1976 Nitro Grass Drag Set Ups

[Ruppsforever]

I just got my sled out of storage and will be doing a complete rebuild of the sled before next winter. I think you gave me the bug back !! Happy Easter to you too !!

[midniterupper]

That is the best news of the year! So glad to have you back racing your Rupp, we all know you and your machine will dominate any race you decide to enter! Congrats! Let us know what you do to tweak her in to get her ready.

This will shake up the good ol' boys at the races for sure. What a huge difference from just a couple of years ago, great seeing Team Red win again!

Thanks again for sharing the great news for our community, looking forward to hearing your progress.

Til then,
-Paul

[upmagnum]

Hey Josh, Good to hear you took Darth out of hibernation.

[Ruppsforever]

Thanks Joe !!! Yep Darth is back in the shop out of storage. Going to completely strip it down and check everything over. Also rebuilding the motor.

[midniterupper]

Well, it's time for a brief but exciting update today! Ended up tearing into the old girl getting stripped down to the bare body fiberglass panels. Easy access to everything while the motor is out so I can clean up the grime out of the engine compartment. So now I can perform some minor body work there and on the outside while I'm at it. Maybe I can get some pics posted of the progress.

Also ended up ordering one driveshaft bearing from Microblue. I was shy that bearing so I figured it would be a good chance to compare them directly. Let you know the difference if any.

Now the real exciting news is that we ordered a new hood from the master Bill Stull! He'll paint it up and make this sled look awesome! Must post pictures of this one for sure. The plan is to test with our original hood and race with the new one, I know it'll really get some attention in the pits now! It will be our pleasure to showcase some of Bill's finest work here at the tracks in Michigan. I believe the sled will be kicking butt in more than one way this year!

That's it for now, much to do!
-Paul

[midniterupper]

Hey, it's s good time for a little update on the Nitro. Been very busy cleaning the lower (bellypan) portion of the sled. It took a lot of effort to remove 45 years of good time grime, and still pulling mud out of the tunnel from last year's grass drags.

The body work I originally said was only "minor" has now consumed 50+ hours of fiberglass, bondo and spot glazing. Oh yeah, did I mention the sanding? Lots and lots of sanding! Everything has blended in quite well; I figure this old sled has been in the body shop at least 3 times as evidenced by the different layers of glass and previous body filler colors. It is sanding in nicely now, still have to finish wet sanding with 400 then clean everything off again. I will paint the engine compartment gloss black with a nice clear coat to finish that area off. Hopefully it will help rinse off the track dust a little better, I drilled some additional drain holes to aid in flushing it out.

I went and bought the paint and supplies needed to do the outer lower half from the local auto paint store. Sealer, base and clear came to about $175.00 along with the essentials for painting. Hopefully I do everything right on it, it's been a few years. The final coat will tell all I'm sure. Good thing with Bill's hood on it no one will look at the lower!

We did get the bearing in for the driveshaft from Microblue. It's hard to tell if there is enough of a difference with this bearing and I'll need to explain why. Now this bearing we ordered is their steel version (it does have a cool blue hue to it) and they offer a ceramic version also. Cost is a factor of course: our standard bearing= $22.95 Micro steel= $65.00 Micro ceramic= $130.00

I don't know the performance compared to the ceramic version but as to the steel, this is what we have found upon installation. When we first opened the package and hand spun the bearing it was like no other! No resistance at all or at least very little, no noise, very smoooth. Then we looked at what else came with the bearing, a lock collar and 2 seals, interesting. Also a little product guide that explained these bearings are not pre-lubed.

So once the one seal was installed (as our original) and we lubed the bearing as they suggested, we found there isn't much difference in the hand spinning resistance between a conventional bearing and the Microblue. Now under load, there may be a difference so we'll see. I think to be fair, all 4 bearings in the driveline would need to be replaced with the Micro's to see improvement. However, only two sizes are currently offered.

Now with that being said, we did reassemble the drivelive into the sled (minus the track) to see how things are spinning in there. We installed the jackshaft into position and locked it down. Then installed the driveshaft along with the chain and sprockets and torqued everything down. We measured straightness and parallelism and end play on both shafts and also rolling (or turning) resistance of the connected shafts. Very little resistance of course but amazingly smooth too. So we are in great shape in there this year, sure is a good feeling to know what is going on in there by first hand observation isn't it? Assurance is a good word...
So now I have to take it all apart again just to put it back together but it was well worth the effort to see it all in action.


