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DGA

XR650R- Building 680 want some input!

70 posts in this topic

Sorry for the long winded post!

My goal is to get more power while still being reliable and not run race gas. I want the motor to be more snappy with lots of low-mid grunt and a healthly over-rev. Here is my plan for mods:

-Ross 102.4mm piston kit @ 11:1

-Nikisil cylinder @ Millenium Technologies

-Falicon Supercrank with knife rod

-Stage 2 Hotcams

-Kibblewhite SS 3mm oversize intake valves

-Kibblewhite SS 1mm oversize exhaust valves

-Kibblewhite valve spring kit

-Cometic complete engine gasket kit

-XR's only high rev CDI

-Bore out my edelbrock to 40mmX42mm

-Dyno tune the carb to the mods

I have heard not to port and polish the head. I was thinking of just smoothing and polishing the exhaust ports. I am doing all the assembly labor.

Do you think this is a good plan of attack or am I missing something, am I choosing the best companies and components? Do you think it would be about the same money to send my motor off to a reputable builder and have them do everything rather than me send individual components off to several companies and put it all together myself.

This is my first bigbore kit but definetly not my first 4-stroke rebuild. I am comfortable tearing down and rebuilding lower ends and topends. I just want some one who has done this before to chime in and give their two cents. I talked to Rob Barnum and Xrs only. I think I can aquire the parts myself cheaper than they sell them. If you know a good place to get the parts, let me know. I was thinking of having about 5 ounces machined off of my flywheel as well, any comments on that?

My current mods are:

-Barnums full exhaust

-Barnums CNC airbox mod

-Uncorked

-Uni Filter

-Xrs only high flow backfire screen

-Edelbrock QS carb

-High performance plug wire

-SS oil filter

Let me know your thoughts or If you recommend a different setup. All input is welcomed, except the "Why would you want more power?" posts :thumbsup:

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Sorry to ask but what's a knife rod?As for your engine I can't tell you much but expect to loose some bottom end if you shave your flywheel unless the HP gains offset it.By the way does anybody knows wich is the biggest single cylinder engine that has seen production...?

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Check this out for the supercrank and knife rod.

http://www.faliconcranks.com/motox.htm

Xrs only had nothing but praises for it and the supercrank.

As for the flywheel, I figured it would make the power delivery a little more lively and quicker revving. If it has less rotating mass it will take less power at the first whack of the throttle to get things moving. Traction may suffer. This is my thoughts. I may be wrong.

Sorry to ask but what's a knife rod?

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Ok, so 1mm oversized intake valves, what about exhaust? Stock size or 1mm over? Yes the more snappy aggressive power delivery is what im after. Im used to riding built cr500's and I love the hit and snap, but I like the usable power of the 650 and it puts it all to the ground unlike the 500. What number is the iridium plug and what brand is your high voltage coil, also where did you get it. It seemed to me I even noticed the bike running smoother when I swapped the stock plug wire for a Taylor spiro-pro V8 wire.

Where did you buy your piston kit? Im going with a ross piston as I heard it was lighter than the J&E. 100MPH wheelies sound right up my alley! My bike right now will wheelie in every gear If I gas it right after I shift also If I've got it wound out towards the top of the gear it seems to have an extra hit on top that will pull the front end all the way up and flip you over if youre not careful. It does this all the way up to third gear, not quite in 4th. That was complements of the Barnums full exhaust. Once I got the edelbrock tuned I got the loss of bottom end back. Which cam did you go with. I see the stage 1 gains loads of low to mid but loses top. Looking at the dyno the stage 2 doesnt lose any low (actually looks like a really small gain) and gains huge mid and over rev.

I would go with a 1mm over sized intake valve. I have the 3mm over sized intake and it does move a lot of power up into the higher rpms and makes the bike much smoother to ride but, I would like a little more bottom end hit and the option to go 3mm on the next rebuild if I would have gone 1mm over the first go around. You can't have both the 3mm over sized intake and the 1mm over sized exhaust valves, they will hit each other. 3mm over sized intake take a lot of grinding to work and you do not have much valve seat left. Well, you have almost none! I was told this and saw it for myself after I did it anyways. I wouldn't do it again. 1mm intake is more then enough take my word for it. Yes, the bike will be faster with the 3mm over sized intake valve and that sounds great but, it's where it puts the horsepower that counts and I have enough at 120mph not to need the little more the 3mm O/S valve gave me up there. The smoother power band is nice but, after a while radical power doesn't sound to bad. The Nikasil cylinder is the way to go. I like the Carrillo rod better but, your crank setup sounds slick. The Carrillo rod is rebuildable. I really like the over bore on my Edelbrock carb. and recommend it for your 680cc monster. It was a 2hp increase on the Dyno for my 680cc motor. Iridium plug, high 45,000 volt coil did make a difference (stock is 35,000) Fluidyne Radiators are nice as is Evens coolant, (got to keep that extra power form heating your bike up) I got tired of my S/S oil filter , went back to stock for now till I get around to cleaning the two S/S filters I have now. #19 needle 16 clicks out and you will be there on the jetting. We have a bike that has the intake and exhaust ports honed, I wouldn't do it again, maybe a little clean up but, not as much as a port job. I would love to have rocker arms with cam rollers!

