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View Full Version : Sprock 350X Bigbore ride report 8/ 15 / 10



sandpuppi101
08-14-2010, 05:34 PM
As alot of you already know I was I believe the 3rd person to actually get my hand's on the new kit's that Corey Sprock put out for the 350X which is now said to be @ 403cc .After being asked alot of question's I thought I would do a write-up on the mod but I wanted to get a little bit of time on it until I had something to imformatively say.Now to make sure all is clear and understood here and what I state in this tread is all " My honest opinion and I am just stating my 2 cent's",I think that everybody who know's me would say I'm straight up,and I say what I'm thinking.. So with that being said here we go.

History:
I orginally first took out the 1st proto-type at Galamis this past winter that was built by Corey Sprock and owned by ATC-Eric.The chasis was an stock '86 350X with still running everything still stock meaning sprocket's,carb,head,ehaust,airbox,axle, etc I believe but I may be wrong,the only thing I knew that was changed were the rear paddle tire's.Also I'd like to add that alot of other's had time too ride the machine also but my 1st impression's were that it was an absolute tractor,meaning it pulled really hard and was easily climbing dune's and whatever else was thrown at it.I was impressed with what the motor was offering but also at the same time,she was a bear too start and seemed to get hot.Granted Eric did not have the decompression cable hooked up to the machine,which was my fault because I brought the wrong cable out to the dune's and the machine was barely shut off since everyone was taking spin's on it.I told myself that I had too have one of these kit's so I ordered one up and hooked the guy's up with a core cylinder too do up for me.

http://i362.photobucket.com/albums/oo64/sandpuppi101/DSC00074.jpg





Timeline Trikefest :
I recieved my cylinder at Trikefest on Thursday as promised and went to work on putting the engine together,actually I watched as our buddy Gary Crumbb assembled it.I came with a rolling 350X chasis and had planned on having a complete running trike ready too go for the drag's on Sat. which gave me less than a full dayto get something going.My buddy Gary rolled up his sleeve's and dove into the trike helping out when ever he could,Thank's Gary BTW,for help on assembly of the rest of the machine.Long story short we did'nt get any runtime on the motor that week due to lack of time and mechanical issue's that were" My own doing".. By this time at TF Gary had also jumped on the bandwagon and had the 2nd Big bore kit up and running.I did'nt get a chance to get any ride time on Gary's but I believe alot of other's got to take his and Eric's for ride's themselve's.I'm not sure on there thought's.

Timeline 'The Farm' aka ~ Muddogs South ~ July '10:
After reasearching the issue from the disaster at Trikefest I found that the high performance cam that I had put in the head I was going to use was dragging on the cam so called bearing seat's( JOURNALS) when the rocker box was torqued down.Just the one corner was dragging,Boy what a stupid set-up for a head IMO,simply putting needle bearing's on the cam would have solved everything ,but that's a discussion itself.Simple fix was going to my shelf and putting on a reworked head and stock cam until I could get a line bore done on the other head that was dragging.The head I used was off an '86 ATC 350X which had maybe 10 hour's of actual time on it ,and the( STOCK) cam was well with-in stock spec's with minimal time also.The head had new valve's and the seat's were also freshened up as well as the guide's reamed and new guide seal's.The port's,intake and exhaust, were knocked down clean but nothing all to major.I simply pulled the head and observed that everything was still like new as far as the cylinder and piston and together it went.With the assembly I used the head from the shelf ,a within stock spec cam and the matching rockerbox( tappet box) cover.
Now a few thing's that I'd like to add are that my motor is a Stock '85 ATC 350X vs those guy's having '86 ATC 350x motor's,not that it matter's IMO.With the head assembly I also had added a few other change's to the set-up I was running.I put the chassis together with part's that were fine to use but I also put it together knowing this was a rider,nothing to showboat,but it is sound mechanically .With the carb I used a QA -O5 which is the stock '85 350X carb ,FYI:QA10 is '86 ATC model carb.I changed the main to a 142 and installed new needle seat,fuel jet stock,18mm float ,air/fuel 2 1/2 out with needle 3rd from top ,ran the airbox with a new uni filter with no outerwear.On the exhaust I used new exhaust gasket's ,stock headpipe ,modified mid section,with a '04 TRX 450R rear muffler with the tip included.On the chain assembly I went with a new 14 tooth front and a new 38 tooth sprocket specialties rear ,running a new 520 o-ring chain.FYI; the stock set-up on the ATC 350X model's is 13-40 I believe so I was gearing higher with my set-up at 14/38.Other than running a set of H-Trac 22x11x9 tire's on stock wheel's that was about it .After the motor was assembled it started up rather easily with by brother Joe-Dirt having the honor's.After some minor tweaking here and there on the clutch and the carb we took it out for a spin.I was happy to say that after me and Joe-Dirt had put a few minute's on the machine I was pretty happy with how the machine was performing . We talked for a few about our thought's on the machine and quicly decided to take the can off the rear and see if that would spunk it up even more.So with that being said the 3 nex nut's were removed and the stock 450R screen /gut's were removed.Once again I let Joe have the honor's and the nachine started on 1st kick that time which was a deffinate plus.It was a bit loud but it was deffinatly a good sound that was thumping.Joe came back with a smile on his face and said it was a big differance.I took it and also noticed that it was alot more snappy myself,a huge difference.FYI: That stock 450R pipe is IMO set-up way too restrictive for emission's and the main jet is a #118 in that stock carb set-up with the '04 TRX 450R.

