boring to 416 or 426??

[Ex_Rider43]

I heard things about 426's breaking the sleeve and overheating but is it true, I know it can overheat but often?? how about cracking the sleeve and the cyl.?? I dont want to resleeve it so its between these 2.

I will be riding trails this winter so it wont overheat but next summer its gonna be a lot of MX so is it better a 416 or 426 for this. I want 11:1 comp also, i have a TC mx cam, compl. exaust, filter, jetted and a sparks timing key.

thanks I apreciate all advices.

[Silverfox@C&DRacing]

I would start with the 416 kit that way you can always go to the 426 later.. I have had my 416 since april of 2000 and have not had any problems...

Originally posted by Silverfox@C&DRacing
I would start with the 416 kit that way you can always go to the 426 later.. I have had my 416 since april of 2000 and have not had any problems...

This girl is 100% correct..:D

[Ex_Rider43]

did you guys saw 426 with problems???

[Ex_Rider43]

oh yeah I forgot something, do you think Id need a new clutch with this or stiffer springs would be ok??

what kind of clutch would you recommend?? I dont want something expensive like hinson.

[hondafox440]

Your stock clutch should work fine. I have the stock clutch on my 440.

[400exBro]

don't get a timing key, they will make it run worse with higher compression pistons, sparks actually suggusts not to run them with higher comp pistons..
the purpose of the higher comp piston is to compress the gas and air more, with the key it will fire before the piston is able to make it all the way to the top of it's stroke, making the newer piston almost useless..

[Ex_Rider43]

are you sure bro?? damn I hope not. are you sure its not for 440 bigbored motors??? I heard about that a couple of months ago...

[400exBro]

well when i got my sparks timing key it said that it is not recomend to run with high compersion engines.
And i think becuase the timing key lets the spark plug fire 6 degrees before stock. this means the piston does not reach it's full travel, the gas and air mixture will not have a chance to compress, when you buy a higher comp piston, you will get a piston that is able to compress the gas and air that much more, so really you just wasted money.
this is why i think it won't work, but talk to sparks, tc or any other engine builder, but i won't do it.
it is up to you if you want to or not.

[Colby@C&DRacing]

Well I guess I need to clear this timing key thing up. The key works great on stock or big bore motors. Yes Sparks recommends not using on high compression motor, but not because it doesn't work but because it creates more heat.( it a liabilty thing) The reason it works is because of combustion lag, the sparks plug has to ignite the fuel before the piston reachs top dead center other wise it is already on its way down when the burn starts and that creates less horse power and is not efficent.:)

[Colby@C&DRacing]

Originally posted by 400exBro
don't get a timing key, they will make it run worse with higher compression pistons, sparks actually suggusts not to run them with higher comp pistons..
the purpose of the higher comp piston is to compress the gas and air more, with the key it will fire before the piston is able to make it all the way to the top of it's stroke, making the newer piston almost useless..

Makes it run worse with a high compression piston is not correct. It runs fine you just need to add a few things to keep the motor cool. It also has no ill effects on the way a high compression piston works. 6 degrees is so small that it has no bearing on a loss of compression besides the air fuel mixture is still compressable until it is completely burnt which is after the piston has started on the way back down

[400exBro]

Originally posted by Colby@C&DRacing
Makes it run worse with a high compression piston is not correct. It runs fine you just need to add a few things to keep the motor cool. It also has no ill effects on the way a high compression piston works. 6 degrees is so small that it has no bearing on a loss of compression besides the air fuel mixture is still compressable until it is completely burnt which is after the piston has started on the way back down

okay i see,.
thanks for explaing that

[Colby@C&DRacing]

NP sometimes people get confused by all the info that is floating around I just want people to be properly educated.

[UglyMotha™]

Originally posted by Colby@C&DRacing
Makes it run worse with a high compression piston is not correct. It runs fine you just need to add a few things to keep the motor cool. It also has no ill effects on the way a high compression piston works. 6 degrees is so small that it has no bearing on a loss of compression besides the air fuel mixture is still compressable until it is completely burnt which is after the piston has started on the way back down



mmmmm so true, my bike runs far from worse but look forward to paying top dollar for race fuel
:eek2:

[wilkin250r]

The basic premise of the advance timing key is simple. Nothing happens instantaneously. It takes TIME for fuel to burn.

In an ideal perfect world, the piston would reach TDC, the fuel would ignite instananeously, and force the piston downward.

However, since it requires time for fuel to ignite, you DON'T want the spark right at TDC. While the fuel would be igniting, the piston would start traveling downward, decompressing the fuel/air mixture before it completely burns, slowing the process even more. By the time the fuel burns completely, you have lost much of your power stroke (and thus, much of your power)


How do you get around this little dilema of physics? Simple, spark BEFORE TDC. This way, the piston can still travel upwards while the fuel STARTS to burn, travel though TDC as the fuel continues to burn, and it will start to create power much earlier in your power stroke, resulting in more power, but also more heat.

The advanced timing key allows the spark to happen a little sooner, so you get a more complete burn, and utilize more of your combustion stroke.

[UglyMotha™]

ya you just think your an engineer http://ricoracing.netfirms.com/Smilies/pullin%20out%20hair.gif


:blah:

[wilkin250r]

Originally posted by UglyMotha™
ya you just think your an engineer http://ricoracing.netfirms.com/Smilies/pullin%20out%20hair.gif


:blah:

Well, I figure if I spew enough junk, other people will begin to believe it.

What do you think a BS degree actually stands for?

[UglyMotha™]

Originally posted by wilkin250r
What do you think a BS degree actually stands for?




i was under the impression that it stood for all the stupid crap ya gotta go thru to get it :p