350X engine build questions

[camoweasel]

Since I decided to tare the engine out to weld in some gussets, I have decided to "freshen up" the engine a bit with a few performance parts. Basically I am asking, what are the best parts to get the most bang for the buck while keeping it fairly reliable? So far my ideas were a cam and 10.25 piston at the correct bore size needed to clean the walls up. As far as big bore kits and strokers, I'm afraid those items will compromise the reliabilty and longevity of the engine. So what is everyone's opinions about pistons and cams? I'm leaning more for a mild/mid power upgrade cam; not a race cam. Webcam, Powroll, or megacycles??

[Dirtcrasher]

Mid range and 10.25:1 will still be very reliable, make sure to have the rockers hardfaced though..........

I believe WEBCAM makes the cams for Megacycles; Thats what I've heard. IDK if Powroll makes there own, the lift and duration compared to the others will let you know. Make sure to clean up the valves, lap the valves (some will argue they are coated, which I'd say "the coatings gone now" )and put new valve seals in.

Yep, just clean up the bore, keep the sleeve as thick as possible rather than go 2MM over like some guys do which doesn't really add anymore power. I agree with you about stroking the engine, it might be a blast for awhile but it won't last 25yrs.

The only downside is your looking at 600$ worth of mods but well worth it IMO........

If your gonna gusset it like I do to any 350X frame I get, now I make sure to use the right lower gusset to accept a 450R master cylinder since the 350X one can't be rebuilt. Easy to do.....

[camoweasel]

Mid range and 10.25:1 will still be very reliable, make sure to have the rockers hardfaced though..........

I believe WEBCAM makes the cams for Megacycles; Thats what I've heard. IDK if Powroll makes there own, the lift and duration compared to the others will let you know. Make sure to clean up the valves, lap the valves (some will argue they are coated, which I'd say "the coatings gone now" )and put new valve seals in.

Yep, just clean up the bore, keep the sleeve as thick as possible rather than go 2MM over like some guys do which doesn't really add anymore power. I agree with you about stroking the engine, it might be a blast for awhile but it won't last 25yrs.

The only downside is your looking at 600$ worth of mods but well worth it IMO........

If your gonna gusset it like I do to any 350X frame I get, now I make sure to use the right lower gusset to accept a 450R master cylinder since the 350X one can't be rebuilt. Easy to do.....

DC, Thanks again for the advise. I'll definitely look into that lower gusset. I have the engine torn out and now the frame is just a roller. I should have plenty of room to do all the gussets now. I've been doing some reseach on the 3 big cam makers for our bikes, (Webcam, Powroll, and megacycles), and they all have different lift and duration numbers as if they are all different cams. The two that sort of have my attention is the Webcam grind #213 and megacycles 162-30. They seem to be the biggest cams availible before you start getting into the race grinds. Any opinions on your favorites? About the valves, and rockers, it seems to me that buying new valves and rockers would be cheaper then having the rockers hard welded or the valves redone?
I know for a fact, my engine has low hours from factory, so I'm betting that there isn't much wear on the top end components. Heck I even bet the factory piston isn't even worn that bad. I just figured it would be nice to have mildly built 350X for braggin rights you know.
I talked to my local ATV shop and he said, he was going to tare into the engine and inspect all components for ware so I knew what to order. I told him I would burn him a copy of the service manual onto a CD so he knew what the tolerances were. Just yesterday there was a brand new webcam and kibbleworth valve spring set on Ebay for 175 bucks with no core. I knew I should have jumped on that earlier but what can you do...

[Dirtcrasher]

Because they build up the cam, the rockers have to have a harder material applied. The crate motor I'm using with 0 miles still has to be hardfaced.

Yeah, 175$ is a good price, esp. with the springs/retainers, then 120 for a piston/rings, 75$ to bore it, IDK what hardfacing is now but it isn't cheap, a gasket set etc; I know my SX cost about 500$ for all the mods motor wise...

From what I've read and others experience, even brand new rockers will not stand up to a hard faced cam.

I'm sure some will say "I never did that and it's just fine". I'd simply go with the cam manufacturers suggestions.............

[SWIGIN]

Web does NOT make megacycle cams and Powroll cams are megacycle. Megacycle is the brand most builder use it seems and the only 1 I use.

It's not the material the cam is made from that determines if you need hardened rockers. It is the high pressure from HD springs that call for hardened rockers.