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Not to hijack the thread here, but approx how much is it to do one these big bore/cam rebuilds? Doing it yourself vs. having a pro do it? Thanks...

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Did you lose any lowend with barnums mid cam? How does it compare to the stage2 hotcam? would my valve guides need to be decked for the stage2 hotcam?

Thanks for all the info BWB

I am using Barnum's Mid cam, it is a stage two (HRC) cam with more lift, I like it for the power it gives from 5200 to the limiter, most cams fall off just a tad as you climb into the top rpm's but, this cam holds the horsepower gain flat to the end. I would stay with stock sized exhaust valve. I have the Weisco 102.4mm 11:1 piston machined for the bigger intake valves and extra lift. The valve guides were decked .030 for the extra lift also. Clay tested to make sure piston to valve clearance was right. The coil is a hot something....they also make a spiecal plug wire but, I have to go look at it to remember what make it is. Maybe someone can chime in and help my failing mind. It is 45,00 volts instead of 35,000 like stock. The new coil won't fit where the stock one does so, I moved it bake and it is mounted to the frame just above the intake valve adjustment cover. NGK IX Iridium 6988 BKR7EIX-11 $6.95

I got all these prices from www.sparkplugs.com

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Would you possibly be talking about a Nology Profire coil and a Nology Hotwire(sparkplug wire)? Ive used these on cars and a CRF450 with great power results. I considered using them on the 650 as well. The Nology coil does put out in excess of 45,000 volts so Im sure we are talking about the same thing. Also I had to move the coil to a different location than stock on the CRF as well. I remember when a buddy of mine and I first tried the Nology coil and wire on the CRF he didnt have something grounded correctly and to my surprise on the first ride I got shocked with 45,000 volts when I touched the levers with the motor running at high RPMS to make matters worse. It was comical im sure I screamed like a girl because I didnt expect it. Luckily I didnt wreck but we had some good laughs and rode it a few more times that way for the fun of it.

The coil is a hot something....they also make a spiecal plug wire but, I have to go look at it to remember what make it is. Maybe someone can chime in and help my failing mind. It is 45,00 volts instead of 35,000 like stock. The new coil won't fit where the stock one does so, I moved it bake and it is mounted to the frame just above the intake valve adjustment cover.

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Dont forget to put the HRC heavy duty cam chain, guides, etc.

Also--its worth having the rocker arms hardened.

Consider 10.5:1 for longer wear and to run on all fuel.

If you build it yourself make sure the piston doesnt hit the valves.

Just FYI guys have taken the XRR to 710cc's

Largest single cylinder might be a steam locomotive in China? j/k.

For production single cylinder dirt bike--might be the ATK 2 stroke?

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Suzuki made a DR750S and DR800S. Those are the biggest singles I know of. Don't think they were sold in the US.

1991_DR800S_red_side_900.jpg

Thats what I meant when asking,thanks.

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I think the weak spot in going big bore is in the rod and crank and associated bearings. I've never heard of any tranny problems on a 650R either way, though logically the extra stress of a huge big bore would undoubtedly lower the life expetancy of almost all components...

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My thoughts exactly. Im going to start by beefing up the clutch as much as possible. I will check to see if Hinson makes an inner hub and pressure plate to go with their clutch basket. In addition to that I will have to put in some heavy springs. I may look into a hydraulic clutch as well. Ive already removed the judder spring and added the extra clutch plates and that made a huge difference in how the clutch grabs, it definetly feels stronger so its putting the power to the rear wheel better now.

I think the weak spot in going big bore is in the rod and crank and associated bearings. I've never heard of any tranny problems on a 650R either way, though logically the extra stress of a huge big bore would undoubtedly lower the life expetancy of almost all components...

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I've had the 680 kit with 11.5:1 compression in my bike for about 3 months now and it is just awesome!! All new meaning to the words hammer down :thumbsup: . I have the quicksilver, t4 full system, and stage 2 hotcam. Hotcam is a good mod but very hard to start not having auto decompression.

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Who does the carb overbores, or can I buy an edlebrock with it already done? Is the edlebrock the best option?

I have a stock bore 11:1 weisco, and stage 2 hotcam, with white bros. header, etc. I think this winter I am going to go to 680, with the bigger intake valves, and redo the lower end as well, and new clutch. May also shave flywheel to, as it will probably see more DS/motard as I will be getting a new bike for dirt. It power wheelies in 5th now, cant' wait to try a decent carb and 30 more cc.

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Hey Bruce,

Jay here don’t help this guy out he has some UN finished business on the CR500RIDERS.COM site he has burnt some of us over there and will not answer our inquiries on getting our money back

your Bro lewisclan

PS ERASE YOUR INFO POST AND DO NOT LET HIM ON YOUR WEB SITE.

O-and by the way thanks for getting my bike all fixed up are you going with us to the kennedy meddows ride this weekend

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I am looking into the ride. What is the story? WoW, sounds serious :thumbsup:

All this is copied into all his posts as quotes anyways.......

