New Hawk, new adventures.

[Megadan]

Originally Posted by grumpyunk

I have seen zero about roller tipped rockers for the CG250. You installed a pair. How well do they work? You mentioned different push rods. Are they necessary to use the roller rockers?
How do you set the cam timing on the CG. I can't see the timing marks on the SG250 that I am working on. What is the trick to see the timing marks?
I have never split one before, so am in murky waters as far as I am concerned. Don't know if I have to remove the cluch basket etc to gain access to the gears inside the case. I just need to remove some bits of a HeliCoil that broke off and hopefully put it back together. I got the roller rockers on a whim figuring they'd cut friction. New cam too, just because it was a low cost option. From the same ali source I think you used. Any pointers on installing the rockers & cam? I have not taken the case apart yet, but will soonly and then put in the cam & rockers. Just no doc to work from...
tom

Added: Have you gotten the bigger cylinder yet? I understand a different crankshaft is necessary. Could be wrist pin diameter, or the actual piston weight imbalance normally incurred with BBKs.
tom

I have roller cam followers, not rockers. I got them from Aliexpress, but they are not difficult to find anywhere.

I expirimented with chromoly pushrods, but not for the rockers. I have since actually gone back to the original units and have been running them without issue. The chromoly units were just too loud and gaining too much gap when the motor got hot. For such a mild cam like mine, they really aren't necessary. Anything more aggressive and I would definitely recommend it.

Did you order the cam from WGK?

You should not need to even touch the clutch side of the motor, just the stator. Seeing the timing marks may require the use of a small inspection mirror, which is what I used.

As far as the bigger cylinder and piston, no word from the broker or seller. I have a feeling they don't want to sell to me because I can't verify to them what type of engine I have. I told them I was using it for an engine other than the one it is listed for, and they never responded.

[Plump Kibbles]

Originally Posted by OneLeggedRider

and the snap crackle pop when I let off the gas. So..

Had this issue when I first got my bike - 200 some miles later after a Mikuni carb, pod filters, and all; I broke down and got a Twin Air pre-oiled YZ450F filter for my stock air box (not sure of the fit of your box) and it took literally all that down-rev popping completely out! My stock filter resembles the Yamaha triangular filter - just wasn't oiled. Well, there was a DROP on the thing just didn't have oil to throw on it. Finally got that filter, popped it on and took off. My bike is actually significantly quieter as well.. try oiling the filter a little heavier if you have a foamie-oil type. That was driving me NUTS as well - kept fiddling with the mix.. That should help!

[grumpyunk]

Mergadan:"I have roller cam followers, not rockers. I got them from Aliexpress, but they are not difficult to find anywhere."

Sorry, I meant cam followers. With the parts shaped and arranged like they are, it is mental gymnastics to keep in mind what is what.

Megadan:"Did you order the cam from WGK?"

No, got the followers, the cam, the cam shaft from "Shop3876010" on aliexpress. Total was ~$30 plus tax.
The packages indicated for the CG125, but the display ad on ali indicated for a CG250 also. The cam shaft was too long, and I did not use it. I did a visual comparison of the cam lobe, and after considering the size, decided it might be better to do one change at a time. I did not measure stock lobe to the one I bought. If I had a machine shop, I could take the lobe, and remove material from the 'heel', and essentially modify the lift, but I'd rather have the cam 'fatter', to open earlier and close a bit later.
I did not do anything to the factory cam except R&R. Found that I could push the oil seal out of the way to gain visual access to set the timing. I think it would have been a real bear as I had difficulty keeping the spring/washer in place while aligning the gear teeth to get the timing marks right when putting the case back together.
Now I am muddled as I know the teeth were end to end, not meshed, and I was feeding things together... Oh. The side case carries the cam & sprocket in a pocket. You have to align the teeth as you put the case halves together.

