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TECH TIP: How To Tune Your Blast for $.12


(2/16/2021)

I purchased a 2021 ZR Blast, and am completely in love with that snowmobile. In fact, I will be buying another one to add to our family fleet. I love that its light, nimble and is easily used by a wide variety of riders with varying skill levels. The fun factor is bar none.

Mine tops out just under 70mph. It wont win a lake race, but it has shamed some fullsize sleds when riding the tight twisties. (Its like cheating)

These dual offset carbides from AC help reduce trail darting and more positive cornering

Ive replaced the single-runner carbides with offset versions from AC, which transformed the front end for more positive cornering, and nearly eliminated any trail darting.

Ideally, Id prefer a stiffer suspension, but Im a Sasquatch. The current shocks work well for a variety of trail riders, which is the point, and they also keep the Blast Retail price affordable. You have the option to crank the rear torsion springs up/down, but If you are riding aggressively in ditches or off jumps, youll probably want to upgrade the shock package, or just go buy a ZR 600 RR.

There is one area needing improvement though, and its the clutching. 

If your Blast has run anything like mine, it hasn't been perfect. Mine would load up on the bottom end, kinda clean itself out, go like a raped ape in mid-range and then fall flat on its face. With that, you could hear the engine pinging and could expect a 1324 Code to flash on your gauge, which is a Knock Sensor.

Team Arctic racers competing with the Blast, and a couple reputable dealers, have reached out with a twelve cent fix to the varying runability. Quite simply, the CVTech TrailBloc clutch needs heavier weights.

Peak operating RPM should be 7600. That said, its a flat curve getting there. There is very little difference noticed between 7200-7600 RPM.

Below is a look at how to add two pennies to each weight (6), and your runability issues are solved. No more bogs, lean run conditions or knock sensor being tripped. If you don't have the correct tools to perform this, Id recommend you visit your dealer.

CVTech Trailblok Drive Clutch

Once main nut is removed, here is a look at how the sheaves separate

A look at the weight (round piece) in its arm

Remove the Weight

Ask your mom for two pennies - twelve total

Insert pennies on bottom

Place the weight on top of the pennies

Finished photo of weight installed over pennies 



Comments (21):

Mike says:
2/16/2021 7:38:00 PM

Only a farmer could be this smart!!
Kale says:
2/17/2021 6:19:00 AM

Mike- Well, you probably aren’t far off. A lot of farmers race! ;)
CATMAN says:
2/17/2021 6:32:00 AM

Kale is that like a $150 - 300 clutch kit!!! Love it.
Kale says:
2/17/2021 7:56:00 AM

CATMAN - Just my two cents, but I don't think the update would be that much. ;)
Phil says:
2/17/2021 1:42:00 PM

Wow I could not have written the clutch commenting better. Have you experienced any bog with your sled in that it cuts out and almost puts you over the handle bars? Mine is at Thomas Sno Sports for this issue and I just forwarded your simple fix for the clutching and hope that they will add the extra weight to my machine. Any concern on AC and warranty with this simple fix?
Jason says:
2/17/2021 3:20:00 PM

I have owned many first year model arctic cat sleds, and seems like every one had it share of stupid little things just like the blast clutch issue. Things that should have been addressed by arctic cat before they sold the sleds. U mean to tell me a/c engineers and testers couldn't figure out this issue prior to selling it, these are the things that make my friends who DONT ride a/c laugh at me for sticking with them.
Thom says:
2/17/2021 6:02:00 PM

Great article! Many thanks for sharing!! Which specific AC off-set carbides did you use? I'd like to try them to resolve the on-trail dartiness that I've noticed too.
Kale says:
2/17/2021 7:29:00 PM

Jason - From what I understand, the weights tested, and approved by Engineering, were not the same that came from CVTech for production. Not sure how that happens, but it did, and it happens with every OEM on varying levels.
Kale says:
2/17/2021 7:34:00 PM

Thom - The staggered carbides I bought were Part #s 2703-599 (Left Hand) and 2703-598 (Right Hand) Think they are around $85 each.
Jim Dimmerman says:
2/20/2021 7:02:00 PM

I can just see it now, guys will be out on the trail digging in there pockets for change. lets see...if 2 pennies work how about a penny and a dime ?? Geez clutching has become so much simpler now. Jim
Kale says:
2/23/2021 9:37:00 AM

Jim Dimmerman - thats really funny. Again, that's just my two cents...
Kale says:
2/23/2021 9:58:00 AM

Phil - I cant speak to any claims of warranty. Again, this was passed on to me from a few Team Arctic racers and reputable dealers who have tried it with success. If a bulletin comes out from the factory with recommended weights, Id make sure to get them replaced at that time.
David says:
2/23/2021 10:48:00 AM

I don't know what we'll do in Canada. No more pennies up here and the border's closed so we can't even head to the US to pick up those high value US pennies.
Chris says:
2/23/2021 10:52:00 AM

