Why 17/45 Sprockets on Hawk 250?
 

Why are the majority of the Hawk owners going with 17/45 sprockets (2.65)? Why not 15/40(2.67)? It will be close to the same ratio and would only need to change the rear sprocket. I know I would have to cut the chain but that's easy stuff. This would shorten the chain by 2 links. Shorter chain less stretching. The 45 tooth sprockets are $25 and not in stock but I can get a 40 tooth for under $19. Has anyone done this combo with any issues? Just think outside the box.

I'm running 16/40 combo that's been working well for me.

That's good to know, so I should be ok with 15/40. I could always do the 16t on front if I feel the need to.

I always prefer to take the reduction on the rear wheel on unit construction m/c power plants. A larger front sprocket is easier on the chain. Although you should fit a new Uni-bear chain or one of equal quality, sooner rather than later.

A new chain is in the plan once I change the sprocket and I'm satisfied with the setup.

Why not try it? What is the worse that could happen?

Ordering the 40t today. I knew the sprocket would work. I was just concerned if anyone had any issues with the combination of the 15/40 sprockets. I'm still waiting on my jets. They're on that slow boat from China.

What is your top speed with this setup? Do you lose any low end for off-road? I may just order the 16t to try it out.

I've thought about this as well. I'm currently running a 17/45 and have toyed with the idea of going to a 17/43???

If I were to do it again, I think perhaps a 16/43 (2.69) may be the sweet spot to start. Easier and cheaper to change the front if you want to make further changes, dropping all the way down to a 40 rear seems extreme to me, and a 43 rear leaves you options of adjusting the front to a 15, 16, or 17?

Is a 14 front available, or too small IDK...

I thought about the 43t. And getting 16t for the front. I got the 40t ordered. Should have it on Monday. I think it's going to work out. Just hope I can get it put on before the weekend. Taking a camping and off road trip this weekend.

My top speed with the 16/40 combo is still only around 70-75 mph depending on the incline and wind. Just not enough power to pull high speeds consistently. I don't ride off road with the Hawk too much but for easy trails it works well for me.

According to my tracking # i'll get my 40t tomorrow. I think the 15/40 will work out perfect but good to know that the 16/40 combo works. I'm about 50/50 on and off road and the off road is mostly flat with only a few man made hills. No hills in South Louisiana lol. The Corp of engineers have set up a great off road area in the Bonnet Carre Spillway in Norco , La. with about 5.5 - 6 miles of trails.

O-ring chain
 

Has anyone tried this chain? XFMT Gold Oil-Sealed Custom O-Ring Heavy Duty Drive 428 x 136 Chain https://www.amazon.com/dp/B019OEZFKW...I20PBHCDVW0MML Not a bad price.

https://www.amazon.com/JT-Sprockets-...n+hdr+130+link

That is what I run with a 16/44 combo.

I looked at them but going with an o-ring chain. Where I ride it has a lot of very fine river sand and when that stuff is wet it gets all up in the chain. I have one on my Honda 200x and never had to worry about it. I would just hose it off and oil it up. The O-rings keeps the sand out of the bearings of the chain. I didn't have any problems with the chain stretching either. 1st trip we made with my 4 wheel the sand ate the crap out of her chain inside and out. You could literally heard the grains of sand grinding away at it. Got an o-ring chain and no problems since. well worth the extra money. IMO the cheapest o-ring chain out there is about 100 times better than a regular chain.

The results
 

I got the sprocket and jets in today. I installed the 110 jet first then swapped out the 50t with the 40t. It all went pretty good. I had to take off 2 links of chain. The results are great. Before with stock sprocket and jet 63 MPh at best now 74 MPh. It's perfect. Cruise 60 MPh with ease.:tup:

I'd been running 17/45 for awhile but changed to 15/45 this afternoon. Once I can give it a whirl I'll report my findings.

The 17/45 makes first gear just a little too fast for my uses, and it maxes out at 63ish mph at 6500 rpms which according to the specs is below the 7000 rpm max HP. Maybe 15/45 will be better on both fronts?

Have you done anything with the carbrerator? Jetting? I was getting 63 mph with the stock 15/50.

Is that speedo 63? or GPS confirmed?

GPS confirmed, and that is even with carb re-jetting. At stock gearing I was afraid to go past 50 due to the high rpm's on a fresh engine, so I'm not sure what I could have gotten.

My problem is wind. With a tailwind I can do 65+ but with any headwind I'm at 60.

This weekend I'll see how the 15/45 does, if I can get into the power band without my hands going numb.

I'm heading out tomorrow for the weekend of camping and trail riding. Going to see how the 15/40 works out. It still has good low-end power. Can still pull a wheelie in 1st. Lol. The 63 and 74 mph are both GPS confirm

Were are you located? What elevation? I'm almost at sea level in south Louisiana. I know years ago I took a trip up in the mountains in Tennessee on a my Yamaha I had and I lost a lot of power at the higher elevations.

I am pretty much sea level Oklahoma. With 17/45 I can get to 60 easily and can even climb a moderate hill at 60, but it just has nothing left above 6000 rpm's. Maybe my exhaust has some bad welds and is extra restrictive.

