Planet Minis

mxracer49 · 07-26-2008, 11:25 AM

Just went down to the mx shop and used their flywheel puller for this XR70. He gave me a complete head out of a United Motors 110. It looks like it will bolt right up to this 70 motor. The cam is different and the head is bigger overall. Probably a long shot if anyone knows but will this head work on the 70? Valves are the same size.

357 Racing · 07-26-2008, 11:55 AM

My guess is that it is china stud spacing.

mxracer49 · 07-26-2008, 12:04 PM

Everything lines up perfectly. The stroke of that 110 motor this head came off is 49.5. The stroke on the 70 is 41.4. ??

Kurlon · 07-26-2008, 01:04 PM

Sounds like an E22 head then. Should work, the cam will be slightly more aggressive than your stock 70 cam, with slightly larger ports. Get it ported and it'll work MUCH better.

mxracer49 · 07-26-2008, 01:46 PM

The only difference is the intake manifold hole is 1/8" larger than the 70 head. Looks like I might have to get a bigger carb and intake manifold.

firepower354 · 07-26-2008, 05:58 PM

Just make sure you use a 28 tooth cam sprocket to fit the new head.

+1 on porting it. I've used several of them.

What's your plans for the 70 head?

mxracer49 · 07-30-2008, 07:45 AM

Quote:

Originally Posted by firepower354

Just make sure you use a 28 tooth cam sprocket to fit the new head.

+1 on porting it. I've used several of them.

What's your plans for the 70 head?

Not sure yet. I just ordered a E22 last night because this United motors head didn't work out. I may order guides and then have a shop here in town put them in. That way I'll still have the stock head and cylinder.

firepower354 · 07-30-2008, 06:19 PM

What didn't work on the head swap?

mxracer49 · 07-30-2008, 08:20 PM

Not real sure. It tried to run but ran terrible. Backfiring and all. It's in perfect time. I checked it 3 times. Valves are all set. Couldn't even get it to start after that.

07-26-2008, 11:25 AM	#1 (permalink)
mxracer49 1st Gear Member Join Date: Oct 2007 Location: Kansas Posts: 111	United Motors 110 head onto a 70? Just went down to the mx shop and used their flywheel puller for this XR70. He gave me a complete head out of a United Motors 110. It looks like it will bolt right up to this 70 motor. The cam is different and the head is bigger overall. Probably a long shot if anyone knows but will this head work on the 70? Valves are the same size.

07-26-2008, 11:55 AM	#2 (permalink)
357 Racing 3rd Gear Member Join Date: Dec 2006 Location: Austin, Texas Posts: 3,576	Re: United Motors 110 head onto a 70? My guess is that it is china stud spacing.

07-26-2008, 12:04 PM	#3 (permalink)
mxracer49 1st Gear Member Join Date: Oct 2007 Location: Kansas Posts: 111	Re: United Motors 110 head onto a 70? Everything lines up perfectly. The stroke of that 110 motor this head came off is 49.5. The stroke on the 70 is 41.4. ??

07-26-2008, 01:04 PM	#4 (permalink)
Kurlon Baron Von BanHammer Join Date: Feb 2005 Location: Windham, ME Posts: 7,863	Re: United Motors 110 head onto a 70? Sounds like an E22 head then. Should work, the cam will be slightly more aggressive than your stock 70 cam, with slightly larger ports. Get it ported and it'll work MUCH better. __________________ http://www.x386.net/TTR 2004 ST3 - 'Duckie'?!?! 2005 CRF70RR - MiniGP Weapon 2005 CRF70 - Dirt Donk 2008 Pitster Pro X4 Motard 1991 GS500E - LRRS/CCS #771

07-26-2008, 01:46 PM	#5 (permalink)
mxracer49 1st Gear Member Join Date: Oct 2007 Location: Kansas Posts: 111	Re: United Motors 110 head onto a 70? The only difference is the intake manifold hole is 1/8" larger than the 70 head. Looks like I might have to get a bigger carb and intake manifold.

07-26-2008, 05:58 PM	#6 (permalink)
firepower354 3rd Gear Member Join Date: Oct 2006 Location: Flint MI Posts: 6,255	Re: United Motors 110 head onto a 70? Just make sure you use a 28 tooth cam sprocket to fit the new head. +1 on porting it. I've used several of them. What's your plans for the 70 head?

07-30-2008, 06:19 PM	#8 (permalink)
firepower354 3rd Gear Member Join Date: Oct 2006 Location: Flint MI Posts: 6,255	Re: United Motors 110 head onto a 70? What didn't work on the head swap?

07-30-2008, 08:20 PM	#9 (permalink)
mxracer49 1st Gear Member Join Date: Oct 2007 Location: Kansas Posts: 111	Re: United Motors 110 head onto a 70? Not real sure. It tried to run but ran terrible. Backfiring and all. It's in perfect time. I checked it 3 times. Valves are all set. Couldn't even get it to start after that.

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