By the way, for some unexplainable reason, we now have a "red trail" leading from the garage to our bedroom. My wife thinks it looks like the old Rupp Red but I assured her she was probably wrong again. Either way, I kinda like it! It looks fast!

So that's about it for now. Still waiting for our new hood to arrive and also for our crank to get finished up but we are not in a rush quite yet, much to do to the sled yet. We did work on the test track to smooth and level it a little better, so now we have to wait for the grass to grow, then we can tear it up again!

Until the next report, Thanks for reading
-Paul

[Ruppsforever]

Hey Paul leave seals off bearings where you can. The outside seal I leave off on the opposite side of the chaincase on that bearing cup. On the Magnum there is no Speedo so I just put a little plug in the hole where the speedo adaptor normally is. I squirt Tri Flow inside there once in a while. Chaincase side is a different story though. You need that seal to keep the oil in chaincase. Also on the jackshaft don't lock that collar just tighten the setscrew. If you have it locked spin it and watch the bearing tower. It will move back and forth. Takes energy away.

[midniterupper]

Hey, I haven't posted for awhile, been really busy this time of year around the farm but anyway, Thanks for sharing your wisdom Josh regarding the seals on my bearings. I still need to pick up some Tri Flow before the final assembly, just to ensure we are offering our best this year. Little things can add up to big gains!

I've been continuing progress on the Nitro, some amazing things are taking place. I picked up my motor components from Kevin and Brad over at Pipestone Small Engine last Thursday. Kevin did a phenomenal job on boring my cylinders. He vapor blasted the outer surfaces, established a perfect crosshatch in honing and chamfered the ports like a true race motor. He ordered Wiseco High Dome pistons and sized the piston clearance as specified for these special pistons. We are now +.060" oversize, still have a ways to go if ever needed. 444 cc's now. No replacement for displacement!

The crank is completed also, he installed all new bearings and even keyed the PTO bearing to prevent any further damage. The new rods are awesome, very beefy. Kevin even stuffed my crank when he was finished. He used a new product from Devcon, ultra light but yet dense. $125.00 for a 3 ounce tube. Blends in so nice too, looks like it just came off the crank grinding line! So we are all set there now, no more blue balls! (bearings!)

Kevin fixed up my cases also, made them look like new. I still want to play with the mods Josh mentioned too, now would be a great time to do the work. I'll install the V-force reeds at assembly same time. Kevin machines the mounting plate so it is a simple drop in installation, they sure look impressive. Way more surface area than the Boyeson's.

The motor ought to purr pretty smooth now, all bearings have been replaced, clutches balanced and everything is fresh. An interesting note from Pipestone I can share with Team Red. Kevin and Brad have their own Dyno in the shop so this allows opportunity for testing many things on our motors. They recommend running Klotz +50 oil at 32:1, they say the oil is very sticky and clings to the piston skirts and cylinder walls, lubricating and actually helps seal the around the piston rings too. Mixes well with C10 fuels. The horsepower gain is due due to improved compression sealing.

Another nice find that Pipestone offers is their special made rubber intake manifolds. They incorporate a steel sleeve right into the molding process which eliminates the egg shape gap that the SPI brand intakes are known for. Which of course creates a hidden tiny air leak right where it mates to the reed block. That lean condition will drive you nuts trying to correct it. It's a great fix! Cheaper than pistons too!

The body work on the lower half is turning out great. All the effort was well worth it, sanding and blending all covered nicely with the sealer I used. I applied 2 coats sealer, 3 base coats red and 4 coats of clear. Buffed it all out with compound and now I need to apply the final wax. Looks better than new, nice deep shiny red. I painted the entire inside of the lower with high gloss black, looks so nice now. It'll look awesome with Bill's hood. I'll try to get some pictures of the sled on here once I get her done.

I still need to get over to Mickey's snowmobile salvage yard too. Gotta get that 6 tower arctic primary and roller secondary to try when we begin testing this year. Pocket book needs to recover first, took quite a hit this year so far but it'll be well worth it all once we start racing again.

Okay, I think that is about it for now. Gotta get back out there and get some more work done. By the way, I am thinking of getting some items rechromed like the rear bumper and the skis. Anyone have a good source? There are shops located in Michigan, just haven't contacted them yet. Powder coat is another option too but I would like to make it look like original if I can.

