Need some input on megacycle cams

[3Wheelermaniac3]

I've had my 1985 350x for about 5 years. About 3 years ago I was riding and the motor seized. After tearing it down I diagnosed that I dropped a valve and totally destroyed the top end along with my brand new 82mm 12:1 piston. I'm thinking it was because of not up grading my my springs and cam. Am I right? Well I've been p/c parts and slowly putting it back together. I'm going to get the complete race Megacycle head package. Has anyone ran this setup on their bikes? How is the performance? Is it worth getting?

[yaegerb]

yep, that could have been the culprit. You need the mid-range cam with a new set of valves and the heavy duty springs with titanium retainers. You will also need to get your rockers flash chromed. Personally I would use webcamshafts.com. They are very competitive on pricing, can get you everything I just mentioned and are really nice people to deal with. If you need another head, I have a good used one for sale. Also, if you are going to all of this trouble, you may want to get in touch with CT racing and think about a 3-angle valve grind with a port and polish.

[oscarmayer]

ok a hi comp piston will not cause you to "drop a valve". what happend was you had a string brake or more common, the lip of the valves got so worn they broke and shot up. then the keepers fell off and the valve fell back intot he moving piston. now mind you this takes abotu ohhhh... .10 miliseconds to happen. i would recommend web cam with better springs and titanium retainers. not because you "have to have them" but because they will give you great pwoer and relyability. the titanium retainers are lighter than steel and help lower weight. better valve springs so you can rev higher. and the mid grade cam so you can get more power out of it. but you do not have to have that. it was a mechanical failure. tuning issues woudl have cause you to melt the piston down at most or if you did not proeprly "prep" the piston you got hot spots and it detonated that would have caused the cyclinder to crack, bend a rod and more.

[jays375]

Alot of 350Xs are know to drop valves.Why is because they are over 20 years old and the stem breaks.Don't know what you ran for fuel.That piston would require race fuel.Another problem is a guide could have let loose.Guides are known to be worn out after twenty years.Don't know what you did to bottom end but that should be done too.I would go smaller piston and smaller cam.I have both in my 350X and it runs really good.Use the money saved for port and polish on head.

[3Wheelermaniac3]

Thanks guys. I was running 93 pump gas. Probably an issue there too.

[Shorty]

Thanks guys. I was running 93 pump gas. Probably an issue there too.
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There's why you blew it up, with ALL 350x's I've built 11.1-13.25 to 1 Run 110 otcane. not half or any of that other bullcrap, the WILL ping with anything under 100 with that much compresion. octane boost is a joke as well, it just takes the water out of your fuel its pointless, buy the real stuff. So PLEASE, next time you build you 350x I would recommend this setup and everyone i have built this for, is very happy with it.




37-38mm Keihin FCR (Find them on ebay for 150-250$)


STD bore wiesco 10.25 to 1 Piston (Run ok on 87, I prefer to run 91)


213 grind cam from webcam shafts, along with the HD springs and hardend rockers (I've had great results with megacycle grind-162-30, you can order cam on a New billet core too which i like a lot.)

Out of the 2 cams, I prefer Mega cycle myself. Web is fine as well. But either one is fine it like the "I like ford and think dodge is crap or vise a versa.
Also the mega cycle cam is a little hotter than web.


And for head work you can go balls out and have every little bit taken out or you can go with a minor polish, either or works fine.




I also do lighten the flywheels up too, the rap up quicker for better throttle response




This PLENTY for a average rider that like to cruise trails and have low maintenance but yet will stay with most modern machines fairly well.




Shorty:D

[jays375]

That is the set up I have with the Mega Cycle cam..Except for the carb installed.I have it and everything to put it on.It is a lot of fun!

[3Wheelermaniac3]

Thanks Shorty. Rub it in my face. Lol. I didn't know that back then when I built it. Thanks for the info truly noted.

[3Wheelermaniac3]

OK some more questions. Oscarmayer what do u mean by prep piston? Jays375 what can I do to my bottem end to make it better? Also Shorty how do I lighten the fly? I'm going to do this right this time. Thanks 3 wheeler saviors.

