Hawk 250 intakes on the exhaust stroke and vise versa

Maillmanmurry · 07-17-2024, 07:52 PM

I recently got a cheap big bore kit and finally got around to putting it in. When I got it all put together it felt like it had no compression. Took the valve cover off and the valves seem to be acting irraticaly, and when I put my hand over the exhaust it sucks on my hand, and when I put my hand over the throttle body it blows air... I'm so lost, can someone help?

Bill Hilly · 07-17-2024, 08:41 PM

Did you put a cam in when you had it apart?
If you did, then valve timing would be the suspect culprit. If not the only thing I can think of is that something is wrong with the way you have the followers installed. I don't think the jug would seat if the followers weren't spread out over the cam though. Did you actually feel the pushrods go in their sockets/cup? Are you sure both valve are completely closing?

Maillmanmurry · 07-17-2024, 10:09 PM

No I didn't. I only had as far as the jug taken apart. I'm pretty sure the pushrods are in the right spot. I kinda wiggled then around in the hole until they kinda pushed down snuggly and I couldn't wiggle them anymore. The valves were closing fully with the head off, I didn't check with it on.

red2003 · Yesterday, 03:44 AM

You DID re-adjust the valves when you reassembled it, right?

Maillmanmurry · Yesterday, 03:50 AM

Ummmmm... Would you laugh if I said no?

red2003 · Yesterday, 07:00 AM

Quote:

Originally Posted by Maillmanmurry

Ummmmm... Would you laugh if I said no?

I won't laugh. But that explains your symptoms. Both valves are too tight and bleeding compression into each other.

bigdano711 · Yesterday, 08:06 AM

I was thinking he's 180* out. Err...he was on the intake stroke when he had it at top dead center and not on the exhaust stroke. I did this once with my Honda Accord when I changed the water pump/timing chain (related job). When I fired it up it sounded and ran like crap. I finally realized my mistake, corrected it, she ran fine.

red2003 · Yesterday, 09:47 AM

Quote:

Originally Posted by bigdano711

I was thinking he's 180* out. Err...he was on the intake stroke when he had it at top dead center and not on the exhaust stroke. I did this once with my Honda Accord when I changed the water pump/timing chain (related job). When I fired it up it sounded and ran like crap. I finally realized my mistake, corrected it, she ran fine.

He can't be 180 out though, he didn't remove the cam.

Aussie_in_MO · Yesterday, 09:49 AM

Still could be 180 out if the cam rotated in the head when the head was off the jug though

red2003 · Yesterday, 09:52 AM

Quote:

Originally Posted by Aussie_in_MO

Still could be 180 out if the cam rotated in the head when the head was off the jug though

This is a pushrod motor, the cam is in the case, not the head.

bigdano711 · Yesterday, 02:01 PM

I didn't remove the cam on my Honda, but still put the timing belt (not chain) on 180* out. Is that not possible with these motors? I honestly don't know.

J4Fun · Yesterday, 02:23 PM

Quote:

Originally Posted by bigdano711

I didn't remove the cam on my Honda, but still put the timing belt (not chain) on 180* out. Is that not possible with these motors? I honestly don't know.

I think it was explained in post #10.

Bill Hilly · Yesterday, 02:35 PM

Quote:

Originally Posted by bigdano711

I didn't remove the cam on my Honda, but still put the timing belt (not chain) on 180* out. Is that not possible with these motors? I honestly don't know.

The cam on these CG motors is gear driven, and sits right on top of the crank. That chrome button looking thing on the side of the jug/ cylinder is a short shaft that the cam followers go on. I initially asked if he had the cam out, because when the jug is removed, it's a good time to change the cam, because the jug has to be removed to get to the cam. I think a lot of people think the extra 20cc from a 70mm big bore kit is a game changer, but the head porting, and long duration cam is more effective. The cams are so cheap , and with the jug already removed, it's just an extra few minutes added to the job. I am not really worried about the cheap cams, but I have learned my lesson on the cheap roller followers. I have a stock motor from a parts bike on my Hawk now, and have been enjoying it just fine, but I do occasionally miss the extra power of my hotter motor.

bigdano711 · Yesterday, 02:29 PM

Quote:

Originally Posted by J4Fun

I think it was explained in post #10.