As I have said before my all time favorit 350x motor was a 10.25 - 1, full race megacycle cam with springs and hardened rockers, full ported head and pipe. That motor ran over 10 years (till I lost track of it) and was raced for most of those years. That is a very dependable motor.

[Cuztom Racing]

We have cuztom cams ground for our drag bikes from megacycle so NO, web does not make cams for megacycle. But I've ran them both and web and megacycle both make great cams.

[needa250r]

i have a 200x needs to be timed. have a timing new chain and guide. lined up the timing marks it gets gas and spark. dont have a book to try an figure it out. need help. any suggestions?

[Dirtcrasher]

Web does NOT make megacycle cams and Powroll cams are megacycle. Megacycle is the brand most builder use it seems and the only 1 I use.

I knew it was one way or the other,

Just curious, what don't you like about Web camshafts? They are the ones that told me the welding they do hardens the cam and I had to use hardened rockers.

Then I've heard guys say "they told me a 200X doesn't need hardfaced rockers". Is that because they are only running 2 valves?

You said you ran a full race cam and a 10.25:1, when I look up full race cam they tell you a high compression piston. I always felt they meant 12:1 for a full race cam. Did you have to shorten your valve guides?

"It is necessary to use new or reconditioned cam followers or rocker arms with each new or reconditioned
cam shaft. Using worn rocker arms or followers will cause damage to the cam. We offer regrinding of
certain tappets and reconditioning of rocker arms for many models."

I figured I'd read through Megacycles PDF. That sounds like a new rocker arm is just fine on their cams? I understood they HAD to be hardfaced?

[SWIGIN]

I knew it was one way or the other,

Just curious, what don't you like about Web camshafts? They are the ones that told me the welding they do hardens the cam and I had to use hardened rockers.

Then I've heard guys say "they told me a 200X doesn't need hardfaced rockers". Is that because they are only running 2 valves?

You said you ran a full race cam and a 10.25:1, when I look up full race cam they tell you a high compression piston. I always felt they meant 12:1 for a full race cam. Did you have to shorten your valve guides?

"It is necessary to use new or reconditioned cam followers or rocker arms with each new or reconditioned
cam shaft. Using worn rocker arms or followers will cause damage to the cam. We offer regrinding of
certain tappets and reconditioning of rocker arms for many models."

I figured I'd read through Megacycles PDF. That sounds like a new rocker arm is just fine on their cams? I understood they HAD to be hardfaced?

Megacycle also says about getting rockers hard faced so that does not make Web speicial. I never liked Webs cam specs, they are just a ok cam for guys who want to say they have a cam IMO. I can name several top engine builder that only use Megacycle cams and that mean alot to me, I can name non that only use Web.

The number of valves have nothing to do with needing or not needing hardened rockers. It is all about the higher spring pressure rubbing a soft rocker on a moving metal object. This is where using a good oil like valvoline VR1 comes into play too. Think of it like this, you can lightly hold a piece of steel to a grinder and grind slow ( stock valve prings).... or you can push like mad and grind real fast ( HD springs).

I always use Megacycles full race cams in 350x motors. They are a great all around cam IMO and I use to trail ride the heck out of my old race quad with that motor. I did shorten the guides but you do not need to. I just blindly followed there suggestion to shorten them when I first built that motor and after I had the motor built I rechecked the guide to retainer clearance and it would of been fine. I'm sure they are just saying to that to keep guys from complaining when there full race cam with less then proper HD springs float and smashes into the guide.

Like you posted, megacycle recommends new or resurfaced hardened rockers for there cams. What that means to me is you at least need to run new rockers on a new cam (no crap) but it is best to run the hard ones. Right now my RX has RD HD springs just like the ones we use for the MC full race cam. But I am running a TC high rev cam ( made by megacycle) with new stock rockers. The only reason I did this is I could not see sending out new rockers to have them welded and hardened. They will not last to long but I don't ride like I used to and when they show wear I will ship them out.

[WilliamJ]

I was taught that it is a long-standing rule that one should always renew the cam followers when a new camshaft is fitted. This presumably is the same for the Honda rockers. The two surfaces need to wear in together. No doubt the hardened followers will wear better.

