RPS Hawk engine change question

CreekWalker · 07-08-2022, 06:40 PM

I realize this is very much a noob question. Laugh at me if you will.

So I bought the EFI version of the Hawk 250 back in the spring. The clutch burnt up. I put in a new clutch assembly, and after another hundred miles, the centrifugal oil filter sheared off and threw metal shavings all over everything. Still under warranty so after this second incident, RPS said they would ship me a refurbished engine if I would pay shipping, which I did.

I was on vacation so it sat in my basement for a couple of weeks and I didn't crack it open until today. Got it bolted on the frame, started to hook everything up ... and came across a wire with nowhere to connect it. Turns out, on my old engine, it screws into the back of the head near the intake. The new engine doesn't have the connection. I didn't even inspect the engine closely before this, but it looks like they shipped me a standard Hawk 250 engine instead of the Hawk 250 DLX engine (the Hawk 250 has "Hawk" stamped on the crank case; the DLX has "Hawk DLX" stamped on the case).

I can't see a single difference in the two engines themselves, except for the wire connection. I back-traced the wire and couldn't make any sense out of it, and googling doesn't give me an answer either. Can someone tell me what this wire is for and can I continue without it? I'm sure I'm not gonna like the answer but I figured I'd ask...

JFOlivier · 07-08-2022, 06:50 PM

Just off the top of my head that looks like the engine temperature sender that goes to the efi. You will need to find somewhere threaded that you can thread that into on the barrel, the head or valve cover.

XLsior · 07-08-2022, 07:02 PM

You could also swap the heads over....

Thumper · 07-08-2022, 08:34 PM

This is not and EFI "issue", but cripes... If you had a carb, no problem. But you don't. Yes, it has to be the temperature sensor for the EFI.

I am sorry that you did not tell them it was an EFI bike and had to have the sensor mount (makes sense that is what it is). But you didn't think it was an issue! If the head you got has the position but not the drilled tapped place to install, you can drill and tap. Otherwise, you are facing the head swap. Uuuggh!

Man. Sorry dude.

CreekWalker · 07-27-2022, 02:15 AM

Just a follow-up in case anyone else finds themselves in this predicament. Should you just go ahead and make the standard Hawk 250 engine work on the 250 DLX bike? The short answer is no.

Not having the ability to drill a mount for the temp sensor in the head, I decided to switch the head from my original engine (250 DLX) with the head from the new engine (standard 250), hoping that would be the only difference between the two engines. It isn't. The connectors for the wiring coming out of the magneto stator are completely different. So, I changed the stator and case cover over too. But then the flywheel rotor is ever so slightly different, and the case/stator assembly won't fit on. So I changed the flywheel rotor over as well.

With those changes, I got the new motor mounted on the bike, wired up ... and now it won't start. Got fire, got gas, but it absolutely won't start. (It acts like it's out of time, but the timing checks out.) I don't know if anyone has been where I'm at and has a suggestion for what I'm overlooking but this is where my engine change project has led me.

Thumper · 07-27-2022, 07:31 AM

Check for spark- remove the plug, reconnect the spark plug wire and turn it over with the plug pushed onto the head. You can use a wooden stick to push it against the head. Should see an obvious spark.

I am sure that you've gone over the wiring more than once!

It would have been much easier to change the stator wiring connector since the stator has the same number of wires, doesn't it? That would have saved you a lot of wrenching. I can't think of any difference in the stator positioning since it is keyed.

Megadan · 07-27-2022, 01:25 PM

Quote:

Originally Posted by Thumper

It would have been much easier to change the stator wiring connector since the stator has the same number of wires, doesn't it? That would have saved you a lot of wrenching. I can't think of any difference in the stator positioning since it is keyed.

There are two types of CG stator. 88mm and 93mm (iirc). Since the DLX runs a higher output 3 phase stator in order to power the electronics, it is the latter. It is also DC CDI for those reasons. Larger stator - larger flywheel.

China Rider 27 · 07-27-2022, 02:24 PM

In my opinion that DLX needs ALL the EFI sensor input to function correctly. I would see if I could find a diagram of the system and verify I could swap all sensors over with the parts to make them function. There should be some diagnostic fault codes showing but I know nothing about the DLX EFI.

Thumper · 07-27-2022, 04:22 PM

Quote:

Originally Posted by Megadan

There are two types of CG stator. 88mm and 93mm (iirc). Since the DLX runs a higher output 3 phase stator in order to power the electronics, it is the latter. It is also DC CDI for those reasons. Larger stator - larger flywheel.