Have a great Memorial Day weekend, Thanks to all who served. Thanks to those who gave their all for this Great Country!
-Paul

[midniterupper]

Okay, it's been awhile since my last update regarding the Nitro Grass Dragger. I have tried a few times to update but for some reason when I go to hit "post" I lose everything I've written so I'll give it another shot today.

The good news is that the motor is back together and seems very strong. It's quite responsive but it took some time to get it there. It did have a bog on hard acceleration at first. Changed the jet needles to 6DH7's and that cleaned up the problem.

The new driveline bearings are awesome, the track and driveline rotate almost effortlessly now. Very happy with that set up. Push or rotate the secondary with 1 finger now.

Now for the not so good news. Using my same set up as last year's races where we were very consistent at 65-67 mph with our best pass clocking in at 69 mph. This year with that set up, we are only reaching 58-59 mph. In some of our testing, we dropped down to only 52-53 mph. Very shocking!

With 16 test passes under our belts so far this season and after much checking, re-checking, realigning and adjusting pretty much everything, we finally hit 61 mph.

The motor is still not spinning at 8000+ very effectively, however at least this year we can play around with the clutch weights enough to get into the 8000+ rpm range. Last year we couldn't at all. So that is a gain for this year, But when I use lighter clutch weights (44-46 gram, A1's, A3's, Polaris 10mw's) my rpm's are up to 8200 but we lose at least 5 mph compared to the 48 gram (A2) weights. We seem to spin around 7700-7900 rpm's using the A2's, but we push 60 mph pretty steadily.

Now I did upgrade the primary spring from the Aaen purple 150/320 rate to a SLP green/pink 160/340 rate and that did help bring our rpm's up just a bit and it holds very steady. Also helped out 1 mph overall too. That leaves us the secondary helix to play with now.

I ended up buying an old arctic cat zl500 for parts but it didn't work out too well. The roller secondary is seized on the jackshaft and will not come off, even using a gear puller and heat. So I left it on, did some other work to the sled and detailed it. I will get it on marketplace this weekend, but I did trade some other parts for testing. The stock A/C primary was bolted on and tested, 58 mph with that clutch mounted, no changes, so not bad. Took it off and put my P-85 back on. In fact, for those of you keeping track of mods and stuff, the Arctic 9 tower primary weighs in at 10.4 pounds compared the the Pol P-85 weighing at 8.4 pounds, both fully dressed and ready to run.

Someone had installed a Black Magic secondary helix on the zl so I took that off to add to our collection. It is a 57/50, probably set up for the roller secondary.
We made a test pass with it and it turned out to be our best yet, finally reaching 61 mph. Still kinda disappointing but we'll take it though, we ain't gonna win races with that speed but we can still play. Hopefully everybody else is having issues this year too! Apparently, smaller helix angles seem to favor higher operating rpm's. So I will get over to Mickey's sled salvage and pick through their stash to see what combinations we can come up with. I'm thinking I may try some 52/44, 48/40 and a 46/38 to get more testing in that direction. Still gotta get a roller secondary from him too, Maybe we'll gain something there.

So we still need to figure this thing out yet, I know it should be faster than last year. Just gotta get the right combination.

Carburetion is still mystifying also. The PTO exhaust temps are not too bad staying mostly around 905-1069 degrees while the MAG side is really cold, hovering around 783-859 degrees. The engine sounds kinda flat when we playback the video runs and along with the rpm's hanging low, there has to be more top speed in the sled somehow. I am just not able to get it there yet.

It almost seems to be faster when the larger jets are installed but then the exhaust temps drop. I installed smaller main jets and adjust the bowl screws but the temps really don't that change much. I am using the stock 230 mains right now in the adjustable bowl type carbs. These are the carbs I got from Pipestone that are honed oversize to 39.5 mm, and the motor seems to like them. I just can't seem to dial them in to raise up the exhaust temps. I'll keep at it though. I swapped the carbs from side to side and the motor sounded terrible! Back firing, bogging, MAG side sounded like a fouled plug. Switch them back and the motor sounds great!??