Timeline ~ Rose City Aug 6-8th '10:
Well I brought the Big Bore up to the ride to get a little more time on the motor and see what she had to offer in the trail's.I did a few minor thing's to the machine since having it at the farm namly changing out the throttle assembly ,cable and rear brake's .Since this was my daughter's 1st trip to the ride I pretty much focused all my attention on riding with her ,me and Gary got out and ran our Bir Bore's togther for a few but I did'nt really get much seat time on it.I did let Gary take her for a spin and he said he could deffinatly notice a differance between mine his and ATC-Eric's.With Gary riding mine and me riding Gary's ,we pulled up side to side with nothing but another mile of open dirt road ahead of us.I was happy too see that Mr . Crumb beat me on approx a 1/2 mile stretch of loose gravel by about 3-5 length's . Bottomline My machine was faster which made me very happy ..
Now since I had to abide by the state rule's I did have the screen /gut's in the rear '450R muffler and Gary I believe was running a Stock Exhaust header with a slip on aftermarket tailpipe,Cobra I think..FYI~

Timeline Present:
I had the chance to get a little more time on the machine and see what else I could do.I am still working on finding the ninche on starting this machine,my MDR 600X is the same way.On a side note I know it's me because Joe-dirt can start it easily.I'll get it figured out but overall I do have plan's for it.I will deffinatly be getting a different exhaust system ,the 450R is just to restrictive.The head will be getting replaced with the one that had the cam issue,that head has extensive porting both intake and exhaust ,Guide's,Seal's, 3 way cut valve/seats',and a deffinate line bore on the cam.I'd also like to put in needle bearing's if anybody has info on doing that,the carb is going to be hopefully be replaced with a bigger vacum type,i'm deffinatly gonna be playing with the gearing also as I have an array of larger and smaller sprocket's to test with.Honestly for me rite now it's all R&D still,nothing is really etched in stone as to what I'm gonna do,it's kinda all trial and error but I do have a direction that I'm shooting for.

http://i362.photobucket.com/albums/oo64/sandpuppi101/SandpuppiRoseCityTrikefest2010066.jpg

http://i362.photobucket.com/albums/oo64/sandpuppi101/SandpuppiRoseCityTrikefest2010063.jpg



I started this thread because alot of people over the past couple week's have been asking me my thought's on the Big Bore and I know alot more of ya's have question's also that I have'nt talked too.I personally think that for a simple bolt on kit which included a resleeved 350X cylinder and a very impressive CP piston with gasket's I made a very good investment.I obviously feel that I have a way's to go to get this engine dialed in to where I'm gonna be 100% in love with it but I also know that I have alot of option's now that I did'nt have before and all relatively simple and cheap.I don't have all the answer's as far as spec's go,you can ask ATC Eric or Corey Sprock about them but I do know that the bore is stock at 80mm and I am now at 88mm .I exchanged my stock 350X cylinder to get the 88mm ,I also recieved a CP piston with base and head gasket.The rest of the add-on's were installed by me and were not included in there kit.(NOTE: My stock 80mm cylinder is in Left of pictiure below,88mm Sprock Big Bore Right)

Rite now as it look's to me I will prolly be using up the rest of the summer and fall getting the motor and chasis dialed into a Michigan trail machine for the most part and then doing a frame up re-do come winter time.The MDR 600X is gonna be my Duner trike and will most likely be seeing action in Silver Lake and Glamis.IMO the 350X is a top pick for me on the trails up here in Michigan and to have that extra power with this 403cc Big Bore is a major plus,add to that the fact that I can still have the dependability of a stock 350X and still run pump gas.I again wanna point out that this is all of my opinion here in what I stated,I did'nt put down other people's thought's and or opinion's either,I am just letting everybody know what I think about the kit I purchased because people wanted to know my thought's ,simple as that..I tried to be as specific as I could on what I did as far as mod's and such but take it with a grain of salt and if ya have question on what I did feel free to let me know.I have a few more pic's of my engine and component's but nothing major.

http://i362.photobucket.com/albums/oo64/sandpuppi101/SandpuppiRoseCityTrikefest2010146.jpg



http://i362.photobucket.com/albums/oo64/sandpuppi101/SandpuppiRoseCityTrikefest2010149.jpg



http://i362.photobucket.com/albums/oo64/sandpuppi101/SandpuppiRoseCityTrikefest2010150.jpg

Mosh
08-17-2010, 09:10 PM
Do they rev quicker with that lighter piston in them?