My old GS series Suzukis had 3 phase stators. I had no idea. So he needs three phase stator, so I guess the non-EFI engine isn't compatible since it doesn't have/fit the 3phase stator. So this engine swap has more fundamental issues!

07-08-2022, 06:40 PM	#1
CreekWalker Join Date: Jul 2022 Posts: 3	RPS Hawk engine change question I realize this is very much a noob question. Laugh at me if you will. So I bought the EFI version of the Hawk 250 back in the spring. The clutch burnt up. I put in a new clutch assembly, and after another hundred miles, the centrifugal oil filter sheared off and threw metal shavings all over everything. Still under warranty so after this second incident, RPS said they would ship me a refurbished engine if I would pay shipping, which I did. I was on vacation so it sat in my basement for a couple of weeks and I didn't crack it open until today. Got it bolted on the frame, started to hook everything up ... and came across a wire with nowhere to connect it. Turns out, on my old engine, it screws into the back of the head near the intake. The new engine doesn't have the connection. I didn't even inspect the engine closely before this, but it looks like they shipped me a standard Hawk 250 engine instead of the Hawk 250 DLX engine (the Hawk 250 has "Hawk" stamped on the crank case; the DLX has "Hawk DLX" stamped on the case). I can't see a single difference in the two engines themselves, except for the wire connection. I back-traced the wire and couldn't make any sense out of it, and googling doesn't give me an answer either. Can someone tell me what this wire is for and can I continue without it? I'm sure I'm not gonna like the answer but I figured I'd ask...
	0

07-08-2022, 08:34 PM	#4
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,342	This is not and EFI "issue", but cripes... If you had a carb, no problem. But you don't. Yes, it has to be the temperature sensor for the EFI. I am sorry that you did not tell them it was an EFI bike and had to have the sensor mount (makes sense that is what it is). But you didn't think it was an issue! If the head you got has the position but not the drilled tapped place to install, you can drill and tap. Otherwise, you are facing the head swap. Uuuggh! Man. Sorry dude. Last edited by Thumper; 07-27-2022 at 07:32 AM.
	0

07-08-2022, 06:50 PM	#2
JFOlivier Join Date: Nov 2020 Location: Northern Neck of Virginia. Posts: 164	Just off the top of my head that looks like the engine temperature sender that goes to the efi. You will need to find somewhere threaded that you can thread that into on the barrel, the head or valve cover.
	0

07-08-2022, 07:02 PM	#3
XLsior Join Date: Aug 2020 Location: Australia Posts: 1,300	You could also swap the heads over....
	1

07-27-2022, 02:15 AM	#5
CreekWalker Join Date: Jul 2022 Posts: 3	Just a follow-up in case anyone else finds themselves in this predicament. Should you just go ahead and make the standard Hawk 250 engine work on the 250 DLX bike? The short answer is no. Not having the ability to drill a mount for the temp sensor in the head, I decided to switch the head from my original engine (250 DLX) with the head from the new engine (standard 250), hoping that would be the only difference between the two engines. It isn't. The connectors for the wiring coming out of the magneto stator are completely different. So, I changed the stator and case cover over too. But then the flywheel rotor is ever so slightly different, and the case/stator assembly won't fit on. So I changed the flywheel rotor over as well. With those changes, I got the new motor mounted on the bike, wired up ... and now it won't start. Got fire, got gas, but it absolutely won't start. (It acts like it's out of time, but the timing checks out.) I don't know if anyone has been where I'm at and has a suggestion for what I'm overlooking but this is where my engine change project has led me.
	0

07-27-2022, 07:31 AM	#6
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,342	Check for spark- remove the plug, reconnect the spark plug wire and turn it over with the plug pushed onto the head. You can use a wooden stick to push it against the head. Should see an obvious spark. I am sure that you've gone over the wiring more than once! It would have been much easier to change the stator wiring connector since the stator has the same number of wires, doesn't it? That would have saved you a lot of wrenching. I can't think of any difference in the stator positioning since it is keyed.
	1

07-27-2022, 02:24 PM	#8
China Rider 27 Join Date: Dec 2018 Location: PNW Posts: 982	In my opinion that DLX needs ALL the EFI sensor input to function correctly. I would see if I could find a diagram of the system and verify I could swap all sensors over with the parts to make them function. There should be some diagnostic fault codes showing but I know nothing about the DLX EFI.
	0