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970?bb 900 cat

H

high time

Well-known member
Nov 28, 2007
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Duluth, MN
Yes, we did our own, but Ted [ cost-a-bunch ] from terra alps racing, does the whole kit. I'm not sure he's on the new forum yet , but he was on the old.
I will never run a big bore with out cast stock pistons again. The 925 with Wiescos was too easy to seize. This project with the stock 1000 pistons is great. Nearly the same cc's as the M-1000 with almost 1000 more RPM.
I'm not quite dialed in on mine yet, don't tell my buddies, they think it's good. But it's not at 200 ponies yet, and it should be. New Jaws D-pipes, and new timing along with not much riding yet. Maybe tomorrow.
A big help was the advice of Brent Linderman.

Owen
 
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Idcatman3

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Nov 26, 2007
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I agree with high time, cast pistons are the only way to go. We've been looking for a big bore for the 900 Cat for a few years, but didn't want to use weisco pistons. This setup works great, we're still dialing in clutching, but even turning ~500 rpms low, it will smoke a stock 900 and beat the '07 M1000 we were with. We've got a few hundred miles on one with no problems so far (except someone leaving the exhaust valve cables unhooked....) It's a testament to how good this is that even without the exhaust valves, it was still kicking my 900's butt.
 
H

high time

Well-known member
Nov 28, 2007
1,413
303
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Duluth, MN
Have you reground your valves? I'm having trouble getting mine to work, although I have them held open for now. They have been cut by the same amout as the cylinder radius. Did you run a timing key? Porting?, Pipes?

I have a gutted and snorkeled intake with 44mm rounds, reeds, ported case and cylinders, Mono block billet heads at 150 lbs comp., 2 deg advanced,and front exit Jaws D-pipes. Then I spin a Camo Chal. Extreme 2.5''.
If I hadn't sold by 40's flatsides, I'd put them back on. There's a lot of munkey biz to get the rounds to work right. You need to install a resistor in the place of the throttle position sensor, brass slides as aluminum ones will freeze and the heavy lift for your thumb. Just for a few more HP.

Owen
 
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Idcatman3

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Nov 26, 2007
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We did regrind the valves to fit. We rode it once and had to regrind them a little more, they were rubbing on the pistons.
We have no timing key, running an '04 900 CDI box. Porting was done by my dad, approximately back to stock specs. We've got a black magic single pipe and can and stock 40mm carbs, VF3 reeds, reed spacers (just for the heck of it we made some). No case porting I believe, but I will check. Speedwerx head cut to the correct bore. Intake is also stock, with the inlet behind the can blocked.
Also turning a Challenger Extreme 162"x2.5".

About the only trouble we are sure we have had with the valves is not having them hooked up. Have a set of gas powered valves on the way.
 
B
Jul 6, 2001
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Watrous, SK
Have you reground your valves? I'm having trouble getting mine to work, although I have them held open for now. They have been cut by the same amout as the cylinder radius. Did you run a timing key? Porting?, Pipes?

I have a gutted and snorkeled intake with 44mm rounds, reeds, ported case and cylinders, Mono block billet heads at 150 lbs comp., 2 deg advanced,and front exit Jaws D-pipes. Then I spin a Camo Chal. Extreme 2.5''.
If I hadn't sold by 40's flatsides, I'd put them back on. There's a lot of munkey biz to get the rounds to work right. You need to install a resistor in the place of the throttle position sensor, brass slides as aluminum ones will freeze and the heavy lift for your thumb. Just for a few more HP.

Owen

Owen, use this block with your TPS. http://www.cpcracing.com/site/256083/product/CP-001-8100

I'm running the VM44's on my 999 and The throttle pull isn't too bad. I cut 1/3rd of the spring out and they pull very easy now and don't stick.
 

Idcatman3

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Nov 26, 2007
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Idaho Falls, Idaho
I'm usually on daily, we've got the jetting pretty well nailed on ours, but the clutching is giving us some headaches. It'll be good to hear more setups on these.

We're also building a triple version with the same cylinders, cut and welded two crankcases, so that will be another animal altogether.

mockuptop.jpg
 
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H

high time

Well-known member
Nov 28, 2007
1,413
303
83
Duluth, MN
Throttle block for TPS

The throttle position sensor detects voltage at wide open , I believe it is supposed to be 4.7 volts. We installed a little reostat that plugs into the ols carb plug. BUT if I do have a voltage on ground problem, then maybe it's holding me back.

Owen
 
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