I have spent a fair amount of time dynoing with those carbs. I hope to have a jetting kit available in the fall. If all goes well and i don't loose another dyno, I should be able to wrap up alot of little thing s on the 800. Some problems with the 40 rounds are: oil injection lever is to short on stock 800's, need new throttle lever assembly (entire throttle, cable, lever). Jetting is slightly different than 700's. When I dynoes back in may/June I could get everything to work for testing but want to make things look and function better for trail usage. Since the pump lever is a different length I need to check oil/fuel ratio. I will keep all posted as things progress.
What I would love to try is 670 ho carbs, 44mm roundies.They could plug rite into the dpm.then I would put ufos on em.racer.ca uses 44mm on there 800 .40 seems small for the displacement of the800.
ay even solve the mid range temps on the rktech head
I tried carbs from 38mm to bored 44 (46mm) and the best was 40mm for overall even on a ported motor. The jetting problems with the larger sizes did not outweigh the power gains. Yes the bigger carbs make more power but for trail use they would be finnicky. The 670HO uses a totally different dpm system and could not be easily transformed to fit the 800 electronics. It had an enrichining circuit that is no longer being used.
Let me tell you all this: I work around and test compressors that can require over 50,000 HP. They can move as much as 40,000lbs of gas per minute through 56" pipes. I have taken sound readings as high as 131 db. My tolerance for loud noises is quite high from my job. When a tiny little 600 tripple went from 10,200 rpm to 0 in .002 seconds, well , lets just say I had a cold one after the hoses were done flapping around. The new dyno will be here in a week or so. Thank god because we got in a few new REV 800's and soon to recieve a 600HO. Time to see the internal changes...
I am replacing the pistons in a 98 670.. thinking about the ones for the 739cc..Have accuried 44 round for those pistons..have no idea, one how this would work and what the jetting should..Any suggestions would be great..Thanks
Wiseco sleeves and pistons. Install at 5 to 7 thou. clearance (depending on your warm up style.) Re-port to accomidate larger sleeve. Open up combustion chamber to match bore. 14:1 compression and .065 squish, if you can run premium all the time. Cut rotary valve to 150-80. Billet RV cover. Gut air box and bore those 44's to 46. BB-0 tube, 7EG06 neddle. 50 pilots. Mains depend on single or twin pipes. Easily capable of 100 ft-lbs and 150 hp. Your next issue is traction.
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