Which engines are OHC? Which are pushrod?

[MAT]

I'm looking for a cheaper 250 street legal dual purpose bike and it has to be OHC (overhead cam, no pushrods). It appears many of the 230cc are actually pushrod motors (Hawks, Bashons). It's confusing, are all the 230cc pushrod motors? Which are OHC, and actually 250cc?

The one I know of is the SSR XF250 which is a 249cc SOHC (Suzuki clone?) but it's a tank at 330# and a bit expensive. I'm looking for something that's lighter and has or can fit wider wheels. The Apollo DB 36 (RX250?) Deluxe looks like a decent bike but one site said it had a new 250 motor and other say it's 230 (223). None state where the cam is located. Pics of the motors appear to be of both types?

My experience thus far with Chinese bikes is with pitbikes, both SSR and Piranha which I race on kart tracks. It's so much fun to beat japanese bikes with 2x the cost of mine in engine mods alone. Thanks.

[coolwhip27]

I'm not sure any of the mainstream chinese bikes are OHC. letsride thinks that the DB-36 might be, from his last post. From how it sounds tho, you'd probably want to look into the Pitster pro XTR 250 SC or LC. The SC is 700$ cheaper than the SSR and is a SOHC. Also much more put together and light compared to the chinese clones. That's as far as I can figer'

[NzBrakelathes]

Look on the left side on the head if there’s a round cover
Also round plugs on the top above valves then it’s ohc
The biggest OHC is 249.9cc I’m not sure if that is sold in the USA but maybe the GPX air cooled might have it in the USA but not xtr or PitsterPro bikes
I could supply n send at around $800

[elkhunter338]

CSC Rx3 says it's OHC 250cc, adventure bike, not sure if you consider this a dual sport.

[letsride]

Looking at Greko96's thread on his new Apollo DB36 Delux. That is an OHC motor if I've ever seen one.
http://www.chinariders.net/showthrea...ht=apollo+db36

[Bruces]

Can I ask what your problem is with the pushrod engines ?

[MAT]

Originally Posted by Bruces

Can I ask what your problem is with the pushrod engines ?

Mostly mental! I've been working on japanese SOHC engines for 40 years so I know them, plus I like to tinker and they have much more potential.

The Pitster Pro is nice but they can't be made street legal in WI. What I'm actually trying to emulate is a TW200 go anywhere rig. I'd like to be able to leave it at a trailhead and not worry if it gets stolen, or if it does I won't be out too much $.

Piranha P190R mini-motard racer
12 Yamaha TTR-125 FT/ice racer
09 KTM 450 XC-F SM racer
75 CB400F Vintage rider

[guitback]

MAT, can I assume you never found an OHC alternative? I fully understand why you would prefer an OHC motor. Consequently, I'm in the same dilemma you were.

[grumpyunk]

There's a lot of tinkering you can do on a CG250(229cc).
- port the cylinder head
- deck the cylinder head
- use flat steel head gasket
- get a 'fat grind' cam(Brazil or ebay)
- get roller tipped cam followers
- get a high compression piston
- fiddle with exhaust/new muffler
- remove catalytic converter
- fiddle with new carb flat slide/round slide/diaphragm/accelerator pump
- fiddle with air cleaner/filter pod
- delete EGR/Pulse air system
- diddle with spark timing/use advance key
- get a 70cc piston/cylinder(machine work)
There is a lot of untapped performance in the CG engine. Raising compression and advancing the timing alone are relatively easy and cheap.
I do not have numbers but the OHC engines seem to produce power at higher rpms which is not necessarily a good thing when off road. Mo betta is torque and control at lower rpms. I guess, with zero knowledge, there's a reason the CG was selected for so many different machines in the same class. More than one, I figure. I think the design will take a whole lot more abuse than an OHC design. OHC engines need more oil flow to the top of the cylinder head to stay alive with non-roller cam followers. Rocker arms are satisfied with little more than a dribble. The CG cam is splashed with oil from the crank and cam gears, keeping the followers lubed as long as there is oil in the sump.
Nothing against OHC engines, having two bikes so designed. Mentally I classify them as 'thoroughbreds' vs the CG pushrod engine being more like a Morgan or maybe a Clydesdale. I don't know horses, obviously.
tom

[Wild Dog]

Originally Posted by grumpyunk

I guess, with zero knowledge, there's a reason the CG was selected for so many different machines in the same class. More than one, I figure. I think the design will take a whole lot more abuse than an OHC design. OHC engines need more oil flow to the top of the cylinder head to stay alive with non-roller cam followers.

The CG was designed from the ground to be Cheap, Simple and Durable, people need to get that in mind. It was never meant to be a racing engine or a performance one.
CB engines (OHC) are overall better engines than a CG, but then again. Honda never made the CG to be a successor of the CB nor a competition to other OHC engines.

Does the CG has untapped potential?? Indeed but the same goes for OHC engines like the CB.

[JerryHawk250]

i own both the CG and CB engines. The CB engine is much easier to get performance parts. With engine mods the CG works great for off road because of the low and mid range torque with minimal improvement on top end whereas the CB performs the best in the mid to high rpm range. On my X22R there was a drastic increase on top end speed. For a dual sport i would stick with the CG engine.

[Megadan]

CG engine = the tractor factor. Tractor simplicity - open splash oiling mixed with a minimal pressurized system, a lot of which goes to the head for cooling purposes. Single cam lobe. Gear driven everything (not including counter balanced motors). Specifically intended for working in harsh conditions, to be reliable with minimal maintenance, and fixed with almost no tools. Makes good mid range and low end grunt.

CB Engine - The performer. Due to chain drives, more pressurized oiling, and the rocker design they will be more sensitive to maintenance needs than the CG, but thanks to having independent cam lobes the cam can be designed to provide better performance, especially at the higher RPM ranges. Not any less reliable, but more sensitive to maintenance.

Either engine can be good at on or off road duty, but the difference will come down to how they are geared via the sprockets. A CB powered bike will always tend to like shorter gearing (bigger rear sprockets) to keep the engine in the upper RPM ranges more. The CG thrives more with slightly taller gearing (smaller rear sprockets) so the RPM's stay in that middle rev range sweet spot of the torque curve more. The CB has the edge in top speed road bike performance though. Like Jerry said, for putting around off road the CG is just a little more friendly and forgiving.