250cc large camshaft
 

Here are the long awaited results of the large camshaft now available for the 250cc. First I will tell you about the buggy used. It is a 250cc Challenger single seat which weighed in at the local scales at 639lbs. It has the MRP performance exhaust, UNI filter, DR Pulley hit set up with the heaviest clutch and lightest pillow springs, stock variator with 18gr rollers. Everything else is stock. I have run three complete runs with reference to 1/8 mile for top speed, 300’ for top speed and 300’ for E/T. The complete run consists of a 3 run average for each category of 1) stock, 2) with large cam, 3) large cam with ported head. The second run with cam installed we found the head would need some work. On the 3rd top speed run with cam installed I thought I lost my engine due to a horrendous noise, the buggy was severely cripples going back to the shop. When I removed the head I found both valves stuck open, so I knew something had hit. Turns out the retainers were hitting the guide seals than on the third run the seals let loose than it became retainer on guide. Not knowing how I was going to check clearances due to the setup requiring the cover to be installed to operate the complete valve system I consulted a good friend Mike with Fowler Racing. The conclusion was I would have to lower the guides, use of stronger springs to eliminate the spring bind and float, but also it was realized that the head flowed too well and that the intake port would have to be reduced to achieve top performance. So I lowered the guides installed better springs and also reduced the intake port along with porting and polishing the exhaust port. I made no changes to the valve grind. So here are the results.
The first run TOP SPEED = 42mph, TOP SPEED 300’ = 32.5mph with an E/T of 9 sec. Let me add that all runs were done on a coarse aggregate paved road.
The second run was with the large cam installed. The first thing to notice was how the engine woke up. Stock when mashed to the floor from dead stop engine would shutter due to the Hit setup, with the cam installed the rear tires spun causing the buggy to fish tail and I had not rejetted for the cam yet still running the 128 jet. After a rejet here are the results. TOP SPEED = 44.6 mph, TOP SPEED 300’ =35.3 mph with an E/T of 8 sec. As you can see top speed as well as e/t increased.
The third run was with the cam with head work done TOP SPEED=50.1mph. TOP SPEED 300’ = 39.9mph with an E/T of 5.9 sec. As you can see there is a huge increase over stock. The credit has to go to Harold from Hwy 9 Power Equipment up in Washington State who developed these cams. There are 2 cams available for the 250 small and large, so far the reports on the small cam have been positive, I will be installing this cam in my Blade and will also post results if no one else has, The cams can be purchased thru SYC Powersports for under $200.00 with exchange of old cam. If interested in the large grind I will be offering a package deal of cam with head mods with port and polish call (662)-301-1563 SYC Powersports for pricing. TOM

I knew the big cam was going to be good, thanks for doing that Tom.

As Tom mentioned the big grind does require some head work to to work correctly. It is recomended to do the head cam package to avoid any damage to the stock head

the small grind also has some good results and its more of a plug and play deal.

as with any performance cam you will need better air intake and exhaust and head work will just be the iceing on the cake.

So this would work for a cn250?

tes it will, but you have to have the head work done

Nice ill have to consider that.

The cam is for the CN/CF 250 however due to its radical nature head work is necessary for this cam and porting and polishing is recommended for optimal performance. If you go back and read my writeup on this cam it is awsome especially with port and polish. If you should have any questions you can contact me via e-mail or phone. tom@sycpowersports.com 662-301-1563 TOM

Do you have the heads ready to go or will you be working on the stock heads as they come in? Whats the turn around time? The finale question, well you know $$$$$$.

Tom your the man for sure. Any word yet on the cf heads and the port to valve size?

This is some pretty neat stuff! just goes to show how much this motor is DE-tuned in stock format. Anything need to be done to the head other than the normal port/polish and port matchup?

I do not have the heads ready to go. I am still in the process in finding heads at a decent price without having to order 50 heads. I am getting close though I think. So for now I will be doing the customers head. In an ideal situation there is a 3 day turnaround however this all depends on current work loads when head is received. Prices depend on work needed to be done to head. For example if you were going with the large cam it requires additional work. The best thing to do is contact me at 662-301-1563 or via e-mail at tom@sycpowersports.com. I am told that the cf250 head is identical to the cn head. I do know that the valves, springs, ect are the same, the question is with the casting itself. I have found that the inlet port is too large on the cn head and needs to be reduced for optimum performance. I do not know if the same is true with the cf head. I hope to have a customers cf head here shortly than I will know for sure. Also the springs that come on the stock heads are not the greatest especially if using the large cam. Spring bind and valve float will be an issur with the large cam and can only expect to find the same with the small cam, but cannot be certain until I spec it out with the small cam which I hope to get to soon. TOM

Have you got any more testing done on these yet Tom? If so, what have you learned? Any luck finding a source for the heads?

