the batch who knows, it's very well made for a Chinese bike. For sure.

As for the overhead valves. I think they just need to be tight. I don't think this motor works the same as other motorcycles, it's based on a super old design. It's a one lobed cam it seems. It's probably due though.:hmm:

As for the shock maybe I blew the seal or something. I literally can put my pinky finger on it and it pushes way down easy. Does anyone know any sweet rear shocks that fit? OOH! :D That actually sounds like a cool idea!

I live in NewHampshire USA. #115 main is what I'm running now. Too rich???:shrug: How does sea level effect my jetting? Where's Bill Nye when you need 'em?:ohno:

Thanks again, you guys rock!

I love NH. I put a bid on a property in Dalton but the seller and I could not meet on a price. I'm in CT. CT and I don't exactly see eye to eye on the whole 2nd amendment thing. I'm a better citizen than a subject so I'm getting out. Either NH or ME. VT is a little to hippy crunchy granola for me.

Anyway, odds are the valves are tight. Not sure if you ever set them but they are wicked tight from the factory. A little loose is ok, tight is no good. IT makes a world of difference once they are properly set, especially on start up.

BTW the higher your elevation the leaner you need it. Less air = less fuel.

Kind of pricey, but, it should fit and provide you adjustments.
http://www.cscmotorcycles.com/TT250-...p/zt27-101.htm

Is there some sort of "size" to go for? I know nothing about shocks.

This one looks awesome. I have no idea if it's too big or small though. :ohno:

http://www.ebay.com/itm/280mm-980lbs...RVC29n&vxp=mtr

Ebay seems to be full of all sorts of types and models for sure.:tup:

the throwing rocks issue can be reduced by lower tire pressure, problem is it calls for 40 psi, due to having no bead lock in the rim. i am running 36 and have not torn a valve off a tube yet, and have climed some huge hills.

i plan to install a bead lock into my rear wheel, just sucks to have to pull the tire off and add. $5 dollar part.

My old dirt bikes could handle 23-28 psi with no issues. and it makes a huge difference in traction.

most 2 strokera use 2 bead locks in he rear, but the hawk would be fine with one.

im also looking for a better rear shock, keep,me in the loop on that.

The carburetor float bowl is very close to the exhaust pipe. This could cause the weird idle problems you are having. The other possibility is a sticking float valve in the carburetor. :D