You should also address the issue people have been having with the tunnels buckling. My son is 12, weighs 93lbs & has 375mi on his Blast. The tunnel is buckling where the rear spars meet the tunnel. The cast pieces the spars bolt to, are cracking. We replaced the non-rebuildable hydraulic shocks in the skid with gas shocks at 40mi because they were completely blown. The tapered top of the tunnel and not having any reinforcement going from the spars to the rear skid bolt (like all the other ZRs) are both weak points. For $8.5k this should not be happening. I have talked to other people that have ZR Blast and they also have noticed the same issues.
Kale says:
2/23/2021 2:24:00 PM

Thanks for input Chris. First Ive heard that one. Ill pay attention to spots you mention. We've ridden our ZR version aggressively trail riding with zero issues in that department. Im 5'16" and too fat to publish a number. Torsion springs are cranked up. I know the conditions I can bottom those shocks easily, so I ride smart through those sections. But we've been able to throw a fair amount at them. Completely blown out at 40 miles raises my eyebrow. Next step for mine is new shock package from FOX. It defeats the affordability of the Blast, but will increase the fun factor for how our family uses it.
Dude says:
2/24/2021 1:03:00 PM

Chris - You are 100% correct we have the same exact problem with ours. My kid weighs a bit less than yours. We race the blast and noticed this happening around a few hundred miles. This is a very common problem as almost every blast being raced is having this issue. There is no way the ZR blasts are going to hold up with adults riding them off groomed trails. I remember when ZR meant the toughest most bad a$$ sled in the industry, meant for ditch banging and racing. They missed the mark here and maybe should consider re-naming it a ZL or even Trail cat. It sure isn’t going to be a blast replacing tunnels every three hundred miles.
2stroke says:
2/24/2021 6:30:00 PM

What differs this CVTech "TrailBloc" drive clutch
from CVTech "PowerBloc-50" or "PowerBloc-80 ??
Paul W Senst says:
2/25/2021 1:57:00 PM

5'16"....Good One FOG......
Steve-0 says:
2/26/2021 8:28:00 AM

Kale,

Great write up. I wrote earlier on a different post here I had a stutter and bog at about 6,000 rpm on my Blast LT. It was annoying but I wasn't going to worry about it til snow season ended. Then a couple weeks ago I was out riding in ten below and it stumbled, then threw a 1324 code. I turned engine off. Started up and rode fine. Then threw another code. Oh oh.

Read up on line and found guys in Canada having same issues. One guy said bad throttle sensor seemed to be problem. So I tightened the throttle up with zip-tie (lol). Fixed 80 percent of the bog, but then it STILL threw a 1324 code.

Off to a dealer!

I told 'em I had been pretty aggressive with the motor. They checked everything out and compression/piston were fine. They tightened throttle cable, put new plug in (said the old one was getting fouled) and ADDED HEAVIER WEIGHTS TO CLUTCH. Said the clutch was allowing engine to over rev. Still wondering why loose throttle was causing engine to run too rich????

Anyway, got it back and it runs perfectly. No more bog, stutters or engine codes. Hits 70 mph on icy trail, about 60 on lake snow (not a ton of that in Minnesota this winter :( )

I got this sled for my wife and kids but honestly I find it hilarious to ride. I ride the Blast now while they take "my" zr800. Lol.

I bought the LT cuz I liked the notion of going off trail in deep snow. That has not been possible this year with the thin crap we have gotten, but this sled is fantastic for novices in the ditches. That long track goes up and down ditch embankments like a little caterpillar. The traction is great. For my kids (or wife) who go slow it makes that riding so much easier. I started this season with one of my daughters sliding sideways down a culvert in my old F800. She got completely totally stuck. I had to go home and get my truck to pull it out. That sled is all power but the short track and heavy tail just want to go sideways on sidehills at slow speeds. The Blast just crawls along no problem.

Anyway, I live on a lake. We have more than two feet of ice right now and very little snow. Could be another month of riding but snow is so thin makes it hard. Sad! But I really like this Blast. The engine is really fun. Great deal of midrange torque. Sounds like a big-bore dirt bike, which I like.

-- oh, except for the heated grips. THEY ARE INSANE. Too hot even when it's 10 below. Lol. I get used to toggling them on and off.



Gbarchives says:
2/26/2021 8:25:00 PM

Makes me miss the old hex clutch. Remember when cat made their own clutches? I’d be so tempted to put nine tower on it. Just not a fan of CV Tech. Guess I’m old.
Kale says:
3/1/2021 4:37:00 PM

Steve-O - Your assessment is spot on. Its unfortunate about the clutch weights coming the way they did out of the gates. It bums me out to hear some have a bad opinion of the Blast based on the runability, when in reality it is a 12 cent fix to get some awesome performance from that engine. Like you, I often take the Blast over my ZR 600 Tucker edition. The smile factor is incredible.

For those of you racing snocross with the Blast and have experienced tunnel issues, heres what I know:

1. Plain and simple, the Blast was not built for the rigors of snocross. It was built as a right-sized trail ripper. (But I cant fault anyone for wanting to race it) Its believed the forces coming through the front suspensions from repeated pounding into face of bumps/jumps on snocross track are being transferred through the bulkhead and putting pressure on tunnel spars by tank.

2. The race shop has gotten some braces into the field for racers to test and more are expected to be made.

3. Shocks - I was made privy that a "stiffer" shock is available for the Blast. As soon as I get the information and part numbers, Ill share that information on the page.

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