Tom is at the bash, I sent a head to him to do. I think Tom will be doing the heads

Tom smoked all 250's at the bash by alot. He was running in the 6's and even beat the boss 500cc 4x4's in the drags

what was everyone else running?

in the 250 class most had bbk, cams, and head work. Tom only had head work and the large grind cam

250 head
 

Well I'm back from the Bash, unpacked and caught up on calls and e-mail, so here is the skinny. The drags were held on a 300' track of packed not so smooth sand. The 150 performed poorly due to gearing and cvt upgrades. The 250 however, I could not have been more pleased with performance. The cam with head work performed flawlesly. I knew it was hot after the first run. Joyner, Carter, Hammerhead no problem, even beat the 500 Boss. I wanted to race the RZ and a really quick 4 wheeler but we never hooked up. Maybe they were avoiding me lol. Really I don't think I would have stood a chance but I still would have raced them. The times started getting slower due to the track getting loose. The last couple of runs I was kinda going sideways down the track due to loss of traction. I feel safe to say that anyone who was there would agree with me . I will be teaming up with Big E to do a cam/ head combo. The head and cam really make the 250 come alive. I hope to get some video up of the races for all to see but I have to figure out how to do it, or should I say my Son has to figure out how to do it since he is of the computer age. TOM

Well 6.72 was Toms fastest and the next was 6.85 that was Mikes Joyner with a 300bb kit, port and polish, cam, and all that jazz. My 150 runs 7.50 but my gearing was to tall and after the first race the sand was so loose my 24in mudlites were spinning off the line. Plus my brakes were out so I could'nt pre load. Karl had the fastest 150 running in the 7.20's

I think being less than a second behind the fastest 250, not so bad for a crossfire

Hey guys here is the 250 Challenger 250cc with SYC Powersports worked head and Harley House large camshaftin action at the 2010 Buggy Bash drags.

http://www.youtube.com/results?search_query=sycpowersports&aq=f

Tom the link is not working Bro.

That thing looks real strong coming off the line,Tom! Made a few of those guys look like they were asleep! :lol: Pretty impressive time too, considering the soft sand. I'm willing to bet your times would even be better with good traction.

EJ : I could not get it to link so you will either have to copy and past in the address bar or you can go to you tube and type sycpowersports in the search and they will come up. TOM

Rick got it posted up in another thread and I got to see it live, but it's just one of those things you can't get enough of. Can't wait til next year Bro.

Me too. Me and the son had a great time this year. We were both bummed on sunday being just about the last ones to leave. Was great meeting you. Hope all in this crazy world goes well and we see a bigger turn out next year. TOM

I'm sure we will see a bigger turnout. I think this is gonna be the year the buggy world gets stood on its ear and alot more people are gonna stand up and take notice. I'm gonna try and get out a bit more and frequent some orv parks in my area to get some word out.

Our problem here is that there are not many ridding places weather public or private land. My neighbor just informed me of a couple places legal to ride which many people don't know about. So I need to start bringing the buggies there for people to see. TOM

Dear SYCARMS...Please respond to my thread 'cn250 rebuild' by sargentargent...No I am not in the military nor have I ever been. Just need some help...please!

Just read and answered your PM, give me a call 662-301-1563. Since the engine isn't in front of me I'll need many details which can be answered quicker on the phone then with my one finger typing.

TOM

Sure. No problem. When is the best time to call?

Anytime morning early afternoon. If I have to leave out it will usually be around 3pm centraltime. I get into the shop 9am . If you get the answering machine leave a message and I'll get right back to you, if the phone just rings it's because I'm on that line, I'll call back as soon as I hang up. If you can't call until evening that's ok too just make sure to leave a message and I'll call you back.

Sounds Good. Have an appointment tomorrow afternoon with the RA doctor so I may call in the evening after I return home.

Head work
 

Hey tom, Im new too buggies but not too the powersports world,raced motor-x for 5 years, ride sleds, and just love all powersports. I will be saving up for your big cam and all the head work,due too the fact that my old race shop is not familiar with these engines ( even thow an engine is an engine ) they say if they do too much without knowing it could throw a rod and damage the crank.Here is my buggy,its a 2005 sunl 250cc, which i belive has the cf 250 motor in it. If i'm wrong please let me know, also let me know if i can still do your big cam kit, Also if you could recomend a clutch set up, i ride hard and also technical (trail wise ) thanks so much for your time and reaserch on the big cam set up for these karts. Mine deff. needs more power, and doing the cam kit sounds easier than my idea of installing a twin sled motor( too loud any way )

Good luck with the mod's.

I know this thread is old but I'm really interested in doing this upgrade on my cn250. Are these parts still available ?

Give me a call on Monday, 662-301-1563