anyone see problems with this motor setup?

[bry14661]

so i have my motor apart right now to fix a seal and replace valves and im doing a stage 2 cam. 11:1 piston. not sure on bore yet either standard with .020 over or a 426 kit. i would like to run the sparks key as well. i also have a 450r carb and im getting a HD cam chain. I would like to run pump 93.
1. is this possible on both bores?
2. do i need HD studs for either?
3. is there much of a difference between the 426 and 440?

[Pipeless416]

i can't answer your last question, but HD studs and using pump gas are more so dependent on your compression ratio. for 11:1, some people go with hd studs just to be safe, but many are just fine with stock studs.

[tri5ron]

JMO,
but as far as the studs go, I'd say your getting very close to "must have" status for the hd's. why would you say that you ARE getting an hd timing chain, but ASK about the necessity of hd studs? not sure I follow your logic on that.

as far as the 93 pump gas goes, at 11:1 compression you will definetly need to run it, and if it dosent ping, consider yourself lucky. but be mentally prepared ahead of time, to accept the possibility of having to run on race gas.

and reguarding the Sparks key, with all things you stated, you should be ok to use it at 426, but the 440 would be getting too big, and will, in all probability, start causing you to have greater heat issues than you will already have.

[bry14661]

well as far as the timing chain i wanted HD cuz i have to replace my chain and i wanted to beef it up a bit just so i can sleep easier at night knowing its tough. I dont have to replace my studs thats why im asking about those. Im prepared to run a mix of cam2 105 and 93 if i must. but im hoping to avoid that by staying stock bore just going .020 over

[Pipeless416]

usually 11:1 cr is the limit where people can get by running 93. bore size doesn't really affect it as much, especially if you're just going one size up. to save yourself some money, just go for a crf450 timing chain. same thing as the hd's, but half the price.

[bry14661]

http://cgi.ebay.com/ebaymotors/TRX400EX-XR400-400EX-XR-400-Heavy-Duty-Timing-Cam-Chain_W0QQitemZ190265928419QQcmdZViewItemQQptZMoto rs_ATV_Parts_Accessories?_trksid=p4506.m20.l1116

thats the HD cam chain i found. Ebay is a dream and has saved me over 250 on my rebuild so far. Do you see a problem with getting that chain or is it legit?

[Pipeless416]

wow! thats cheap. theres no brand or anything, but who knows about that. i would probably take a chance on it, and if it starts slapping prematurely, then at least you know for the future. somebody correct me im wrong, but an hd timing chain is an hd timing chain.

[Colby@C&DRacing]

If you run the sparks key you will have to run a mix of race gas. The advanced timing does wonders for the 400ex but it creates a lot of heat.

[katch26]

but isnt a "hd timing chain" just an oem crf chain?

[katch26]

Originally posted by Colby@C&DRacing
If you run the sparks key you will have to run a mix of race gas. The advanced timing does wonders for the 400ex but it creates a lot of heat.

is that in general or on an 11:1 piston/ or over bore/ or both?

[bry14661]

Originally posted by Colby@C&DRacing
If you run the sparks key you will have to run a mix of race gas. The advanced timing does wonders for the 400ex but it creates a lot of heat.

would an oversized oil cooler or a fan help and prevent the requirement of race gas. i mean i have no problem running 105 for the harescramble season but when im bombin on our practice track i dont wanna be burnin $8.60 CAM2 105 octane

[tri5ron]

The requirement for "race gas" comes from high compression ratios.
nothing else.
not bore size,
not timing key,
not oil coolers.

that being said,... advancing the timing will raise your cylinder pressure a bit...
(note that, compression ratio, and cylinder pressure are not the same thing.)
...Hence, you will create more heat, than you would without the advance key.
Is it alot more heat?....no.
Will a bigger oil cooler help?....(it cant hurt!, but still has nothing to do with the race gas issue)
note- 11:1 compression ratio, ALSO creates more heat than stock compression ratio.

heat and higher pressures are what blow gaskets and studs,

so if it was me,....
running 11:1, increased bore,with a timing advance key,....
I'd be **sleeping better at night** knowing I had installed the HD studs when I was doing the rebuild

SO,... 11:1 compression ratio, (on whatever size bore), is getting borderline on the point where you may need to run above 93 octane.
(JMHO)

[bry14661]

ok so im staying with standard bore. well 85.5 because im gonna bore it over since the cylinder was .002 off and slightly egg shape.

so if race gas requirement comes from compression why is there so much controversy about what compression to start running race gas? im not saying your wrong just curious. ide like to be able to run 93 bombin around but i have no problem running c16 or cam2 on raceday

[bjg696]

Can i run a timing key with a 440?