TheRealFatShady
08-17-2010, 09:48 PM
Any videos of it?

sandpuppi101
08-19-2010, 10:57 AM
Do they rev quicker with that lighter piston in them?


I did'nt really notice anything huge as far as throttle response with my particular set-up with the 450R pipe and having the gut's still in there as far as revving Mosh,but I could absolutely tell the difference when I took the screen outta the 450R exhaust but I think with running a DG or Cobra I'd notice a HUGE differance .IMO that stock 450R pipe is just way to restrictive..I don't have any vid Shady.

atc400x
09-10-2010, 06:53 PM
well guys here is the deal from my side this is garry if you dont already know that. rodgers does beat mine with his gearing and set up he knows way more than i do about such as he is THE MAD SCIENTIST mine with the dg pipe does rev tighter and quicker I think he will vouch for that. i think they they have a lot of possibilties. how ever it is going to be hard to set on up better than some one like Rodger or Jason Hall they have been at this a long time and I still have a LOT to learn. any way i love mine and am thinking real hard on a second one so i can set them up diffrently one for sand and one for dirt. Any questions just ask ATC400X

Cuztom Racing
09-21-2010, 05:06 AM
Very impressive! PM sent sandpuppi!

Anyone know how i can get up with this Corey Sprock fellow or get my hands on one of his big bore kits??

ATC-Eric
09-21-2010, 04:35 PM
You can hit me up at 573-581-1382. Do it!

Cuztom Racing
09-21-2010, 07:16 PM
On a drilling rig and cant call at the moment so PM sent ATC-ERIC!!

Tecate performance
10-16-2010, 11:39 AM
megacycle cams still has the needle bearing cams, one to fit in your stock journal diameter and one oversized.
for your starting issues, you may want to run a manual decompression lever. i use a 79-82 xr500 decompression cable, it will fit right in the 350x bracket on the head. then i run it to a yz400/426 decompression lever, nice and small on the bars. i run that on my 500x engine, follow the starting drill and it starts like a dream.

sandpuppi101
10-20-2010, 12:35 PM
megacycle cams still has the needle bearing cams, one to fit in your stock journal diameter and one oversized.
for your starting issues, you may want to run a manual decompression lever. i use a 79-82 xr500 decompression cable, it will fit right in the 350x bracket on the head. then i run it to a yz400/426 decompression lever, nice and small on the bars. i run that on my 500x engine, follow the starting drill and it starts like a dream.

So let me see if I got this correct.What your saying is that Megacycle offer's a bearing set-up for the cam on the stock 350X instead of running the orginal cam journal set-up that is on a stock 350X head/Rockerbox.And if that's in fact what your stating then is there any mod that need's to be done to the OEM journal or does it just drop rite in .If so I guess I had absolutely no idea that that was avaliable..And if it's avaliable in oversize also then that could be the savior to all of us with head's that are trashed out .

Tecate performance
10-20-2010, 02:15 PM
So let me see if I got this correct.What your saying is that Megacycle offer's a bearing set-up for the cam on the stock 350X instead of running the orginal cam journal set-up that is on a stock 350X head/Rockerbox.And if that's in fact what your stating then is there any mod that need's to be done to the OEM journal or does it just drop rite in .If so I guess I had absolutely no idea that that was avaliable..And if it's avaliable in oversize also then that could be the savior to all of us with head's that are trashed out .

thats right. go to their website megacyclecams.com and check it out. they've had that set up for a while with the 350x and xr500(same cam). the setup that fits in your stock head journals have the cam journals turned down to fit needle bearings with an o.d. for the head journals. that is used when your head is in good shape. the other setup uses larger o.d. bearings that fit in the head after the damaged journals have been bored oversize. the cam is a two piece design, the flange comes off so the middle needle bearing can slide on. pretty pricy though, since you're buying a new billet cam, but you're also getting a performance profile. but if you have work in your head already, plus they're getting harder to find, i guess its not too bad. check the 79-82 xr/ft500 page as well, they have a sketch of the 2 piece cam. you can run the xr500 cams/profiles as well for the bigger builds.

Bryan Raffa
10-20-2010, 10:26 PM
Nice Info,,, I never knew!!!!

murfman
09-29-2011, 12:20 AM
Any updates on this big bore kit?