M7 Big bore Clutching

[Ski-Laxn]

Ok before you tell me to search I Did.

Sled 05 153 with a Vohk 866 topend, BMP pipe, y pipe, boondocker box, egts, and a koso af gauge that works when it wants. Still fine tuning.

Clutch set up.
Primary 65g cutler adjustables, with slp Black yellow 120/310
Secondary 36* stock helix,BMP torsional with BMP black on second from end.

I need 8100 RPM.
can only get about 7600-7700 occasionally it will go higher. My question is do I need heavy weights for the SLP spring?
Should I change to a 300 finish rate?

 

[tatorsalad]

need more info what elevation are you running at heilex ect

 

[Ski-Laxn]

Sorry the elevation is 8500-11000. Helix is the stock 36*

 

[IShartd]

At that Elev, id thought you could easily swing more weight, I ride a 800 BB and swing 70G weight at 8300 rpm from 7500'-10500'. So It would not seem unreasonably for you to be able to run at least 68g weights all day,if not more. Is there a power problem? Are you Power Valves opening? get the AC orange/white for the primary and throw the stock AC white back in the secondary. I would also get rid of the Y pipe, thats flatlander equipment, try it with the stock one, you might be suprised.

Oh one more thing, have you actually weighed the weights, they tend to vary a lot.

 

[Ski-Laxn]

I am still trying to get the box dialed in. I was pulling fuel from the box. Seems like if i feather the throttle and not hold wide open it would creep up there. But if you hammer it and hold it only hits 7600.

 

[IShartd]

i think your lean on the bottom at the very least. if you jump on the throttle from low rpm and it bogs, im saying lean. Most of the orignial m7 bogging issues was as a result of this condition, check the plugs, use this as a baseline then you can tune from your EGTs. What are your EGTs saying?

 

[Ski-Laxn]

At idle egts are at about 450. Running down the trail everything is about 1000-1250.
At full throttle there at about 900-1000. But full throttle bogs out.

 

[IShartd]

What fuel #s are you running up top? I run 3 up high on the 7800 and 8100 range at my temps are consistent 1125 at WOT.

 

[Ski-Laxn]

Will go look. Be right back

 

[Ski-Laxn]

Here are my #'s I adjusted to today at 10000'.
3000 01 01 03
5000 02 03 02
6700 04 03 03
7800 03 03 04
8100 04 06 08
All testing was done going across a field of powder. Did a sidehill and cut up full throttle and she bogged.

 

[mooseman800]

Sounds a little rich up top. Had the same type of thing happen on my modded M7 and just lowered the boondocker a touch on the full throttle numbers. The too lean on top (in my case) was high revs and over 1400 degrees. Increased fuel 6 pts and had the sled rev too low, not reaching 8000, maybe 7500 to 7600. tuned another 3 pts less and nailed it. Peak RPMS at 1120 to 1140 degrees

 

[IShartd]

Id take them all back to 0 and start again, do some plug readings, we know this is going to be super hot in the middle and you need to put fuel at it on the top for the long pulls, just try not to throw to much at it at one time. vary your throttle position and see how hot it gets, i would try to tune plugs first, this is the most accurate, piston wash takes to much time to build up and is a pain to see on a lay down engine if the head isnt off. Match your plugs with your temp readings, I am rarely ever over 1200 degrees, and thats when Im keeping constant throttle in the 5800 rpm-6200 rpm range.

Your way to rich up top, i wouldnt even worry about the low and mid ranges for the 7800 and 8200, cause if your in this rpm range your mashing the throttle anyway, concentrate with the high settings for those areas.

Until you can get your temps right, I wouldnt worry about the clutching. with your #s all over the place like this, I would assume the bog is fuel related rather than clutch, however clutching will compound the feeling of the lack of power. one thing at a time.

And you can struggle all day long with trying to get the hot spot out of the middle, you may never get that figured out, its just the way that engine is.

my #s
0 0 0
0 0 0
0 0 0
0 0 3 1
0 1 3 1

 

[Ski-Laxn]

Thanks for the help. I was thinking that it was still a tuning issue and not clutch.

 

[IShartd]

let us know what you come up with.

 

[Ski-Laxn]

Will ride later in the week.

 

[sledhed88]

I'm runnin rkt 800kit. 70gr weights wit stock spring. An stock helix wot orange in secondary. Not quite pullin full rpm mite try 68s. Have a slight bog sometimes off the bottom. Not sure if its the slp twins or my primary sprng?? Any help? Other than that it runs well

 

[IShartd]

My advice would be to scrap the twins and never look back.

 

[Ski-Laxn]

Ok rode on Friday. Lots of powder and some hills. When running down the trail egt's fluctate between 1000 and 1210. When climbing if you take off and go full throttle and back off a little bit on the throttle. They will run 1235 at 8000rpm give it full throttle will bog to 7700 and 1000* on egt's. Back out clears up and goes hard again.
3000 01 01 01
5000 01 01 01
6700 03 03 03
7800 01 01 01 1
8100 01 01 00 1
Does anybody have negatives at the top end.
Clutching is now slp Black yellow 120-310 63g cutler weights. Secondary 36* helix, Bikeman torsional with bikeman black in second to tightest.
Still having issues getting to stay at 8000.