I would go with a 1mm over sized intake valve. I have the 3mm over sized intake and it does move a lot of power up into the higher rpms and makes the bike much smoother to ride but, I would like a little more bottom end hit and the option to go 3mm on the next rebuild if I would have gone 1mm over the first go around. You can't have both the 3mm over sized intake and the 1mm over sized exhaust valves, they will hit each other. 3mm over sized intake take a lot of grinding to work and you do not have much valve seat left. Well, you have almost none! I was told this and saw it for myself after I did it anyways. I wouldn't do it again. 1mm intake is more then enough take my word for it. Yes, the bike will be faster with the 3mm over sized intake valve and that sounds great but, it's where it puts the horsepower that counts and I have enough at 120mph not to need the little more the 3mm O/S valve gave me up there. The smoother power band is nice but, after a while radical power doesn't sound to bad. The Nikasil cylinder is the way to go. I like the Carrillo rod better but, your crank setup sounds slick. The Carrillo rod is rebuildable. I really like the over bore on my Edelbrock carb. and recommend it for your 680cc monster. It was a 2hp increase on the Dyno for my 680cc motor. Iridium plug, Nology 45,000 volt coil, (stock is 35,000) Fluidyne Radiators are nice as is Evens coolant, (got to keep that extra power form heating your bike up) I got tired of my S/S oil filter , went back to stock for now till I get around to cleaning the two S/S filters I have now. #19 needle 16 clicks out and you will be there on the jetting. We have a bike that has the intake and exhaust ports honed, I wouldn't do it again, maybe a little clean up but, not as much as a port job. I would love to have rocker arms with cam rollers!

I am using Barnum's Mid cam, it is a stage two (HRC) cam with more lift, I like it for the power it gives from 5200 to the limiter, most cams fall off just a tad as you climb into the top rpm's but, this cam holds the horsepower gain flat to the end. I would stay with stock sized exhaust valve. I have the Weisco 102.4mm 11:1 piston machined for the bigger intake valves and extra lift. The valve guides were decked .030 for the extra lift also. Clay tested to make sure piston to valve clearance was right. The coil is a hot something....they also make a spiecal plug wire but, I have to go look at it to remember what make it is. Maybe someone can chime in and help my failing mind. It is 45,00 volts instead of 35,000 like stock. The new coil won't fit where the stock one does so, I moved it bake and it is mounted to the frame just above the intake valve adjustment cover. NGK IX Iridium 6988 BKR7EIX-11 $6.95

I got all these prices from www.sparkplugs.com

The Hot Cams have the stock lift as does the HRC. Barnum also sells a radical cam that is more then the stage two and has the higher lift, I rode his bike with it and it was about the same with more high end punch. He was running a one pound lighter flywheel also, so, there was more bottom end snap. Making it hard to decide what you would loose (bottom end) with just the radical cam. With the much better connecting rod, and crank, heavy duty clutch springs, cam chain, sooner or later the ground becomes the week link

I live less then thirty minutes from Edelbrock and they bored all of my Edelbrocks as well as Jays. I have Edelbrocks on the XR400 also. I think the Mikuni is better but, for ease of starting and tuning the Edelbrock is much better. I Mikuni has six jets and the pump adjustment, the Edelbrock you only change the needle and adjust the pump squirt and pump throw if it is off. There is a jet in it but, you don't change it. The Edelbrock is not a race carburetor but, many, many use it for that. I have used the Kehin FCR41, Mikuni HRS42, TM40 and ridden a bike with a TMR41, The Kehin 41 is awesome but, it is a pain to fit (Heating and bending the plastic tank and grinding off a lot of the valve chain adjustment housing) I loved the way the HRS42 worked but, I didn't take the time to change the pump nozzle and it ran wet in a stock bike I wish I would have kept it, The TM40 took a lot of time till I found the magic that worked for me (TM40's, HRS40,42,45 &48mm are for Harley's and run like junk setup that way on our bike). It was supper smooth. The TMR41 was flawless.

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My thoughts exactly. Im going to start by beefing up the clutch as much as possible. I will check to see if Hinson makes an inner hub and pressure plate to go with their clutch basket. In addition to that I will have to put in some heavy springs. I may look into a hydraulic clutch as well. Ive already removed the judder spring and added the extra clutch plates and that made a huge difference in how the clutch grabs, it definetly feels stronger so its putting the power to the rear wheel better now.

:thumbsup: This guy likes to rip people off. He has done it over and over. Here is a link. Follow all the other links, and, you can see his track record.He is scum,and, he'll happily rip you off too. He goes by these known screen names: 973kgt, kgt, 97, DGA. See what happens when you screw people Mr. Damon Adams. :applause:

http://www.cr500riders.com/cgi/yabb/YaBB.pl?num=1156746292/0

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I believe this might be the same Damon Adams who also completely misrepresented, scammed and ripped off Techguy (another TT'r) and temporarily smudged the reputation of Off-Road.com, etc. Read these links for more info because it sounds like the same guy...

First Link

Second Link

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Yup, That his him! He's been ripping people off all over the place, going from one forum to the next, then back again. :thumbsup:

It would be good for your members if one of the mods stickied this some place so that everyone will see it.

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