engine mod questions, opinions

[ssduane]

Since I got the engine out and split for transmission repairs I figured I would go ahead and do some internal upgrades and some external.

I found my tranny parts, should be here tomorrow and Wednesday. I read up on Cody300ex's engine mods and ordered some hotcams stage 1 and the kittlewhite valve springs/keepers along with the gasket kit from them. Saw you posted doing a Stage 3 kit, ?. Ordered a FMF power core 4 slipon to go with the WB head pipe I got last week. I'm going to drop the head of at a local machine shop and have them deck it .020" and clean up the intake ports were the manifold mounts up (its off almost 3/32" on both sides) and polish the intake/exhaust ports. Anything else you all might recommend.

I didn't ordered the hardened rocker arms, I'm already kinda over budget concidereing I had to fork out 250 bucks for gears and 100 bucks for 2 day shipping on these parts. This quad doesn't race and is a recreatioanl quad. If need be I can replace the rockers later if it won't be bad for the engine.

Also, cam timing is set with the tensioner installed right and what about after the head is milled, will the stock tensioner makeup the extra slack?

Thanks all,
Duane

[dork]

as far as the ports go, you'll want to blend the seat inserts into the head, don't necessarily grind everything flush, just blend it with the port so there's no sharp edges. dont make the bowl more than 90% of the valve diameter. make sure the short side radius in the intakes is a smooth radius. don't enlarge the cross section much in the throat either. you can clean up the casting marks in the port, it won't do much though. when you blend the manifold with the head its best to leave a little step down into the head instead of getting carried away. also leave a step down into the header from the exhaust port. use 80 grit on the intake and polish the exhaust if you want.

as far as the cam timing goes, the milled head will retard cam timing slightly, in your case about 2 crank degrees which will move the powerband up slightly. also the tensioner will take up the slack as long as its in good shape. try to push it in with medium pressure by hand when its extended, it should hold its position and not collapse. you also may want to do a new timing chain. what piston are you running.

[ssduane]

Thanks for the info dork (that doesn't sound right). The quad is an 05, stock piston. I'll hold off on the chain since it doesn't have that many hours on it, probably less than forty since new. My step daughter was terrible at shifting (thinks pounding on the shifter would make it shift better) and my son has learned how to shift a lot better also.

After next season I'll probably go into the top end and bore it with a some other mods so it'll get all new stuff then. As of now it'll have-

Uni filter
Jetted
WB head pipe with FMF PC1V muffler
Webcams stage 1
Kittlewhite springs/keepers
.020" mill on the head

So left will be-
hardened rockers
Rev box (can't seem to find one though, where are you'll getting them)
Big Bore kit 330cc (maybe a stroker)
Oil cooler
400ex carb or a Eddy carb

[bwamos]

Good info.

I also just want to make sure you do not polish the intake ports. ;) You want some light turbelence as it helps agitiate the air/fuel mix to promote it's atomization/vaporization.

Polish the exhaust side. Leave the intake semi rough. Some builders even make it rougher than the normal tooling will.

Also you don't need to harden the rockers for hotcam's. It's a drop-in style cam. You do need to check for wear on the existing rockers though. If you have moderate to high wear, it could cause premature wear on both the rockers and the cam.

[ssduane]

Ya, I have some experience on porting heads, done a few SBC heads in my past, so I have all the gear, course it'll be more work on these smaller ports.

thanks for the response on the rockers, I'll double check the stockers and make sure they are good to go. I figured the rockers might be a good idea for uping the rev limiter. What about rev box's, where are you guys finding them. I am having a hard time finding one.

[161xchonda]

I know Big Gun makes a rev box. Not sure who else does though.

[modifyit]

Hetrick racing makes or will mod. yours

[bradley300]

if you want different timing i think the big gun is the only one out. if you just want to get ride of the stock rev limiter, most engine builders ill do that for 50-75 bucks to your stock one

[2muchquad]

if you just want to get ride of the stock rev limiter, most engine builders ill do that for 50-75 bucks to your stock one

A few of us on here may know how to eliminate the stock rev limiter;)

[ssduane]

Well :D ,

I posted a question months ago, so how do you do it.

PM me please if you don't want it public.

She really needs that limiter gone and now I have to go smaller on the rear gear, this thing raps up quick and by the time you know it your in fifth wanting much more.

Right now shes got a 14/38 combo with 20"s on it. Thats giving me a 2.71 reduction, I'm thinking of going to a 14/36 which will give me a 2.57. I don't think a 14/37 will be as noticable which only a 2.64 reduction. I gotta do some math and figure out what speeds these will give me first.

[2muchquad]

I run 14/36 with 20s for harescrambles and its still geared low,i can blow it up in 5th if i wanted to because it pulls hard up top without a rev limiter.im gonna try a 33t rear.14/36 may be perfect though as i still do most of my hill climbs in 2 and 3rd gear.theres a capacitor in the cdi that needs to be drilled out,this will eliminate the rev limiter in reverse as well.i will look for the schematics,i had them around here somewhere.I guess theres another way by grounding one of the switches on the bottom of the motor by the brake pedal.i think Bwamos knows that one;)

[ssduane]

Right on, I'll be waiting on your reply on the schematic.

Thanks again.

[Sjorge450R]

Originally posted by bwamos
Good info.

I also just want to make sure you do not polish the intake ports. ;) You want some light turbelence as it helps agitiate the air/fuel mix to promote it's atomization/vaporization.



you beat me to it...lol

[modifyit]

Not shure how this works but can't you just put a revlimiter off another quad ie: 450 which probably rev out at 8000 or even off a street bike they rev in the 10000 + instead of deleting it completly to be on the safe side ??

[2muchquad]

Not shure how this works but can't you just put a revlimiter off another quad ie: 450 which probably rev out at 8000 or even off a street bike they rev in the 10000 + instead of deleting it completly to be on the safe side ??

no:D

[bwamos]

No. Reason is it is built into the CDI (Capacitance Dischharge Ignition) unit. So if wire in one from a different bike you are going to have jacked up ignition timing. Not to mention most street bikes have 2-4 cylinders. ;)

On a lot of quads you can get the rev limit "increased" without remiving the rev limit. I beieve they drill out the epoxy and swap out a resistor on the board.