Noram Ge Clutch ?

church7

church7

New member
We are running a 14t Noram heavy shoe clutch red springs with a 59 rear sprocket on a flat usually fairly dry 1/10th oval. We run a restricted Subaru EX27 spec motor in a QRC winged kart
All we can get is about 2700rpm out of it, we moved up to a 63 rear sprocket ran the same line and no change in rpm, tach barely moved from going into the corner and coming out and down the straight. tach is working, it takes off at about 1800rpm. i did just change the shoe settings from what looked like a more gradual setting to a more aggressive setting. Any ideas, clutch is brand new

Thanks
 
If it was the gear ratio, you should pick up close to 100 RPM for every tooth you add to the axle to be going the same speed. Sounds like you're going slower. I'd be looking at other things. The first thing I'd be checking is the compression pressure.
 
My son is a rookie who really runs a tight bottom line, so we kept gearing up 14/63 so he could get out of the hole quicker after scrubbing off in the corners,
Normally we avg about 100rpm per tooth change, that's what surprised me, there was no change. This is a brand new motor put together this year, Im convinced something is not right with this thing, Im waiting to get our old motor back and see how it reacts. I did notice 2 light blue marks on the edge of the shoes, Im suspecting some slippage, the clutch seemed hotter than normal the last 2 weeks. would you lose rpm if the clutch wasnt locking up fully.
Thanks Guys
 
That's what I suspected flattop1,
so last week we ran a 14-63 set up and the tach maxed out at about 2500 rpm and hardly moved during the race.
this week i put a 14-56 set up in and we seemed to have more speed but the tach topped out at around 2700 rpm, the track and his line was pretty much the same
I'm confident the tach is ok, it shows about 1800 and then the kart starts moving, I put the tach right in front of the go pro so i could read it every bit of the race.
I'm confused, this new Subaru has got me stumped
 
Now I'm really confused, you took seven teeth off the axle and now you're turning more RPM. That makes no sense at all. The fact that you're only turning 2700 RPM really surprises me. There's something seriously wrong somewhere!
14/63 2500 RPM = 17.89MPH
14/56 2700 RPM = 21.73MPH
You take off seven teeth and go 4 miles an hour faster? I suggest you take that kart to someone who knows what they're doing. That sounds harsh, I don't mean it to.
 
Trust me Alvin, I hear ya, I have replaced every part of this kart and back again 1 part at a time to try and track down the problem. My son won 3-4 heats and 3 Features last year as a rookie. We were not always the fastest kart, but we were competitive and quick enough that he could hold them off once out front.
The only thing thats different is the brand new motor we had put together this year. We have 3 builders who can seal our engines, The guy from our track is pretty good, BUT I know he rushed to get this one together for the first race of the year, I'm convinced he's missed something. You hate to point fingers and blame someone else, BUT. We threw a chain and broke our motor from last year. I am hoping to get the old one back for this week to get in back in the kart and I'm positive it will come back to life.
Seriously, we dropped to a 56 and the tach peaked at about 2700 thats it, and the kart ran as quick as it did all year so far.
The Governor is gone, at least the lever is gone. The bolt hole is sealed. I'm frickin stumped, the only thing I haven't done is check the compression. I'm close to pulling the thing apart myself to check the timing, the rings and rod bolts. Something is holding this motor back. Thanks for your input guys, much appreciated
 
Although I'm not familiar with that engine/kart combo or how many rpms you're trying to reach, I would have to guess you guys are really off on gear. Stock governor is set at 4000 rpm from the factory, so even if it wasn't removed correctly it's not the governor that's restricting your rpm. The 1/10th miles tracks that I run on are roughly a 12/64, or possibly an 11t driver on a flat kart with a clone. I would drop down to a 12 tooth driver and see how that goes.
 
church7 said:
Trust me Alvin, I hear ya, I have replaced every part of this kart and back again 1 part at a time to try and track down the problem. My son won 3-4 heats and 3 Features last year as a rookie. We were not always the fastest kart, but we were competitive and quick enough that he could hold them off once out front.
Click to expand...
Interesting, and how many rpm's did you turn last year, with what gear?

How sure are you about that track size?
 
Last year we ran a 14-65 gear, at 3900 to 4000 rpm. These Subarus peak out there, lots of torque but lower rpm than Hondas.
Since my son was a rookie and learning on the fly, He discovered early that if he was out front and ran a real tight line he could hug the bottom and it was real tough to get by him on the outside. So he would scrub so much speed off we kept gearing it up to get him out of the hole a little quicker
We would blow them away on the starts by 4-5 kart lengths by the middle of turn 1-2. So each week I would bump it up a tooth until we hit about 4000. This year he is running a little more conventional line.
As far as the track size, I never really measured it out manually, I'm going by the size shown from MyLaps
 
the new rear tires are about 1 inch dia. smaller than last years. so the rpm should be even higher than last year with the same gear. the plug looks good, your avg tan colour. Im taking this motor to another reputable engine builder and I am going to have him dyno it and then pull it apart and go over it top to bottom. I keep wondering if the timing chain is out a link retarding the timing a little. i don't think they used offset keys to advance timing when he put it together. i stumped and we only have 2 weeks of racing left, so we are pretty much chalking this season up to "it was a learning Experience"
Thanks for all you input, its nice to be able to bounce ideas off of someone else
 
One tooth on the timing chain would be a bunch of timing. Not likely.

Of course it all depends on the ratio your running and the size of your tires, but 1 inch in circumference, I assume that's what you're talking about, is close to two teeth on the axle with a 4 to 1 gear ratio and 34 inch tires. 1 inch in diameter is a different story.

I have spreadsheets to figure this stuff out.
 
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