Hawk engine swap to Zongshen PR250/300

[Dusman]

Originally Posted by ather1232002

Can you please share your experience of this engine in terms of performance, engine heating and reliability in comparison with your previous 250cc engine?

Also, I have tried to get actual HP/Torque numbers for this engine but every website is suggesting different numbers.
Like, Aj1 says 15.5KW(20HP), a manual shown in youtube video says 16KW(21HP), few sites says 24HP, few says 27 HP. So it is very much confusing.

Sorry for taking so long to get back to you. I had surgery and out of comission for a few weeks. In terms of heat, I haven’t had any heat problems. Reliability has been excellent thus far, however, my previous Hawk 250 engine was very reliable. I just wanted a little more power and a 6 speed tranny since I travel the highways frequently (55-65 mph) and need to be able to cruise at those speeds relatively easily for at least 30 minutes at a time.

As far as power rating/performance specs are concerned, my understanding is that a stock PR250 engine with a 2 valve head delivers @ 19 HP to the back wheel. The reason the numbers may be varying so much in the sources you’re looking at could be because there are not only 2 and 4 valve versions of the 250 version of this engine, but also 2 and 4 valve versions of the PR300. I have the PR300 with a 2 valve head, and I’m probably making @ 24HP. I could get the 4 valve head and push it to 27HP, but I really like the fuel economy the way it is right now and I don’t really need that extra power.

[bigdano711]

Tell me more about this PR300. Is it air cooled? Where do I get one? Have you swapped a PR300 into a carb'ed Hawk?

[Dusman]

Originally Posted by bigdano711

Tell me more about this PR300. Is it air cooled? Where do I get one? Have you swapped a PR300 into a carb'ed Hawk?

Indeed I did swap it into a carbed Hawk. 6 speed, counterbalanced, 274cc (says 300cc, but list most bikes, it's not an actual 300cc). Either way, it's about 24-25 HP and with that 6th gear, chugs on down the highway pretty good. Top speed is about 85mph, but that's way too fast for the aerodynamics of a Hawk (at least for me. lol).

You can either order a PR300 from China via Alibaba, or do what I did, and order a big bore kit from Aliexpress (the 300cc kit) for the PR250 engine, and order the engine itself from XPro's eBay site. Then install the PR300/big bore kit into the PR250. The counterbalanced, 6 speed PR250 & the PR300 share the same bottom end; i.e., other than the 25cc in difference, they are the same engine. The PR250 engine goes in and out of stock quite frequently on XPro's eBay site, so you may want to set up a notification to let you know when it's in stock if it isn't right now.

The engine is air-cooled, but many put an oil cooler on it. I always wanted to get something with a 6th gear and a little more oomph, but with this engine now, I'm totally satisfied. It's still easy to work on, has about 12-13 more wheel HP than a stock, carbed Hawk, and parts are readily available.

See my video below for an overview: