Question about Hawk 250 mods before or after break in

[motorcyclelove]

I'm getting close to ordering a Hawk 250 and I know right off I want to do sprocket mods and air box mods. I will be using this 80% of the time on road commuting to work 22 miles one way mostly posted 55. Do I need to wait until after initial break in period to do any mods or can I do them during assembly of the bike?

[Bruce's]

Other than switching the oil to synthetic ,you can mod it as you feel like when you feel like .Change the oil right away to a good Dino oil and run it at least several hundred miles for proper break in before going to synthetic oil if that is your plan .

[BlackBike]

I would say break in the motor first, 500 miles or so. Then you have established your base line and the performance will be stable . Then you can start jetting the carb. If you jet it one way at 20 miles after then, the performance may change, it may require something totally different by 500 miles. If you are comuunting it won't take long to reach 500.

[Wolftrax]

I'm a proponent of hard break ins and personally didn't do any mods until after 500 miles. During the first 500 miles I changed the oil at 0, 50 100 and 500 miles and adjusted the valves twice. I use Shell Rotella 15w40. After 500 miles I did the gearing, mikuni, pod and exhaust and have a perfect running bike with absolutely "0" problems. The Hawk engine definately loosens up significantly during the first 500 miles and doing the mods on a broken in engine may give you better tune.

[HawkTwoFifty]

Originally Posted by Wolftrax

I'm a proponent of hard break ins and personally didn't do any mods until after 500 miles. During the first 500 miles I changed the oil at 0, 50 100 and 500 miles and adjusted the valves twice. I use Shell Rotella 15w40. After 500 miles I did the gearing, mikuni, pod and exhaust and have a perfect running bike with absolutely "0" problems. The Hawk engine definately loosens up significantly during the first 500 miles and doing the mods on a broken in engine may give you better tune.

Hi Wolftrax, when you say that the Hawk engine significantly loosens up after the engine break-in period, what does this refer to? Does this mean that the engine performance increases after the break-in period, or does it mean that certain specs in the engine loosen up and thus require tweaking?

Just wondering if "loosen up" on this engine is a good thing or a bad thing. Thanks!

[Ariel Red Hunter]

Originally Posted by HawkTwoFifty

Hi Wolftrax, when you say that the Hawk engine significantly loosens up after the engine break-in period, what does this refer to? Does this mean that the engine performance increases after the break-in period, or does it mean that certain specs in the engine loosen up and thus require tweaking?

Just wondering if "loosen up" on this engine is a good thing or a bad thing. Thanks!

It is a good thing. It means that the parts have become well bedded in, and there is much less friction in the engine and transmission, which also means the engine is running cooler...ARH

[Megadan]

I had 17/45 sprockets on my bike from day 1, mile 0. While I did not do any intake or exhaust mods at this point, there is honestly nothing wrong with doing so.

More importantly though, regardless if you do sprockets, exhaust, etc, is the state of tune on the carburetor. Like me, you are going to use the bike mostly on-road, and you want to sustain highway speeds. So here is my recommendation.

1. Tune the carb, even if you do no other mods immediately. If you have the stock carb, then follow the endless tuning examples found here and on the web. Shim that needle with at least one washer, and definitely put in at least a 105 mikuni main jet - possibly a 110 depending on your altitude or air temps. (stock intake and exhaust).
2. Do the sprockets if you plan to sustain 55-60mph. My bike could hold 55 all day long with the 17/45 combination even before it was broken in. On the stock 15/50 that motor will be turning almost 7400rpm at 55mph with the throttle cranked pretty far open. Even just a 17 tooth front sprocket will drop those revs down 1000rpm, and you will find it will actually take less throttle to hold that same speed. with the 17/45 the engine chugs along nicely at 5800-5900rpm, which puts it right in the meat of the torque curve. I found this to be almost perfect for holding 50-55mph all day long at maybe 1/2 to 3/4 throttle.

The reasoning behind both of these is simple. Tuning the carb will keep the cylinder temps in check AND give you more power. Running a lean main jet at wide open for 20 minutes will eventually do harm. Combine that with the lower operating RPM and reduced throttle will also allow the engine to run a bit cooler and happier while holding said speed.