Wish you had responded earlier so I would not have taken the clutch, oil spin filter. and gears apart on the clutch side. I did not need to do that. One filter screw got messed, even using an hammer impact. I replaced all three with allen head screws, to keep the balanced.
The hardest thing, besides timing the cam, when putting the case back together was the kick starter mechanism. One of the parts wants to move out of place, the one that rides against the right case wall. Not seeing it as it came apart, and viewing pictures online here of the re-assembly after valve failure, gave me not much to work on. Finally moved it in one direction, that allowed the kick start shaft to align, and it went together fine.
I have a bunch of pictures, but don't know if anyone would want to see them, and where to post.
tom

[franque]

@tom - make your own thread, I'd love to see it, and I would be happy to help with any issues you're experiencing.

[Megadan]

Originally Posted by grumpyunk

Megadan:"Did you order the cam from WGK?"

No, got the followers, the cam, the cam shaft from "Shop3876010" on aliexpress. Total was ~$30 plus tax.
The packages indicated for the CG125, but the display ad on ali indicated for a CG250 also. The cam shaft was too long, and I did not use it. I did a visual comparison of the cam lobe, and after considering the size, decided it might be better to do one change at a time. I did not measure stock lobe to the one I bought. If I had a machine shop, I could take the lobe, and remove material from the 'heel', and essentially modify the lift, but I'd rather have the cam 'fatter', to open earlier and close a bit later.
I did not do anything to the factory cam except R&R. Found that I could push the oil seal out of the way to gain visual access to set the timing. I think it would have been a real bear as I had difficulty keeping the spring/washer in place while aligning the gear teeth to get the timing marks right when putting the case back together.
Now I am muddled as I know the teeth were end to end, not meshed, and I was feeding things together... Oh. The side case carries the cam & sprocket in a pocket. You have to align the teeth as you put the case halves together.

Wish you had responded earlier so I would not have taken the clutch, oil spin filter. and gears apart on the clutch side. I did not need to do that. One filter screw got messed, even using an hammer impact. I replaced all three with allen head screws, to keep the balanced.
The hardest thing, besides timing the cam, when putting the case back together was the kick starter mechanism. One of the parts wants to move out of place, the one that rides against the right case wall. Not seeing it as it came apart, and viewing pictures online here of the re-assembly after valve failure, gave me not much to work on. Finally moved it in one direction, that allowed the kick start shaft to align, and it went together fine.
I have a bunch of pictures, but don't know if anyone would want to see them, and where to post.
tom

So there are a few things to note here.
1. Any cam from Aliexpress is going to be a stock equivalent replacement. You likely wont see any performance improvement. What you want from the camshaft is the exact type of cam I ordered from WGK. More duration, no added lift.

2. There are two types of camshafts made for the CG engines. The only difference is with the mounting shaft of the cam to the gear. Our Hawks use the snap ring style, which is shorter than the later purely press fit design. Sounds to me like you ordered the latter.

3. The side case does carry the cam in a pocket, correct. But you can align the teeth in place and feed the central camshaft shaft through from the stator side of the case. Not sure if you watched my cam install video at all, but a lot of this was either shown or noted verbally.

Sorry that I did not respond sooner, but I often have moments in my life where I simply don't have the time to get on here. The best thing you could do whenever going into a project like this would be to start your own thread. There are a ton of experienced people here who have taken the motors down, or are familiar with my own build that could likely answer the questions you would have had.

I would be interested in a thread on your work and the pictures, as franque stated.

[drstansbury@yahoo.]

Just got a hawk 250 and watched your videos today on the cam install. If I like this bike I plan on doing heavy mods like you have. Are you happy with the cam you installed or would you recommend different cam profile or timing changes?

[Megadan]

Originally Posted by drstansbury@yahoo.

Just got a hawk 250 and watched your videos today on the cam install. If I like this bike I plan on doing heavy mods like you have. Are you happy with the cam you installed or would you recommend different cam profile or timing changes?

I am very happy with the cam I installed. Would I have done a different cam? maybe. It would be nice to have a bit more top end power, which is generally where this motor really lacks, BUT I also love that the particular cam I used needs no other supporting upgrades to work, and it definitely give a bit of a bump in the power department. It takes the Hawk's existing power curve and gives it "more" within that same RPM range, and maybe just a tiny but more up top, but not a ton.

So, if you want more top end, a different cam profile will definitely be a better choice. If you want more grunt, then a ported head, advanced timing key, exhaust, and this cam will up your tractor factor a pleasurable amount.

