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680 almost ready to go!???


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My winter project is almost ready to go.

Heres what i got so far:

cylinder bored to 102.4mm and nikasil plated at millennium technologies

10:1 comp wiseco

stage 2 hotcam

unifilter

hopefully an edelbrock soon

still unsure about what exhaust to get

QUESTIONS:

I am going to be breaking in both the cylinder/piston AND cam at the same time, the cam instructions say not to let the motor idle, and keep it above 3000 rpm, BUT the cylinder break in says to let it idle for 15 minutes, and then take it easy, varrying throttle etc... HOW do i break them both in at the same time???

Also since i will be adding all of these things on right away, and putting on a new edelbrock, what do i adjust the edelbrock to??? I am worried that i will get it fired up, and it will run like crap, and i wont break it in correctly.

Will 600 degrees gasket maker work on the head or do i need higher temp?

Which exhaust, good sounding, but not overly loud?

thank you very much for any help or input

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dont understand why they would say keep it above 3,000 RPM's for the new cam, its the same as breaking in a cam that came in a brand new bike from the factory. But you also dont have to let it idle for 15 minites, the first ride you only wanta ride it for a total of 15 minites anyway. Ya gota do a few heat cycles before you start riding it hard.

I'd say first 3-4 rides 15-30 minites easy keep it under half throttle to break it in, then the next few rides start getting into the throttle a little harder, but always fluctuating the throttle.

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Yep the first start up of my new bikes i don't even ride it,just get it hot/warm let it cool down completely.

Next run i ride through the throttle to good loads up and down for say 5 to 10 minutes feel it out,stop it drop the oil.

From then on i just punish them,thing is everyone says it's wrong but my bikes are allways faster than my mates of the same type and last longer.

You see tolerances and matalurgy have come a long way from "run it in easy".

The cross hatching in the bore is much finer than it used to be and i believe is bedded in inside about 20 miles under load.

If you run it in slow it'll be a slow bike that wears out faster,thereby needing Honda parts sooner.

Honest.

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The least noise for the most power is hands down the Moriwaki! Nothing even comes close for doing both. Most free flowing with just the right backpressure and the most glass packing for the lowest sound of any full flow exhasut. Hard to find now a days. Barnums exhaust is the second best flowing out of the exhausts I have tested and been on the dyno. Real close to the same flow and power with the full open tip but, loud like any other of the mufflers that stay small (littler glass packing). It did come with three tips for different sound/tuning but, each tip changes the power and jetting of the bike. There is a guy selling one off this group for a lot less then they cost. His name is Damon (DGA) and I would read the thread some.

https://www.thumpertalk.com/forum/showthread.php?p=5713970#post5713970

FMF powerbomb, Pro Circuit T-4 system, Staintune, are all going to give lots (did I say lots? well more then lots) of power in the lower rpm's and the bike may be a little of a hand full:busted:

I have used quite a few different exhausts but, once you go 680cc and cam; looking for low end is NOT an issue! It starts to be the other way around.......looking on how you can move some of the power up the rpm range. Trying to chug up and steep loose rocky twisty when the bike wants to jump twenty feet with just the smallest twitch of the throttle or when you want to blast something simulare with the throttle open in third and the tire is ripping the terraferma up by the yard, sending it into the next county, power down low will not be your issue:ride:

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The least noise for the most power is hands down the Moriwaki! Nothing even comes close for doing both. Most free flowing with just the right backpressure and the most glass packing for the lowest sound of any full flow exhasut. Hard to find now a days. Barnums exhaust is the second best flowing out of the exhausts I have tested and been on the dyno. Real close to the same flow and power with the full open tip but, loud like any other of the mufflers that stay small (littler glass packing). It did come with three tips for different sound/tuning but, each tip changes the power and jetting of the bike. There is a guy selling one off this group for a lot less then they cost. His name is Damon (DGA) and I would read the thread some.

https://www.thumpertalk.com/forum/showthread.php?p=5713970#post5713970

FMF powerbomb, Pro Circuit T-4 system, Staintune, are all going to give lots (did I say lots? well more then lots) of power in the lower rpm's and the bike may be a little of a hand full:busted:

I have used quite a few different exhausts but, once you go 680cc and cam; looking for low end is NOT an issue! It starts to be the other way around.......looking on how you can move some of the power up the rpm range. Trying to chug up and steep loose rocky twisty when the bike wants to jump twenty feet with just the smallest twitch of the throttle or when you want to blast something simulare with the throttle open in third and the tire is ripping the terraferma up by the yard, sending it into the next county, power down low will not be your issue:ride:

yea ive read awsome stuff about the PC t-4, thats the system im gona get when i get some spair cash.

I would really like to do a 680 kit with the HRC goodies and porting work but i would end up having to dump $2,000 into it....And sadly ive already got $10,200 into the bike! and its not enough power:banghead:

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yea ive read awsome stuff about the PC t-4, thats the system im gona get when i get some spair cash.

I would really like to do a 680 kit with the HRC goodies and porting work but i would end up having to dump $2,000 into it....And sadly ive already got $10,200 into the bike! and its not enough power:banghead:

If the bike is going to be used in the dirt, it is not a good idea to port the head of the XR650R. WE have done it and it make the power way to lazy. Mr. Lewis is running a ported polished head and it just doesn't respond like the others.

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  • 1 month later...

In 2004 I went 680cc with a steel sleeve. Four years later beating the snot out of the bike it is finaly not quite as strong as it was in 2004. Problems that I have had? Barnum siezed it on the dyno two months old. It was a cold sieze from not letting it warm up. That is one of the real bad points of a steel sleeve because, the piston and the sleeve do not expand at the same rate (piston expands much faster) so, you have to have .004" piston to cylinder clearance but, with Nikasil you can be as little as .002" (most run .0025"). Then Barnum ran it down to 500cc of oil on a round trip run to El Mirage lake bed after rebiulding the top end. I went with a Rekluse auto clutch. Way to much power and it grenaded. So, I am back the a stock clutch with heavy duty springs and no Judder spring. It has been ran into the ground sense but, it just keeps going. I thought it was a goner when all the clutch metal went through the engine but, two years and it is still going. I did adjust my valve lash once in those four years and one valve was a little loose. The Stainless steel valves do not dish like the soft stock intake. The stock intake valves get tight from dishing, stainless seems to be the perfect fix for this. I keep thinking it's time to rebiuld this 680cc bike and go Nikasil Like Mike Powell and others but, I keep squeezing in "one more ride" sense the the clutch let go. Funny thing is I have been going on that "one more ride" every week or so for almost two years:excuseme: This engine has taken me past what I thought was bullet proof. I bet it is just waiting for me to take it on one last big ride, like the April ride or a big Pigfest ride and get me 60 miles from camp and make me walk:banghead: ? Big Red Pigs can be real evil like that.

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The reason most cam recommend 3K rpm is to supply the cam with plenty of oil.Coat the cam well with a moly base engine assembly lube.

You don't want to put a load on a fresh engine,until it's broke in.

IMO,I would bring it up to temp,then shut it down,let it cool completey.Do this at least 2 times.

Then ride it at different RPM's not putting it under load,and don't let it idle.Don't run it wide open.

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