[jays375]

Rebuild the bottom end,new bearings.Plus even if it was done before.It should come apart to be cleaned and looked at.

[Dirtcrasher]

You had more lift and clearance has to be checked with the spring compressed; It can hit the valve guide. MUST BE CHECKED!!

Did it run at all? Was it in time? Did you check and set all rocker arms at TDC per the cams spec?? Mine likes .008, not .003.

Use new rockers or get them hardened.

Power isn't cheap and if you don't do it per the specs, things can happen.

[3Wheelermaniac3]

The bottom end hasn't been rebuilt. I will do that. It ran extremely well on pump gas. If I can remember I'm pretty sure I set the valves at.003 before it blew up.

[3Wheelermaniac3]

Also what can hit the valve guide.

[Dirtcrasher]

If there is more lift, the valve spring cap and retainers can hit the end of the valve guide.

When you buy a cam they explain what is critical.

If you want power, be ready to pay for it (Like a grand). And as SWIGIN has suggested, I run ONLY VR1 racing oil.

[3Wheelermaniac3]

Yea I'm gonna get shortened valve guides. Any idea on how to get more oil to the top of the head? Is it needed?

[yaegerb]

Lots of ideas on how to do it. Haven't seen one yet that was aesthetically pleasing. When you rebuild your motor use molybdenum grease on the camshaft and the surfaces where the cam rides. Also blow all of your oil passages out with air and you shouldn't have a problem with oil getting to the head.

Why are you going to buy shortened valve guides? The oem valve guides are fine.

[jays375]

Also refer to manual about filling area under cam with oil.

[WIkid500]

Been running the megacycle setup with a needle bearing on each side of the cam in my 200x for about four years now. Zero issues, they make good parts and the lady I talked to out there seemed to know her stuff.

[3Wheelermaniac3]

Ahh I figured if I was gonna go this far with it shortened valve stems would not hurt. In the future if I go bigger I'll already have them installed.

[3Wheelermaniac3]

Almost forgot should I get rid of the 12:1 piston and .50 over sleeve and go back with standard bore.

[3Wheelermaniac3]

I have 2 250r's and 2 four strokes. Yea I don't get the crazy power of the 2stroke out of my x but I love tinkering with stuff and the x was my first sport bike. I've since neglected it and now its time to give it the attention it needs. Don't know what this has to do with anything but I felt like saying it. Lol

[Dirtcrasher]

Like I said, it comes with paperwork. If I can find mine I'll scan it for you.

There are just certain "prior to assembly" things that have to be checked.

I can't recall his name but a guy on the board built a really nice 350X (big bore and allot of other great goodies). He had an issue after a short period of time. He popped off the head and everything got ate up because. It all happened because he set the valves at .003. It's that easy......

[jays375]

I would use the piston that has been suggested to you.Ditch the current one.Stock bore isn't a must.Megacycle dies very high quality work.Not only do they hard face your rockers.They give them a overall clean up.

[3Wheelermaniac3]

OK will do. Thanks dirtcrasher if you find it pm it to me. I'll look into 50 over 10.25:1 pistons. Thanks for all the input guys.

[SWIGIN]

10.25-1 piston
megacycle full race cam
hardened rockers
HD valve springs
national quality port job
38mm round slide (PE or PJ I forget)
HD clutch springs

That is my all time favorite 350x motor for all around usage. And I have seen these motors last well over a decade with quality beating...lol

[3Wheelermaniac3]

Thanks guys. Found a 10.25:1 piston from wiesco for 149.00 with rings. Not too bad. Looking into ner bitten end bearings and complete gasket and seal kit. I've got to split the cases to powdercoat the centers so new bearings are no biggie.

[3Wheelermaniac3]

I've been looking everywhere for bearings. Any idea on where? Crank ect.

[3Wheelermaniac3]

Man I caint find them anywhere. I'm scratching my head on this one.

[Hurricane635]

Main brgs. are Honda only, Vesrah makes a quality rod kit. It shares the rod with trx350d, if that helps.

[3Wheelermaniac3]

Thanks again