Intermittent rpm loss

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theUltamateTBM

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• Jan 31, 2018

• #1

I am have an issue with random rpm loss on long pulls or back to back pulls on a 13 m8 I had the issue last year and found a bad roller in primary so this year I put a new primary on and am still getting the same results. I have a full slp pipe and a tki belt drive at a 2.52 ratio with a 153 2.6 also running mds weights and a team tied setup I generally ride around 5k ft any input would really help

 

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M8onEdge

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Rigby, Idaho

• Jan 31, 2018

• #2

Are you running 084 or 083 belt? I struggled getting consistent rpms with the 084. Easier to blow the 083 however!

 

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theUltamateTBM

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• Jan 31, 2018

• #3

084 belt primary spring is a 100/340 secondary is a black silver 160/280

 

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jim

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• Jan 31, 2018

• #4

You need more backshift pressure to keep Rs when the clutching gets hot & belts get sticky. You will typically increase the spring tension/rate a bit or move to a more aggressive helix. You also need to look at your Rs. I have found that one key to hitting Rs all day, hot or cold clutching, is to target peak RPMs just above peak HP for your set-up...that way when it loads up, you are dropping into more power, not less...and falling off the pipe is less likely.

 

Vern

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hyrum utah

• Jan 31, 2018

• #5

M8onEdge said:

Are you running 084 or 083 belt? I struggled getting consistent rpms with the 084. Easier to blow the 083 however!

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Same here, seems as soon as the 084 gets hot rpms start dropping. I prefer the 083

 

armey37

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• Feb 1, 2018

• #6

Same with mine on long hard deep powder pulls. I just switch to Speedwerx 170/270 and hoping that will help. Also lighten my Mds weights. Do you have extra venting?

 

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sno*jet

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• Feb 1, 2018

• #7

jim said:

You need more backshift pressure to keep Rs when the clutching gets hot & belts get sticky. You will typically increase the spring tension/rate a bit or move to a more aggressive helix.

Click to expand...

you mean less aggressive helix- shallower angle right? thats what i was thinking anyway.
might be worth trying the 083 belt tho. ive been back and forth on mine, and notice a little more rpm with the 083, but it makes a bit more mess under the hood as it wears faster. good luck!

 

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jim

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• Feb 1, 2018

• #8

I meant more aggressive in that it applies more spring and helix pressure to keep the sheaves from opening up as easily and backshifts more aggressively...so yes, less helix angle.

 

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theUltamateTBM

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• Feb 2, 2018

• #9

What would you recommend for a helix angle the one I have is a 71-55-36 Or a 71-57-36

 

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theUltamateTBM

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• Feb 3, 2018

• #10

Bump

 

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sno*jet

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• Feb 3, 2018

• #11

smaller number the better on the secondaries i been around, if youre having sluggish backshifting, and sounds like you are. also straight cut helix will backshift more consistently.