hawk 250 big bore kit?

[Gh426]

"do some good old boy tricks most dont have a clue about you be supprised. Id also like to get mine on ethonal for cooling purposes since we got a big gas tank i think i could still have a 180 mile distance all id ride in a day."

oK SO you went all e85 on me... yes I am down, You gonna run a small tank to "pickle" the carb back to reg gas just before shutting her down?

You got a cam in mind? how much was this 2nd head? got a link?

I am wating on these extra tricks.. C'mon you gonna spill da beans??

gh

[slowroller]

The csc tt250 head is better out box than hawk head but is a emissions head so you have to block off emissions port. Mine is a non emission head i found searching. The only thing to look for is bolt holes and bore size bore is 67mm if your not sure. They range in price from 50 to 150 dollars.

[slowroller]

Also get a thin shim head gasket if you can the one i got is around .016 thick. Stock is .041 thick and my piston is in hole .030. Make sure to use copperkote or hylamar sealer.

[Megadan]

There is more to having a larger bore than just making the hole bigger and putting in a bigger cylinder.

One thing that has to be kept in mind is that these are air cooled engines. Part of being air cooled means that they rely on the thermal mass of the cylinder to actually regulate their running temperatures. With a larger bore that means a smaller cylinder body, and that means less material to absorb and transfer the heat away. That is why most of the "larger" 270cc versions are liquid cooled only.

CCW offered a big bore kit for a time, but they stopped selling it for a number of reasons, one of them being that the motor was more prone to over heating more quickly when stationary, but also the cost involved was just out of the realm that most people were willing to spend, especially on a cheap bike.

As Jerry said, if you want to get more scoot under your boot then look into porting and decking the head. Even if you lack all tools to do it, the total investment is still well under $100, and there is decent gain to be had. I personally wouldn't even consider a bigger bore on this engine until I did head work anyway. It already can't breathe worth a crap past 7500rpm anyway, and bumping engine capacity with no change to head flow means it would fall short even sooner and flatten out. The strength of these CG engines is their mid range punch already. Where they need help is up top.

[slowroller]

When we ran go carts we were dyno motors 5 nights a week when box stock project got big u change and rechange everything in motors till you get something you think is good. Then you get out run by someone with a good handling freerolling cart lol. These bikes are the same get it free rolling = free hp

[jimwildman]

This is how I solved it. Ill post up details in another thread once its complete. I still have to tear it down and paint the frame prior to final assembly. It was alot of work but I do enjoy it. It is more then double the HP and weighs a mere 7lbs more then the stock engine. Im concerned about the cush drive in the stock wheel.

[Gh426]

E85 / e50 is great at cooling, but yes port work, raising compression via shaving the head, thinner head gasket. probably good to run the play doh on the piston valve interference test, all great stuff

[Megadan]

Originally Posted by Gh426

E85 / e50 is great at cooling, but yes port work, raising compression via shaving the head, thinner head gasket. probably good to run the play doh on the piston valve interference test, all great stuff

If you saw how much deck height there is between the piston and the top of the jug, you wouldn't be worried about valve clearance unless you put in a higher lift cam. I shaved 1mm from my head, and I could probably do the same again and still not hit the piston.

[zanoknight]

Originally Posted by NzBrakelathes

You would be better changing the whole engine to the OHC CB250-F engine with 2549cc (Can't recall bore and stroke just now)

The Hawk or CSC TT 250 only run the base model push rod engines etc.

There is a 300cc push rod motor that's water cooled and suitable for the 3 wheel trikes but that would work out rather complex

Do you know if the motor is an easy swap? I dont want to have to weld in extra motor mounts.

[Red]

Can anyone help me find valve tappet adjusting screws for a 2017 RPS Hawk 229cc

[Deckard_Cain]

Originally Posted by Red

Can anyone help me find valve tappet adjusting screws for a 2017 RPS Hawk 229cc

Did you remove the valve cover yet? 3 bolts to pull that off, then you'll see the screws and lock nuts on top.

[TxTaoRider]

There is that 300cc Xcross air cooled motor out there. Too bad it looks difficult to get here in the states. For trail riding I'd take extra ccs and torque over top end power.

[RedCrowRides]

There is a quality big bore kit that will take the 223cc engine up to 239cc that isnt too pricey, it is available from Joe Henner Motorsports ,as are roller rockers and head porting services. He is our engine mod guru for the RXB 250's with the 223cc motor. ,he also offers offset flywheel timing keys that advance the timing 4 degrees that really wakes these engines up all by itself ( really, you will be amazed how noticeable a change a $20 part can and does make ) he also offers ProCom and Big Gun CDI boxes., either of which will also help.Joes prices are very reasonable and apart from that he is a very knowledgeable and stand up guy ,way more folks from Chinariders need to know about him, he is a legend on the RXB 250 board on FaceBook.

[tknj99]

Originally Posted by RedCrowRides

There is a quality big bore kit that will take the 223cc engine up to 239cc that isnt too pricey, it is available from Joe Henner Motorsports ,as are roller rockers and head porting services. He is our engine mod guru for the RXB 250's with the 223cc motor. ,he also offers offset flywheel timing keys that advance the timing 4 degrees that really wakes these engines up all by itself ( really, you will be amazed how noticeable a change a $20 part can and does make ) he also offers ProCom and Big Gun CDI boxes., either of which will also help.Joes prices are very reasonable and apart from that he is a very knowledgeable and stand up guy ,way more folks from Chinariders need to know about him, he is a legend on the RXB 250 board on FaceBook.

I look forward to getting my head back from Joe who will be porting and polishing it. I will post a review of that. I also purchased his 4 degree timing key and once i get the tools to do that work will also post up a review of what each one has done to the Brozz 250 performance characteristics.
I look forward to providing very positive reviews

[alex_in_az]

Originally Posted by tknj99

I look forward to getting my head back from Joe who will be porting and polishing it. I will post a review of that. I also purchased his 4 degree timing key and once i get the tools to do that work will also post up a review of what each one has done to the Brozz 250 performance characteristics.
I look forward to providing very positive reviews

that 4 degree timing key is by far and away the best bang for the buck tuning mod on the CG engines, you will not regret doing it