Brozz 250 - 4 Degree Timing Key Install

[tknj99]

So i went to install the 4 degree timing key i received from Joe Henner and learned a few things:
1. You need to remove the exhaust header to reach the 2 bolts on the exhaust side (7mm)
2. You need to remove the cap with the 3 8mm bolts which will then expose another 8mm bolt which ultimately allows the whole cover to come off. Be careful when you remove this cap as the gear assembly behind the cap has a washer which may fall off as in my case and i just replaced where it should go later.
3. A Harbor Freight 3/8" impact wrench and probably 1/2" for that matter are not powerful enough to spin the flywheel bolt off.. I was able to get around this by using a chisel wedged between the metal ridge on top of the flywheel and the frame and then could remove the flywheel bolt (lefty loosie).
When replacing the bolt later you can use a bolt wedged between the gear assembly to torque it down to 54 ft/lb
4. The following flywheel puller doesn't work on the Brozz and ill need to figure out which one does.. when i connected it and turned the bolt inwards it eventually just seats against the outside of the puller as it doesnt insert far enough. Also i noticed the larger section of the puller is threaded but there is no outside thread for this to go onto with the Brozz and is just smooth. Not sure if its the same case for the Hawk. I think if the inner bolt was longer it would have worked.
https://www.amazon.com/gp/product/B01I5YP2WI/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
5. I wasnt sure on the torque spec for all of the 8mm case bolts and just tightened down by feel. If anyone knows the spec please let me know as i will have to do this again at some point.
6. I didnt locktite the flywheel bolt or any of the case bolts since i will need to do the work again. If anyone knows if these should or shouldnt be locktited, please let me know

I plan to find the correct flywheel puller and luckily am within the return period. All in all, was a good learning experience and the bike still fires right back up, so no harm no foul and will attack this on another day and then ultimately review the performance gain.

[tknj99]

Just found this video and if i cant figure out the right puller i may try what is suggested in the video

[gwowzer]

Looks to me, I have not done this operation, but if you make your own longer bolt like he does in that video, plus source a regular puller, it should come right off. You can find big jawed pullers at a local hardware store.

[gwowzer]

https://www.amazon.com/ChgImposs-Sep...0335484&sr=8-5

[tknj99]

I'm also very curious to hear about the torque specs on those 8mm bolts. The Brozz technical thread states the following but that seems like way too much torque in my opinion. If i had to guess they are maybe 16 ft/lb

Engine------Bolt/Nut

M8 35～45

[Deckard_Cain]

Originally Posted by tknj99

I'm also very curious to hear about the torque specs on those 8mm bolts. The Brozz technical thread states the following but that seems like way too much torque in my opinion. If i had to guess they are maybe 16 ft/lb

Engine------Bolt/Nut

M8 35～45

That DIY puller method in the YT vid should work. Curious why that 28mm puller you bought didn't reach all the way.

This is the one I bought and used on my 2020 Hawk:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I looked up 8mm typical torque specs, for grade 8.8 bolts, it's usually 17-19ft lbs.

But this is for 8mm shank diameter, not the 8mm socket you use to remove the bolts with- if that's how we're referring to those bolts (I don't recall my own), then they are likely an M6 shank, which is only 7-8ft lbs, all assuming coarse thread.

*I used and cross referenced three different engineering or fastener specialist sources for the preceding torque information.

Sources:

https://www.fastenermart.com/files/m...en_torques.pdf
http://www.dansmc.com/torque_chart.htm
https://www.engineeringtoolbox.com/m...ue-d_2054.html

[franque]

The measurement is the thread diameter, not the head! Unless the Chinese went with a heavier design for no reason, those are M6 bolts, not M8. 84-108 inch pounds. You can use low strength loctite if you want, but it's not necessary.

Don't put a ft-lb torque wrench on it, it won't be precise. Just use a 1/4" ratchet and not too much wrist when you put it on, it'll be close enough.

[grumpyunk]

I used a regular three-legged puller when removing the flywheel. The kind that have removable and flippable grabbers. I set it for the longest reach and tightened the center bolt against the flywheel bolt. Whang with a hammer. HARD, after tightening the bolt to maybe 30 ft/lb. Be sure to center the draw bolt in the head of the flywheel bolt to prevent the head from getting bent. You do have to hit pretty hard.
The first starter gear reduction set can be removed from the side case behind the three bolted cover(it pulls out after removing the bolts). The next reduction gear can be removed with a bit of fiddling before the flywheel is removed.
The final drive gear & sprag clutch WILL fall off the flywheel after the flywheel is removed, so be prepared. It can be refitted by rotating while pushing it into position.
Make sure the taper on the crankshaft is clean and dry. Clean with brake cleaner or ?? before fitting the flywheel. The internal taper on the flywheel should also be clean and dry to insure the parts fit tightly. The key does NOT hold the flywheel in position, it just aligns for spark timing. The tapers are the holding mechanism, so they have to be clean and dry.
There will be a little oil when the side cover is removed so have a pan to catch it or be prepared otherwise. If the gasket remains in one piece, you can reuse it. If you do, clean it well so it is as dry as possible, and wipe a smear of RTV or gasket maker onto the surface, almost painting it, that thin. It will seal by filling any imperfections in the gasket or mating surface. The starter gear cover should be cleaned, and the O-ring lightly oiled so it will compress and slide into place rather than being cut or sliced as it is inserted.
tom

add If you can, it would be a good idea to replace the Philips headed screws in the center cover with allen heads while they are out. The Philips will tend to set and be difficult to remove after they have been in place for a while. Allen heads are inexpensive and you will be happy when you can remove them easily in the future. That and a nickel.

[Deckard_Cain]

Originally Posted by franque

The measurement is the thread diameter, not the head! Unless the Chinese went with a heavier design for no reason, those are M6 bolts, not M8. 84-108 inch pounds. You can use low strength loctite if you want, but it's not necessary.

Don't put a ft-lb torque wrench on it, it won't be precise. Just use a 1/4" ratchet and not too much wrist when you put it on, it'll be close enough.

That was my worry when they were saying 8mm bolt.... I had a feeling they meant the socket size used, not the thread shank diam!

[Megadan]

My 1/2" electric impact took my flywheel bolt right off. Yours may have just bee installed by the Chinese Hulk that day on the assembly line.

The flywheel puller that works for us Hawk guys is an M16 bolt that threads into the flywheel and pushes against the crank. The one I used came from this type of puller (usage 3) https://www.ebay.com/itm/3in1-Flywhe...wAAOSw9GhYdSYH

If you search a bit you can sometimes find one from a US based seller. Otherwise it is the slowboat wait.

Another trick for tightening down the flywheel bolt. Turn the engine away from TDC and feed some length of small rope through the spark plug hole into the cylinder. Once you go to tighten the bolt the rope will wedge between the piston and the head and hold the crank still so you can tighten it. Obviously make sure you can still remove said rope, so leave a bit of it sticking out of the plug hole lol. This method can also be used for removing the flywheel bolt if you don't have power tools.

The flywheel bolt doesn't need loctite, but it could be added if you desire it.

The case bolts I personally do put loctite on, but this is just me. As others have mentioned the torque spec for M6 bolts usually doesn't exceed 9ft-lbs/108in-lbs. Not only because they are small bolts, but they are also threaded into some very soft aluminum, and those threads will strip out quite easily if you over torque the bolts.

[tknj99]

Thanks guys, that last few threads have me thinking, grumpyunk's in particular, that everything past the point of removing the flywheel is a black hole for me and i may need to watch some more videos or wait for the JerryHawk video to come out .... i have no doubt that ill be able to remove the flywheel with the tool i have and by using an inserted screw to add some space to allow it to be separated, but am alittle worried especially with the thought of things falling down after removing the flywheel as mentioned..sprag clutch and final drive gear, etc. If its something that can easily be fitted back on thats fine, as long as its not something can affect the bike if installed in the wrong orientation or position. Also will have to research more on the crankshaft taper mentioned and what it may look like at the point of disassembly for cleaning.
Interestingly i didn't notice a gasket on the side cover when removed nor its mating surface on the engine, i think i saw a rubber oring on that 3 bolt cover though if i recall.
Also, for reference i didnt see any phillips head screws in the side cover, maybe that varies between bikes.

@Megadan: i think the HF 3/8" and 1"2 air impact guns although they say it has the torque just dont have much more than 45 ft/lb's as i saw in a youtube test video recently. The chisel wedged between the flywheel metal bump and the frame worked well with removal of the flywheel bolt and then using a screw between the gears worked well when replacing the flywheel bolt for me. hopefully neither of these methods can lead to any damage of the components.

[tknj99]

Rewatched the attached video as well as JerryHawk's previously YT Venom timing key install and im not seeing anything fall off when the flywheel is removed. I now see the groove on the flywheel sitting on the stock timing key and then when the flywheel is removed, the crankshaft with attached key and large gear are exposed.
Question, what is the best way to remove the stock timing key? pliers or flat head screwdriver? and when seating the new timing key does it just plop in or need to be banged into place? does it matter if its sitting towards the back of the shaft or closer to the front?
Just trying to get as prepared as possible, thanks guys

[JerryHawk250]

Originally Posted by tknj99

Rewatched the attached video as well as JerryHawk's previously YT Venom timing key install and im not seeing anything fall off when the flywheel is removed. I now see the groove on the flywheel sitting on the stock timing key and then when the flywheel is removed, the crankshaft with attached key and large gear are exposed.
Question, what is the best way to remove the stock timing key? pliers or flat head screwdriver? and when seating the new timing key does it just plop in or need to be banged into place? does it matter if its sitting towards the back of the shaft or closer to the front?
Just trying to get as prepared as possible, thanks guys

It will be a snug fit. You can pry it out with a screw drive and gently tap the new one in place.
I had other obligations to take care over the weekend so didn't get to work on either bike. Besides it was too damn cold and wet outside. lol

[grumpyunk]

TKNJ: No screws? Most have an access port that can be removed to use a socket/lever to rotate the crankshaft for valve clearance adjustment. The bolt that holds the flywheel becomes accessible to use after removing the center cap.
If you don't have one, then you must remove the side cover to have something for turning the crankshaft.
I think you can see the allen head screws replacing the Philips(JIS).
tom

[TxTaoRider]

Ok, all this discussion of the 4degree key talked me into it. I ordered the key from Joe at henner today an a puller off ebay.
This "cheap toy" is starting to cost me. Lol