This morning I ordered a new recordable tach and GPS speed sensor from Wahl Brothers. I have been using the old VDO Extreme tachs from our old Ski-Doo racing days so I don't know how exact and accurate they actually are, though they both seem to read pretty close to each other. This new tach and speed sensor ought to prove more accurate so we'll have to see, maybe I'm already running at 8k. Anxious to try the GPS system too. Maybe my radar gun is reading low this year....

Okay, that's about it for now. We have about 2 more weeks of testing before I have to clean up the sled for a couple of Vintage shows. I've never entered a sled in any kind of show so it should be fun. Then we have 1 week of testing before our first race August 27 & 28th, can't wait but I sure hope we are running stronger!

Take care all, remember: Ride 'em, Don't Hide 'em!
Until next time,
-Paul

[midniterupper]

Greetings from Northern Michigan! It's a beautiful day here today, clear skies (other than a little smoke from the fires out West), low humidity and cooler temps. Perfect day for testing!

This update won't take very long but info worth sharing. First, I can't say enough good things about the new tach I bought from Wahl Brothers. It's a EGT TX-2, runs about $400.00 at this time and very well worth it, let me tell you why. It is a recordable/playback tach, will record up to 20 minutes total time. Must be for the Yammies! I have mine set for 5 minutes recording time in case I'm delayed for some reason. Both 1:1 and 1:3 playback speed. Only records 1 run into memory whereas the old VDO held 4 runs. I can live with that.

A really neat feature that is helping me out is that it is both analog and digital, reads exactly every single rpm. With one of my primary weight changes I was finally able to spin the motor at 8350 with the aid of the digital feature, I now know that I can reach that rpm. Also, this tach incorporates a slick GPS mount that plugs into the back of the tach. I mounted my receiver unit right on the black hood scoops, blends right in nicely while giving the old girl a new, high tech look! Works great! Be sure to give it a minute to locate a satellite while you're setting up for a run.

It does take a wile to get the hang of recording and playback but once you do, you'll love it. A very helpful and useful tuning aid for sure.

We have been able to get the sled up into the mid sixties again but very finicky. I again tried the Thunder Shift Kit on the primary only this time I lightened the arm combination to 47.4 grams each. This raised our rpm's up to 8350 but dropped our top speed down to only 55 mph verses 66 mph using modified A-2 arms weighing in at 48.6 grams. The motor spins at 8175 with those arms. Both are engaging at 5800 rpm.

11 mph loss just by swapping arms, amazing isn't it? Makes me think there is an arm combination that will get us well into the 70's, just a matter of discovering it.

I'm still waiting to play with more helixes and even try out a polaris secondary too. Who knows, maybe a different combination will gain more top end there too.

One other thing I had a problem with is my carbs gumming up quickly. The sled produced a terrible bog off the starting line and it turned out to be the carbs needed a good cleaning again. The fuel I'm using this year is Sunoco Standard (110 oct.) and mixing 32:1 with the Klotz R-50. May want to keep an eye or ear out just in case you run into the same issue. Very nice fuel and oil though if you happen to be looking.

I will keep you posted on what we find out when we get back to testing.

I won't be testing for a couple of weeks now, have 2 Vintage sled shows to enter the sled in so we'll see how she makes out in that arena. Don't have Bill's new hood yet so I'll have to make do with mine for now, I think we'll hold our own for now. Next year with Bill's hood, the sled should be a show stopper!

That's it for now, gotta get busy detailing the sled for the shows!
Take care now,
-Paul

[Ruppsforever]

You definitely have something going on with one carburetor. Also that is too much octane for that motor. Spinning it at around 8000 Rpms you should be good with 93 octane. You don't really have any serious work on that motor and you should be good with 93 octane. I did a little experiment on my Dyno once. I always used 110 Octane Turbo Blue. I tried 114 Sunoco and I lost 7 HP !!! I tried different oil mix ratios with these two fuels. And I never came close to the power with 110 Turbo Blue at 50:1 Amsoil. Not to scare you but I have had some very bad luck with running Klotz R-50. Lost a few snowmobile engines and my dirt bike ran like shit with that oil. I couldn't find any Amsoil for the next Drag race so I got that Klotz. Sled ran like crap and ended up blowing the base gaskets that day. I never ran that oil in my Drag sleds again. I tried using that oil up on my old Nitro that I trail rode. Grenaded that motor. Then tried to use the rest up on my dirt bike. It ran so crappy I fouled out plugs all the time !! I switch from Klotz to Yamalube on my dirt bike and I haven't fouled a plug in 3 years !!!

