oldskool Posted January 13, 2013 Report Share Posted January 13, 2013 I just can't find the tune on my recent build. +4mil crank,64.50 mm bore, 34mm mikuni's. I started with330 mains and I'm at 240 now. Started with 35 pilots,now at 27.5. The bike is doing better on top,but seems to come and go. Coming off the line,it just wants to fall down hard. I'm running 19cc domes on pump gas. Is it possible for the bike to start easy and idle fine, then fall down under load with these domes. I guess my question is should I try 20cc domes? I have also dropped the needle to last slot, this was no help with the falling down coming off the line Quote Link to comment Share on other sites More sharing options...
Pastrykiller Posted January 13, 2013 Report Share Posted January 13, 2013 What are your compression numbers? Quote Link to comment Share on other sites More sharing options...
Jereme6655 Posted January 13, 2013 Report Share Posted January 13, 2013 Oh boy. This should be in the jetting section.....but we'll help. What is your entire setup.....what pipes, air filter....everything. also you should be around a 27.5 pilot.....and no where near a 240. Also what is your elevation.....and your kicking compression. Im asking because a 19cc dome is a seriously high compression dome for pump fuels unless you have altitude effecting you that much. Quote Link to comment Share on other sites More sharing options...
oldskool Posted January 13, 2013 Author Report Share Posted January 13, 2013 Pastrykiller, I got 139 right cylinder and 145 left side Jereme6655, 64.50 bore +4 long rod crank coolhead Rad valve for stock intakes. I cut the cones off of the rad vale and opened them up some billet intakes with no cross over 34mm mikuni's 27.5 pilot, 260 main, needle clip now in 3rd slot uni pods timing plate set at +4 B9ES plugs New OEM stator 1 year ago pick-up gapped at .020 spark is there, but seems a little weak T6 pipes( I KNOW, but thats all I have) 800 FT Ported cylinders I've had good success with a couple top end builds using stock carbs and intakes, minor jetting, but I cant get this one Quote Link to comment Share on other sites More sharing options...
Pastrykiller Posted January 13, 2013 Report Share Posted January 13, 2013 Try using a B8ES plug. 19's on pump gas with 150 comp...u need to bump those domes up to 20-21. The gap on the pickup might be too far as well. Try .017 on the gap to close it up. Quote Link to comment Share on other sites More sharing options...
okbeast Posted January 13, 2013 Report Share Posted January 13, 2013 Tried a new set of plugs? With your jetting as far as it was it could have fouled up a set. Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted January 13, 2013 Report Share Posted January 13, 2013 I'd of thought 19s would be higher than that. Who cut your domes? What type of porting is it? Quote Link to comment Share on other sites More sharing options...
oldskool Posted January 14, 2013 Author Report Share Posted January 14, 2013 Larry, I thought the comp would be higher also,BUT the cylinders did not have a fresh bore. I did use new 795's The guy that cut the domes is a very well known builder. I'm not interested in putting a bad word out. I just thought a 19cc would be too small for my engine running pump gas. Gonna do like pastrykiller said and try some 20's and close the pick-up gap New plugs for sure Okbeast, I got three sets of black ones. At least I'm fat. That might be a lot of my problem. See I lost my last motor(very strong) due to running lean. I'm SCARED! LOL Quote Link to comment Share on other sites More sharing options...
Jereme6655 Posted January 14, 2013 Report Share Posted January 14, 2013 only 139 and 145 running 19cc domes? wow. im at 1100ft.....running a dune/play port with 20cc domes and I was kickin 156 each side. im wondering if your rings are so sloppy that your fighting blow by. Id try closing that gap like previously stated to .018 and then new plugs. agree on the br8es plugs Quote Link to comment Share on other sites More sharing options...
oldskool Posted January 14, 2013 Author Report Share Posted January 14, 2013 Forgot to mention that my comp tester is 1/8 of an inch shorter than the plug. Don't think that will make a big difference Quote Link to comment Share on other sites More sharing options...
Pastrykiller Posted January 14, 2013 Report Share Posted January 14, 2013 Try the comp tester again. Hold the throttle wide open and get on the bike. Kick the shit out of it at least until the needle stops moving. My tester would stop at 140 if I kicked on it while I stood beside the bike. I got another 15-20 psi while sitting on it and kicking it like a son of a bitch. Quote Link to comment Share on other sites More sharing options...
oldskool Posted January 14, 2013 Author Report Share Posted January 14, 2013 Ok fellows, I'm gonna try all suggestions. IT will be next weekend before I can do anything else. Thanks Quote Link to comment Share on other sites More sharing options...
oldskool Posted January 15, 2013 Author Report Share Posted January 15, 2013 Another question. Will my stock carbs/intakes fuel my +4 crank at 379cc for a 500 ft wot run Quote Link to comment Share on other sites More sharing options...
Nightmare Posted January 15, 2013 Report Share Posted January 15, 2013 Another question. Will my stock carbs/intakes fuel my +4 crank at 379cc for a 500 ft wot run stock carbs are good till about 70 to 75 hp. Sent from my SGH-T679 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
oldskool Posted January 15, 2013 Author Report Share Posted January 15, 2013 OK, I'm gonna try them for now. I was running 280 main 27.5 pilot before +4 crank. You think I should start 330/300 main? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.