Hawk dlx problem / big bore kit install
 

I have a 2023 Hawk DLX. I recently bought the true 250cc Big bore kit from motocult. I went to install the kit last night and ran into a major problem. The kit came with a 16 mm wrist pin which from all I have read is correct, but it’s too wide to fit my crankshaft. It appears to be a 15 mm crank shaft opening. To make matters worse, the piston I removed is damaged and I can’t reinstall it. I can’t find any piston that uses a 15 mm wrist pin. Every one that I can find is 16 mm. What should I do. I left a message for Devin at Motocult and I’ll waiting for his answer but I wanted to get as many ideas as possible.

Is your engine overhead cam by chance? That is the only reason I can think of for it having a 15mm wrist pin.

you could get a sheet of wet dry 240 git and hone out the opening to fit a 16mm pin.


just roll is up and twist rather than reem...then when your close use a finer grit like 600 until the 16mm slides in.


it wont be much material to remove going from 15mm to 16mm... It's not a rotating assembly as the piston just pivots on the pin so it should be fine.

It is the counterbalanced engine. I don’t believe it is overhead cam, just normal pushrod.

I thought about sanding it down 1mm, like you said but I was worried about the durability of it. Do you think it would be ok?

When you say "15 mm crank shaft opening", do you mean connecting rod opening? I think that's what you are referring to. Find the correct rod or have the rod machined to 16mm. It is nearly a new bike!

If there is a roller pin bearing, that surface needs to be perfectly round and smooth. You will be doing this all over again right if the bearing fails!! And the shrapnel from the failure will drop into your crankcase :ohno:

The wrist pin surface must be round, and centered, and smooth as glass.

You might see what Devin has to say.

Hand reaming can be easy to screw up. I would really advise finding a rod with the 16mm inner diameter on the piston side. Megadan sez OEM stock is a 16mm, so it should be available.

The piston had a 16mm opening, the shaft that the piston and wrist pin connect to has a smaller diameter.

The wrist pin holds the piston on the connecting rod. I think you mean rod, not shaft? There must be a connecting rod available for the 2023 with a 16mm bore for the wrist pin.

Is there a pin bearing like the one in this photo? If so, that rod needs to have a good machined surface for the bearing. The main bearing on the crankshaft end is the other kind of bearing in the photo below the gudgeon pin (wrist pin).

If you called the connecting rod a shaft in your email to Devin, he will probably know that you mean the rod.

Attachment 30224

Attachment 30225

I sent Devin pictures of the two wrist pins and the connecting rod.

There is no roller bearing on a CG250 upper connecting rod. It should be a 16mm opening but these engines can get parts binned...


Unless its a CG200 engine...


I have sanded mine after changing pistons and cylinder of various occasions for various reasons, engine still runs fine.


The piston pivots on the pin separate to the pin in the connecting rod the connection rod moves up and down and rocks back and forth...yes its gets some oil lubrication...But for the most part it is more about removal servicing then operation.


Have you measured both pins? do they look the same...From what I have seen on Aliexpress is there are no 70mm pistons with 15mm pins. The only 67mm piston with a 15mm pin on Aliexpress appears specific to a honda crf 230F application.


Are you 100% sure that the original pin is 15mm OD and that the upper connecting rod opening was not damaged slightly when removing the old piston...



So if you want to get the bike running again without costing a fortune my advice is just carefully sand out the upper connecting rod till the 16mm pin slides in snug. You could smear some copper grease if you're concerned but it will likely wash off with running engine oil...

I would say that very few ,if any people have bought the new DLX with counterbalanced motor , and already decided to do the big bore kit. I would say that all of the new counterbalanced ones will have a bigger wrist pin. What I am wondering, are you sure that it was actually a 229cc to begin with ?. Did you see it on the base of the cylinder (jug)?.. Maybe the new DLX is a true 250cc. You may be better off to try to return the kit. I don't read keep up with everything, and while I knew that the new Hawk X was counterbalanced, I didn't realize the DLX was too. I wasn't even real sure if the counterbalanced one were still pushrod motors. Good Luck.

My 229cc Bashan Storm has a naturally aspired (carb), counterbalanced pushrod engine. Who knows what connecting rod they put in the engine in the 2023 Hawk DLX (OP). Exactly what is in the OP's Hawk??????

Parts? Well this is the major barrier to widespread acceptance of Chinese motorcycles. No access to parts diagrams, wiring diagrams, etc.

So we rely on sites like this one for anecdotal success stories. But here we have Megadan saying it should have a 16mm wrist pin. Maybe this is a difference between the counterbalanced v non-counterbalanced engine?

But most of us have not replaced a piston, so we can't help.

Update: I measured my piston and it is 65mm and the wrist pin is 15mm. Devin from motocult is helping me but said he has never seen this before. I’m still trying to find a replacement cylinder, so if you guys have any thoughts, I’d love to hear them. Also the motor claims to be a 167fmm and it has 250cm on the it. I’m starting to think it is a cg200.

If the bike is new/under warranty and has a 65mm piston it is not a 167fmm, but a 165fmm making a CG200 which explains the 15mm pin. I would contact the supplier and consider returning the bike or getting the engine correctly replaced under false pretense.


How wide is the cylinder outside diameter/case opening? if its a true CG250 case (bottom half) then the opening should be about 74mm ish.

Outside diameter 69.5