Jetting for 675cc BBK, any thoughts?


6 replies to this topic
  • zackm58941

Posted June 01, 2005 - 08:30 PM

#1

Hi, I just called TR and my cylinder and kit was shipped out today so maybe by sat or monday by the latest I should have it. Seeing I already have the dynojet stage 1 jet kit with a 165 main jet and a 55 pilot jet, what jets would you think I would run with the 675cc bbk w/10:1 CR? The fuel screw is what is was from the factory but I just twisted it to about 2-1/4 turns out, sound good? I didnt pay attention what the stock was, anyone remember? I'm like right at sea level so thats one thing you need to know. If anyone knows for sure or for those of you who have this kinda kit or close to it (R orL), feel free to chime in. I just wanted to get a little info b/c I dont wanna put everything back together and break in in hard with it running too lean. Thanks for the help!!

Zack

  • jlpskydive

Posted June 02, 2005 - 03:09 AM

#2

Hi, I just called TR and my cylinder and kit was shipped out today so maybe by sat or monday by the latest I should have it. Seeing I already have the dynojet stage 1 jet kit with a 165 main jet and a 55 pilot jet, what jets would you think I would run with the 675cc bbk w/10:1 CR? The fuel screw is what is was from the factory but I just twisted it to about 2-1/4 turns out, sound good? I didnt pay attention what the stock was, anyone remember? I'm like right at sea level so thats one thing you need to know. If anyone knows for sure or for those of you who have this kinda kit or close to it (R orL), feel free to chime in. I just wanted to get a little info b/c I dont wanna put everything back together and break in in hard with it running too lean. Thanks for the help!!

Zack

Man I can't wait to hear the report on your new set up. Please post final cost and diffculty of set up. Oh and of course how it runs. :)

  • Rover31

Posted June 02, 2005 - 05:38 AM

#3

Zack
I talked to my mechneck friend about this same subject the other day, he said that the cam is what makes the most diff. on jetting changes. Just upping compression does not alter jetting, it does not alter the air flow. Adding a cam will however. This changes the Amount and duration of air flowing, that changes your jetting.
Although if you went with an overbore that also changes the amount of air drawing in and that would also change jetting.
Am I making sense??
Refresh our brain cells with what you had done again.
Travis
edit
Duh after rereading your post a 675 kit would be an overbore, stupid me
so yeah you will have to rejet.
My thoughts are that you would benifit most from a new carb. There is another post going on here about that subject that I replied to. check it out.
If you stay with stock I think I would call some carb experts or pro tuners they would know best. My thoughts +5 on idle, +10-15 on main, clip up 2 then go down from there.

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  • zackm58941

Posted June 02, 2005 - 07:50 AM

#4

Thanks guys! The hotcams stage 1 looks like it has a bit more duration than the stocker, I wish I had a degree kit and I would know how much for sure but o well. I also did a mild port and polish on the head too. I was to my surprise very good in its stock state but what the hell, why not? On the intake side, I just basically knocked down the casting lines, I wanted it to be somewhat rough to promote better fuel atomization. The exhaust side I basically matched the ports to the size of my bigger header pipe, its right to the copper gaskets on the head for those of you who have seen it. I guess the kit comes with a jetting spec card that TR set up or something, but this was good too. Now I got some ideas for what to start from I guess, I wish someone had a cheap jet kit that had an assortment for little$$. I'll post back to my original thread when I start the rebuild and I'll take a bunch of pics of everything too.

Thanks again,
Zack

  • jlpskydive

Posted June 21, 2005 - 08:15 AM

#5

How did this turn out??? Where's my dam report???? How can I be envious without you throwing how much better the bike is now in my face???? Come on I'm just looking for a reason to go do the same setup for myself.... Help a brother out!!!! :)

  • zackm58941

Posted June 21, 2005 - 09:41 AM

#6

Okay now, calm down :) . Well everything is back together and put on a good 500 miles so everything is all brokin' in. I have to say that I'm overall happy with the bike, you get use to the added power quick when you do a lot of street driving but on the trails its like a new bike. So much more torque its unbelievable! I mean going from a near stock bike to this is awesome! I raced one of my buddies with a stock 2004 650L the 2nd night I had it done and we both took off from a dead stop and my bike was at least 6 or 7 bike lengths ahead. The most trouble has been the jetting, right now I have a 60 pilot jet and in the mail is a 165 and 170 Keihin main jets. I also bought the FMF Q2 and should be here this friday so I cant wait for that!!! I replaced the dyno jet needle with the stock one with .042" shim under it and the bike is so much frekin better! I cant believe I wasted my $$$ on that crap, for anyone reading this, just go by new jets and shim the needle plus drill the slide.

Any who, I do wish that Thumper Racing would have told me they were not giving me the 10.5:1 piston :) ! I mean I dont have to worry about putting 93oct in there but I just am wounder how much more power I could have gotten with having that piston vs. the 9:1 they gave me. I thought about sending it back and just ordering a Wiseco 10:25:1 102.4 mm piston but the bike had been apart for a few weeks and I just couldnt wait any longer, I'm sure someone can relate. One thing I really love is how the clutch feels/bike performs with the heavier clutch springs. Even if you just have a stock bike or if you put larger tires on or just want that firmer shifts get them! You wont be dissapointed, after riding my bike then trying a stock 650L it was like night and day! Overall I say it was worth it but if I were to do it again (still thinking about it) I would just get the Wiseco 10.25:1 102.4 mm piston and just send the cylinder to Wiseco to have the machine work done, its only 50 buck for them to bore and hone to the new piston. They prob could get it done a lot quicker then TR did... So thats my review and hope this helps ya out there jlpskydive, let me know if you have any other Q's!

Zack

  • jlpskydive

Posted June 21, 2005 - 11:07 AM

#7

That's what I wanted to hear. Thanks much. I think I might go the Wiesco route. The "Oh we don't make that anymore," line from TR probably would have sent me over the edge.





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