I'll know more this weekend when I try a speed run with the 15/45

Oklahoma sea level? :hmm:Aren't you about 800-1000 ft above sea level? lol South La. 6-10' above lol. I removed the end cap on the spark arrestor. It helped some.

Map says I'm 471 ft above sea level. I removed the endcap but didn't really notice a difference. I've seen some images of the inside of some exhausts and they looked horribly restrictive, maybe mine is.

My hawk been running very good with 17t-39t.Today I hit 72 mph @7000rpm with a fair amount of wind hitting my chest.Next week I'm going with 17t-42t and I think it will be the best combination for my weight and street riding.
80-20 tires
115-30 jets
k and a filter
ngk spark plug
Pro-circuit t-4 exhaust
168 lbs.
Mystef's accurate cluster.
Side note:The Ducati s2r1000 has taken the back seat since I purchased the Hawk,it's a ton of fun for an affordable price.

I never really paid attention to what it looked like on the inside. It was dark when I took the spark arrestor off and took off the end cap. Maybe take a long 1" rotary drill and bore a hole right through the center.:D I know sounds crazy :crazy: but who will be the first to try it.

Tried the 15/45 today and RPM's at 60 aren't something I'm comfortable with for any sort of distance. Went back to 17/45. I think 16/45 might be the sweet spot for me.

I don't know how bad the muffler is. What I do know is that the head pipe is terrible, and the exhaust gasket is awful on the Hawk.

Got back from my weekend camping /off road trip. 212 mile over the weekend through trails and steep hills. The 15/40 combo worked perfect to me. The 110 jet really helped out. I'm 5'11" 180 pounds so not a lot of weight to carry around. There were a few hills that look like there was no way I can make that but went right up. I wish I would of had a helmet cam. We rode past midnight on Friday night, all day Saturday and night and Sunday. Don't know why my butts so sore lol. I'm not changing anything. it runs to good. I'm glad I mounted some bright LED's on my daughters side by side to light up the trails. Next on list are some LED's for the Hawk.

That should work.

I'll have to take mine off one weekend and see how bad it is. I'm an old guy and don't like the loud exhaust like I use to lol. But there may be a few things I could do to make it flow better and still keep the exhaust quiet down enough.

Before you take the exhaust pipe (head pipe) off, I would suggest you get a copper o-ring exhaust gasket for a Honda CRF-230. Then re-torque the exhaust to head bolts, step by step to 15 ft/pds (with the copper o-ring gasket). After you have the head pipe mounted, then re-mount the muffler.

I think that's the same as I used on my Honda 200x. I should have 1 or 2 laying around. I'll check on that tonight.

I think a pair of these LEDs mounted vertical should fit where the reflectors are up front. https://www.amazon.com/autvivid-Driv...cm_wl_huc_item I'll take some measurements tonight.


Update: I measured up everything and it looks like they will fit. It might be close to hitting the plastic on the tank but I think I can make a bracket to offset for clearance. If you never been off-road trail in the woods at night you are missing a great experience. Ran across a couple of deer this pass weekend. I really need to invest in a helmet cam for the next time I go.

There are sprocket combinations that should be avoided, I found a chart somewhere a while back when I was changing my Duc's gearing. I believe the reason was a combination of vibration and wear do to an interaction between the sprockets and chain, but don't recall the details. It may not be a big deal on a low power/low speed machine, but if your desired gearing can be had with a better combination of sprockets it would be the better way to go. I think I wound up running one of the 'wrong' combos on one of my 999s and didn't notice anything wierd but I didn't ride either one a lot to really know, I also did a few swaps trying to find the best gearing & chain size and don't recall what combo either one ended up with. I did a 525 to 520 conversion on one of them and the reduced weight could be felt in the acceleration. Getting the lightest combination on a CB should help it too, but of course smaller lighter parts that are strong are usually more $.

It's not so much the sprocket combination but the correct amount of links in the chain for the sprocket. There is a chart somewhere and I can't put my hands on it. It gets a little complicated but with the wrong links of chain and sprocket what happens is the same links end up on the same tooth of the sprockets more often. So if you have say a bent or damaged tooth on the sprocket it could wear those particular link quicker. I'm sure if you google it you could find information on it. What you want to avoid is have a chain link equally divisible by the teeth on the sprocket. example: 120 link chain divided by 40 tooth sprocket means on 3 rotations of the sprocket the same 3 links hit the same tooth. Same for front sprocket. Just make sure the amount of links aren't equally divisible by the number of teeth on the sprocket. So on my 15/40 combo I need to avoid a 120 tooth chain.

If you're looking for a decent helmet camera, I suggest the Sena Prism Tube. It's about $120 on amazon, shoots in 1080p, comes with a mic/speaker. Perfect for me.

As for the sprockets, what is your top speed with the new combo?

Yes, that's right.

what you say is totaly correct....
If we rode own bikes in a totaly sterile room it could
have a bearing on chain / sprocket life..
But I ride mine in the real world with water / mud / dust
& the chain totaly dry after 10 mins riding..
Wheather the sprockets can be devided into each other or not
has diddy squart to do with chain / sprocket life in the real world..




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