They big thing to try and be is realistic though, even if I took this engine from about 15hp stock to 20ish+ as it sits, it' still only 20hp pushing a 300lb bike with large diameter wheels and off road bike aerodynamics (not that great). Would I do it all again though? absolutely. I love tinkering around with these cheap bikes.

[grumpyunk]

MegaDan .. I put the cylinder on before putting the cam in place. I removed the oil seal and was able to see the alignment dot/mark. When installing the shaft the cam rides on, I aligned the teeth, and then put it in place. I remember backing off the cam gear teeth so when it rotated into place, it would end up in the proper timing. The little spring washer did not want to stay where it belonged.
I used the orignal cam & gear. The gear had a snap ring as did the new one I did not use, so the gear could be separated from the cam itself. I did not take them apart and align the shapes, but think both were totally 'stock' in grind.
I did use the roller tipped cam folowers. Setting the clearance to .003 seems to be working nicely. When warmed, I can still hear a slight tappy. I think the roller tips add a bit to the torque and hp. No measure as I don't have that many hours on the machine.
Of course, when I went for the second spin, about 5-9 miles, the countershaft gear fell off. Coasted to a stop, thankfully. Next time out, the nuts holding the exhaust pipe to the head worked loose. I had used a new copper gasket, and tightened enough to squish the gasket, but not enough, I guess. Got some metric nuts that had a built in washer and some 'teeth' on the washer surface. Hope they stay.
I used Blue Loctite on the gear, but it did not stay. Does anyone have a good torque spec for the small drive gear retainer bolts?
I appreciate everyones' answers and comments.
If I made a picture post where should I put it?
tom

[franque]

Make a thread... I'm not sure what you mean when you say that the countershaft gear fell off? Pictures will help.

[grumpyunk]

In this sub-forum... Nah, street.

The small gear on the countershaft(external) that links the engine to the rear wheel sprocket via chain. Internally you have the main shaft and the counter shaft. Counter being the one that receives the power from the main, the main being fed power via the clutch.
Maybe I have it wrong. Anyway the small sprocket. No pics except this one.
Gear indicated its desire to depart by doing so, leaving me w/o power...
tom

[franque]

That's just a countershaft sprocket. I'll be happy to help when you start your own thread. The subforum isn't too important, at least to me. Perhaps @JerryHawk250 can delete/move these posts once you've started a new thread so that we're not polluting Dan's thread.

[drstansbury@yahoo.]

Megadan when you installed the cam did you use the stock keyway or the 4* advanced keyway? Looking to build mine in basically the same configuration as yours. Any help is appreciated

[Megadan]

Originally Posted by drstansbury@yahoo.

Megadan when you installed the cam did you use the stock keyway or the 4* advanced keyway? Looking to build mine in basically the same configuration as yours. Any help is appreciated

At the time I only had the standard Key, so that is what I put it back together with. I went back and did the 4 degree key later on after experimenting with different CDI boxes for a little while.

[drstansbury@yahoo.]

Was the key worth doing? I'd think it would make for responsiveness. Did it cause any issues such as hard start or timing issues with the cam?

[Megadan]

Originally Posted by drstansbury@yahoo.

Was the key worth doing? I'd think it would make for responsiveness. Did it cause any issues such as hard start or timing issues with the cam?

Yeah, for the money it is a worthwhile mod to do. Paired with the OEM CDI it still starts easy and gives a more lively power curve across the board. It has no effect on the cam timing, which is timed off the crankshaft on a separate gear.

As with most of the upgrades I have done, individually they all had an appreciable effect, if small. When they are all combined together is when they really shine.

Even without a ported head or camshaft, you could do a full exhaust, advanced timing key, and either an airbox mod or whatever other intake you desire, and end up with a good running peppy little machine. A ported head with those mods just wakes the bike up that much more, and the cam even more so.

My bike is built to what I call Hawk Plus lol. I haven't greatly altered the power curve, just woke up the motor about as much as is possible without getting into more in depth and costly endeavors trying to chase those last couple of HP. That was my goal from the start.