Post #8 implies something else.

Yesterday, 03:44 AM	#4
red2003 Join Date: Jan 2007 Location: Northern Vermont, USA Posts: 1,259	You DID re-adjust the valves when you reassembled it, right? __________________ First Chinabike: 2006 Roketa RSX200E Current Chinabikes: 2023 Titan DLX & 2022 Lifan KP Mini w/ 210cc BRT kit, 22 RWHP!
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Yesterday, 08:06 AM	#7
bigdano711 Join Date: Jun 2023 Location: Big Piney, WY Posts: 475	I was thinking he's 180* out. Err...he was on the intake stroke when he had it at top dead center and not on the exhaust stroke. I did this once with my Honda Accord when I changed the water pump/timing chain (related job). When I fired it up it sounded and ran like crap. I finally realized my mistake, corrected it, she ran fine. __________________ 2023 Hawk 250 from XPRO off of Amazon MOUNTAIN MAN RC + MOTO on YouTube "If there were more bloody noses, there would be less wars." - Hagbard Celine "Someday, after mastering the waves, the winds, the tides and gravity, we shall harness for God the energies of love and then, for the second time in the history of the world, man will have discovered fire." - Pierre Teilhard de Chardin
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Yesterday, 09:49 AM	#9
Aussie_in_MO Join Date: Feb 2024 Location: SW Missouri Posts: 163	Still could be 180 out if the cam rotated in the head when the head was off the jug though __________________ ---------- 2023 Templar X 2009 Triumph Bonneville 1976 Yamaha DT175 1974 Honda MT125
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Yesterday, 02:01 PM	#11
bigdano711 Join Date: Jun 2023 Location: Big Piney, WY Posts: 475	I didn't remove the cam on my Honda, but still put the timing belt (not chain) on 180* out. Is that not possible with these motors? I honestly don't know. __________________ 2023 Hawk 250 from XPRO off of Amazon MOUNTAIN MAN RC + MOTO on YouTube "If there were more bloody noses, there would be less wars." - Hagbard Celine "Someday, after mastering the waves, the winds, the tides and gravity, we shall harness for God the energies of love and then, for the second time in the history of the world, man will have discovered fire." - Pierre Teilhard de Chardin
	1

07-17-2024, 07:52 PM	#1
Maillmanmurry Join Date: Jul 2024 Posts: 3	Hawk 250 intakes on the exhaust stroke and vise versa I recently got a cheap big bore kit and finally got around to putting it in. When I got it all put together it felt like it had no compression. Took the valve cover off and the valves seem to be acting irraticaly, and when I put my hand over the exhaust it sucks on my hand, and when I put my hand over the throttle body it blows air... I'm so lost, can someone help?
	0

07-17-2024, 08:41 PM	#2
Bill Hilly Join Date: Feb 2021 Posts: 978	Did you put a cam in when you had it apart? If you did, then valve timing would be the suspect culprit. If not the only thing I can think of is that something is wrong with the way you have the followers installed. I don't think the jug would seat if the followers weren't spread out over the cam though. Did you actually feel the pushrods go in their sockets/cup? Are you sure both valve are completely closing?
	0

07-17-2024, 10:09 PM	#3
Maillmanmurry Join Date: Jul 2024 Posts: 3	No I didn't. I only had as far as the jug taken apart. I'm pretty sure the pushrods are in the right spot. I kinda wiggled then around in the hole until they kinda pushed down snuggly and I couldn't wiggle them anymore. The valves were closing fully with the head off, I didn't check with it on.
	0

Yesterday, 03:50 AM	#5
Maillmanmurry Join Date: Jul 2024 Posts: 3	Ummmmm... Would you laugh if I said no?
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