[Ruppsforever]

Miss all your updates !! Did you get things figured out with the sled ??

[midniterupper]

Hey, Thanks for the wake up call Josh. Didn't realize how long it has been since the last Rupp Report. Been very busy around here lately which isn't always conducive to our grass drag season, but it's all good....

Anyway, back in August we entered the Nitro in 2 Vintage snowmobile shows here in northern Michigan. We didn't place at all but we sure had fun camping in the race trailer, meeting new people and getting great deals on swap meet sled parts. We now have (3) separate Polaris secondary clutches ready to bolt on, 6 different helixes, 2 extra secondary springs and (2) K&N 38mm air filter elements, all for $100.00! Can't beat those deals!

The sleds at the shows were amazing. They ranged from 1960's Skidoo's to 1950 Polaris's to Eagle River factory twin track racers. Even the very last production model of a Ski-Roule that has never been fired up. Really cool iron out there. Of course, we still think the Nitro should've won something but there was no class for the racers. If you ever get a chance to attend one of these multi-day shows, be sure to get there. Amazing detail and countless hours!

Well, the sled just isn't coming around yet. Not sure why at all. We have made over 40 test passes this year so far and our best top speed is only 59 mph lately.
We have switched fuels and oils in our testing along with several clutch combinations and carb settings without much change in performance.

So far, the best oil and fuel mixture that seems to agree with this motor this season is VP C-12 and Yamalube R2 oil at a 40:1 ratio. Nice clean mixture, less smoke (people at the track were complaining about the smoke I made going down the track!) and it's easier to read the plugs. I also dropped in a couple of BR9EV plugs to help increase my exhaust temps. Setting the gap at .020" seemed to help a bit also.

For the carbs, still running the 38's that Kevin honed to 39.5 using the adjuster type bowls. I have 190 mains with the screws opened about 1/2 turn out. I also raised the needles to the #2 clip position. That seemed to help even out the exhaust temps and get us back into the 900-1000 degree range. I know it's still cold but it's better than it was. The motor is strong and responsive, doesn't miss a beat!

Clutching is pretty steady now. Engaging at 5800 rpm using the A-2 arms weighing in at 48.6 grams and using the SLP spring. Running down the track we are spinning at anywhere from 7800 rpm (best actual mph) to over 8700 rpm using some polaris secondaries and helix combinations, and lighter primary weights. More rpm does not equate to more mph! Just as Josh told me!
The arctic 51/49 helix with their yellow spring set at 14#'s seems most effective. With the drive belt removed, you can literally rotate the track with one finger. I've never seen a track spin so effortlessly, I wouldn't think I'm losing power there in the drive line but you never know. I'm running 19/35 for gearing which gives us a 1.842 ratio. Combined weight of the sled with fuel and me on it is 575 pounds. Sure seems like we would go faster!

That's the complete set up I'm using now. If you guys see something I'm doing wrong, please point it out to me. I'm open to any and all suggestions to improve our top speed and performance at the track! I'm running out of ideas on my own at this point.

As far as the races so far this year, it has been a struggle. The guys we beat last year are beating us this year. Our first race was at Nelson's SnowMotion back in August. It was 91 degrees at the track, miserable racing. My motor in the Vintage finals was 154 degrees at the starting line, hottest I've ever let it go. There was no Vintage stock class so we raced in the Vintage Improved and Open Mod classes. We took home 3rd in each.

Next race was in Muskegon, we took home 2nd in Stock, 2nd in Improved and 3rd in Open. Not terrible but we are getting spanked out there. We always have them off the line and for the first 60 feet, then they catch me at half track and then they get way ahead at the finish line.
There was a race last weekend near Lansing but we skipped it because I didn't want to race when the sled is not it's best. So I need to do more testing this week for sure, we have races schedule for the next 3 weeks!
There is 1 Yamaha and 1 Polaris XCR that is just kicking my butt. They both are extremely fast and they both are very knowledgeable regarding setting up their sleds to win. They set the bar very high!

So that's the latest from here. Trying to come up with things to try out. Still trying to figure out how we lost almost 10 mph from last year. I guess Racing is an addiction, ultimate performance is an obsession. What a puzzle have we on our hands!