My last little bit of advice would be to avoid sustained highway riding for at least 300 miles. Go out for a day or two on the weekend and just ride around town and go on adventures. Put the bike in a situation where you are shifting and revving the motor up and down often.

If you are a fellow lover of hard break-ins like myself and others, then do it methodically. Make sure to give the engine a few heat cycles before really laying into it, pay close attention to your valve lash and make sure that carb is tuned well, and change the oil often(do this regardless). It will saturate with fuel quickly until those rings seat, and it's beneficial to keep as much particulate out of the oil as possible - both things that can do harm if that engine is pushed hard.

My bike has done 1800 miles now, hard break in with a tuned carb and sprockets, with the mods done around the 700 mile mark. Pumps 165psi cold compression and over 170 hot, and shifts like butter.

[HawkTwoFifty]

Originally Posted by Megadan

I had 17/45 sprockets on my bike from day 1, mile 0. While I did not do any intake or exhaust mods at this point, there is honestly nothing wrong with doing so.

More importantly though, regardless if you do sprockets, exhaust, etc, is the state of tune on the carburetor. Like me, you are going to use the bike mostly on-road, and you want to sustain highway speeds. So here is my recommendation.

1. Tune the carb, even if you do no other mods immediately. If you have the stock carb, then follow the endless tuning examples found here and on the web. Shim that needle with at least one washer, and definitely put in at least a 105 mikuni main jet - possibly a 110 depending on your altitude or air temps. (stock intake and exhaust).
2. Do the sprockets if you plan to sustain 55-60mph. My bike could hold 55 all day long with the 17/45 combination even before it was broken in. On the stock 15/50 that motor will be turning almost 7400rpm at 55mph with the throttle cranked pretty far open. Even just a 17 tooth front sprocket will drop those revs down 1000rpm, and you will find it will actually take less throttle to hold that same speed. with the 17/45 the engine chugs along nicely at 5800-5900rpm, which puts it right in the meat of the torque curve. I found this to be almost perfect for holding 50-55mph all day long at maybe 1/2 to 3/4 throttle.

The reasoning behind both of these is simple. Tuning the carb will keep the cylinder temps in check AND give you more power. Running a lean main jet at wide open for 20 minutes will eventually do harm. Combine that with the lower operating RPM and reduced throttle will also allow the engine to run a bit cooler and happier while holding said speed.

My last little bit of advice would be to avoid sustained highway riding for at least 300 miles. Go out for a day or two on the weekend and just ride around town and go on adventures. Put the bike in a situation where you are shifting and revving the motor up and down often.

If you are a fellow lover of hard break-ins like myself and others, then do it methodically. Make sure to give the engine a few heat cycles before really laying into it, pay close attention to your valve lash and make sure that carb is tuned well, and change the oil often(do this regardless). It will saturate with fuel quickly until those rings seat, and it's beneficial to keep as much particulate out of the oil as possible - both things that can do harm if that engine is pushed hard.

My bike has done 1800 miles now, hard break in with a tuned carb and sprockets, with the mods done around the 700 mile mark. Pumps 165psi cold compression and over 170 hot, and shifts like butter.

Hi Megadan, I am so glad to see you mention the topic of hard engine break-ins above in your post. The topic of hard engine break-in has totally peaked my curiosity to the point that I havent ridden my new Hawk 250 this entire weekend because I need to know if its safe to do a hard engine break-in on my new engine. It has been driving me almost crazy to fully understand this topic as best that i can.

So far, I have gained an understanding that the hard engine break-in procedure allows the piston rings to fully seal to the cylinder walls, resulting in more engine power and reliability, (which makes sense) but I am wondering if hard break-in will jeopardize any other engine parts or operation? I have been reading a site called Motoman which has a lot of great info. But then I also find opposing views elsewhere online and I just cant seem to make up my mind.

Would you happen to have any links, info, or personal experience on the topic which lead you to decide on hard engine break-ins? I think that its a great idea so far, but am fearful that a hard break-in may jeopardize other engine components or operations. Could you please be so kind to post your reasons for being in favor of hard engine break-ins, or any info that influenced you to be a fan of it? Thanks so much!!!!