With a new cam and followers it is mandatory to run the new cam at about 2000 rpm for 20 minutes to break it in - you should always use a special cam lube for the build to help the process and it should be supplied with the cam. If you have to shut down for any reason during the 20 mins you should cut the power totally and go back up to 2000 rpm when you re-start.

The reason that a higher CR is recommended is because the race cam has more valve overlap. This means it has a lower dynamic CR as some of the intake charge gets pushed out at lower revs. Increasing the CR helps to offset this at low rpm. And at high rpm, where there is less time for the gas to be pushed out, and where it is being sucked though by the high speed exhaust gas, the cylinder is really well filled and you make a lot more power.

Does anyone have the timing and lift figures for these after market cams?

[Dirtcrasher]

Thanks for the info. Good to know Megacycle cam is the way to go, I'll be doing this soon to a crate motor....

The reason I mentioned a 2 valves engine (200X) is you said it was the HD springs that required the hardfacing.
The 350X having one assembly operating 2 valves on both the intake and exhaust would require more force; I can see them wanting hardfacing as one lobe is opening 2 heavy springs. But in the case of a 200X one lobe runs one valve. Regardless, I'd go with their recommendations.

[SWIGIN]

I was taught that it is a long-standing rule that one should always renew the cam followers when a new camshaft is fitted. This presumably is the same for the Honda rockers. The two surfaces need to wear in together. No doubt the hardened followers will wear better.

With a new cam and followers it is mandatory to run the new cam at about 2000 rpm for 20 minutes to break it in - you should always use a special cam lube for the build to help the process and it should be supplied with the cam. If you have to shut down for any reason during the 20 mins you should cut the power totally and go back up to 2000 rpm when you re-start.

The reason that a higher CR is recommended is because the race cam has more valve overlap. This means it has a lower dynamic CR as some of the intake charge gets pushed out at lower revs. Increasing the CR helps to offset this at low rpm. And at high rpm, where there is less time for the gas to be pushed out, and where it is being sucked though by the high speed exhaust gas, the cylinder is really well filled and you make a lot more power.

Does anyone have the timing and lift figures for these after market cams?

You got it 100% right.

[camoweasel]

So I take it, the general consensus is use hard-faced rockers instead of new OEM rockers. I see now why HD springswould create more wear and tare on the rockers. I use 15W-40 diesel rated oils which are loaded with tons of zinc and phosphorous both great anti-wear additives. They most likely have just as much anti-wear additive as does the VR1 oils. So with the new cam, I should just worry about the springs, and use the new seals that come with the new gasket kit? Do I need to worry about retainers or guides? Also MC also sells needle bearing cams. Are they nessesary?

[SWIGIN]

Thanks for the info. Good to know Megacycle cam is the way to go, I'll be doing this soon to a crate motor....

The reason I mentioned a 2 valves engine (200X) is you said it was the HD springs that required the hardfacing.
The 350X having one assembly operating 2 valves on both the intake and exhaust would require more force; I can see them wanting hardfacing as one lobe is opening 2 heavy springs. But in the case of a 200X one lobe runs one valve. Regardless, I'd go with their recommendations.

That 1 large 200x valve should be heavier then 1 smaller 350x single valve meaning the 200x valve should need a much larger spring to control that valve then the 350x. I have no idea if that is the way it is since I do not build up 200x motors but they should take a bigger spring then 1 350x valve.

But you'r right that 1 spring is probally weaker then the dual setup but I'd still use hard rockers.

[SWIGIN]

So I take it, the general consensus is use hard-faced rockers instead of new OEM rockers. I see now why HD springswould create more wear and tare on the rockers. I use 15W-40 diesel rated oils which are loaded with tons of zinc and phosphorous both great anti-wear additives. They most likely have just as much anti-wear additive as does the VR1 oils. So with the new cam, I should just worry about the springs, and use the new seals that come with the new gasket kit? Do I need to worry about retainers or guides? Also MC also sells needle bearing cams. Are they nessesary?

Needle bearing cams are a great way to save a head you have hundreds of dollars into and the cam journals are wasted....so no you don't need one unless your journals are shot. You are using good oil for sure but since I dont know what you are building exactly I wont say what you need or dont need.

What I recomend as a great mild build is a 10.25 piston, full race cam or the next one down if you are really scared of the race cam...lol, nice head work,38mm PE carb, cobra header and whatever silencer you like.

Ask MC what springs they reconmend for whatever cam you pick out and buy them.