Thanks guys! Take care now.
Until next time, -Paul

[Ruppsforever]

Paul the only way you will find that 10 mph that you lost from last year is to undo every change you did to the sled over the winter. And I mean everything !! Sometimes expensive parts aren't going to perform like the cheaper stuff. You know what you all changed undo all those changes. Try it.....

[mrmotors]

I agree with Josh, powerful easy to overthink it. You might have done fixed it til its broke----

[midniterupper]

Hey, Thanks for your helpful input and advice! It all certainly helps and you're right, I need to undo what I already did. I'm overlooking something that's probably obvious to others. Sorta like not being able to see the forest through all the trees, right?

I have been trying to evaluate exactly what changes I've done since 1 year ago. Some changes were definitely needed, some maybe not so much. My biggest concern from last year was the crank bearings. They were very loose and had turned blue so I know that needed attention. Kevin did a great job on it and at least now, we are able to reach 8800 rpm's with no fear of scattering the crank.

I still need to validate that the 39.5 mm carbs are in fact working properly. I need to install the original carbs and see what the exhaust temps do and see if they affect our top speed. Also along that line, I could try swapping the V-Force reeds back to the Boyesen's just to compare the performance. So we have some things to try out. Bad timing on my part though to wait this late in our season to experiment and regain our lost performance.

Also, I think I'd like to play with my gearing ratio too. Maybe my 19/35 (1.842) ratio is a tad too low for ultimate acceleration in 500'? It's not too difficult to swap some gears to make a comparison pass or two, so it may be worth a try to play with those.

Thinking about the clutching, I figured maybe it's worth a try to replace both clutch springs with brand new ones just to see if they may have taken a set over time and use. I have new ones coming in next week, shouldn't hurt to throw those on as a good baseline.

Yesterday I put the sled in the air and checked all idlers, hyfax and drive sprockets. The drivers are about 1/2 the thickness they were when I installed them so they will need replacing this winter. Better get ahold of Rick Weaver for those. I did find 2 forward idlers that "squeaked" as they rotated. Apparently they were rubbing a little bit on the track lugs (alignment issue) so just for today's testing, I removed them. We'll see after a few passes if they affected anything.

I found a couple of Arctic helixes and unidentified springs to try that I haven't used yet either. We'll throw them in today just for documentation purposes, maybe we'll find a lost treasure!

Okay, I'd better get back at it now, lots to do here on the farm and to the sled before Saturday's race! But Thanks again to our Rupp community for sharing your thoughts and ideas, it really helps when you're down. I needed the encouragement. I know we'll get this thing figured out, it's all still a learning process as we all know. So please keep your suggestions coming and I'll let you know how they work out.

Until next time,
Thanks again, -Paul

[mutt]

For sure 19/35 is to high not too low. Around 88mph at 8500 rpm. When you change gear going to affect clutching. Will have to start over unless your lucky

[midniterupper]

Hi Mutt, I appreciate your reply and interest in this sled. Gearing is on the play list to try, do you have a recommendation to try first? I was thinking for grins just try my old 19/39 combo for 500' drag racing just to see what happens.

Today's testing got our exhaust temps at 850/1020 so the mag side is getting close. Also, the first pass using the 53/44 arctic helix got us up to 8433 rpm but only 53 mph. Switched to another arctic helix that I picked up from an old zrt600 that I stripped almost 10 years ago. Found the old clutch set in a forgotten box. Thought they were good but both have cracks and chunks missing but there was an old secondary red spring and a beat up black helix. Don't know anything about them but I cleaned them up and installed them just to see.

Good thing they were here! I made one pass (no other changes) and Boom! Back to 61 mph instantly! 8 mph just by changing the helix and spring so I know there is a magic combination just waiting for us. Very encouraging and good enough to at least show up at the races.

Tomorrow we should have some time for a little more testing. Reviewing our notes from this year, it looks like the Polaris secondary with a 46/36 helix gave us 63 mph earlier this year so we may try a couple passes with that clutch combo.

Looks like we may be on our way back up so we'll see what tomorrow brings.

Keep you posted!
-Paul

[Ruppsforever]

Paul did you do this testing after switching reeds and carbs back to what you had last year ??

[Ruppsforever]

Also if I may add. You are changing too many things at once. Once you get to a sweet spot you do just small changes. Like clutch spring tension or grinding weights a little different. Like Mutt says if you change gearing that changes clutching completely. But yeah you might luck out.